document_title: Don't Worry, Be Happy

question_text: who was in dont worry be happy video

question_tokens: who was in dont worry be happy video

text: Don't Worry, Be Happy

text: Background[edit]

text: The Indian mystic and sage Meher Baba (1894–1969) often used the expression "Don't worry, be happy" when cabling his followers in the West.[3]

text: In the 1960s, the expression was printed up on inspirational cards and posters of the era. In 1988, McFerrin noticed a similar poster in the apartment of the jazz duo Tuck & Patti in San Francisco.[citation needed] Inspired by the expression's charm and simplicity, McFerrin wrote the now famous song, which was included in the soundtrack of the movie Cocktail, and became a hit single the next year. In an interview by Bruce Fessier for USA Weekend magazine in 1988 McFerrin said, "Whenever you see a poster of Meher Baba, it usually says 'Don't worry, be happy,' which is a pretty neat philosophy in four words, I think."[4]

text: Linda Goldstein, the song's producer, said the song gave McFerrin "the freedom to explore," adding, "He is a man of infinite, unfathomable, boundless voices and everything he has ever heard has gone into his brain, from the Mickey Mouse Club theme to the Metropolitan Opera."[5]

text: Composition[edit]

text:
"Don't Worry, Be Happy" (2008)

A 24-second audio sample of Bobby McFerrin's "Don't Worry, Be Happy".

Problems playing this file? See media help.

text: he "instruments" in the a cappella song are entirely overdubbed voice parts and other sounds made by McFerrin, using no instruments at all; McFerrin also sings with an affected accent.[6]

text: Music video[edit]

text: The comedic original music video for the song stars McFerrin, Robin Williams, and Bill Irwin,[7] and is somewhat shorter than the album version.

text: Chart performance[edit]

text: Originally released in conjunction with the film Cocktail in 1988, the song originally peaked at No. 88 on the Billboard Hot 100.[8] The song was re-released the same year and peaked at No. 1 on September 24, 1988[8] displacing "Sweet Child o' Mine" by Guns N' Roses which had previously held the No. 1 spot.[9]

text: The song also peaked at No. 11 on the Billboard Hot R&B/Hip-Hop Tracks chart[10] and No. 7 on the Billboard Hot Adult Contemporary Tracks chart.[8] The song was also a hit in the United Kingdom and on the UK Singles Chart, the song reached number 2 during its fifth week on the chart (kept from the top spot by Whitney Houston's "One Moment in Time").[11]

text: In Canada, the song reached No. 1 on its 8th week.[12]

text: The song is the first a cappella song to reach the Billboard Hot 100 chart and one critic noted it is a "formula for facing life's trials."[13]

text: While the song reached No. 1 on the charts, its album Simple Pleasures reached No. 12 on the album charts after starting out at No. 20 when it was first released.[9]

text: Usage in popular culture[edit]

text:
Comedian George Carlin wrote in Napalm and Silly Putty that many Americans would embrace the philosophy of denial in the song.[14]
Featured in the 1988 romance film Cocktail, starring Tom Cruise and Elisabeth Shue. It was also released as part of the film's official soundtrack.
The song was used in George H. W. Bush's 1988 U.S. presidential election as Bush's 1988 official presidential campaign song, without Bobby McFerrin's permission or endorsement. In reaction, Bobby McFerrin (a Democrat) publicly protested that particular use of his song, including stating that he was going to vote against Bush, and completely dropped the song from his own performance repertoire, to make the point even clearer. The George H. W. Bush campaign then reportedly desisted from further use of the song.[15]
In 1989, Delacorte Press published a book titled Don’t Worry, Be Happy with the song’s lyrics, 20 new verses written by McFerrin, and illustrations by Bennett Carlson.
The song became an unofficial anthem in Jamaica after Hurricane Gilbert struck the island in September 1988 (coinciding with the song's release) and caused months of hardship to the population. The song is often erroneously attributed to Bob Marley.[16][17]
In 1997, the song was featured in the direct-to-video film Casper: A Spirited Beginning.
In 2001, Mondo Club recorded the titular single. The performer was Trevor Taylor.[18]
In 2005, featured in the biographical military drama Jarhead, starring Jake Gyllenhaal.
In 2006, the song was parodied in the animated film Flushed Away.
In 2008, the song was featured in the Disney/Pixar animated film WALL-E. McFerrin had previously provided vocal work for Pixar's short film Knick Knack.
In November 2014, it was featured as a mashup with "Winter Wonderland" by a cappella group Pentatonix featuring Tori Kelly on the album That's Christmas to Me.[19]
It was featured in the dance video game Just Dance 2015.
In 2017, the song was covered by Kermit Ruffins, Irvin Mayfield, Jason Marsalis, Cyril Neville, Haley Reinhart, and Glen David Andrews for Ruffins and Mayfield's album A Beautiful World.[20]

text: Awards[edit]

text: The song is ranked No. 31 on VH1's 100 Greatest One Hit Wonders of the 80s and also appears on Rolling Stone's list of the 15 Best Whistling Songs of All Time.[21] At the 1989 Grammy Awards, "Don't Worry, Be Happy" won the awards for Song of the Year, Record of the Year, and Best Male Pop Vocal Performance.

text: Charts[edit]

text:
Chart (1988–89)
Peak
position

Australia (ARIA)[22]
1

Austria (Ö3 Austria Top 40)[23]
1

Belgium (Ultratop 50 Flanders)[24]
2

Canadian RPM 30 Retail Singles[25]
1

Canadian RPM Top Singles[26]
1

France (SNEP)[27]
29

Germany (Official German Charts)[28]
1

Irish Singles Chart[29]
3

Italy (FIMI)[30]
18

Netherlands (Dutch Top 40)[31]
2

Netherlands (Single Top 100)[32]
3

New Zealand (Recorded Music NZ)[33]
2

Norway (VG-lista)[34]
5

South African Chart[35]
4

Spain (AFYVE)[36]
5

Sweden (Sverigetopplistan)[37]
2

Switzerland (Schweizer Hitparade)[38]
2

UK (Official Charts Company)[39]
2

US Billboard Hot 100[40]
1

US Billboard Hot Adult Contemporary[40]
7

US Hot R&B/Hip-Hop Singles[40]
11

text:
Chart (2016)
Peak
position

Poland (Polish Airplay Top 100) [41]
75

text: Certifications[edit]

text:
Region
Certification
Certified units/Sales

Germany (BVMI)[42]
Platinum
500,000^

United States (RIAA)[43]
Gold
1,000,000^

^shipments figures based on certification alone

text: Cover versions[edit]

text: Versions of "Don't Worry, Be Happy" have been recorded by several artists. The Katsimiha Brothers made a Greek cover of the song with original lyrics, and Montenegrin musician Rambo Amadeus made a parody entitled "Don't Happy, Be Worry", as a critique to the optimism of the music scene in the former Yugoslavia in the face of war and economic depression. In addition, the lyrics of "Fight the Power" by hip-hop artists Public Enemy refer critically to "Don't Worry, Be Happy". A version of this song sung by The Hit Crew is also added into the Big Mouth Billy Bass, a very popular animatronic singing toy. Hermes House Band covered the song on their Rhythm of the Nineties album in 2009. Reggae artist Cas Haley covered the song as a hidden bonus track on his Favorites album (together with former Jah Roots lead singer, Josh Heinrichs). Also in 1989 Dutch rock DJ Alfred Lagarde recorded a version in Dutch with a heavy Surinam accent under the name Johnny Camaro. Spanish Ska band The Locos covered this song in a similar style, Ska.


document_title: Water fluoridation

question_text: where is the highest level of fluoride stored in the teeth

root

text: Water fluoridation

text: Goal

text: The goal of water fluoridation is to prevent tooth decay by adjusting the concentration of fluoride in public water supplies.[2] Tooth decay (dental caries) is one of the most prevalent chronic diseases worldwide.[24] Although it is rarely life-threatening, tooth decay can cause pain and impair eating, speaking, facial appearance, and acceptance into society,[25] and it greatly affects the quality of life of children, particularly those of low socioeconomic status.[24] In most industrialized countries, tooth decay affects 60–90% of schoolchildren and the vast majority of adults; although the problem appears to be less in Africa's developing countries, it is expected to increase in several countries there because of changing diet and inadequate fluoride exposure.[8] In the U.S., minorities and the poor both have higher rates of decayed and missing teeth,[26] and their children have less dental care.[27] Once a cavity occurs, the tooth's fate is that of repeated restorations, with estimates for the median life of an amalgam tooth filling ranging from 9 to 14 years.[28] Oral disease is the fourth most expensive disease to treat.[29] The motivation for fluoridation of salt or water is similar to that of iodized salt for the prevention of intellectual disability and goiter.[30]

tag: p

text: The goal of water fluoridation is to prevent a chronic disease whose burdens particularly fall on children and the poor.[24] Another of the goals was to bridge inequalities in dental health and dental care.[31] Some studies suggest that fluoridation reduces oral health inequalities between the rich and poor, but the evidence is limited.[3] There is anecdotal but not scientific evidence that fluoride allows more time for dental treatment by slowing the progression of tooth decay, and that it simplifies treatment by causing most cavities to occur in pits and fissures of teeth.[32] Other reviews have found not enough evidence to determine if water fluoridation reduces oral-health social disparities.[9]

text: Health and dental organizations worldwide have endorsed its safety and effectiveness.[3] Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water.[33] Further research showed that moderate fluoridation prevents tooth decay.[34]

text: Implementation

text: Fluoridation does not affect the appearance, taste, or smell of drinking water.[1] It is normally accomplished by adding one of three compounds to the water: sodium fluoride, fluorosilicic acid, or sodium fluorosilicate.

text:
Sodium fluoride (NaF) was the first compound used and is the reference standard.[35] It is a white, odorless powder or crystal; the crystalline form is preferred if manual handling is used, as it minimizes dust.[36] It is more expensive than the other compounds, but is easily handled and is usually used by smaller utility companies.[37] It is toxic in gram quantities by ingestion or inhalation.[38]
Fluorosilicic acid (H2SiF6) is the most commonly used additive for water fluoridation in the United States.[39] It is an inexpensive liquid by-product of phosphate fertilizer manufacture.[35] It comes in varying strengths, typically 23–25%; because it contains so much water, shipping can be expensive.[36] It is also known as hexafluorosilicic, hexafluosilicic, hydrofluosilicic, and silicofluoric acid.[35]
Sodium fluorosilicate (Na2SiF6) is the sodium salt of fluorosilicic acid. It is a powder or very fine crystal that is easier to ship than fluorosilicic acid. It is also known as sodium silicofluoride.[36]

tag: ul

text: These compounds were chosen for their solubility, safety, availability, and low cost.[35] A 1992 census found that, for U.S. public water supply systems reporting the type of compound used, 63% of the population received water fluoridated with fluorosilicic acid, 28% with sodium fluorosilicate, and 9% with sodium fluoride.[40]

text: Recommendations

text: The Centers for Disease Control and Prevention developed recommendations for water fluoridation that specify requirements for personnel, reporting, training, inspection, monitoring, surveillance, and actions in case of overfeed, along with technical requirements for each major compound used.[41]

text: Although fluoride was once considered an essential nutrient, the U.S. National Research Council has since removed this designation due to the lack of studies showing it is essential for human growth, though still considering fluoride a "beneficial element" due to its positive impact on oral health.[42] The European Food Safety Authority's Panel on Dietetic Products, Nutrition and Allergies (NDA) considers fluoride not to be an essential nutrient, yet, due to the beneficial effects of dietary fluoride on prevention of dental caries they have defined an Adequate Intake (AI) value for it. The AI of fluoride from all sources (including non-dietary sources) is 0.05 mg/kg body weight per day for both children and adults, including pregnant and lactating women.[43]

text: In 2011, the U.S. Department of Health and Human Services (HHS) and the U.S. Environmental Protection Agency (EPA) lowered the recommended level of fluoride to 0.7 mg/L.[44] In 2015, the U.S. Food and Drug Administration (FDA), based on the recommendation of the U.S. Public Health Service (PHS) for fluoridation of community water systems, recommended that bottled water manufacturers limit fluoride in bottled water to no more than 0.7 milligrams per liter (mg/L)(milligrams per liter, equivalent to parts per million).[45]

text: Previous recommendations were based on evaluations from 1962, when the U.S. specified the optimal level of fluoride to range from 0.7 to 1.2 mg/L (milligrams per liter, equivalent to parts per million), depending on the average maximum daily air temperature; the optimal level is lower in warmer climates, where people drink more water, and is higher in cooler climates.[46]

text: These standards are not appropriate for all parts of the world, where fluoride levels might be excessive and fluoride should be removed from water, and is based on assumptions that have become obsolete with the rise of air conditioning and increased use of soft drinks, processed food, fluoridated toothpaste, and other sources of fluorides.[6] In 2011 the World Health Organization stated that 1.5 mg/L should be an absolute upper bound and that 0.5 mg/L may be an appropriate lower limit.[6] A 2007 Australian systematic review recommended a range from 0.6 to 1.1 mg/L.[12]

text: Occurrences

text: Fluoride naturally occurring in water can be above, at, or below recommended levels. Rivers and lakes generally contain fluoride levels less than 0.5 mg/L, but groundwater, particularly in volcanic or mountainous areas, can contain as much as 50 mg/L.[14] Higher concentrations of fluorine are found in alkaline volcanic, hydrothermal, sedimentary, and other rocks derived from highly evolved magmas and hydrothermal solutions, and this fluorine dissolves into nearby water as fluoride. In most drinking waters, over 95% of total fluoride is the F− ion, with the magnesium–fluoride complex (MgF+) being the next most common. Because fluoride levels in water are usually controlled by the solubility of fluorite (CaF2), high natural fluoride levels are associated with calcium-deficient, alkaline, and soft waters.[47] Defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits. It can be accomplished by percolating water through granular beds of activated alumina, bone meal, bone char, or tricalcium phosphate; by coagulation with alum; or by precipitation with lime.[5]

text: Pitcher or faucet-mounted water filters do not alter fluoride content; the more-expensive reverse osmosis filters remove 65–95% of fluoride, and distillation removes all fluoride.[7] Some bottled waters contain undeclared fluoride, which can be present naturally in source waters, or if water is sourced from a public supply which has been fluoridated.[48] The FDA states that bottled water products labeled as de-ionized, purified, demineralized, or distilled have been treated in such a way that they contain no or only trace amounts of fluoride, unless they specifically list fluoride as an added ingredient.[48]

text: Evidence

text: Existing evidence suggests that water fluoridation reduces tooth decay. Consistent evidence also suggests that it causes dental fluorosis, most of which is mild and not usually of aesthetic concern.[9][12] No clear evidence of other adverse effects exists, though almost all research thereof has been of poor quality.[13]

text: Effectiveness

text: Reviews have shown that water fluoridation reduces cavities in children.[9][16][49] A conclusion for the efficacy in adults is less clear with some reviews finding benefit and others not.[9][49] Studies in the U.S. in the 1950s and 1960s showed that water fluoridation reduced childhood cavities by fifty to sixty percent, while studies in 1989 and 1990 showed lower reductions (40% and 18% respectively), likely due to increasing use of fluoride from other sources, notably toothpaste, and also the 'halo effect' of food and drink that is made in fluoridated areas and consumed in unfluoridated ones.[2]

text: A 2000 UK systematic review (York) found that water fluoridation was associated with a decreased proportion of children with cavities of 15% and with a decrease in decayed, missing, and filled primary teeth (average decreases was 2.25 teeth). The review found that the evidence was of moderate quality: few studies attempted to reduce observer bias, control for confounding factors, report variance measures, or use appropriate analysis. Although no major differences between natural and artificial fluoridation were apparent, the evidence was inadequate for a conclusion about any differences.[13] A 2007 Australian systematic review used the same inclusion criteria as York's, plus one additional study. This did not affect the York conclusions.[50] A 2011 European Commission systematic review based its efficacy on York's review conclusion.[10] A 2015 Cochrane systematic review estimated a reduction in cavities when water fluoridation was used by children who had no access to other sources of fluoride to be 35% in baby teeth and 26% in permanent teeth.[51] The evidence was of poor quality.[51]

text: Fluoride may also prevent cavities in adults of all ages. A 2007 meta-analysis by CDC researchers found that water fluoridation prevented an estimated 27% of cavities in adults, about the same fraction as prevented by exposure to any delivery method of fluoride (29% average).[52] A 2011 European Commission review found that the benefits of water fluoridation for adult in terms of reductions in decay are limited.[16] A 2015 Cochrane review found no conclusive research regarding the effectiveness of water fluoridation in adults.[51] A 2016 review found variable quality evidence that, overall, stopping of community water fluoridation programs was typically followed by an increase in cavities.[53]

text: Most countries in Europe have experienced substantial declines in cavities without the use of water fluoridation.[3] For example, in Finland and Germany, tooth decay rates remained stable or continued to decline after water fluoridation stopped. Fluoridation may be useful in the U.S. because unlike most European countries, the U.S. does not have school-based dental care, many children do not visit a dentist regularly, and for many U.S. children water fluoridation is the prime source of exposure to fluoride.[31] The effectiveness of water fluoridation can vary according to circumstances such as whether preventive dental care is free to all children.[54]

text: Fluorosis

text: Fluoride's adverse effects depend on total fluoride dosage from all sources. At the commonly recommended dosage, the only clear adverse effect is dental fluorosis, which can alter the appearance of children's teeth during tooth development; this is mostly mild and is unlikely to represent any real effect on aesthetic appearance or on public health.[12] In April 2015, recommended fluoride levels in the United States were changed to 0.7 ppm from 0.7–1.2 ppm to reduce the risk of dental fluorosis.[55] The 2015 Cochrane review estimated that for a ﬂuoride level of 0.7 ppm the percentage of participants with ﬂuorosis of aesthetic concern was approximately 12%.[51] This increases to 40% when considering ﬂuorosis of any level not of aesthetic concern.[51] In the US mild or very mild dental fluorosis has been reported in 20% of the population, moderate fluorosis in 2% and severe fluorosis in less than 1%.[55]

text: The critical period of exposure is between ages one and four years, with the risk ending around age eight. Fluorosis can be prevented by monitoring all sources of fluoride, with fluoridated water directly or indirectly responsible for an estimated 40% of risk and other sources, notably toothpaste, responsible for the remaining 60%.[56] Compared to water naturally fluoridated at 0.4 mg/L, fluoridation to 1 mg/L is estimated to cause additional fluorosis in one of every 6 people (95% CI 4–21 people), and to cause additional fluorosis of aesthetic concern in one of every 22 people (95% CI 13.6–∞ people). Here, aesthetic concern is a term used in a standardized scale based on what adolescents would find unacceptable, as measured by a 1996 study of British 14-year-olds.[13] In many industrialized countries the prevalence of fluorosis is increasing even in unfluoridated communities, mostly because of fluoride from swallowed toothpaste.[57] A 2009 systematic review indicated that fluorosis is associated with consumption of infant formula or of water added to reconstitute the formula, that the evidence was distorted by publication bias, and that the evidence that the formula's fluoride caused the fluorosis was weak.[58] In the U.S. the decline in tooth decay was accompanied by increased fluorosis in both fluoridated and unfluoridated communities; accordingly, fluoride has been reduced in various ways worldwide in infant formulas, children's toothpaste, water, and fluoride-supplement schedules.[32]

text: Safety

text: Fluoridation has little effect on risk of bone fracture (broken bones); it may result in slightly lower fracture risk than either excessively high levels of fluoridation or no fluoridation.[12] There is no clear association between fluoridation and cancer or deaths due to cancer, both for cancer in general and also specifically for bone cancer and osteosarcoma.[12][13] Other adverse effects lack sufficient evidence to reach a confident conclusion.[13]

text: Fluoride can occur naturally in water in concentrations well above recommended levels, which can have several long-term adverse effects, including severe dental fluorosis, skeletal fluorosis, and weakened bones; water utilities in the developed world reduce fluoride levels to regulated maximum levels in regions where natural levels are high, and the WHO and other groups work with countries and regions in the developing world with naturally excessive fluoride levels to achieve safe levels.[59] The World Health Organization recommends a guideline maximum fluoride value of 1.5 mg/L as a level at which fluorosis should be minimal.[60]

text: In rare cases improper implementation of water fluoridation can result in overfluoridation that causes outbreaks of acute fluoride poisoning, with symptoms that include nausea, vomiting, and diarrhea. Three such outbreaks were reported in the U.S. between 1991 and 1998, caused by fluoride concentrations as high as 220 mg/L; in the 1992 Alaska outbreak, 262 people became ill and one person died.[61] In 2010, approximately 60 gallons of fluoride were released into the water supply in Asheboro, North Carolina in 90 minutes—an amount that was intended to be released in a 24-hour period.[62]

text: Like other common water additives such as chlorine, hydrofluosilicic acid and sodium silicofluoride decrease pH and cause a small increase of corrosivity, but this problem is easily addressed by increasing the pH.[63] Although it has been hypothesized that hydrofluosilicic acid and sodium silicofluoride might increase human lead uptake from water, a 2006 statistical analysis did not support concerns that these chemicals cause higher blood lead concentrations in children.[64] Trace levels of arsenic and lead may be present in fluoride compounds added to water, but no credible evidence exists that their presence is of concern: concentrations are below measurement limits.[63]

text: The effect of water fluoridation on the natural environment has been investigated, and no adverse effects have been established. Issues studied have included fluoride concentrations in groundwater and downstream rivers; lawns, gardens, and plants; consumption of plants grown in fluoridated water; air emissions; and equipment noise.[63]

text: Mechanism

text: Fluoride exerts its major effect by interfering with the demineralization mechanism of tooth decay. Tooth decay is an infectious disease, the key feature of which is an increase within dental plaque of bacteria such as Streptococcus mutans and Lactobacillus. These produce organic acids when carbohydrates, especially sugar, are eaten.[65] When enough acid is produced to lower the pH below 5.5,[66] the acid dissolves carbonated hydroxyapatite, the main component of tooth enamel, in a process known as demineralization. After the sugar is gone, some of the mineral loss can be recovered—or remineralized—from ions dissolved in the saliva. Cavities result when the rate of demineralization exceeds the rate of remineralization, typically in a process that requires many months or years.[65]

text: All fluoridation methods, including water fluoridation, create low levels of fluoride ions in saliva and plaque fluid, thus exerting a topical or surface effect. A person living in an area with fluoridated water may experience rises of fluoride concentration in saliva to about 0.04 mg/L several times during a day.[3] Technically, this fluoride does not prevent cavities but rather controls the rate at which they develop.[67] When fluoride ions are present in plaque fluid along with dissolved hydroxyapatite, and the pH is higher than 4.5,[66] a fluorapatite-like remineralized veneer is formed over the remaining surface of the enamel; this veneer is much more acid-resistant than the original hydroxyapatite, and is formed more quickly than ordinary remineralized enamel would be.[65] The cavity-prevention effect of fluoride is mostly due to these surface effects, which occur during and after tooth eruption.[68] Although some systemic (whole-body) fluoride returns to the saliva via blood plasma, and to unerupted teeth via plasma or crypt fluid, there is little data to determine what percentages of fluoride's anticavity effect comes from these systemic mechanisms.[69] Also, although fluoride affects the physiology of dental bacteria,[70] its effect on bacterial growth does not seem to be relevant to cavity prevention.[71]

text: Fluoride's effects depend on the total daily intake of fluoride from all sources.[14] About 70–90% of ingested fluoride is absorbed into the blood, where it distributes throughout the body. In infants 80–90% of absorbed fluoride is retained, with the rest excreted, mostly via urine; in adults about 60% is retained. About 99% of retained fluoride is stored in bone, teeth, and other calcium-rich areas, where excess quantities can cause fluorosis.[59] Drinking water is typically the largest source of fluoride.[14] In many industrialized countries swallowed toothpaste is the main source of fluoride exposure in unfluoridated communities.[57] Other sources include dental products other than toothpaste; air pollution from fluoride-containing coal or from phosphate fertilizers; trona, used to tenderize meat in Tanzania; and tea leaves, particularly the tea bricks favored in parts of China. High fluoride levels have been found in other foods, including barley, cassava, corn, rice, taro, yams, and fish protein concentrate. The U.S. Institute of Medicine has established Dietary Reference Intakes for fluoride: Adequate Intake values range from 0.01 mg/day for infants aged 6 months or less, to 4 mg/day for men aged 19 years and up; and the Tolerable Upper Intake Level is 0.10 mg/kg/day for infants and children through age 8 years, and 10 mg/day thereafter.[72] A rough estimate is that an adult in a temperate climate consumes 0.6 mg/day of fluoride without fluoridation, and 2 mg/day with fluoridation. However, these values differ greatly among the world's regions: for example, in Sichuan, China the average daily fluoride intake is only 0.1 mg/day in drinking water but 8.9 mg/day in food and 0.7 mg/day directly from the air due to the use of high-fluoride soft coal for cooking and drying foodstuffs indoors.[14]

text: Alternatives

text: The views on the most effective method for community prevention of tooth decay are mixed. The Australian government review states that water fluoridation is the most effective means of achieving fluoride exposure that is community-wide.[12] The European Commission review states "No obvious advantage appears in favour of water fluoridation compared with topical prevention".[16] Other fluoride therapies are also effective in preventing tooth decay;[24] they include fluoride toothpaste, mouthwash, gel, and varnish,[73] and fluoridation of salt and milk.[15] Dental sealants are effective as well,[24] with estimates of prevented cavities ranging from 33% to 86%, depending on age of sealant and type of study.[73]

text: Fluoride toothpaste is the most widely used and rigorously evaluated fluoride treatment.[15] Its introduction in the early 1970s is considered the main reason for the decline in tooth decay in industrialized countries,[3] and toothpaste appears to be the single common factor in countries where tooth decay has declined.[74] Toothpaste is the only realistic fluoride strategy in many low-income countries, where lack of infrastructure renders water or salt fluoridation infeasible.[75] It relies on individual and family behavior, and its use is less likely among lower economic classes;[15] in low-income countries it is unaffordable for the poor.[75] Fluoride toothpaste prevents about 25% of cavities in young permanent teeth, and its effectiveness is improved if higher concentrations of fluoride are used, or if the toothbrushing is supervised. Fluoride mouthwash and gel are about as effective as fluoride toothpaste; fluoride varnish prevents about 45% of cavities.[73] By comparison, brushing with a nonfluoride toothpaste has little effect on cavities.[57]

text: The effectiveness of salt fluoridation is about the same as that of water fluoridation, if most salt for human consumption is fluoridated. Fluoridated salt reaches the consumer in salt at home, in meals at school and at large kitchens, and in bread. For example, Jamaica has just one salt producer, but a complex public water supply; it started fluoridating all salt in 1987, achieving a decline in cavities. Universal salt fluoridation is also practiced in Colombia and the Swiss Canton of Vaud; in Germany fluoridated salt is widely used in households but unfluoridated salt is also available, giving consumers a choice. Concentrations of fluoride in salt range from 90 to 350 mg/kg, with studies suggesting an optimal concentration of around 250 mg/kg.[15]

text: Milk fluoridation is practiced by the Borrow Foundation in some parts of Bulgaria, Chile, Peru, Russia, Macedonia, Thailand and the UK. Depending on location, the fluoride is added to milk, to powdered milk, or to yogurt. For example, milk powder fluoridation is used in rural Chilean areas where water fluoridation is not technically feasible.[76] These programs are aimed at children, and have neither targeted nor been evaluated for adults.[15] A systematic review found low-quality evidence to support the practice, but also concluded that further studies were needed.[77]

text: Other public-health strategies to control tooth decay, such as education to change behavior and diet, have lacked impressive results.[32] Although fluoride is the only well-documented agent which controls the rate at which cavities develop, it has been suggested that adding calcium to the water would reduce cavities further.[78] Other agents to prevent tooth decay include antibacterials such as chlorhexidine and sugar substitutes such as xylitol.[73] Xylitol-sweetened chewing gum has been recommended as a supplement to fluoride and other conventional treatments if the gum is not too costly.[79] Two proposed approaches, bacteria replacement therapy (probiotics) and caries vaccine, would share water fluoridation's advantage of requiring only minimal patient compliance, but have not been proven safe and effective.[73] Other experimental approaches include fluoridated sugar, polyphenols, and casein phosphopeptide–amorphous calcium phosphate nanocomplexes.[80]

text: A 2007 Australian review concluded that water fluoridation is the most effective and socially the most equitable way to expose entire communities to fluoride's cavity-prevention effects.[12] A 2002 U.S. review estimated that sealants decreased cavities by about 60% overall, compared to about 18–50% for fluoride.[81] A 2007 Italian review suggested that water fluoridation may not be needed, particularly in the industrialized countries where cavities have become rare, and concluded that toothpaste and other topical fluoride are the best way to prevent cavities worldwide.[3] A 2004 World Health Organization review stated that water fluoridation, when it is culturally acceptable and technically feasible, has substantial advantages in preventing tooth decay, especially for subgroups at high risk.[8]

text: Usage

text: As of November 2012, a total of about 378 million people worldwide received artificially fluoridated water. The majority of those were in the United States. About 40 million worldwide received water that was naturally fluoridated to recommended levels.[18]

text: Much of the early work on establishing the connection between fluoride and dental health was performed by scientists in the U.S. during the early 20th century, and the U.S. was the first country to implement public water fluoridation on a wide scale.[17] It has been introduced to varying degrees in many countries and territories outside the U.S., including Argentina, Australia, Brazil, Canada, Chile, Colombia, Hong Kong, Ireland, Israel, Korea, Malaysia, New Zealand, the Philippines, Serbia, Singapore, Spain, the UK, and Vietnam. In 2004, an estimated 13.7 million people in western Europe and 194 million in the U.S. received artificially fluoridated water.[18] In 2010, about 66% of the U.S. population was receiving fluoridated water.[82]

text: Naturally fluoridated water is used by approximately 4% of the world's population, in countries including Argentina, France, Gabon, Libya, Mexico, Senegal, Sri Lanka, Tanzania, the U.S., and Zimbabwe. In some locations, notably parts of Africa, China, and India, natural fluoridation exceeds recommended levels.[18]

text: Communities have discontinued water fluoridation in some countries, including Finland, Germany, Japan, the Netherlands, and Switzerland.[83] On August 26, 2014, Israel stopped mandating fluoridation, stating "Only some 1% of the water is used for drinking, while 99% of the water is intended for other uses (industry, agriculture, flushing toilets etc.). There is also scientific evidence that fluoride in large amounts can lead to damage to health. When fluoride is supplied via drinking water, there is no control regarding the amount of fluoride actually consumed, which could lead to excessive consumption. Supply of fluoridated water forces those who do not so wish to also consume water with added fluoride. This approach is therefore not accepted in most countries in the world."[84][85] This change was often motivated by political opposition to water fluoridation, but sometimes the need for water fluoridation was met by alternative strategies. The use of fluoride in its various forms is the foundation of tooth decay prevention throughout Europe; several countries have introduced fluoridated salt, with varying success: in Switzerland and Germany, fluoridated salt represents 65% to 70% of the domestic market, while in France the market share reached 60% in 1993 but dwindled to 14% in 2009; Spain, in 1986 the second West European country to introduce fluoridation of table salt, reported a market share in 2006 of only 10%. In three other West European countries, Greece, Austria and the Netherlands, the legal framework for production and marketing of fluoridated edible salt exists. At least six Central European countries (Hungary, the Czech and Slovak Republics, Croatia, Slovenia, Romania) have shown some interest in salt fluoridation; however, significant usage of approximately 35% was only achieved in the Czech Republic. The Slovak Republic had the equipment to treat salt by 2005; in the other four countries attempts to introduce fluoridated salt were not successful.[86][87]

text: History

text: The history of water fluoridation can be divided into three periods. The first (c. 1801–1933) was research into the cause of a form of mottled tooth enamel called the Colorado brown stain. The second (c. 1933–1945) focused on the relationship between fluoride concentrations, fluorosis, and tooth decay, and established that moderate levels of fluoride prevent cavities. The third period, from 1945 on, focused on adding fluoride to community water supplies.[34]

text: In the first half of the 19th century, investigators established that fluoride occurs with varying concentrations in teeth, bone, and drinking water. In the second half they speculated that fluoride would protect against tooth decay, proposed supplementing the diet with fluoride, and observed mottled enamel (now called severe dental fluorosis) without knowing the cause.[89] In 1874, the German public health officer Carl Wilhelm Eugen Erhardt recommended potassium fluoride supplements to preserve teeth.[90][91] In 1892 the British physician James Crichton-Browne noted in an address that fluoride's absence from diets had resulted in teeth that were "peculiarly liable to decay", and who proposed "the reintroduction into our diet ... of fluorine in some suitable natural form ... to fortify the teeth of the next generation".[92]

text: The foundation of water fluoridation in the U.S. was the research of the dentist Frederick McKay (1874–1959). McKay spent thirty years investigating the cause of what was then known as the Colorado brown stain, which produced mottled but also cavity-free teeth; with the help of G.V. Black and other researchers, he established that the cause was fluoride.[93] The first report of a statistical association between the stain and lack of tooth decay was made by UK dentist Norman Ainsworth in 1925. In 1931, an Alcoa chemist, H.V. Churchill, concerned about a possible link between aluminum and staining, analyzed water from several areas where the staining was common and found that fluoride was the common factor.[94]

text: In the 1930s and early 1940s, H. Trendley Dean and colleagues at the newly created U.S. National Institutes of Health published several epidemiological studies suggesting that a fluoride concentration of about 1 mg/L was associated with substantially fewer cavities in temperate climates, and that it increased fluorosis but only to a level that was of no medical or aesthetic concern.[96] Other studies found no other significant adverse effects even in areas with fluoride levels as high as 8 mg/L.[97] To test the hypothesis that adding fluoride would prevent cavities, Dean and his colleagues conducted a controlled experiment by fluoridating the water in Grand Rapids, Michigan, starting January 25, 1945. The results, published in 1950, showed significant reduction of cavities.[33][98] Significant reductions in tooth decay were also reported by important early studies outside the U.S., including the Brantford–Sarnia–Stratford study in Canada (1945–1962), the Tiel–Culemborg study in the Netherlands (1953–1969), the Hastings study in New Zealand (1954–1970), and the Department of Health study in the U.K. (1955–1960).[94] By present-day standards these and other pioneering studies were crude, but the large reductions in cavities convinced public health professionals of the benefits of fluoridation.[31]

text: Fluoridation became an official policy of the U.S. Public Health Service by 1951, and by 1960 water fluoridation had become widely used in the U.S., reaching about 50 million people.[97] By 2006, 69.2% of the U.S. population on public water systems were receiving fluoridated water, amounting to 61.5% of the total U.S. population; 3.0% of the population on public water systems were receiving naturally occurring fluoride.[99] In some other countries the pattern was similar. New Zealand, which led the world in per-capita sugar consumption and had the world's worst teeth, began fluoridation in 1953, and by 1968 fluoridation was used by 65% of the population served by a piped water supply.[100] Fluoridation was introduced into Brazil in 1953, was regulated by federal law starting in 1974, and by 2004 was used by 71% of the population.[101] In the Republic of Ireland, fluoridation was legislated in 1960, and after a constitutional challenge the two major cities of Dublin and Cork began it in 1964;[94] fluoridation became required for all sizeable public water systems and by 1996 reached 66% of the population.[18] In other locations, fluoridation was used and then discontinued: in Kuopio, Finland, fluoridation was used for decades but was discontinued because the school dental service provided significant fluoride programs and the cavity risk was low, and in Basel, Switzerland, it was replaced with fluoridated salt.[94]

text: McKay's work had established that fluorosis occurred before tooth eruption. Dean and his colleagues assumed that fluoride's protection against cavities was also pre-eruptive, and this incorrect assumption was accepted for years. By 2000, however, the topical effects of fluoride (in both water and toothpaste) were well understood, and it had become known that a constant low level of fluoride in the mouth works best to prevent cavities.[102]

text: Economics

text: Fluoridation costs an estimated $1.06 per person-year on the average (range: $0.25–$11.19; all costs in this paragraph are for the U.S.[2] and are in 2017 dollars, inflation-adjusted from earlier estimates[4]). Larger water systems have lower per capita cost, and the cost is also affected by the number of fluoride injection points in the water system, the type of feeder and monitoring equipment, the fluoride chemical and its transportation and storage, and water plant personnel expertise.[2] In affluent countries the cost of salt fluoridation is also negligible; developing countries may find it prohibitively expensive to import the fluoride additive.[103] By comparison, fluoride toothpaste costs an estimated $9–$18 per person-year, with the incremental cost being zero for people who already brush their teeth for other reasons; and dental cleaning and application of fluoride varnish or gel costs an estimated $97 per person-year. Assuming the worst case, with the lowest estimated effectiveness and highest estimated operating costs for small cities, fluoridation costs an estimated $16–$25 per saved tooth-decay surface, which is lower than the estimated $95 to restore the surface[2] and the estimated $162 average discounted lifetime cost of the decayed surface, which includes the cost to maintain the restored tooth surface.[28] It is not known how much is spent in industrial countries to treat dental fluorosis, which is mostly due to fluoride from swallowed toothpaste.[57]

text: Although a 1989 workshop on cost-effectiveness of cavity prevention concluded that water fluoridation is one of the few public health measures that save more money than they cost, little high-quality research has been done on the cost-effectiveness and solid data are scarce.[2][46] Dental sealants are cost-effective only when applied to high-risk children and teeth.[104] A 2002 U.S. review estimated that on average, sealing first permanent molars saves costs when they are decaying faster than 0.47 surfaces per person-year whereas water fluoridation saves costs when total decay incidence exceeds 0.06 surfaces per person-year.[81] In the U.S., water fluoridation is more cost-effective than other methods to reduce tooth decay in children, and a 2008 review concluded that water fluoridation is the best tool for combating cavities in many countries, particularly among socially disadvantaged groups.[32] A 2016 review of studies published between 1995 to 2013 found that water fluoridation in the U.S. was cost-effective, and that it was more so in larger communities.[105]

text: U.S. data from 1974 to 1992 indicate that when water fluoridation is introduced into a community, there are significant decreases in the number of employees per dental firm and the number of dental firms. The data suggest that some dentists respond to the demand shock by moving to non-fluoridated areas and by retraining as specialists.[106]

text: Controversy

text: The water fluoridation controversy arises from political, moral, ethical, economic, and safety concerns regarding the water fluoridation of public water supplies.[83][107] Public health authorities throughout the world state that water fluoridation at appropriate levels is a safe and effective means to prevent dental caries.[3] Authorities' views on the most effective fluoride therapy for community prevention of tooth decay are mixed; some state water fluoridation is most effective, while others see no special advantage and prefer topical application strategies.[12][16]

text: Those opposed argue that water fluoridation has no or little cariostatic benefits, may cause serious health problems, is not effective enough to justify the costs, and pharmacologically obsolete,[2][108][109][110] while some argue that the practice presents a conflict between the common good and individual rights.[111]


document_title: Optic nerve

question_text: ganglion axons forming the optic nerve run to the

text: Optic nerve

text: Structure[edit]

text: The optic nerve is the second of twelve paired cranial nerves and is technically part of the central nervous system, rather than the peripheral nervous system because it is derived from an out-pouching of the diencephalon (optic stalks) during embryonic development. As a consequence, the fibers of the optic nerve are covered with myelin produced by oligodendrocytes, rather than Schwann cells of the peripheral nervous system, and are encased within the meninges. Peripheral neuropathies like Guillain–Barré syndrome do not affect the optic nerve. However, most typically the optic nerve is grouped with the other eleven cranial nerves and considered to be part of the peripheral nervous system.

text: The optic nerve is ensheathed in all three meningeal layers (dura, arachnoid, and pia mater) rather than the epineurium, perineurium, and endoneurium found in peripheral nerves. Fiber tracts of the mammalian central nervous system (as opposed to the peripheral nervous system) are incapable of regeneration, and, hence, optic nerve damage produces irreversible blindness. The fibres from the retina run along the optic nerve to nine primary visual nuclei in the brain, from which a major relay inputs into the primary visual cortex.

text: The optic nerve is composed of retinal ganglion cell axons and glial cells. Each human optic nerve contains between 770,000 and 1.7 million nerve fibers,[3] which are axons of the retinal ganglion cells of one retina. In the fovea, which has high acuity, these ganglion cells connect to as few as 5 photoreceptor cells; in other areas of retina, they connect to many thousand photoreceptors.

text: The optic nerve leaves the orbit (eye socket) via the optic canal, running postero-medially towards the optic chiasm, where there is a partial decussation (crossing) of fibres from the temporal visual fields (the nasal hemi-retina) of both eyes. The proportion of decussating fibers varies between species, and is correlated with the degree of binocular vision enjoyed by a species.[4] Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex, while other axons terminate in the pretectal nucleus and are involved in reflexive eye movements. Other axons terminate in the suprachiasmatic nucleus and are involved in regulating the sleep-wake cycle. Its diameter increases from about 1.6 mm within the eye to 3.5 mm in the orbit to 4.5 mm within the cranial space. The optic nerve component lengths are 1 mm in the globe, 24 mm in the orbit, 9 mm in the optic canal, and 16 mm in the cranial space before joining the optic chiasm. There, partial decussation occurs, and about 53% of the fibers cross to form the optic tracts. Most of these fibres terminate in the lateral geniculate body.[1]

text: Based on this anatomy, the optic nerve may be divided in the four parts as indicated in the image at the top of this section (this view is from above as if you were looking into the orbit after the top of the skull had been removed): 1. the optic head (which is where it begins in the eyeball (globe) with fibers from the retina; 2. orbital part (which is the part within the orbit). 3. intracanicular part (which is the part within a bony canal known as the optic canal); and, 4. cranial part (the part within the cranial cavity, which ends at the optic chiasm).[2]

text: From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain. In more specific terms, fibers carrying information from the contralateral superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly, to the cuneus[citation needed].

text: Function[edit]

text: The optic nerve transmits all visual information including brightness perception, color perception and contrast (visual acuity). It also conducts the visual impulses that are responsible for two important neurological reflexes: the light reflex and the accommodation reflex. The light reflex refers to the constriction of both pupils that occurs when light is shone into either eye; the accommodation reflex refers to the swelling of the lens of eye that occurs when one looks at a near object as in reading (lens adjusts to near vision).[1]

text: The eye's blind spot is a result of the absence of photoreceptors in the area of the retina where the optic nerve leaves the eye.[1]

text: Clinical significance[edit]

text: Disease[edit]

text: Damage to the optic nerve typically causes permanent and potentially severe loss of vision, as well as an abnormal pupillary reflex, which is diagnostically important. The type of visual field loss will depend on which portions of the optic nerve were damaged. In general:

text:
Damage to the optic nerve anterior to the optic chiasm causes loss of vision in the eye on the same side as the damage.
Damage at the optic chiasm typically causes loss of vision laterally in both visual fields (bitemporal hemianopsia). It may occur with large pituitary tumors pituitary adenoma. (see image on right of Paris seen with bitemporal hemianopsia)

text: Damage to the optic tract, which is behind (posterior) to the chiasm, causes loss of the entire visual field from the side opposite the damage (so if the left optic tract is cut, there is a loss of vision from the entire right visual field).

text: Injury to the optic nerve can be the result of congenital or inheritable problems like Leber's Hereditary Optic Neuropathy, glaucoma, trauma, toxicity, inflammation, ischemia, infection (very rarely), or compression from tumors or aneurysms. By far, the three most common injuries to the optic nerve are from glaucoma, optic neuritis (especially in those younger than 50 years of age), and anterior ischemic optic neuropathy (usually in those older than 50).

text: Glaucoma is a group of diseases involving loss of retinal ganglion cells causing optic neuropathy in a pattern of peripheral vision loss, initially sparing central vision. Glaucoma is associated with increased intraocular pressure that damages the optic nerve as it exits the eyeball. Although glaucoma does eventually damage the optic nerve, it is primarily a disease of eye not of the nerve.

text: Optic neuritis is inflammation of the optic nerve. It is associated with a number of diseases, the most notable one being multiple sclerosis. The patient will likely experience varying vision loss and eye pain. The condition tends to be episodic.

text: Anterior ischemic optic neuropathy is commonly known as "stroke of the optic nerve" and affects the optic nerve head. There is usually a sudden loss of blood supply and nutrients to the optic nerve head (where the nerve exits the eyeball). Vision loss is typically sudden and most commonly occurs upon waking up in the morning. This condition is most common in diabetic patients 40–70 years old.

text: Optic nerve hypoplasia is the underdevelopment of the optic nerve resulting in little to no vision in the affected eye.

text: Tumors, especially those of the pituitary gland, can put pressure on the optic nerve causing various forms of visual loss. Similarly, cerebral aneurysms (swelling of blood vessels) can also affect the nerve.

text: Trauma can cause serious injury to the nerve. Direct optic nerve injury can occur from a penetrating injury to the orbit, but the nerve can also be injured by indirect trauma in which severe head impact or movement stretches or even tears the nerve [1]

text: Ophthalmologists and optometrists can detect and diagnose some optic nerve diseases but neuro-ophthalmologists are often best suited to diagnose and treat diseases of the optic nerve.

text: The International Foundation for Optic Nerve Diseases (IFOND) sponsors research and provides information on a variety of optic nerve disorders.

text: Regeneration[edit]

text: Similar to other CNS tracts, the optic has very limited regenerative potential after injury. However, some new techniques are being developed to increase this potential.[5]

text: Additional images[edit]

text:
MRI scan of human eye showing optic nerve.

The ophthalmic artery and its branches. (optic nerve is yellow)

Superficial dissection of brain-stem. Lateral view.

Dissection of brain-stem. Lateral view.

Scheme showing central connections of the optic nerves and optic tracts.

Nerves of the orbit. Seen from above.

Nerves of the orbit, and the ciliary ganglion. Side view.

The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section.

Structures of the eye labeled

This image shows another labeled view of the structures of the eye

Optic nerve.Deep dissection.Inferior view.

Optic nerve.Deep dissection.Inferior view.

Optic nerve

Optic nerve

Human brain dura mater (reflections)

Optic nerve

Optic nerve

Optic nerve

Cerebrum.Inferior view.Deep dissection

Cerebral peduncle, optic chasm, cerebral aqueduct. Inferior view. Deep dissection.


document_title: History of manga

question_text: what was the first form of manga in japan

text: History of manga

text: Before World War II[edit]

text: Manga is said to originate from scrolls dating back to the 12th and 13th centuries. During the Edo period (1603-1867), another book of drawings, Toba Ehon, embedded the concept of manga.[6] The word first came into common usage in the late 18th century[7] with the publication of such works as Santō Kyōden's picturebook Shiji no yukikai (1798),[8][9] and in the early 19th century with such works as Aikawa Minwa's Manga hyakujo (1814) and the celebrated Hokusai Manga books (1814–1834) containing assorted drawings from the sketchbooks of the famous ukiyo-e artist Hokusai who lived from 1760–1849.[10] Rakuten Kitazawa (1876–1955) first used the word "manga" in the modern sense.[11]

text: Writers stress continuity of Japanese cultural and aesthetic traditions as central to the history of manga. They include Frederik L. Schodt,[1][12] Kinko Ito,[2] Adam L. Kern,[3][4] and Eric Peter Nash.[13] Schodt points to the existence in the 13th century of illustrated picture scrolls like Chōjū-jinbutsu-giga that told stories in sequential images with humor and wit.[1] Schodt also stresses continuities of aesthetic style and vision between ukiyo-e and shunga woodblock prints and modern manga (all three fulfill Eisner's criteria for sequential art).[14] While there are disputes over whether Chōjū-jinbutsu-giga or Shigisan-engi was the first manga, both scrolls date back to about the same time period. However others like Isao Takahata, Studio Ghibli co-founder and director, contends there is no linkage with the scrolls and modern manga.[15]

text: Schodt and Nash also see a particularly significant role for kamishibai, a form of street theater where itinerant artists displayed pictures in a light box while narrating the story to audiences in the street.[1][13] Torrance has pointed to similarities between modern manga and the Osaka popular novel between the 1890s and 1940, and argues that the development of widespread literacy in Meiji and post-Meiji Japan helped create audiences for stories told in words and pictures.[16] Kinko Ito also roots manga historically in aesthetic continuity with pre-Meiji art, but she sees its post-WWII history as driven in part by consumer enthusiasm for the rich imagery and narrative of the newly developing manga tradition. Ito describes how this tradition has steadily produced new genres and markets, e.g., for girls' (shōjo) manga in the late 1960s and for Ladies Comics (redisu) in the 1980s.[2]

text: Kern has suggested that kibyoshi, picture books from the late 18th century, may have been the world's first comic books.[3] These graphical narratives share with modern manga humorous, satirical, and romantic themes.[3] Although Kern does not believe that kibyoshi were a direct forerunner of manga, for Kern the existence of kibyoshi nonetheless points to a Japanese willingness to mix words and pictures in a popular story-telling medium.[4] The first recorded use of the term "manga" to mean "whimsical or impromptu pictures" comes from this tradition in 1798, which, Kern points out, predates Katsushika Hokusai's better known Hokusai Manga usage by several decades.[10][17]

text: Similarly, Inoue sees manga as being a mixture of image- and word-centered elements, each pre-dating the Allied occupation of Japan. In his view, Japanese image-centered or "pictocentric" art ultimately derives from Japan's long history of engagement with Chinese graphic art,[citation needed] whereas word-centered or "logocentric" art, like the novel, was stimulated by social and economic needs of Meiji and pre-war Japanese nationalism for a populace unified by a common written language. Both fuse in what Inoue sees as a symbiosis in manga.[18]

text: The roots of the wide-eyed look commonly associated with manga dates back to shōjo magazine illustrations during the late 19th to early 20th centuries. The most important illustrators associated with this style at the time were Yumeji Takehisa and particularly Jun'ichi Nakahara, who, influenced by his work as a doll creator, frequently drew female characters with big eyes in the early 20th century. This had a significant influence on early manga, particularly shōjo manga, evident in the work of influential manga artists such as Makoto Takahashi and Riyoko Ikeda.[19]

text: However, other writers such as Takashi Murakami have stressed events after WWII, but Murakami sees Japan's surrender and the atomic bombing of Hiroshima and Nagasaki as having created long-lasting scars on the Japanese artistic psyche, which, in this view, lost its previously virile confidence in itself and sought solace in harmless and cute (kawaii) images.[20] However, Takayumi Tatsumi sees a special role for a transpacific economic and cultural transnationalism that created a postmodern and shared international youth culture of cartooning, film, television, music, and related popular arts, which was, for Tatsumi the crucible in which modern manga have developed.[21]

text: For Murakami and Tatsumi, trans-nationalism (or globalization) refers specifically to the flow of cultural and subcultural material from one nation to another.[20][21] In their usage, the term does not refer to international corporate expansion, nor to international tourism, nor to cross-border international personal friendships, but to ways in which artistic, aesthetic, and intellectual traditions influence each other across national boundaries.[20][21] An example of cultural trans-nationalism is the creation of Star Wars films in the US, their transformation into manga by Japanese artists, and the marketing of Star Wars manga to the US.[22] Another example is the transfer of hip-hop culture from the US to Japan.[23] Wong also sees a major role for trans-nationalism in the recent history of manga.[24]

text: Thus, these scholars see the history of manga as involving historical continuities and discontinuities between the aesthetic and cultural past as it interacts with post-WWII innovation and trans-nationalism.

text: After World War II[edit]

text: After World War II, Japanese artists subsequently gave life to their own style during the occupation (1945–1952) and post-occupation years (1952-early 1960s), when a previously militaristic and ultranationalist Japan was rebuilding its political and economic infrastructure.[1][Note 1] Although Allied occupation censorship policies specifically prohibited art and writing that glorified war and Japanese militarism,[1] those policies did not prevent the publication of other kinds of material, including manga. Furthermore, the 1947 Japanese Constitution (Article 21) prohibited all forms of censorship.[25] One result was the growth of artistic creativity in this period.[1] In the forefront of this period are two manga series and characters that influenced much of the future history of manga. These are Osamu Tezuka's Mighty Atom (Astro Boy in the United States; begun in 1951) and Machiko Hasegawa's Sazae-san (begun in 1946).

text: Astro Boy was both a superpowered robot and a naive little boy.[26] Tezuka never explained why Astro Boy had such a highly developed social conscience nor what kind of robot programming could make him so deeply affiliative.[26] Both seem innate to Astro Boy, and represent a Japanese sociality and community-oriented masculinity differing very much from the Emperor-worship and militaristic obedience enforced during the previous period of Japanese imperialism.[26] Astro Boy quickly became (and remains) immensely popular in Japan and elsewhere as an icon and hero of a new world of peace and the renunciation of war, as also seen in Article 9 of the Japanese constitution.[25][26] Similar themes occur in Tezuka's New World and Metropolis.[1][26]

text: By contrast, Sazae-san (meaning "Ms. Sazae") was drawn starting in 1946 by Machiko Hasegawa, a young woman artist who made her heroine a stand-in for millions of Japanese men and especially women rendered homeless by the war.[1][27] Sazae-san does not face an easy or simple life, but, like Astro Boy, she too is highly affiliative and is deeply involved with her immediate and extended family. She is also a very strong character, in striking contrast to the officially sanctioned Neo-Confucianist principles of feminine meekness and obedience to the "good wife, wise mother" (ryōsai kenbo, りょうさいけんぼ; 良妻賢母) ideal taught by the previous military regime.[28][29][30] Sazae-san faces the world with cheerful resilience,[27][31] what Hayao Kawai calls a "woman of endurance."[32] Sazae-san sold more than 62 million copies over the next half century.[33]

text: Tezuka and Hasegawa were also both stylistic innovators. In Tezuka's "cinematographic" technique, the panels are like a motion picture that reveals details of action bordering on slow motion as well as rapid zooms from distance to close-up shots.[1] More critically, Tezuka synchronised the placement of panel with the reader's viewing speed to simulate moving pictures. Hence in manga production as in film production, the person who decides the allocation of panels (Komawari) is credited as the author while most drawing are done by assistants. This kind of visual dynamism was widely adopted by later manga artists.[1] Hasegawa's focus on daily life and on women's experience also came to characterize later shōjo manga.[27][31][34]

text: Between 1950 and 1969, increasingly large audiences for manga emerged in Japan with the solidification of its two main marketing genres, shōnen manga aimed at boys and shōjo manga aimed at girls.[1][35] Up to 1969, shōjo manga was drawn primarily by adult men for young female readers.[1][36]

text: Two very popular and influential male-authored manga for girls from this period were Tezuka's 1953-1956 Ribon no Kishi (Princess Knight or Knight in Ribbons) and Mitsuteru Yokoyama 1966 Mahōtsukai Sarii (Little Witch Sally).[1] Ribon no Kishi dealt with the adventures of Princess Sapphire of a fantasy kingdom who had been born with male and female souls, and whose sword-swinging battles and romances blurred the boundaries of otherwise rigid gender roles.[1] Sarii, the pre-teen princess heroine of Mahōtsukai Sarii,[Note 2] came from her home in the magical lands to live on Earth, go to school, and perform a variety of magical good deeds for her friends and schoolmates.[37] Yokoyama's Mahōtsukai Sarii was influenced by the US TV sitcom Bewitched,[38] but unlike Samantha, the main character of Bewitched, a married woman with her own daughter, Sarii is a pre-teenager who faces the problems of growing up and mastering the responsibilities of forthcoming adulthood. Mahōtsukai Sarii helped create the now very popular mahō shōjo or "magical girl" subgenre of later manga.[37] Both series were and still are very popular.[1][37]

text: Shōjo manga[edit]

text: In 1969, a group of women manga artists later called the Year 24 Group (also known as Magnificent 24s) made their shōjo manga debut (year 24 comes from the Japanese name for 1949, when many of these artists were born).[39][40] The group included Hagio Moto, Riyoko Ikeda, Yumiko Oshima, Keiko Takemiya, and Ryoko Yamagishi[27] and they marked the first major entry of women artists into manga.[1][27] Thereafter, shōjo manga would be drawn primarily by women artists for an audience of girls and young women.[1][35][36]

text: In 1971, Ikeda began her immensely popular shōjo manga Berusaiyu no Bara (The Rose of Versailles), a story of Oscar François de Jarjayes, a cross-dressing woman who was a Captain in Marie Antoinette's Palace Guards in pre-Revolutionary France.[1][27][41][42] In the end, Oscar dies as a revolutionary leading a charge of her troops against the Bastille. Likewise, Hagio Moto's work challenged Neo-Confucianist limits on women's roles and activities [28][29][30] as in her 1975 They Were Eleven, a shōjo science fiction story about a young woman cadet in a future space academy.[43]

text: These women artists also created considerable stylistic innovations. In its focus on the heroine's inner experiences and feelings, shōjo manga are "picture poems"[44] with delicate and complex designs that often eliminate panel borders completely to create prolonged, non-narrative extensions of time.[1][27][35][36][45] All of these innovations – strong and independent female characters, intense emotionality, and complex design – remain characteristic of shōjo manga up to the present day.[34][41]

text: Shōjo manga and ladies' Comics from 1975 to today[edit]

text: In the following decades (1975–present), shōjo manga continued to develop stylistically while simultaneously evolving different but overlapping subgenres.[46] Major subgenres have included romance, superheroines, and "Ladies Comics" (in Japanese, redisu レディース, redikomi レヂィーコミ, and josei 女性 じょせい), whose boundaries are sometimes indistinguishable from each other and from shōnen manga.[12][27]

text: In modern shōjo manga romance, love is a major theme set into emotionally intense narratives of self-realization.[47] Japanese manga/anime critic Eri Izawa defines romance as symbolizing "the emotional, the grand, the epic; the taste of heroism, fantastic adventure, and the melancholy; passionate love, personal struggle, and eternal longing" set into imaginative, individualistic, and passionate narrative frameworks.[48] These romances are sometimes long narratives that can deal with distinguishing between false and true love, coping with sexual intercourse, and growing up in a complex world, themes inherited by subsequent animated versions of the story.[35][47][49] These "coming of age" or Bildungsroman themes occur in both shōjo and shōnen manga.[Note 3][Note 4][51]

text: In the Bildungsroman, the protagonist must deal with adversity and conflict,[51] and examples in shōjo manga of romantic conflict are common. They include Miwa Ueda's Peach Girl,[52][53] Fuyumi Soryo's Mars,[54] and, for mature readers, Moyoco Anno's Happy Mania,[36][55] Yayoi Ogawa's Tramps Like Us, and Ai Yazawa's Nana.[56][57] In another shōjo manga Bildungsroman narrative device, the young heroine is transported to an alien place or time where she meets strangers and must survive on her own (including Hagio Moto's They Were Eleven,[58] Kyoko Hikawa's From Far Away,[59] Yû Watase's Fushigi Yûgi: The Mysterious Play, and Chiho Saito's The World Exists For Me[60]).

text: Yet another such device involves meeting unusual or strange people and beings, for example, Natsuki Takaya's Fruits Basket[61]—one of the most popular shōjo manga in the United States[62]—whose orphaned heroine Tohru must survive living in the woods in a house filled with people who can transform into the animals of the Chinese zodiac. In Harako Iida's Crescent Moon, heroine Mahiru meets a group of supernatural beings, finally to discover that she herself too has a supernatural ancestry when she and a young tengu demon fall in love.[63]

text: With the superheroines, shōjo manga continued to break away from neo-Confucianist norms of female meekness and obedience.[12][35] Naoko Takeuchi's Sailor Moon (Bishōjo Senshi Sēramūn: "Pretty Soldier Sailor Moon") is a sustained, 18-volume narrative about a group of young heroines simultaneously heroic and introspective, active and emotional, dutiful and ambitious.[64][65] The combination proved extremely successful, and Sailor Moon became internationally popular in both manga and anime formats.[64][66] Another example is CLAMP's Magic Knight Rayearth, whose three young heroines, Hikaru, Umi, and Fuu, are magically transported to the world of Cephiro to become armed magical warriors in the service of saving Cephiro from internal and external enemies.[67]

text: The superheroine subgenre also extensively developed the notion of teams (sentai) of girls working together,[68] like the Sailor Senshi in Sailor Moon, the Magic Knights in Magic Knight Rayearth, and the Mew Mew girls from Mia Ikumi's Tokyo Mew Mew.[69] By today, the superheroine narrative template has been widely used and parodied within the shōjo manga tradition (e.g., Nao Yazawa's Wedding Peach[70] and Hyper Rune by Tamayo Akiyama[71]) and outside that tradition, e.g., in bishōjo comedies like Kanan's Galaxy Angel.[72]

text: In the mid-1980s and thereafter, as girls who had read shōjo manga as teenagers matured and entered the job market, shōjo manga elaborated subgenres directed at women in their 20s and 30s.[46] This "Ladies Comic" or redisu-josei subgenre has dealt with themes of young adulthood: jobs, the emotions and problems of sexual intercourse, and friendships or love among women.[46][73][74][75][76]

text: Redisu manga retains many of the narrative stylistics of shōjo manga but has been drawn by and written for adult women.[77] Redisu manga and art has been often, but not always, sexually explicit, but sexuality has characteristically been set into complex narratives of pleasure and erotic arousal combined with emotional risk.[12][73][74] Examples include Ryō Ramiya's Luminous Girls,[78] Masako Watanabe's Kinpeibai[79] and the work of Shungicu Uchida[80] Another subgenre of shōjo-redisu manga deals with emotional and sexual relationships among women (akogare and yuri),[81] in work by Erica Sakurazawa,[82] Ebine Yamaji,[83] and Chiho Saito.[84] Other subgenres of shōjo-redisu manga have also developed, e.g., fashion (oshare) manga, like Ai Yazawa's Paradise Kiss[85][86] and horror-vampire-gothic manga, like Matsuri Hino's Vampire Knight,[87] Kaori Yuki's Cain Saga,[88] and Mitsukazu Mihara's DOLL,[89] which interact with street fashions, costume play ("cosplay"), J-Pop music, and goth subcultures in complex ways.[90][91][92]

text: By the start of the 21st century, manga for women and girls thus represented a broad spectrum of material for pre- and early teenagers to material for adult women.

text: Shōnen, seinen, and seijin manga[edit]

text: Manga for male readers can be characterized in different ways. One is by the age of its intended audience: boys up to 18 years old (shōnen manga) and young men 18 to 30 years old (seinen manga).[93] Another approach is by content, including action-adventure often involving male heroes, slapstick humor, themes of honor, and sometimes explicit sexuality.[94][Note 5] Japanese uses different kanji for two closely allied meanings of "seinen"—青年 for "youth, young man" and 成年 for "adult, majority"—the second referring to sexually overt manga aimed at grown men and also called seijin ("adult," 成人) manga.[95][Note 6][96] Shōnen, seinen, and seijin manga share many features in common.

text: Boys and young men were among the earliest readers of manga after World War II.[97] From the 1950s on, shōnen manga focused on topics thought to interest the archetypical boy: sci-tech subjects like robots and space travel, and heroic action-adventure.[98][99] Shōnen and seinen manga narratives often portray challenges to the protagonist’s abilities, skills, and maturity, stressing self-perfection, austere self-discipline, sacrifice in the cause of duty, and honorable service to society, community, family, and friends.[97][100]

text: Manga with solitary costumed superheroes like Superman, Batman, and Spider-Man did not become popular as a shōnen genre.[97] An exception is Kia Asamiya's Batman: Child of Dreams, released in the US by DC Comics and in Japan by Kodansha. However, lone heroes occur in Takao Saito's Golgo 13 and Koike and Kojima's Lone Wolf and Cub. Golgo 13 is about an assassin who puts his skills to the service of world peace and other social goals,[101] and Ogami Itto, the swordsman-hero of Lone Wolf and Cub, is a widower caring for his son Daigoro while he seeks vengeance against his wife's murderers. However, Golgo and Itto remain men throughout and neither hero ever displays superpowers. Instead, these stories "journey into the hearts and minds of men" by remaining on the plane of human psychology and motivation.[102]

text: Many shōnen manga have science fiction and technology themes. Early examples in the robot subgenre included Tezuka’s Astro Boy (see above) and Fujiko F. Fujio’s 1969 Doraemon, about a robot cat and the boy he lives with, which was aimed at younger boys.[103] The robot theme evolved extensively, from Mitsuteru Yokoyama's 1956 Tetsujin 28-go to later, more complex stories where the protagonist must not only defeat enemies, but learn to master himself and cooperate with the mecha he controls.[104] Thus, in Neon Genesis Evangelion by Yoshiyuki Sadamoto, Shinji struggles against the enemy and against his father, and in Vision of Escaflowne by Katsu Aki, Van not only makes war against Dornkirk’s empire but must deal with his complex feelings for Hitomi, the heroine.

text: Sports themes are also popular in manga for male readers.[97] These stories stress self-discipline, depicting not only the excitement of sports competition but also character traits the hero needs to transcend his limitations and to triumph.[97] Examples include boxing (Tetsuya Chiba’s 1968-1973 Tomorrow's Joe[105] and Rumiko Takahashi's 1987 One-Pound Gospel) and basketball (Takehiko Inoue’s 1990 Slam Dunk[106]).

text: Supernatural settings have been another source of action-adventure plots in shõnen and some shõjo manga in which the hero must master challenges. Sometimes the protagonist fails, as in Tsugumi Ohba and Takeshi Obata's Death Note, where protagonist Light Yagami receives a notebook from a Death God (shinigami) that kills anyone whose name is written in it, and, in a shōjo manga example, Hakase Mizuki's The Demon Ororon, whose protagonist abandons his demonic kingship of Hell to live and die on earth. Sometimes the protagonist himself is supernatural, like Kohta Hirano's Hellsing, whose vampire hero Alucard battles reborn Nazis hellbent on conquering England, but the hero may also be (or was) human, battling an ever-escalating series of supernatural enemies (Hiromu Arakawa's Fullmetal Alchemist, Nobuyuki Anzai's Flame of Recca, and Tite Kubo's Bleach).

text: Military action-adventure stories set in the modern world, for example, about WWII, remained under suspicion of glorifying Japan’s Imperial history[97] and have not become a significant part of the shōnen manga repertoire.[97] Nonetheless, stories about fantasy or historical military adventure were not stigmatized, and manga about heroic warriors and martial artists have been extremely popular.[97] Some are serious dramas, like Sanpei Shirato's The Legend of Kamui and Rurouni Kenshin by Nobuhiro Watsuki, but others contain strongly humorous elements, like Akira Toriyama's Dragon Ball.

text: Although stories about modern war and its weapons do exist, they deal as much or more with the psychological and moral problems of war as they do with sheer shoot-'em-up adventure.[97] Examples include Seiho Takizawa's Who Fighter, a retelling of Joseph Conrad's story Heart of Darkness about a renegade Japanese colonel set in WWII Burma, Kaiji Kawaguchi's The Silent Service, about a Japanese nuclear submarine, and Motofumi Kobayashi's Apocalypse Meow, about the Vietnam War told in talking animal format. Other battle and fight-oriented manga are complex stories of criminal and espionage conspiracies to be overcome by the protagonist, such as City Hunter by Hojo Tsukasa, Fist of the North Star by Tetsuo Hara, and in the shōjo manga From Eroica with Love by Yasuko Aoike, a long-running crime-espionage story combining adventure, action, and humor (and another example of how these themes occur across genres).

text: For manga critics Koji Aihara and Kentaro Takekuma,[107] such battle stories endlessly repeat the same mindless themes of violence, which they sardonically label the "Shonen Manga Plot Shish Kebob", where fights follow fights like meat skewered on a stick.[108] Other commentators suggest that fight sequences and violence in comics serve as a social outlet for otherwise dangerous impulses.[109] Shōnen manga and its extreme warriorship have been parodied, for example, in Mine Yoshizaki's screwball comedy Sgt. Frog (Keroro Gunso), about a platoon of slacker alien frogs who invade the Earth and end up free-loading off the Hinata family in Tokyo.[110]

text: Sex and women's roles in manga for males[edit]

text: In early shōnen manga, men and boys played all the major roles, with women and girls having only auxiliary places as sisters, mothers, and occasionally girlfriends. Of the nine cyborgs in Shotaro Ishinomori's 1964 Cyborg 009, only one is female, and she soon vanishes from the action. Some recent shōnen manga virtually omit women, e.g., the martial arts story Baki the Grappler by Itagaki Keisuke and the supernatural fantasy Sand Land by Akira Toriyama. However, by the 1980s, girls and women began to play increasingly important roles in shōnen manga, for example, Toriyama's 1980 Dr. Slump, whose main character is the mischievous and powerful girl robot Arale Norimaki.

text: The role of girls and women in manga for male readers has evolved considerably since Arale. One class is the pretty girl (bishōjo).[Note 7] Sometimes the woman is unattainable, but she is always an object of the hero's emotional and sexual interest, like Belldandy from Oh My Goddess! by Kōsuke Fujishima and Shao-lin from Guardian Angel Getten by Minene Sakurano.[111] In other stories, the hero is surrounded by such girls and women, as in Negima by Ken Akamatsu and Hanaukyo Maid Team by Morishige.[112] The male protagonist does not always succeed in forming a relationship with the woman, for example when Bright Honda and Aimi Komori fail to bond in Shadow Lady by Masakazu Katsura. In other cases, a successful couple's sexual activities are depicted or implied, like Outlanders by Johji Manabe.[113] In still other cases, the initially naive and immature hero grows up to become a man by learning how to deal and live with women emotionally and sexually, like Yota in Video Girl Ai by Masakazu Katsura, Train Man in Train Man: Densha Otoko by Hidenori Hara, and Makoto in Futari Ecchi by Katsu Aki.[114][115] In poruno- and eromanga (seijin manga), often called hentai manga in the US, a sexual relationship is taken for granted and depicted explicitly, as in work by Toshiki Yui [116] and in Were-Slut by Jiro Chiba and Slut Girl by Isutoshi.[117] The result is a range of depictions of boys and men from naive to very experienced sexually.

text: Heavily armed female warriors (sentō bishōjo) represent another class of girls and women in manga for male readers.[Note 8] Some sentō bishōjo are battle cyborgs, like Alita from Battle Angel Alita by Yukito Kishiro, Motoko Kusanagi from Masamune Shirow's Ghost in the Shell, and Chise from Shin Takahashi's Saikano. Others are human, like Attim M-Zak from Hiroyuki Utatane's Seraphic Feather, Johji Manabe's Karula Olzen from Drakuun, and Alita Forland (Falis) from Sekihiko Inui's Murder Princess.[118]

text: As of 2013 national censorship laws and local ordinances remain in Japan and the public response to the publication of manga with sexual content or the depiction of nudity has been mixed. Series have an audience and sell well but their publication also encounters opposition. In the early 1990s the opposition resulted in the creation of Harmful manga lists and a shift in the publishing industry. By this time large publishers had created a general manga demand but the corollary is that they were also susceptible to public opinion in their markets. Faced with criticism from certain segments of the population and under pressure from industry groups to self-regulate, major publishing houses discontinued series, such as Angel and 1+2=Paradise, while smaller publication companies, not as susceptible to these forces, were able to fill the void.[5][119]

text: With the relaxation of censorship in Japan after the early 1990s, a wide variety of explicitly drawn sexual themes appeared in manga intended for male readers that correspondingly occur in English translations.[96] These depictions range from mild partial nudity through implied and explicit sexual intercourse through bondage and sadomasochism (SM), zoophilia (bestiality), incest, and rape.[120] In some cases, rape and lust murder themes came to the forefront, as in Urotsukidoji by Toshio Maeda[121] and Blue Catalyst from 1994 by Kei Taniguchi,[122] but these extreme themes are not commonplace in either untranslated or translated manga.[96][123]

text: Gekiga[edit]

text: Gekiga literally means "drama pictures" and refers to a form of aesthetic realism in manga.[124][125] Gekiga style drawing is emotionally dark, often starkly realistic, sometimes very violent, and focuses on the day-in, day-out grim realities of life, often drawn in gritty and unpretty fashions.[124][126] Gekiga arose in the late 1950s and 1960s partly from left-wing student and working class political activism[124][127] and partly from the aesthetic dissatisfaction of young manga artists like Yoshihiro Tatsumi with existing manga.[128][129] Examples include Sampei Shirato's 1959-1962 Chronicles of a Ninja's Military Accomplishments (Ninja Bugeichō), the story of Kagemaru, the leader of a peasant rebellion in the 16th century, which dealt directly with oppression and class struggle,[130] and Hiroshi Hirata's Satsuma Gishiden, about uprisings against the Tokugawa shogunate.[131]

text: As the social protest of these early years waned, gekiga shifted in meaning towards socially conscious, mature drama and towards the avant-garde.[125][129][132] Examples include Koike and Kojima's Lone Wolf and Cub[133] and Akira, an apocalyptic tale of motorcycle gangs, street war, and inexplicable transformations of the children of a future Tokyo. Another example is Osamu Tezuka's 1976 manga MW, a bitter story of the aftermath of the storage and possibly deliberate release of poison gas by U.S. armed forces based in Okinawa years after World War II.[134] Gekiga and the social consciousness it embodies remain alive in modern-day manga. An example is Ikebukuro West Gate Park from 2001 by Ira Ishida and Sena Aritou, a story of street thugs, rape, and vengeance set on the social margins of the wealthy Ikebukuro district of Tokyo.[135]