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zoom RSS 大気汚染物質の出生前暴露による幼児の知能への影響/米国

<<   作成日時 : 2009/07/31 00:51   >>

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 大気汚染物質の出生前暴露により幼児の知能に悪影響がある可能性がコロンビア大から報告された。
 ニューヨーク市の子宮内で多環芳香族炭化水素PAHの高いレベルにさらされた子供は5歳時の全IQ、言語性IQが有意に低下していた。
 化石燃料とたばこの燃焼により放出される多環芳香族炭化水素PAH polycyclic aromatic hydrocarbonsは世界中の都市部でよく検出される。
 出生前から5才まで249人の都市の子供の発達を調査した。ハーレムかサウスブロンクスのワシントンハイツに住む18-35才の非喫煙の黒人とドミニカ系アメリカ人の子供である。
 母親は妊娠後半に大気汚染物質測定のために監視装置を付けた。56.2%の子供が2.26ng/m3 という高濃度の汚染に曝されていた。WPPSI評価で平均98.72と低下していた。高濃度暴露された子供は全体で4.31低く、言語性スコアは4.67低かった。
 妊娠女性の大気汚染暴露は子供のIQに影響する。
 どのようなメカニズムで起きているのかはわかっていない。
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Prenatal Air Pollution Exposure Linked to Low Childhood IQ
High Exposure May Lower Future IQ of Unborn Children by More Than Four Points
By TODD NEALE
MedPage Today
July 25, 2009
http://abcnews.go.com/Health/MindMoodNews/Story?id=8160222

画像Prenatal exposure to pervasive air pollutants may adversely affect a child's intelligence by preschool, researchers reported today.
PHOTO: Prenatal Air Pollution Exposure Linked to Low Childhood IQ
Fetus
(Getty Images)

In New York City, children exposed to high levels of polycyclic aromatic hydrocarbons in the womb had significantly lower full-scale and verbal IQ scores when they turned 5, according to Frederica Perera, a professor of environmental health sciences at Columbia University, and colleagues.

"The present findings are of concern because verbal and full-scale IQ scores measured ... during the preschool period were shown to be predictive of subsequent elementary school performance in a range of populations," they reported online in the journal Pediatrics.

Polycyclic aromatic hydrocarbons, released by the burning of fossil fuels and tobacco, are ubiquitous in urban areas worldwide. Although previous studies have connected these pollutants with neurodevelopment issues, none has looked specifically at their relationship to intelligence, Perera said.

So she and colleagues followed the development of 249 urban children from the prenatal period to age 5 years.

The youngsters were born to non-smoking, black and Dominican-American women ages 18 to 35 who lived in Washington Heights, Harlem or the South Bronx.

The mothers wore personal air monitors during the third trimester of pregnancy to measure exposure to air pollutants.

Overall, 56.2 percent of the children were exposed to high levels of pollution in the womb, defined as a level greater than 2.26 nanograms per cubic meter. Levels ranged from 0.49 to 34.48 nanograms.

When the children were 5, they were evaluated using the Wechsler Preschool Primary Scale of Intelligence. The mean score was 98.72, which falls in the average range.

Statistically, the scientists controlled for tobacco smoke exposure, the child's gender and gestational age, ethnicity, maternal intelligence and education, and the quality of care at home.

After those factors were accounted for, the full-scale score of youngsters with high exposure was 4.31 points lower than the others' while their verbal score was lower by 4.67 points.

Pregnant Women's Air Pollution Exposure May Affect Baby's IQ

"The decrease in full-scale IQ score among the more exposed children is similar to that seen with low-level lead exposure," Perera said.

Joel Schwartz, an epidemiologist at the Harvard School of Public Health who was not involved in the study, called the difference in IQ points significant from a public health standpoint.

"The key thing to remember is that we are predicting not what happens to a particular child, whose performance can fluctuate from test to test," Schwartz said. "Rather, epidemiology is predicting on average, what would happen to a population if its IQ was four points lower than another population. For population differences this is quite a noticeable effect."

The children will be followed until they are 11 to evaluate more long-term outcomes.

The scientists don't know what mechanism is at work here, but theorized that it might be the result of endocrine disruption, binding of pollutants to various receptors involved in development, DNA damage, epigenetic effects, or oxidative stress.

They could not confirm a direct causal link, but if one were confirmed, it would be prudent to seek ways to lower children's exposure to these airborne pollutants.

"Fortunately," Perera said, "airborne polycyclic aromatic hydrocarbon concentrations can be reduced through currently available controls, alternative energy sources, and policy interventions."

This article was developed in collaboration with ABC News.

---------------------------------------------------
Published online July 20, 2009
PEDIATRICS Vol. 124 No. 2 August 2009, pp. e195-e202 (doi:10.1542/peds.2008-3506)

Prenatal Airborne Polycyclic Aromatic Hydrocarbon Exposure and Child IQ at Age 5 Years
Frederica P. Perera, DrPHa,b, Zhigang Li, MPSa,b,c, Robin Whyatt, DrPHa,b, Lori Hoepner, MPHa,b, Shuang Wang, PhDa,b,c, David Camann, MSd and Virginia Rauh, ScDa,b

a Department of Environmental Health Sciences
b Columbia Center for Children's Environmental Health
c Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, New York
d Southwest Research Institute, San Antonio, Texas

OBJECTIVE: This study evaluated the relationship between prenatal exposure to airborne polycyclic aromatic hydrocarbons (PAHs) and child intelligence.

METHODS: Children of nonsmoking black or Dominican-American women residing in New York City were monitored from in utero to 5 years of age, with determination of prenatal PAH exposure through personal air monitoring for the mothers during pregnancy. At 5 years of age, intelligence was assessed for 249 children by using the Wechsler Preschool and Primary Scale of Intelligence-Revised. Multivariate linear regression models were used to estimate and to test the associations between prenatal PAH exposure and IQ.

RESULTS: After adjustment for maternal intelligence, quality of the home caretaking environment, environmental tobacco smoke exposure, and other potentially confounding factors, high PAH levels (above the median of 2.26 ng/m3) were inversely associated with full-scale IQ (P = .007) and verbal IQ (P = .003) scores. Children in the high-exposure group had full-scale and verbal IQ scores that were 4.31 and 4.67 points lower, respectively, than those of less-exposed children (?2.26 ng/m3). The associations between logarithmically transformed, continuous, PAH levels and these IQ measures also were significant (full-scale IQ: β = --3.00; P = .009; verbal IQ: β = --3.53; P = .002).

CONCLUSION: These results provide evidence that environmental PAHs at levels encountered in New York City air can affect children's IQ adversely.

Key Words: prenatal . fetal . polycyclic aromatic hydrocarbons . air pollution . IQ

Abbreviations: CI―confidence interval . CCCEH―Columbia Center for Children's Environmental Health . HOME―Home Observation for Measurement of the Environment . PAH―polycyclic aromatic hydrocarbon . WPPSI-R―Wechsler Preschool and Primary Scale of Intelligence-Revised . TONI-3―Test of Maternal Nonverbal Intelligence, Third Edition . ETS―environmental tobacco smoke

Accepted Mar 25, 2009.

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