The study found that children exposed to high levels of PAHs in New York City had full scale and verbal IQ scores that were 4.31 and 4.67 points lower, respectively than those of less exposed children. High PAH levels were defined as above the median of 2.26 nanograms per cubic meter （ng/m3）.

    "These findings are of concern because these decreases in IQ could be educationally meaningful in terms of school performance," says Frederica Perera, DrPH, professor of Environmental Health Sciences and director of the CCCEH at Columbia University Mailman School of Public Health and study lead author. "The good news is that we have seen a decline in air pollution exposure in our cohort since 1998, testifying to the importance of policies to reduce traffic congestion and other sources of fossil fuel combustion byproducts."

    The study included children who were born to non-smoking Black and Dominican American women age 18 to 35 who resided in Washington Heights, Harlem or the South Bronx in New York. The children were followed from in utero to 5 years of age. The mothers wore personal air monitors during pregnancy to measure exposure to PAHs and they responded to questionnaires.

    At 5 years of age, 249 children were given an intelligence test known as the Wechsler Preschool and Primary Scale of the Intelligence, which provides verbal, performance and full-scale IQ scores. The researchers developed models to calculate the associations between prenatal PAH exposure and IQ. They accounted for other factors such as second-hand smoke exposure, lead, mother's education and the quality of the home caretaking environment. Study participants exposed to air pollution levels below the average were designated as having "low exposure," while those exposed to pollution levels above the average were identified as "high exposure." A total of 140 children were classified as having high PAH exposure.

    "The decrease in full-scale IQ score among the more exposed children is similar to that seen with low-level lead exposure," noted Dr. Perera. "This finding is of concern because IQ is an important predictor of future academic performance, and PAHs are widespread in urban environments and throughout the world. Fortunately, airborne PAH concentrations can be reduced through currently available controls, alternative energy sources and policy interventions."

    The study findings are published in the August 2009 issue of Pediatrics.

    This research was funded by the National Institute of Environmental Health Sciences （NIEHS）, a component of the National Institutes of Health, the U.S. Environmental Protection Agency and several private foundations.

    研究發現：在紐約，對于接觸濃度高的多環芳烴的兒童比相對少接觸的兒童的完全智商和語言智商分別低4.31分和4.67分。高濃度多環芳烴的定義是超過2.26毫微克/每立方的中間值。

    "這些發現值得關注，因為智商的降低對于孩子在學校的表現有著重大的意義，"哥倫比亞大學環境健康科學教授Frederica Perera DrPH說。"好消息是從1998年到現在，我們對于空氣污染物的接觸一直在下降，這證明了致力于降低交通讀堵塞和化石燃料的副產品的其他來源的政策的重要性。"

    研究中包括住在紐約華盛頓高地、黑人住宅區和南布朗克斯，年齡從18歲到35歲的婦女的孩子，他們的母親是不吸煙的多米尼加人。這些兒童從出生前到5歲時都接受跟蹤。研究中的母親在懷孕期間帶上個人空氣檢測器來檢測她們說接觸到的多環芳烴的濃度，并接受問卷調查。

    249名兒童在5歲時，接受名為韋氏學齡前兒童智力量表的智力測試，測試可以提供語言、表現和全面的智商分數。研究人員開發了數種模型來計算出出生前多環芳烴得接觸與智商之間的關系。他們把與二手煙的接觸、母親的教育和家庭照顧環境的質量等因素都計算在內。對空氣污染物接觸濃度高的研究參與者歸為"低接觸",接觸濃度高的歸為"高接觸".總共有140名兒童被分為多環芳烴的高接觸者。

    "對于多環芳烴接觸較多的兒童的全面治理分數的下降跟與鉛有較低程度接觸的兒童相似，"Perera說。"這一研究發現值得關注，因為智力是未來學習表現的一個重要預測的因素，多環芳烴在城市環境和全世界都廣泛傳播。"幸運的是，可以通過現有的控制方法、替代能源和政策干預來減少在空氣中運動的多環芳烴。

    研究結果公布在2009年八月的《小兒科學》。

    研究由國家環境衛生科學研究所、美國環境保護機構和幾個私人基金會贊助。