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.

    研究发现：在纽约，对于接触浓度高的多环芳烃的儿童比相对少接触的儿童的完全智商和语言智商分别低4.31分和4.67分。高浓度多环芳烃的定义是超过2.26毫微克/每立方的中间值。

    "这些发现值得关注，因为智商的降低对于孩子在学校的表现有着重大的意义，"哥伦比亚大学环境健康科学教授Frederica Perera DrPH说。"好消息是从1998年到现在，我们对于空气污染物的接触一直在下降，这证明了致力于降低交通读堵塞和化石燃料的副产品的其他来源的政策的重要性。"

    研究中包括住在纽约华盛顿高地、黑人住宅区和南布朗克斯，年龄从18岁到35岁的妇女的孩子，他们的母亲是不吸烟的多米尼加人。这些儿童从出生前到5岁时都接受跟踪。研究中的母亲在怀孕期间带上个人空气检测器来检测她们说接触到的多环芳烃的浓度，并接受问卷调查。

    249名儿童在5岁时，接受名为韦氏学龄前儿童智力量表的智力测试，测试可以提供语言、表现和全面的智商分数。研究人员开发了数种模型来计算出出生前多环芳烃得接触与智商之间的关系。他们把与二手烟的接触、母亲的教育和家庭照顾环境的质量等因素都计算在内。对空气污染物接触浓度高的研究参与者归为"低接触",接触浓度高的归为"高接触".总共有140名儿童被分为多环芳烃的高接触者。

    "对于多环芳烃接触较多的儿童的全面治理分数的下降跟与铅有较低程度接触的儿童相似，"Perera说。"这一研究发现值得关注，因为智力是未来学习表现的一个重要预测的因素，多环芳烃在城市环境和全世界都广泛传播。"幸运的是，可以通过现有的控制方法、替代能源和政策干预来减少在空气中运动的多环芳烃。

    研究结果公布在2009年八月的《小儿科学》。

    研究由国家环境卫生科学研究所、美国环境保护机构和几个私人基金会赞助。