Remembering 9/11

It’s been over a decade since the tragedy of 9/11, and the Columbia Center for Children’s Environmental Health reflects on lessons learned through its environmental health research.

The Center’s World Trade Center Pregnancy Study, launched in December 2001, is assessing the effects of prenatal exposure to contaminants released by the WTC destruction on gestational age, birth size, respiratory health, and neurocognitive development in 330 women who had term pregnancies. Women were enrolled into the study at delivery between December 2001 and June 2002 from three participating hospitals located within two miles of the World Trade’s Center site.

In lower Manhattan, the event released large amounts of dust and toxic pollutants into the air, including fine particulate matter derived from the burning of materials during the explosion and fires, construction debris, and asbestos. These exposures are known to be especially toxic to the vulnerable populations of pregnant women and their unborn infants, and have been linked to reduced fetal growth and subsequent neurodevelopmental problems. Widespread psychological distress could also affect birth outcomes and subsequent child functioning.

Thus far, study results show that babies born to women who were pregnant on 9/11 and lived near the WTC in the weeks after 9/11 were born lighter and shorter than were babies born to women living further away. Previous research shows that even small reductions in birth weight may lead to learning and behavioral problems. A summary of other key findings as well can be found below.

This study is the only one of its kind to compare women with known exposure levels living and working close to the WTC site to a control group living and working further away from the site. The study is also unique in that pregnant women were enrolled prior to delivery, thereby eliminating participation bias that could arise from already knowing the outcome of their pregnancy.

Research Findings

Fetal Growth & Gestational Duration

Center investigators assessed the impact of gestational timing of the WTC disaster and distance from the towers in the four weeks after September 11, 2001, on birth outcomes (e.g. newborn size) in 300 non-smoking women who were pregnant at the time of the event. The observed adverse effects suggest an impact of pollutants and/or stress related to the WTC disaster and have implications for the health and development of exposed children (Lederman, et al., 2004).

Term infants born to women who were pregnant on 9/11 and who were living within a 2-mile radius of the WTC during the month after the event showed significant decrements in term birth weight (-149 g) and birth length (-0.82 cm), compared with infants born to the other pregnant women studied, after controlling for sociodemographic and biomedical risk factors.

The decrements remained significant with adjustment for gestational duration (-122 g and -0.74 cm, respectively).

Women in the first trimester of pregnancy at the time of the WTC event delivered infants with significantly shorter gestation (-3.6 days) and a smaller head circumference (-0.48 cm), compared with women at later stages of pregnancy, regardless of the distance of their residences or work sites from the WTC.

Genetic Damage in Newborns

Center investigators analyzed associations between newborn size and genetic damage (benzo[a]pyrene-DNA adducts) found in blood samples at birth from mother and babies. Findings suggest that exposure to elevated levels of PAH (indicated by PAH-DNA adducts in cord blood) may have contributed to reduced fetal growth in women exposed to the WTC event (Perera, et al., EHP, 2005).

The mean adduct levels in cord and maternal blood were highest among newborns and mothers who resided within one mile of the WTC site during the month following 9/11, intermediate among those who worked but did not live within this area, and lowest in those who neither worked nor lived within one mile (reference group).

Among newborns of mothers living within one mile of the WTC site during this time period, levels of cord blood adducts were inversely correlated with linear distance from the WTC site. This means that the further a pregnant woman was from the towers, the less genetic damage was found in her blood and her baby’s blood.

There were no independent fetal growth effects of either genetic damage (PAH-DNA adducts) or environmental tobacco smoke (ETS), but genetic damage combined with in utero exposure to ETS was associated with decreased fetal growth.

A doubling of genetic damage among ETS-exposed subjects corresponded to an estimated average 276 g (8 percent) reduction in birth weight and a 1.3 cm (3 percent) reduction in head circumference.

In separate analysis, Center investigators compared the levels of benzo[a]pyrene-DNA adducts as a proxy for PAH-DNA (genetic) damage measured mothers’ and babies’ blood samples at delivery. Four different populations of mothers (total of 867) and newborns (total of 822) were compared representing a 30-fold range of exposure to ambient PAH. Populations include residents in Northern Manhattan, participants in a study of the effects of the World Trade Center disaster, residents in Krakow, Poland, and residents in Tongliang, China. Findings suggest that the fetus may be 10-fold more susceptible to DNA damage than the mother, and that in utero exposure to polycyclic aromatic hydrocarbons may disproportionately increase carcinogenic risk (Perera et al., 2005).

Mean adduct concentrations in both maternal and cord blood and the proportion of samples with detectable adducts, increased across the populations [Northern Manhattan < World Trade Center (WTC) < Krakow < Tongliang], consistent with the trend in estimated ambient exposure to PAH. Women and babies in the WTC study had less genetic damage than women living in major cities in Poland and China where chronic exposures to PAH in air are higher.

Although previous (non-Center) experiments conducted on laboratory animals indicate that the mother’s body protects the fetus to a degree from pollution, thus exposing the fetus to an estimated 10-fold lower PAH dose than its mother, this study found genetic damage in newborns in four different research populations to be similar to or higher than in the mothers.

Collaborators

Center investigators contributing to the World Trade Center Pregnancy Center Study include Frederica Perera (PI), Sally Lederman (co-PI), Julie Herbstman (co-PI), Deliang Tang, Virginia Rauh, Yi Hsuan Tu, Wei Yann Tsai, Mark Becker, Janet L. Stein, Jeffrey King, Giuseppe Del Priore, Andreas Sjodin, Matthew Kurzon, Richard S. Jones, Larry L. Needham, Megan Niedzwiecki, and Richard Y. Wang

Funding and support for the research was provided by the September 11th Fund, New York Community Trust, United Way of New York City, New York Times 9/11 Neediest Fund, 9/11 Children’s Fund through the National Philanthropic Trust in Philadelphia, PA, The National Institute of Environmental Health Sciences, and the U.S. Environmental Protection Agency.

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