F, V Rauh, WY Tsai, P Kinney, D Camann, D Barr, T Bernert, R Garfinkel,
Y-H Tu, D Diaz, J Dietrich and RM Whyatt. 2002. Effects
of Transplacental Exposure to Environmental Pollutants on Birth
Outcomes in a Multi-Ethnic Population. Environmental
doi:10.1289/ehp.5742. [Online 31 October 2002].
In an innovative, community-based research project, Perera et
al. discovered that "environmental pollutants
at levels currently encountered in New York City adversely impact
fetal development." Their work, focused on two inner-city
minority populations and carried with the collaboration of community
groups, examined the impact of polycyclic aromatic hydrocarbons
(PAHs), environmental tobacco smoke (ETS) and an organophosphate
pesticide (chlorpyrifos). They found effects linking elevated levels
of the environmental contaminants to smaller birth weight
and smaller head circumference. For the endpoints
measured in people studied (all non-smokers) ETS had no effect.
did they do? Perera et al. studied associations
between exposure to PAHs, chlorpyrifos and ETS and birth outcome
in pregnant African American and Dominican volunteers living in
Dominican Heights, Central Harlem and South Bronx. A total of 263
women participated in the research. Active smokers were excluded
from the study, as were women who reported not smoking but whose
blood cotinine levels were high enough to suggest active smoking.
et al. assessed exposure to the contaminants using a combination
of 3 methods:
volunteers wore a small backpack containing air sampling equipment
during two days in their third trimester of pregnancy. The sampled
air was then analyzed for PAH levels by an independent laboratory.
cord blood was collected at birth and maternal serum was sampled
within one day following birth.
completed a 45-minute survey which provided information about
smoking history, alcohol use, travel, consumption patterns of
to contain PAHs (e.g., grilled meat), pesticide use in the home,
medical records, Perera et al. obtained measurements of
birth weight, length and head circumference, and then looked for
associations between these birth outcomes and the environmental
contaminants, using statistical techniques to control for potential
did they find? All participants in the survey had detectable
inhalation levles of at least one PAH. Chlorpyrifos was detected
in 98% of all maternal serum and 94% of all umbilical cord blood.
Forty-two percent of mothers and 45% of newborns had cotinine levels
indicative of ETS exposure.
had a significant adverse effect on birth weight and head circumference
among African American but not Dominican infants. For African American
babies, higher exposure in the womb to PAHs was associated with
lower birth weight and smaller head circumference, while exposure
to chlorpyrifos was associated with decreased birth weight. After
adjusting statistically for chlorpyrifos exposure, African American
babies experienced a 10% in birthweight and 2% in head circumference
with the highest level of PAH exposure.
Dominicans, chlorpyrifos exposure was associated with decreased
was not a significant predictor of adverse birth outcome.
does it mean? As noted by the authors, "this study
provides evidence that environmental pollutants at levels currently
encountered in New York City adversely impact fetal development."
the sample size was relatively small and the environmental sampling
was not exhaustive, the research nonetheless revealed clear impacts
of exposure to PAHs and chlorpyrifos and thus should heighten concern
about environmental exposures that are experienced by residents
of large urban centers.
Perera et al. note, "a number of studies have reported
that reduction in head circumference at birth or during the first
year of life correlates with lower I.Q. as well as poorer cognitive
functioning and school performance in childhood." The finding
in this report indicating lower head circumference with higher PAH
exposure would suggest that PAH contamination is yet another factor
undermining inner city school performance. This suggests that steps
to reduce PAH exposure, for example by controlling diesel emissions,
should be pursued actively.