Exposure in the womb to perfluorooctane sulfonate and
perfluorooctanoate — ubiquitous man-made chemicals
used in a variety of consumer products — is
statistically associated with lower weight
and head circumference at birth, according to an analysis
of nearly 300 umbilical cord blood samples
led by researchers at the Johns Hopkins Bloomberg School of
Public Health.
The results are published in the July 31 online
edition of the journal Environmental Health
Perspectives. Some of the study's findings were
previously reported in February at a Society of
Toxicology workshop.
Perfluorooctane sulfonate and perfluorooctanoate are
polyfluoroalkyl compounds, whose uses
include protective coating on food-contact packaging,
textiles and carpets and the manufacturing of
insecticides and other industrial products.
The study, conducted in Baltimore, found small
decreases in head circumference and body
weight in association with higher concentrations of PFOS
and PFOA among infants born vaginally. The
study also reported a negative association with PFOS and
PFOA concentrations and the infant's
ponderal index, which is a measurement of weight for length
similar to the body mass index. For
unknown reasons, the reductions in birth weight and head
circumference were not observed among 65
infants born by Caesarean section. The researchers also did
not find any associations between PFOS
and PFOA concentrations and length at birth or gestational
age.
"These small but significant differences in head
circumference and body weight provide the
first evidence for a possible association between exposures
to PFOS and PFOA and fetal growth.
However, the differences are small, and their impact on
health is uncertain," said Benjamin Apelberg,
lead author of the study and a research associate in the
Bloomberg School's
Department of Epidemiology.
The health impact from exposure to PFOS and PFOA is
not fully known, but previous studies
found that these compounds could cause tumors and
developmental toxicity in laboratory animals at
doses much higher than those observed in the Johns Hopkins
study.
The researchers analyzed cord serum from 293 newborns
delivered at The Johns Hopkins
Hospital between 2004 and 2005. The samples were tested for
the presence of PFOS and PFOA and
eight other polyfluoroalkyl compounds. The samples were
then matched to anonymous patient records,
which included measurement of height, weight and head
circumference of infants and other health
information.
PFOA was detected in all the samples and PFOS in all
but two. The concentrations for both
were lower than those typically detected in adults in the
United States and lower than those known to
cause tumors and developmental problems in laboratory
animals; more study is needed to understand
health effects at these lower exposure levels.
Lynn Goldman, co-author of the study and a professor
in the Bloomberg School's
Department of
Environmental Health Sciences, said, "Our study
population has a large proportion of mothers at
greater risk for adverse birth outcomes. Because of this,
and also because this is the first study to
report these associations, we need to be cautious in
interpreting these findings until they can be
replicated in other population."
Additional study authors are Frank R. Witter, Julie B.
Herbstman, Antonia M. Calafat, Rolf U.
Halden and Larry Needham. Witter is with the School of
Medicine and Halden, the Bloomberg School.
Herbstman, formerly a doctoral student at the Bloomberg
School, is now at the Columbia Mailman
School of Public Health. Calafat and Needham are with the
Centers for Disease Control and
Prevention.
The research was supported by funding from the
Bloomberg School of Public Health's Maryland
Mothers and Babies Study, Cigarette Restitution Fund, Johns
Hopkins Medical Institutions, Johns
Hopkins Center for a Livable Future and Heinz Family
Foundation.