Exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in the womb 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, 2007, online edition of the journal Environmental Health Perspectives. Some of the study's findings were previously reported at a Society of Toxicology workshop held in February.
PFOS and PFOA are polyfluoroalkyl compounds (PFCs)--ubiquitous man-made chemicals used in a variety of consumer products, including as a protective coating on food-contact packaging, textiles and carpets and in the manufacturing of insecticides and other industrial products.
The study, conducted in Baltimore, Md., found small decreases in head circumference and body weight in association with 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 (BMI). For unknown reasons, the reductions in birth weight and head circumference were not observed among 65 infants born by caesarian 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, PhD, lead author of the study and a research associate in the Bloomberg School of Public Health's Department of Epidemiology.
The health impact from exposure to PFOS and PFOA is not fully known, but previous studies found these compounds could cause tumors and developmental toxicity in laboratory animals at doses much higher than those observed in the Hopkins study.
The researchers analyzed cord serum from 293 newborns delivered at Johns Hopkins Hospital in Baltimore 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 of the samples and PFOS in all but two of the samples. The concentrations for both compounds 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.
"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 populations," said Lynn Goldman, MD, co-author of the study and a professor in the Department of Environmental Health Sciences at the Bloomberg School of Public Health.
Addition authors of "Cord Serum Concentrations of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA) in Relation to Weight and Size at Birth" include Frank R. Witter, Julie B. Herbstman, Antonia M. Calafat, Rolf U. Halden and Larry Needham. Witter is with the Johns Hopkins School of Medicine. Halden is with the Johns Hopkins Bloomberg School of Public Health. Herbstman, formerly a doctoral student in Epidemiology at the JHSPH 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 Johns Hopkins Bloomberg School of Public Health's Maryland Mothers and Babies Study, the Cigarette Restitution Fund, Johns Hopkins Medical Institutions, Johns Hopkins Center for a Livable Future and the Heinz Family Foundation.