PFOS and PFOA in Humans
New Study Links Prenatal Exposure to Lower Birth Weight
Scientists have accumulated a wealth of evidence that
perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA, also
known as perfluorooctanoic acid) accumulate in the environment and
humans. Animal studies have shown these compounds to cause a variety of
health effects, including reduced birth size and infant mortality. Now
researchers are presenting the first evidence to suggest that human
exposure to the chemicals is linked to reduced birth weight
[
EHP 115:1670–1676; Apelberg et al.].
PFOS, PFOA, and related polyfluoroalkyl compounds (PFCs) that can be
transformed into these chemicals in the environment are used in a wide
range of consumer applications, including oil and water repellents for
fabric, apparel, and carpets, and paper coatings such as fast-food
wrappers. The chemicals have been found in the blood of people
throughout the world.
The new study shows that infants born with higher
concentrations of PFOS and/or PFOA in their umbilical cord serum (a
measure the researchers used as a marker of
in utero
exposure) had lower birth weights. The authors calculate the reduction
as –69 g for PFOS and –104 g for PFOA. The study population included
293 infants born in Baltimore, Maryland, in 2004 and 2005. In earlier
research, PFOA had been found in all these infants, and PFOS had been
found in 99% of them. Infants with higher levels of PFOS and PFOA also
had smaller head circumferences and lower scores on the ponderal index,
a measure of body mass at birth. The study was not designed to allow
the cohort to be followed in the future.
The results are consistent with those of
toxicologic studies conducted with mice and rats that also have linked
exposure to PFOS and PFOA with low birth weight—albeit at doses that
resulted in much higher body burdens than those seen in the Baltimore
infants. Both compounds have also been tied to developmental delays in
animal studies. Previous studies in humans have correlated low birth
weight with obesity, diabetes, and cardiovascular diseases later in
life.
The researchers stress that the effect was small
but statistically significant. They also note that the concentrations
of PFOS, PFOA, and other PFCs in the infants' blood were relatively low
compared with levels tested in other studies.
The results were statistically adjusted to
consider other potential sources of altered birth weight, such as
maternal smoking, diabetes, and hypertension. The new study did not
find a correlation between levels of the compounds and socioeconomic
status, as had previous research. The researchers also found no
evidence of an association between the infants' exposure to the
chemicals and their cholesterol or triglyceride levels, despite
previous human and animal studies suggesting that these blood lipids
are particularly sensitive to PFC exposure.
Originally published on http://www.ehponline.org/docs/2007/115-11/ss.html
