By Kerry Grens
NEW YORK (Reuters Health) - Babies' early exposure to chemicals used in non-stick and stain-resistant products was not linked to small body size at age seven in a new study from Denmark looking at the chemicals' effects on growth.
Previous research has tied prenatal exposure to elevated levels of perfluorinated chemicals, such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), to both lower birth weights in boys and greater risk of obesity in young adulthood among both men and women.
Although the latest study did not find any effects on growth during childhood, Julie Herbstman, an assistant professor at Columbia Mailman School of Public Health who was not involved in the study, said, "I don't think it's definitive about the effects of prenatal exposure to perfluorinated compounds."
Perfluorinated chemicals have been widely used in consumer products, from stain-resistant carpet to non-stick cookware and food packaging.
Companies in the U.S. have begun to phase out use of perfluorinated chemicals in response to health concerns, but the chemicals persist in the body and in the environment, taking years to break down.
To see whether exposure to these chemicals influences growth after birth, Camilla Schou Andersen at Bispebjerg and Frederiksberg University Hospital in Denmark and her colleagues tracked more than 800 children from the womb to seven years of age.
The researchers collected blood from mothers while they were pregnant and from the umbilical cord blood when the babies were born to determine the levels of perfluorinated chemicals the children were exposed to in utero.
Then, seven years later, the research group measured the children's waists and overall body size.
The concentrations of perfluorinated chemicals the kids were exposed to before birth had no bearing on children's growth later on, the researchers report in the American Journal of Epidemiology.
"Prenatal exposure to perfluoroalkyl acids may reduce the infancy weight and body mass index in boys, but the present results suggest that a growth deficit may be recovered between infancy and childhood," they write.
Eight of the largest manufacturers of PFOA in the U.S. have agreed to eliminate products containing PFOA and emissions of the chemical by 2015.
The main producer of PFOS, 3M, eliminated the chemical from its products in 2002.
The Danish researchers note in their report that it's possible perfluorinated chemicals have a greater effect during development than later in childhood. And that low-birthweight is itself associated with adult obesity risk, which could explain the link to later-life obesity seen in other studies.
Herbstman said the study was well conducted, but that it needs to be repeated in other populations to be able to say for sure that perfluorinated chemicals don't affect children's growth.
It's also possible that the chemicals could affect children later in life, during puberty, because perfluorinated compounds are known to interfere with hormones and puberty is a time of significant hormonal changes, she added.
Moreover, body size later in life is not the only concern regarding the consequences of low birth weight, Herbstman pointed out.
"You worry about kids having cognitive problems, cardiovascular problems. Just because you're not seeing an association with (body size) at age seven, this doesn't reassure me these compounds are safe," she said.
SOURCE: http://bit.ly/1auHnIR American Journal of Epidemiology, online July 3, 2013.