Testing amniotic fluid collected from pregnant women two to three decades ago, researchers detected low levels of three common chemicals – the phthalates DEHP and DiNP and the stain-resisting chemical PFOS – in almost every sample they examined.
This study is important because it measures these contaminants directly in amniotic fluid. It is the first published study to measure PFOS and one of just a handful that have measured the phthalates in the fetal liquid.
There is no definitive answer yet about whether pre-birth exposure to these two phthalates or PFOS harms the developing child or has long-lasting effects.
Amniotic fluid may be a good marker of what a fetus is exposed to because only some of what is found in the blood or urine of the mother crosses the placenta and enters the fetus. The ability to more accurately determine exposure is important for studies looking at health effects.
DEHP, DiNP, and PFOS have been measured in the urine and blood of pregnant women and the umbilical cord blood of newborns. There is very little information about the presence of these chemicals in human amniotic fluid.
The phthalates DEHP and DiNP are added to polyvinyl plastic to make it flexible. These chemicals are used in products such as soft plastic toys, medical tubing, wall coverings, floor tiles, shower curtains and food packaging. People are exposed primarily through eating, touching or breathing them in from the air. Once phthalates enter the body, they quickly metabolize and are excreted in urine in less than a day.
Animal studies show DEHP is linked to liver cancer and may have reproductive effects. A recent study linked prenatal exposure to poorer reflexes in newborn boys. Because of concerns for children’s health, the United States and Europe have banned DEHP and other phthalates from children’s toys and products and DiNP from children’s toys small enough to chew.
PFOS is used to manufacture stain-repellent coatings for carpets, textiles and paper. People are exposed through eating food contaminated by the packaging and breathing household dust. PFOS can circulate in blood for several years. PFOS may affect thyroid function and the important suite of thyroid hormones that direct development, metabolism and reproduction.
In this study, researchers analyzed stored samples of amniotic fluid from 300 women in Denmark who were pregnant with sons between 1980 and 1996. They measured indicators for seven phthalates and the perflourinated chemical PFOS. The amniocenteses were performed from the 10th to the 30th week of pregnancy.
One DEHP marker, one DiNP marker and PFOS were detected in 96 to 99 percent of the amniotic fluid samples.
The later in pregnancy the amniocentesis was performed, the higher the level of each chemical in the amniotic fluid. Additionally, over the 16 years when amniotic fluid samples were collected, DEHP metabolite levels appeared to decrease and DiNP metabolite levels appeared to increase.
There was little change in PFOS levels over this time period, which is interesting because industrial use of this chemical was increasing. There did not appear to be any association between chemical levels and either the mother’s age or how many times she had been pregnant.