Almost 100 Percent Of Pregnant Women Test Positive For These Four Groups Of Chemicals Including Some That Are Banned
Four groups of chemicals are found in virtually 100 percent of all U.S. pregnant women, including some banned since the 1970s and others used in common products such as non-stick cookware, processed foods and personal care products. Not only were the chemicals found in pregnant women tested but also in amniotic fluid providing some of the best evidence to date of fetal exposures.
Analyzing data for 163 chemicals, researchers detected polychlorinated biphenyls (PCBs), organochlorine pesticides, perfluorinated compounds (PFCs), phenols, polybrominated diphenyl ethers (PBDEs), phthalates, polycyclic aromatic hydrocarbons (PAHs) and perchlorate in 99 to 100 percent of pregnant women. Among the chemicals found in the study group were PBDEs, compounds used as flame retardants now banned in many states including California, and dichlorodiphenyltrichloroethane (DDT), an organochlorine pesticide banned in the United States in 1972.
UC Riverside scientists have done research using rat tissue that shows that PBDEs disrupt mechanisms that are responsible for releasing hormones in the body. Moreover, their work has shown that like polychlorinated biphenyls (PCBs), whose manufacture in the U.S. was discontinued in 1977, PBDEs alter calcium signaling in the brain -- a critical mechanism for transmitting information between and within brain cells, for learning and memory, and for regulating the release of hormones in the body.
"Long-term exposures to PBDEs may pose a human health risk, especially to infants and toddlers who are more likely to ingest household dust or acquire these chemicals through mother's milk," said Margarita Curras-Collazo, an associate professor of cell biology and neuroscience.
Testing amniotic fluid collected from pregnant women two to three decades ago, other researchers have detected low levels of three common chemicals -- the phthalates DEHP and DiNP and the stain-resisting chemical PFOS -- in almost every sample they examined.
Bisphenol A (BPA), which makes plastic hard and clear, and is found in epoxy resins that are used to line the inside of metal food and beverage cans, was identified in 96 percent of the women surveyed. Prenatal exposure to BPA has been linked to adverse health outcomes, affecting brain development and increasing susceptibility to cancer later in life, according to the researchers.
"It was surprising and concerning to find so many chemicals in pregnant women without fully knowing the implications for pregnancy," said lead author Tracey Woodruff, PhD, MPH, director of the UCSF Program on Reproductive Health and the Environment.
"Several of these chemicals in pregnant women were at the same concentrations that have been associated with negative effects in children from other studies. In addition, exposure to multiple chemicals that can increase the risk of the same adverse health outcome can have a greater impact than exposure to just one chemical," said Woodruff, an associate professor in the UCSF Department of Obstetrics and Gynecology and Reproductive Sciences.
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.
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.
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.
One DEHP marker, one DiNP marker and PFOS were detected in 96 to 99 percent of the amniotic fluid samples.
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.
Exposure to chemicals during fetal development has been shown to increase the risk of adverse health consequences, including preterm birth and birth defects, childhood morbidity, and adult disease and mortality according to the research team.
"Our findings indicate several courses of action. First, additional research is needed to identify dominant sources of exposure to chemicals and how they influence our health, especially in reproduction," said Woodruff. "Second, while individuals can take actions in their everyday lives to protect themselves from toxins, significant, long-lasting change only will result from a systemic approach that includes proactive government policies."
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.