(New York, NY - October 24, 2019) -Exposure during the first trimester of pregnancy to mixtures of suspected endocrine-disrupting chemicals found in consumer products is related to lower IQ in children by age 7, according to a study by researchers at the Icahn School of Medicine at Mount Sinai and Karlstad University, Sweden, published in Environment International in October. This study is among the first to look at prenatal suspected endocrine-disrupting chemical mixtures in relation to neurodevelopment.
Scientists measured 26 chemicals in the blood and urine of 718 mothers during the first trimester of their pregnancies in the study of Swedish mothers and children, known as SELMA. These chemicals included bisphenol A (BPA), which is found in plastic food and drink containers, as well as pesticides, phthalates, and other chemicals found in consumer products. Some of the 26 are known to disrupt endocrine (hormone) activity in humans; others have been shown to do so only in animals, or are suspected of endocrine disruption because they share chemical features with known disruptors.
Researchers later followed up with the children at age 7 and found that those whose mothers had higher levels of the chemicals in their system during pregnancy had lower IQ scores--particularly boys, whose scores were lower by two points. Within the mixture, bisphenol F (BPF), a BPA-replacement compound, made the highest contribution to lowering children's IQ, suggesting that BPF is not any safer for children than BPA.
The study found that other chemicals of concern in the mixture were the pesticide chloropyrifos; polyfluoroalkyl substances, which are found in cleaning products; triclosan, a chemical found in antibacterial soaps; and phthalates, which are found in soft polyvinyl chloride plastics and cosmetics. Many of the chemicals only stay in the body a short time, meaning that even a short-term exposure may be detrimental, so researchers believe this indicates that preventing exposures to pregnant women or women trying to become pregnant is critical to preventing neurological harm to children.
"This study is significant because most studies evaluate one chemical at a time; however, humans are exposed to many chemicals at the same time, and multiple exposures may be harmful even when each individual chemical is at a low level," said Eva Tanner, PhD, MPH, postdoctoral researcher in the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai.
Carl-Gustaf Bornehag, PhD, Professor at Karlstad University, says it shows that exposure to mixtures of chemicals in ordinary consumer products may affect child brain development and that some chemicals believed to be safer, like BPF, may not be any safer for children.
The chemicals interfere with hormone activity, even at low levels. Previous studies link numerous suspected endocrine disruptors, including phthalates and BPA, to neurodevelopmental difficulties in children.
Some of these chemicals cross the placenta during pregnancy, exposing the fetus and potentially causing irreversible developmental damage. While ending exposure to a short-lived pollutant may eliminate adverse effects in adults, exposure during critical periods of fetal development may be permanent, with subtle endocrine changes potentially influencing health outcomes into adulthood, Dr. Tanner said.
Dr. Tanner says this study only assessed exposure at a single time during early pregnancy, so more research needs to be done to understand how exposures throughout later pregnancy and childhood may influence the results. The researchers note that several of the chemicals studied only stay in the body for a short amount of time, so the mothers in the study may have had additional exposures before or after their blood and urine samples were taken.
Researchers note the study was observational, and further studies are needed to confirm these findings.
Karlstad University, Örebro University, Lund University, and the National Institute for Health and Welfare in Helsinki, Finland, made significant contributions to this research. This research was funded in part by the National Institute of Environmental Health Sciences (R01ES028811-01) and the European Union (EDC-MixRisk 634880).
About the Mount Sinai Health System
The Mount Sinai Health System is New York City's largest integrated delivery system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai's vision is to produce the safest care, the highest quality, the highest satisfaction, the best access and the best value of any health system in the nation. The Health System includes approximately 7,480 primary and specialty care physicians; 11 joint-venture ambulatory surgery centers; more than 410 ambulatory practices throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and 31 affiliated community health centers. The Icahn School of Medicine is one of three medical schools that have earned distinction by multiple indicators: ranked in the top 20 by U.S. News & World Report's "Best Medical Schools", aligned with a U.S. News & World Report's "Honor Roll" Hospital, No. 12 in the nation for National Institutes of Health funding, and among the top 10 most innovative research institutions as ranked by the journal Nature in its Nature Innovation Index. This reflects a special level of excellence in education, clinical practice, and research. The Mount Sinai Hospital is ranked No. 14 on U.S. News & World Report's "Honor Roll" of top U.S. hospitals; it is one of the nation's top 20 hospitals in Cardiology/Heart Surgery, Diabetes/Endocrinology, Gastroenterology/GI Surgery, Geriatrics, Gynecology, Nephrology, Neurology/Neurosurgery, and Orthopedics in the 2019-2020 "Best Hospitals" issue. Mount Sinai's Kravis Children's Hospital also is ranked nationally in five out of ten pediatric specialties by U.S. News & World Report. The New York Eye and Ear Infirmary of Mount Sinai is ranked 12th nationally for Ophthalmology and Mount Sinai South Nassau is ranked 35th nationally for Urology. Mount Sinai Beth Israel, Mount Sinai St. Luke's, Mount Sinai West, and Mount Sinai South Nassau are ranked regionally.
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