For immediate release: August 25, 2017
Boston, MA – Women with higher urinary concentrations of a common type of flame retardant had reduced likelihood of clinical pregnancy and live birth than those with lower concentrations, according to researchers at Harvard T.H. Chan School of Public Health. The study, conducted in the Fertility Clinic at Massachusetts General Hospital, is the first to examine associations between organophosphate flame retardants (PFRs)—which are used in polyurethane foam in many products, including upholstered furniture, baby products, and gym mats—and reproductive outcomes in women. [[Note on September 8, 2017: The researchers note that to their knowledge flame retardants are not in yoga mats.]]
“These findings suggest that exposure to PFRs may be one of many risk factors for lower reproductive success,” said first author Courtney Carignan, who conducted the work while a research fellow in the Department of Environmental Health at Harvard Chan School and now is an assistant professor at Michigan State University. “They also add to the body of evidence indicating a need to reduce the use of these flame retardants and identify safer alternatives.”
The study was published online August 25, 2017 in Environmental Health Perspectives.
One in six couples struggles with infertility—a proportion likely to rise as increasing numbers of people in developed countries delay childbearing. Previous studies have linked exposure to products containing hormone-disrupting chemicals, such as pesticides and phthalates, to infertility and poorer reproductive success.
The flame retardant PentaBDE, used in polyurethane foam, was phased out more than a decade ago after it was linked with negative health effects in animal and epidemiologic studies. PFRs were introduced as a safer alternative, but they have been found in animal studies to cause hormone disruption. Studies have also shown that PFRs can migrate out of furniture and other products into the air and dust of indoor environments.
For this study, the researchers analyzed urine samples from 211 women undergoing in vitro fertilization (IVF) at the Massachusetts General Hospital Fertility Center between 2005 and 2015. The women were enrolled in the Environment and Reproductive Health (EARTH) study, which looks at how environmental chemicals and lifestyle choices affect reproductive health. The statistical analysis took into consideration factors including maternal age and race, smoking history, and body mass index (BMI).
The researchers found that the urinary metabolites (products of a chemical that has been metabolized) of three PFRs— TDCIPP, TPHP, and mono-ITP—were detected in more than 80% of participants. On average, compared to women with lower concentrations of these metabolites, women with higher concentrations had a 10% reduced probability of successful fertilization, 31% reduced probability of implantation of the embryo, and a 41% and 38% decrease in clinical pregnancy (fetal heartbeat confirmed by ultrasound) and live birth.
“Couples undergoing IVF and trying to improve their chances of success by reducing their exposure to environmental chemicals may want to opt for products that are flame-retardant free,” said senior author Russ Hauser, Frederick Lee Hisaw professor of reproductive physiology and acting chair, Department of Environmental Health.
Further research is needed on the potential impact of male partners’ exposure to flame retardant chemicals and on the joint effects on both men and women of exposure to different types of environmental chemicals, the researchers said.
Other Harvard Chan authors include Lidia Mínguez-Alarcón, Paige Williams, and Jennifer Ford.
This study was supported by grants ES009718, ES022955, ES000002, and T32ES007069 from the National Institute of Environmental Health Sciences (NIEHS).
“Urinary Concentrations of Organophosphate Flame Retardant Metabolites and Pregnancy Outcomes among Women Undergoing in Vitro Fertilization,” Courtney C. Carignan, Lidia Mínguez-Alarcón, Craig M. Butt, Paige L. Williams, John D. Meeker, Heather M. Stapleton, Thomas L. Toth, Jennifer B. Ford, and Russ Hauser, Environmental Health Perspectives, August 25, 2017, doi: 10.1289/EHP1021
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Harvard T.H. Chan School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory to people’s lives—not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at Harvard Chan School teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America’s oldest professional training program in public health.