A first-of-its-kind epidemiologic study shows a link between exposure to organophosphate flame retardants (PFRs) and infertility. The results, in women recruited from an academic fertility clinic, reflect levels of exposure that are not abnormal or high, say the researchers.
Published in Environmental Health Perspectives, the analysis included 211 women enrolled in the Environment And Reproductive Health (EARTH) prospective cohort study who provided 1 or 2 urine samples per in vitro fertilization (IVF) cycle. Established in 2004, EARTH was designed to evaluate environmental and dietary determinants of fertility from patients undergoing assisted reproduction at the Massachusetts General Hospital Fertility Center.
The average age of the participants was 35, 87% were white, 75% had never smoked and 34% had a prior pregnancy. The cause of infertility was female factor in 36%, male factor in 29%, and unexplained in 35% of the cases.
The five PFS metabolites examined in the women’s urine were [bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPHP), isopropylphenyl phenyl phosphate (ip-PPP), tert-butylphenyl phenyl phosphate (tb-PPP), and bis(1-chloro-2-propyl phosphate (BCIPP). They were measured with negative electrospray ionization liquid chromatography tandem mass spectrometry (LC-MS/MS). Multivariable generalized linear mixed models were used to evaluate the association between PFR metabolites and IVF outcomes, accounting for multiple IVF cycles per woman.
According to researchers from the National Institute of Environmental Health Sciences, PFRs are commonly used in consumer products that contain polyurethane foam. They are alternatives to polybrominated diphenyl ethers (PBDEs), which had been used in the foam and electronics but were phased out in the mid-2000s because of concerns about persistence, bioaccumulation, and toxicity.
In the epidemiologic study, 3 of the PFS metabolites were detected at high frequency in urine samples—BDCIPP 87%, DPHP 94%, and ip-PPP 80%—whereas detection frequencies were low for tb-PPP and BCIPP (14% and 0%, respectively). In the adjusted multivariable models, decreased success for several IVF outcomes was seen across increasing quartiles of both summed and individual PFR metabolites. Significant decreases in adjusted means from the lowest to highest quartile of mean PFR were observed in the proportion of cycles resulting in successful fertilization (10% decrease, P trend = 0.04), implantation (31%, P trend = 0.02), clinical pregnancy (41%, P trend = 0.004) and live birth (38%, P trend = 0.05).
The PFR metabolite concentrations in the women’s urine, the authors noted, was similar to or lower than that in other adult populations in the United States, Norway and Australia. Their research, they said, is the first epidemiologic study to explore the effects of PFRs on female reproduction. The findings may be more relevant to older women because the mean age of the population was 35 years but are limited by the fact that male partner exposure to PFRs was not considered and may contribute to the association that was observed.