Exposure to Flame Retardants May Lower Male Reproductive Hormone.
Men exposed to higher levels of chemicals used as flame retardants had decreased levels of a hormone associated with sperm counts and male reproductive function, a new study led by School of Public Health researchers shows.
The study, published online in the journal Reproductive Toxicology, found that higher serum levels of some types of polybrominated diphenyl ethers, or PBDEs—chemicals that were used as flame retardants in furniture containing polyurethane foam—were associated with decreased levels of the hormone inhibin-B, and increased levels of the hormone FSH, a pattern that is sometimes present in men who are sub-fertile or infertile.
The authors wrote, “While hormone analysis would be used in combination with other reproductive function tests, clinical evaluations, and semen analysis in the determination of fertility status, we have evidence that PBDEs may be disrupting the hypothalamo-pituitary-testicular axis.”
The authors collected three rounds of serum samples from 27 healthy men in the Boston area. They noted that the study was small and urged that results be replicated in a larger study.
The study found that the association between PBDE levels and decreased inhibin-B was especially pronounced in men ages 40 and older. Inhibin-B is produced in the testis and is important for the production of semen. The authors said their findings were consistent with two other studies reporting that PBDE exposure was associated with decreases in inhibin-B and sperm concentration, but that three other previous studies had reported a positive association between PBDEs and inhibin-B.
“Human studies have found associations between PBDE exposure and male reproductive hormones, (but) the direction of associations are inconsistent,” they said.
This was the first study to use repeated serum measures to assess the association between the chemical additive and male reproductive hormones.
PBDEs were used in furniture from the 1970s until 2004, when US chemical manufacturers voluntarily withdrew PentaBDE, a chemical mixture that contained PBDEs, from production. However, older products containing PentaBDE remain in use in houses, offices, and vehicles. PentaBDEs also are found in some food products.
The study found no significant associations between PBDEs and testosterone concentrations.
The authors noted that their study participants were predominately white, highly educated men—not representative of the general population.
The study was led by Colleen Makey, a postdoctoral research fellow in environmental health at SPH. Co-authors from SPH include Michael McClean, associate professor of environmental health, Janice Weinberg, professor of biostatistics, and Thomas Webster, professor of environmental health. Other authors include Lewis Braverman, professor of medicine at the School of Medicine; Elizabeth Pearce, associate professor of medicine at MED, and Andreas Sjödin from the Centers for Disease Control and Prevention.
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