Brominated flame retardant impairs male hormones
Animals may be feminized as a result of exposure to DE-71, or Penta, a commercial flame retardant mixture, according to research published online in Toxicology and Applied Pharmacology. The results “affirm that the effects of the [P]enta mixtures may pose real concerns for adverse effects on human reproductive function and sexual development,” according to the paper’s authors.
Previous research showed that exposure to the Penta polybrominated diphenyl ether (PBDE) mixture could significantly delay puberty and suppress the production of the androgenic hormones that stimulate and control the development and maintenance of masculine characteristics in male Wistar rats. The new research was conducted by a group of reproductive toxicologists from the U.S. EPA’s National Health and Environmental Effects Research Laboratory, who used in vivo tests with three different rat models to confirm these anti-androgenic effects.
If an androgen receptor is blocked, animals may be feminized. To gain insight into what was happening at the receptor level, the reseachers also used an in vitro test with the MDA-kb2 cell line, which contains a human androgen receptor. They found that the Penta mixture as a whole as well as a number of its component compounds, or congeners, interfered with the ability of dihydrotestosterone (DHT), a male hormone five times more potent than testosterone, to bind with the androgen receptor.
The brominated diphenyl ether–100 (BDE–100) congener, which is one of the PBDEs most likely to bioaccumulate in wildlife, was the most effective inhibitor of androgen receptor binding. “BDE–100 appears to be a fairly potent competitive inhibitor of the androgen receptor,” according to the paper. Anti-androgenicity is relatively rare, says Tammy Stoker, the paper’s lead author, who adds that “this is one of the higher anti-androgenic receptor findings” compared with other chemicals that have been shown to impair androgen ability.
Because increasing concentrations of PBDEs are being detected in the environment as well as in animals and humans, “other possible health effects need to be explored,” Stoker says, adding that her lab is involved in follow-up studies.
