Flame retardants in dust may alter men's hormone levels.

Meeker, JD, PI Johnson, D Camann and R Hauser. 2009. Polybrominated diphenyl ether (PBDE) concentrations in house dust are related to hormone levels in men. Science of the Total Environment doi:10.1016/j.scitotenv.2009.01.03.

Testosterone levels were significantly lower in men who lived in homes with high concentrations of flame retardants in house dust than those in homes with low levels of the chemicals in the dust.

The study of 24 adult men is the first to compare PBDE levels in dust with hormone levels in adult men.

This study was small, and the findings must be considered preliminary. However, it does suggest that a common household exposure to the chemicals known as PBDEs may be associated with altered hormone levels in men.

PBDEs are chemicals widely used to reduce the flammability of electronics, plastics and furniture. The chemicals are known to leach out of products and are widely found in house dust. Indoor dust is thought to be one of the main sources of human exposure to the chemicals.

Animal studies show that PBDEs have hormonal properties, including mimicking estrogens and interfering with testosterone.

Researchers recruited the men from infertility clinics in the US and then measured hormone levels in their blood and PBDE levels in their homes. Levels of testosterone traveling by itself -- not attached to a carrier molecule -- in the blood were estimated to be about 15 percent lower among men with high concentrations of three PBDEs in their homes compared to those with low levels of PBDEs.

Levels of luteinizing hormone, which stimulates the release of testosterone, and follicle-stimulating hormone, which is involved in the production of sperm, were about 30 percent lower in men with high PBDE exposure.

Consistent with recent studies, the study also found higher levels of the thyroid hormone, thyroxine, in men with higher PBDE exposure.