The research adds to the growing suspicion that low-dose exposures to phthalates and other common chemicals may be reducing testosterone levels or function in men, and thereby contributing to rising obesity rates and an epidemic of related disorders, such as Type 2 diabetes, said lead author Richard Stahlhut, M.D., M.P.H., a Preventive Medicine resident at the University of Rochester. The study was published today in the online edition of the journal Environmental Health Perspectives.
"Substantial declines in testosterone levels and sperm quality have been observed in the United States and other countries over the last several decades which and it urgently requires explanation," Stahlhut said. "While we can’t say yet that phthalates are a definite cause, I am certain they are on the list of chemicals that demands careful study."
Phthalates have been widely used for more than 50 years, but only recently implicated as a possible health risk in people. Animal studies have shown consistently that phthalates depress testosterone levels. Recent human studies have found that phthalates are associated with poor semen quality in men and subtle changes in the reproductive organs in boy babies. This connection between phthalates and testosterone helped to establish a basis for the study, Stahlhut said.
Stahlhut’s group hypothesized that phthalates might have a direct link to obesity, since low testosterone appears to cause increased belly fat and pre-diabetes in men. They analyzed urine, blood samples and other data from the National Health and Nutrition Examination Survey. The NHANES is a large, multi-ethnic, cross-section sampling of the
Source:University of Rochester Medical Center