Exposure to Phthalate Tied to Reduced Testosterone Level

Adults and young boys exposed to high levels of phthalates, found in plastics, have low levels of testosterone in the blood.

The main sex hormone in men is testosterone that contributes to a variety of functions in both sexes. This not just includes the physical growth and strength, but also brain function, bone density as well as cardiovascular health. Over the last 50 years, experts have observed a drop in the level of testosterone in men and a rise in health conditions. The related health conditions include reduced semen quality and genital malformation in newly-born boys.

Animal and cellular studies conducted in the past have revealed that few phthalates curb the effect of testosterone on the body organs and tissues. In this new study, led by researchers at the University of Michigan, it was investigated whether the wide use of PVC plastics as well as personal care products, offered similar detrimental effects on humans.

"We found that reduced levels of circulating testosterone were associated with increased phthalate exposure in several key populations, including boys ages 6-12, and men and women ages 40-60," said John Meeker, associate professor of environmental health science at the U-M School of Public Health.

According to the researchers, this finding can stand as a crucial health implication as reduced testosterone levels in young boys negatively affect the reproductive development; and as they enter mid age - it can impair sexual functions, cognitive functions and bone health in men and women.

To investigate the association between the two conditions, the researchers examined the levels of testosterone as well as exposure to phthalate in 2,208 subjects who were a part of the U.S. National Health and Nutrition Examination Survey that was conducted between 2011 and 2012.

They also examined the urine samples to measure the concentration of 13 substances that were left once the body metabolizes the phthalates. The testosterone level was measured using the blood sample.

They observed an opposite association between phthalate exposure and levels of testosterone at several stages of life. Women aged between 40-60 years had high concentrations of phthalate that was linked with 10.8-2-4 percent drop in testosterone levels. Whereas in boys, the higher concentration of metabolites of phthalate called di-(2-ethylhexyl) phthalate (DEHP) was tied to 24-34.1 percent drop in testosterone levels.

"While the study's cross-sectional design limit the conclusions we can draw, our results support the hypothesis that environmental exposure to endocrine-disrupting chemicals such as phthalates could be contributing to the trend of declining testosterone and related disorders," Meeker said. "With mounting evidence for adverse health effects, individuals and policymakers alike may want to take steps to limit human exposure to the degree possible."

The finding was documented in Journal of Clinical Endocrinology & Metabolism.