REDUCED TESTOSTERONE TIED TO ENDOCRINE- DISRUPTING CHEMICAL EXPOSURE
Men, women and
children exposed to high levels of phthalates -- endocrine-disrupting chemicals
found in plastics and some personal care products -- tended to have reduced
levels of testosterone in their blood compared to those with lower chemical
exposure, according to a new study published in the Endocrine Society's Journal of Clinical Endocrinology
& Metabolism (JCEM).
Testosterone is the
main sex hormone in men. It contributes to a variety of functions in both
sexes, including physical growth and strength, brain function, bone density and
cardiovascular health. In the last 50 years, research has identified a trend of
declining testosterone in men and a rise in related health conditions,
including reduced semen quality in men and genital malformations in newborn
boys.
Animal and cellular
studies have found that some phthalates block the effects of testosterone on
the body's organs and tissues. Researchers set out to examine whether these
chemicals, which are widely used in flexible PVC plastics and personal care
products, had a similar effect in humans.
"We found
evidence 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 one of the study's authors, John
D. Meeker, MS, ScD, of the University of Michigan School of Public Health in
Ann Arbor, MI. "This may have important public health implications, since
low testosterone levels in young boys can negatively impact reproductive
development, and in middle age can impair sexual function, libido, energy,
cognitive function and bone health in men and women."
The cross-sectional
study examined phthalate exposure and testosterone levels in 2,208 people who
participated in the U.S. National Health and Nutrition Examination Survey,
2011-2012. Researchers analyzed urine samples to measure concentrations of 13
substances left after the body metabolizes phthalates. Each participant's
testosterone level was measured using a blood sample.
Researchers found an inverse
relationship between phthalate exposure and testosterone levels at various life
stages. In women ages 40-60, for example, increased phthalate concentrations
were associated with a 10.8 to 24 percent decline in testosterone levels. Among
boys ages 6-12, increased concentrations of metabolites of a phthalate called
di-(2-ethylhexyl) phthalate, or DEHP, was linked to a 24 to 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."
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