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Endocrine-disrupting Chemical Effects Testosterone

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.
August 15, 2014
General chemical structure of phthalates.
(R and R' are general placeholders)
(Image credit: Wikipedia)
According to a new paper published in the Endocrine Society's Journal of Clinical Endocrinology and Metabolism, men, women and children who are exposed to high levels of phthalates tend to have reduced levels of testosterone in their blood compared to those with lower chemical exposure. Phthalates or phthalate esters are esters of phthalic acid.  They are mainly used as plasticizers. Plasticizers are substances that are added to plastics to increase their flexibility, transparency, durability, and longevity. One example of plasticizers is the new car smell. The manufacturing process of phthalates is by reacting phthalic anhydride with alcohol(s) that range from methanol and ethanol up to tridecyl alcohol; these can be either as a straight chain or with some branching. They are divided into two distinct groups; they have various applications, toxicological properties, and classification, based on the number of carbon atoms in their alcohol chain.
The main sex hormone in men is testosterone. However, testosterone has a variety of functions in both men and women. These functions include physical growth and strength, brain function, bone density and cardiovascular health. There has been a trend in the last 50 years. A declining testosterone in men and a rise in heath related conditions which include reduced semen quality in men and genital malformations in newborn boys.
Some studies conducted in animals and cells have found that some phthalates block the effects of testosterone on the body's organs and tissues. Researchers wanted to find out if these chemicals, which are used in flexible polyvinyl chloride (PVC) plastics and personal care products, had a similar effect in humans. There are two different forms of PVC. One is rigid; it is sometimes abbreviated as RPVC like construction pipe; the other as previously mentioned is flexible. The later form is also used in plumbing, electrical cable insulation, faux leather, signage, inflatable products and other applications where it replaces rubber.
"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. Urine samples were analyzed 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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Source: Endocrine Society