It’s not the plastics themselves that are affecting testosterone levels in men, women and children - it’s the endocrine-disrupting phthalates they contain. These chemicals make plastics more flexible and are used in hundreds of non-plastic products, including some soaps, shampoos, hair sprays, and nail polishes as well as packaging, inflatable toys and other children's playthings. A new study from the University of Michigan School of Public Health found that the more exposure to phthalates in your life, the higher the risk of declining testosterone levels, the main sex hormone in men that also plays an important role in physical growth and strength, brain function, bone density and cardiovascular health in both sexes.
Testosterone levels in the general population have been dropping in the last 50 years, leading to greater prevalence of reduced semen quality in men and genital malformations in baby boys, the Michigan researchers said. They note that animal and cellular studies have shown that phthalates block the effects of testosterone on the body's organs and tissues. Researcher John D. Meeker, M.S., Sc.D., explained that “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."
My take? It's a good idea to avoid phthalates, but it is also very difficult, since they're found in so many different products. You can't even be sure that a product labeled "phthalate free" won't expose you to the chemicals - there may be none of the compound in the product itself, but they may be present in the packaging. By the way, the European Union and other countries have banned phthalates in consumer products, and in 2007 California became the first state in the U.S. to ban use of six phthalates in children's products and toys.
John D. Meeker, Kelly K. Ferguson. “Urinary Phthalate Metabolites Are Associated With Decreased Serum Testosterone in Men, Women, and Children From NHANES 2011–2012.” The Journal of Clinical Endocrinology & Metabolism, 2014; jc.2014-2555 DOI: 10.1210/jc.2014-2555