By: Rachael Rettner, MyHealthNewsDaily Senior Writer
Published: 05/08/2013 01:09 PM EDT on MyHealthNewsDaily
Chronic exposure to the chemical bisphenol A (BPA) may lower testosterone levels in men, a new study from China suggests.
In the study, men who were exposed to BPA because they worked in a chemical plant for at least six months had lower levels of testosterone in their blood compared with those who worked in a tap water factory.
Specifically, chemical plant workers had reduced levels of "free" testosterone, which is the form thought to have the greatest influence on the body. (Most testosterone in the body is not "free," but is bound to a protein.)
The findings provide even more evidence that BPA may change men's sex hormone levels, said study researcher Dr. De-Kun Li, a senior research scientist at Kaiser Permanente's Division of Research in Oakland, Calif.
Previous studies, also conducted on Chinese factory workers, have suggested that BPA may lower sperm counts as well as increase the risk of sexual dysfunction in men -- health effects that are controlled in part by sex hormones.
BPA is similar to the female hormone estrogen, meaning that it could have effects on the human body. The effect of BPA on men may be more immediate and easier to detect than the effect on women, because men have very low levels of estrogen to begin with, Li said. [See Is BPA Really a Health Hazard?]
However, whether similar effects would be seen in the general population at lower exposure levels is not known, and need to be studied further. BPA is found in some plastics, canned food containers and other food packaging, and most people in the U.S. have the chemical in their urine.
Heather Patisaul, an associate professor at North Carolina State University who studies the effects of BPA, noted that the study looked at BPA in the blood, rather than the urine. BPA levels in the blood are thought to be a better measure of chronic exposure to the chemical, but are typically very low, and could be influenced by environmental contamination, Patisaul said.
Men who don't work in a chemical factory would likely have BPA levels in their blood that are too low to detect, Patisaul said. In the study, about 70 percent of men who worked in the chemical plant had detectable levels of BPA in their blood, while the same was true of 5 percent of those who worked in the water factory.
"This data should not raise alarm bells for men who don't work in chemical factories," Patisaul said.
Patisaul said that the new study was small and did not do a great job of accounting for differences in hormone levels that might be due to the time of day samples were collected.
The study was published online May 6 in the journal Fertility and Sterility.
Pass it on: Exposure to BPA in the workplace is linked to lower testosterone levels in men.
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Vinyl Shower Curtains
The <a href="http://www.cbsnews.com/2100-18560_162-6506892.html" target="_hplink">phthalate</a> DEHP has been found in vinyl products, and has been <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453150/" target="_hplink">linked to respiratory problems</a>. <em>Flickr photo by <a href="http://www.flickr.com/photos/krossbow/1968630550/" target="_hplink">krossbow</a></em>
Fragrances not only trigger asthma but, the researchers say, have been shown to mimic estrogen, and <a href="http://www.silentspring.org/pdf/in_the_news/product-test-press-release.pdf" target="_hplink">can make breast cancer cells grow</a> in laboratory tests.
Like in air fresheners, the fragrances in dryer sheets can trigger asthma and <a href="http://www.silentspring.org/pdf/in_the_news/product-test-press-release.pdf" target="_hplink">mimics estrogen</a>. <em>Flickr photo by <a href="http://www.flickr.com/photos/cckaiser/3937339260/" target="_hplink">cckaiser</a></em>
It goes without saying that perfumes can similarly trigger respiratory issues. Some may also <a href="http://www.silentspring.org/pdf/in_the_news/product-test-press-release.pdf" target="_hplink">mimic estrogen</a>. <em>Flickr photo by <a href="http://www.flickr.com/photos/photographygal123/4661217208/" target="_hplink">Lauren Tucker Photography</a></em>
Sunscreens have some of the <a href="http://www.silentspring.org/pdf/in_the_news/product-test-press-release.pdf" target="_hplink">largest concentrations of chemicals</a>, according to the researchers, including <a href="http://www.webmd.com/asthma/news/20120307/study-links-common-household-products-asthma" target="_hplink">cyclosiloxanes</a>, according to WebMD, which produced <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1566344/" target="_hplink">liver and lung damage</a> in mice in one study.
Even "alternative" cleaning solutions, considered by many of us to be greener and safer, tested positive for some of the 55 chemicals the researchers focused on. They suggest cleaning with baking soda and vinegar, when appropriate.
In detergents and soaps, watch out for <a href="http://www.webmd.com/asthma/news/20120307/study-links-common-household-products-asthma" target="_hplink">alkylphenols</a>, which seem to exhibit <a href="http://www.epa.gov/opptintr/existingchemicals/pubs/actionplans/np-npe.html" target="_hplink">estrogen-like properties</a>.
Many cosmetics contain parabens as preservatives, but the class of chemical is shown to act similarly to estrogen. However, like many potential endocrine disruptors, parabens have been <a href="http://www.fda.gov/cosmetics/productandingredientsafety/selectedcosmeticingredients/ucm128042.htm" target="_hplink">approved up to a certain amount by the FDA</a> for use in cosmetics, and most are used at levels far below the upper limit. <em>Flickr photo by <a href="http://www.flickr.com/photos/jenniewoo/3733993/" target="_hplink">Jennie Faber</a></em>
Shampoo And Conditioner
Along with cleaning solutions, the researchers tested "alternative" shampoos and conditioners and discovered potentially harmful chemicals. In fact, according to the press release: <blockquote>A consumer who used the tested alternative surface cleaner, tub and tile cleaner, laundry detergent, bar soap, shampoo and conditioner, facial cleanser and lotion and toothpaste would be exposed to 19 of the target compounds.</blockquote> Like cosmetics, many may also contain parabens.