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MEDIA CENTER Plastic Ups the Endocrine Ante According to Population Council Research NEW YORK (5 January 2004) — According to recently released research from Population Council scientists and collaborators, rats exposed to chronic, low levels of a common agent used in plastics develop an increase in sex hormone levels, researchers report. DEHP [di-(2-ethylhexyl) phthalate] is a phthalate ester, a compound used in plastics from shampoo bottles to medical tubing. DEHP is abundant in the environment, and estimates suggest that the average person consumes about 6 mg a day. Phthalate esters have been implicated in disruption of testicular function, but previous studies have only looked at acute exposures in large amounts. Matthew Hardy and colleagues examined the effect of chronic exposure on pubertal rats. The researchers exposed the rats to DEHP, in amounts similar to those that would be encountered in the environment, for 4 weeks or longer. Measuring the concentrations of hormones in the blood, the researchers found that both estradiol and testosterone were increased in exposed rats. Interestingly, Leydig cells, which produce the hormones, actually decreased their testosterone output, but the total number of hormone-producing cells rose. While none of the rats developed cancer, proliferation of Leydig cells has been implicated in some testicular cancers. In addition, high levels of circulating steroid hormones could lead to early puberty. The authors suggest that, despite differences between rat and human physiology, a lowering of the acceptable intake standard may be warranted.
After publication, the article will be available at: http://www.pnas.org/cgi/doi/10.1073/pnas.0305977101.
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