BPA Exposure Disrupts Turtle Reproduction

Exposure to bisphenol A (BPA), a chemical used in various plastic consumer products, is disrupting turtle reproduction in terms of their sexual differentiation, according to a new study.

When people throw out food storage products and resins that line plastic food and beverage containers, for instance, which are made with BPA, often these products end up in aquatic environments such as rivers and streams where turtles reside. Now, researchers from the University of Missouri, Westminster College, the US Geological Survey (USGS) and the Saint Louis Zoo have determined that BPA - which mimics estrogen - can alter a turtle's reproductive system.

This suggests that the chemical could cause harmful effects on environmental, as well as human health.

"Normally, the painted turtle's sex is determined by the temperature of the environment during their development in the egg - cooler temperatures yield more male turtles, while warmer temperatures mean females are more likely to develop," Dawn Holliday, one of the researchers, said in a statement. "However, when turtle eggs are exposed to environmental estrogens, their sex is no longer determined by the temperature, but rather by the chemical to which they're exposed."

To better determine how this chemical pollution is affecting wildlife, the research team applied a liquid form of BPA on hundreds of painted turtle eggs - mimicking BPA levels found in samples from waterways. The eggs were then exposed to cooler temperatures similar to those needed to produce male turtles. Afterward, the scientists examined the turtles' sex organs to determine the effects of BPA on their development.

They found that the male turtles had in fact developed sex organs with features typically found in females.

"We already know the genetic marker where the temperature-dependent sex determination occurs, which provides us a good indication of where the endocrine disruption is taking place," explained Sharon Deem, a lead investigator on the study. "Our findings show that BPA essentially overrides the temperature in determining the sex of the turtle, creating turtles that are probably unable to reproduce."

Turtles are known as an "indicator species," meaning they are good indicators of the health of an entire ecosystem. So by understanding how BPA exposure is affecting turtles, scientists can gain insight into how it's also affecting other species, too, including humans.

The results were published in the journal General and Comparative Endocrinology.

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