As concern about the cumulative impacts of these chemicals grows among the scientific community, some studies are suggesting that the effects of these compounds could extend to future generations.
For example, investigators at the National Institute of Environmental Health Sciences have found that adverse effects can be seen in both the granddaughters and grandsons of mice who were developmentally exposed to diethylstilbestrol (DES), a synthetic form of estrogen that caused reproductive problems in pregnant women and their fetuses. While DES was taken off the market in 1971, there are many other compounds that have similar, estrogenic effects.
“This study is the flagship of estrogen mimickers and why we worry about them,” said Shanna Swan, director of the University of Rochester's Center for Reproductive Epidemiology and a leading expert on reproductive effects of environmental exposures. “The fact that these chemicals can effect future generations has been a huge lesson for the science community.”
Other research has found that low doses of these chemicals can cause significant changes in those exposed to them and their developing offspring. One recent study published in Environmental Health Perspectives found that when rats are exposed to low levels of BPA during lactation, their offspring had an increased chance of breast cancer.
As the evidence that synthetic estrogens may pose a health risk mounts, researchers are uncovering these compounds in new places.
Earlier this month, researchers in Germany found traces of an unknown estrogenic substance leaching into mineral water stored in polyethylene terephthalate (PET) bottles, a commonly used plastic for storing foods and beverages.
The study is the first to find that these containers are leaching synthetic estrogens.
“We already knew that BPA was leaching from polycarbonate baby bottles, so we decided to test bottles of mineral water to see if there was any estrogenic activity,” said Martin Wagner, a PhD student in aquatic toxicology at Johann Wolfgang Goethe University in Frankfurt.
The scientists tested 20 brands of mineral water and found that 60 percent of the samples tested positive, with estrogenic activity in plastic bottles appearing twice as high as compared to activity in water from glass bottles.
In addition, the researchers found that mud snails placed inside the bottles filled with fresh water experienced reproduction rates double of control snails, which suggests that substances from the packaging, and not the water itself, caused the reproductive change.
“The results show that these leached chemicals are important enough to change reproduction in only eight weeks,” Martin said.
Further testing is needed to identify the source of the estrogenic activity, but Wagner said the study’s significance is that it shows people are exposed to more environmental endocrine disruptors than what was previously thought.
“We’re dealing with this chemical mixture, a cocktail effect, and I would say that if you look at a single compound then you might underestimate the exposure to these environmental estrogens,” he said.
Ralph Vasami, executive director of a plastics industry group, the PET Resin Association, said ongoing research on the safety of PET for the past three decades has revealed no safety issues or reasons for concern.