Alternatives to the chemical bisphenol A, often used in plastic products, were found to cause genetic abnormalities in mice — and may also threaten human reproductive health.
Twenty years ago, a Washington State University researcher discovered genetic abnormalities in laboratory mice after they were accidentally exposed to the chemical bisphenol A, known as BPA, commonly found in plastic products.
Now, Patricia Hunt and her colleagues have found that alternatives to the chemical are also causing genetic abnormalities in mice — and may also threaten human reproductive health.
“We stumbled on an effect yet again,” said Hunt, a professor in the WSU School of Biological Sciences and lead author of a study published Thursday in Current Biology. “This is a more stable plastic, but it induced similar effects on the process of making eggs and sperm.”
BPA has long been used in plastic products such as soda pop and reusable water bottles, as well as food-can coatings. Scientists say trace amounts of the chemical can leach out those products.
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The research by Hunt and others led the U.S. Food and Drug Administration (FDA) to ban the use of BPA in baby bottles and children’s drinking cups in 2012. The Washington Legislature has also limited its use.
Hunt and her team’s latest discovery found reproductive defects in mice kept in plastic cages made with Bisphenol S (BPS), a common replacement for BPA.
They said mice exposed to BPS experienced changes in how the germ cells in their testes and ovaries copy and splice DNA while producing sperm and eggs. The researchers found similar results with alternative chemicals BPF, BPAF and diphenyl sulfone.
“These findings add to growing evidence of the biological risks posed by this class of chemicals,” Hunt said.
The researchers also found the issues occurring in the male germline lasted several generations after the initial exposure. The mice were not clear of the effects until about the fourth or fifth generation. The genetic changes led to a reduction in viable sperm as well as an increase in abnormal eggs, Hunt found.
“The good news is, if we could eliminate them (the chemicals) we could slowly turn any testis effects back to normal,” she said. “The bad news is, if we’re like mice, it would take generations.”
Hunt, who was labeled the “accidental toxicologist” by Scientific American magazine, said the pervasive use of the plastics may also compromise basic biological research.
“It’s now becoming almost impossible to run experiments without contamination,” Hunt said.
“We study the germline, which is super sensitive to hormones and chemicals like bisphenols that act like or interfere with our hormones. So we are like the canary in the coal mine,” she said.
Hunt found a residue on her mice cages and lab results showed it was BPS. After eliminating the contamination, she then began to test the effect of BPS on mice.
The FDA last month said BPA does not pose a health hazard when used in food containers. And the American Chemistry Council said earlier this year that a large FDA study found the chemical is safe as it’s currently used.
But Hunt said the FDA studies do not match up with studies done by independent researchers.
“When you do those kinds of big studies of BPA, you see little or no effects,” Hunt said. “But people like me go, look what it does to eggs, look what it does to the brain, look what it does to the heart, so there’s been this big disconnect between these independent researchers and these big toxicology tests.”
Hunt said more research is needed for a safe solution. She encouraged consumers to get rid of any plastic products showing physical signs of change and damage because they may be leaching the components that they are made from.
Hunt’s WSU colleagues in the research are Tegan Horan, a research intern and the paper’s first author, as well as scientific assistants Hannah Pulcastro and Crystal Lawson, and former postdoctoral fellows Mary Gieske and Caroline Sartain. Joining them are Roy Gerona and Spencer Martin of the University of California, San Francisco.
The study was funded by the National Institutes of Health.