BPA substitutes may be just as bad as the popular consumer plastic | Science

In the past decade, concerns about the health effects of bisphenol A have forced food and beverage manufacturers to largely abandon the use of plain plastic in many household items. In its place, they turned to more than 50 "BPA-free" alternatives. Now, researchers report that some of these substitutes can cause the same harmful effects in mice, especially in reproductive cells. If the new findings are found in other animal and human studies, they could undermine efforts to alleviate consumer health concerns about plastics in food and beverage containers.

"He suggests that these replacement bisphenols are not safe," says Patrick Allard, a molecular biologist at the University of California (UC), Los Angeles, who did not participate in the event. study.

Concerns about BPA began to swirl since its introduction into commercial products in the 1940s. Since then, it has become ubiquitous in water bottles, toys, canned toppings and even cash receipts , its clarity and robustness making it an essential component of polycarbonates and other common plastics. A study conducted in 2003-2004 by the United States Centers for Disease Control and Prevention found that 93% of Americans had at least some traces of BPA in their blood. Nevertheless, extensive studies conducted by the US Food and Drug Administration have not shown that BPA is harmful to human health at normal levels of exposure, although the finding remains controversial.

In 2003, while conducting studies on unrelated BPA mice, Patricia Hunt, Reproductive Biologist at Washington State University in Pullman, and her colleagues discovered that the compound was leaching out of plastic cages. female mice. The result was an increase in chromosomal abnormalities in laboratory animals and their offspring. This discovery, along with others in animals suggesting that BPA "disrupts" hormone receptors for estrogen, triggered an avalanche of studies that showed that the number of chromosomes was halved and that the chromosomal segments were mixed during meiosis. the production of sperm and eggs. The discovery also led to new mouse cages, made of a more durable plastic called polysulfone.

But in recent studies, Hunt and his colleagues have noticed some bizarre results in their mice. It was "an experience of already seen strange," says Hunt. "Our control studies started to get crazy." After months of work, Hunt and his colleagues found the problem of contamination of cages damaged by washing and other normal wear.

Hunt sent samples of damaged and undamaged cages to Roy Gerona, a chemist at the University of San Francisco. Gerona and his colleagues determined that the damaged cages leached the compounds that manufacturers often use to replace BPA, such as bisphenol S (BPS) and diphenylsulfone.

Gerona is perplexed by an additional curiosity: polysulfone does not contain BPS. After evaluating the starting material and leachate, Gerona says he believes polysulfone is degraded to produce BPS and other BPA-like compounds.

After controlling the contamination, Hunt and his colleagues decided to directly test the effects of alternatives to BPA. They fed pregnant female mice at low doses of BPA, BPS, diphenylsulfone or placebo. Compared to unexposed females, those exposed to BPA or its alternatives produced more protein markers for genetic damage during meiosis, they report today. Current Biology.

In previous studies, this type of genetic lesion has caused aneuploidy, an abnormal number of chromosomes that can cause miscarriage in females, and a decrease in sperm count in males. In addition, in the current study, Hunt and colleagues have shown that the effect lasts beyond mothers and fetuses directly exposed to BPA and its alternatives. Genetic abnormalities persisted for two generations of male mice not exposed to BPA and its substitutes.

What it means for people is hard to say. "No one has ever proven that it causes damage to levels that people are normally exposed to," says Oliver Jones, a chemist at RMIT University in Melbourne, Australia. However, Hunt and others suggest that the strong similarities in the chemical structure between BPA and some of its alternatives mean that consumers may be cautious about the labels that tout "BPA free" products.

The study also raises concerns about the reliability of large-scale BPA studies, says Monica Colaiacovo, a geneticist at Harvard Medical School in Boston. Ongoing studies on the effects of BPA typically house animals in plastic cages previously thought to be non-bisphenolic. However, Hunt's cages inadvertently subject the animals to contamination.

"If you already produce an effect in your control [animals]you might not see a significant difference "in your experimental animals, says Colaiacovo. This could make it even more difficult for scientists in the future to resolve the real dangers of BPA and its family of replacements.