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Even ‘safe’ plastic may be dangerous, study reveals

The ‘safe’ chemicals used in plastics to replace hormone-disrupting BPA may carry the same risks, a new study reveals.  

In 1999, now-renowned scientist Patricia Hunt accidentally discovered that most plastic products contain a chemical that disrupts hormones.

Bisphenol A (BPA) – which was used in children’s toys, medical devices, and food packaging – could affect cancer risk, fertility, and more, Hunt’s Washington State University team found.

Within 15 years, Hunt’s study had driven the US – and countries around the world – to ban BPA, mandating manufacturers to use safe alternatives, such as BPS. 

But today, Hunt reveals, she has suffered ‘deja vu’: her latest research reveals replacement chemicals inflicted the same damage on the sperm and eggs of lab mice.

Hunt says that concerned consumers should just stick to one rule: it doesn’t matter what chemicals are on the label, ‘plastic products that show physical signs of damage or aging cannot be considered safe.’

Patricia Hunt, a Washington State University scientist, discovered BPA disrupts hormones in 1999. Now BPA is banned and alternatives are used. Her latest study today reveals the alternatives are risky

Hunt warns that our demand for plastic gives firms the impetus to override a slow, outdated regulatory system.

Regulators cannot keep up with the pace of new chemicals entering the market, allowing companies to push out poorly-tested alternatives as a quick-fix for our modern day products.

‘[R]egulatory agencies charged with assessing chemical safety cannot keep pace with the introduction of new chemicals,’ she and her team write in the new study, published today in Current Biology. 

They add: ‘[I]t is easier and more cost effective under current chemical regulations to replace a chemical of concern with structural analogs rather than determine the attributes that make it hazardous.’

The first study, 20 years ago, was not planned. 

Hunt had dedicated her career to looking at fertility and aging – how the age of eggs affects genes. 

One day, after weeks of monitoring lab mice, her results came back wildly different, derailing the relative stability of the animals’ hormones.

It transpired that a lab worker had accidentally cleaned the cage with a different detergent; one which contained BPA. 

At the time, BPA was not a widely-recognized word. But Hunt decided to pursue it, and in doing so propelled herself into the sphere of regulation, government, and media. 

These days, there are scores of public health warnings against BPA, urging people to check that their products contain safe alternatives. Water bottle companies are swift to react to any anti-plastic story that they do not use BPA in products marketed to the general public; they use BPS.

Hunt insists that even she was surprised by the results of the new study, published today in Current Biology.

Again, it happened somewhat by accident. 

This time, the changes were more subtle because not all of the cages were contaminated, but a fair few. And this time, they were contaminated by something believed to be harmless.

They saw that the disturbance in the lab was causing problems in the production of both eggs and sperm.

Once they got the contamination under control, the researchers conducted additional controlled studies to test the effects of several replacement bisphenols, including a common replacement known as BPS. 

Those studies confirm that replacement bisphenols produce remarkably similar chromosomal abnormalities to those seen so many years earlier in studies of BPA.

Hunt notes that the initial inadvertent exposure of their animals was remarkably similar to what might happen in people using plastics in that the exposure was accidental and highly variable. Not all of the animals’ cages were damaged, and so the findings differed among animals in different cages.

She adds that–although determining the levels of human exposure is difficult–their controlled experiments were conducted using low doses of BPS and other replacement bisphenols thought to be relevant to exposure in people using BPA-free plastics.

These problems, if they hold true in people as has been shown in the case of BPA, will carry over to future generations through their effects on the germline. 

The researchers showed that, if it were possible to eliminate bisphenol contaminants completely, the effects would still persist for about three generations.

Hunt says more work is needed to determine whether some replacement bisphenols might be safer than others, noting that there are dozens of such chemicals now in use. 

She also suspects that other widely used and endocrine-disrupting chemicals, including parabens, phthalates, and flame retardants, may be having similarly adverse affects on fertility that warrant much more study.

‘The ability to rapidly enhance the properties of a chemical has tremendous potential for treating cancer, enhancing medical and structural materials, and controlling dangerous infectious agents,’ the researchers write. 

‘Importantly, this technology has paved the way for ‘green chemistry,’ a healthier future achieved by engineering chemicals to ensure against hazardous effects.’ 

However, they warn, more needs to be done to regulate such chemicals to avoid a merry-go-round of public health scandals.