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Wednesday, June 29, 2022

What is BPA and why is it present in many plastic products?

Bisphenol A, or BPA, is a chemical commonly used to make hard, clear plastics. It is an endocrine disruptor associated with many negative health outcomes, including cardiovascular disease and diabetes. In 2013, the US government banned its use in baby products that come into contact with food, such as bottles or infant formula packaging.

At the time, the U.S. Food and Drug Administration concluded that some exposure was safe for adults. But other health agencies, including the European Food Safety Authority, have concluded that BPA levels considered safe by the FDA may have adverse health effects on adults as well.

In early June 2022, the FDA indicated that it was revisiting how much BPA is safe for adults, announcing that it would be reviewing its guidance on the use of BPA in food contact plastics.

As a synthetic polymer chemist, I think a lot about how to develop new polymers, with particular attention to how to do it in an environmentally friendly way. It’s natural to wonder why companies aren’t simply replacing BPA with another chemical if health is such an issue. The secret to what makes BPA such an indispensable ingredient in plastics lies in the same thing that leads to health risks – the chemical structure of the molecule.

Bisphenol A consists of two carbon rings with small alcohol groups attached and is used to make strong, transparent plastics.
Darkness3560/Wikimedia Commons

What is BFA?

BPA is a small molecule made up of two carbon rings with linked oxygen and hydrogen attached to each end. BPA can react with other carbon-based molecules to form long chains, with the BPA molecules sewn together by small chemical bonds.

Almost all of the BPA produced in the world is used to make plastics, mostly a special type called polycarbonate. BPA-derived polycarbonates are clear, incredibly strong, lightweight, and do not begin to melt or lose structural integrity until very high temperatures are reached. These properties make polycarbonates excellent for use in everything from eyeglass lenses to water bottles.

It’s all about the structure

In chemistry, structure means everything. The reasons different materials have different properties have to do with their chemical structure.

BPA polymers are rigid because the carbon rings in BPA molecules are themselves rigid. Compare this to polyethylene, a thin and flexible material used to make plastic bags. The long chains of repeating molecules that make up polyethylene are very flexible. So the plastics they produce are also very flexible.

Table With Many Colored Sunglasses.
BPA plastics are strong, clear, lightweight, and have a high melting point, making them the ideal lens material for your glasses.
Nipitfon Na Chiang Mai/EyeEm via Getty Images

How are BPA leached out of plastic?

In the manufacture of BPA plastic, almost all of the individual BPA molecules are chemically bonded to the plastic. Thus, most of the BPA that leaches out of food containers or water bottles comes from the slow breakdown of plastic.

When BPA polycarbonates are exposed to water and heat — say, when you put a plastic bottle in the dishwasher — the chemical bonds that bind these BPA molecules together can break in a process known as hydrolysis. Because of their unique structure, BPA polycarbonates are generally more susceptible to hydrolysis than plastics such as polyethylene.

Hydrolysis breaks down plastic on a chemical level, with a small amount of BPA molecules being released into the environment. In one study, researchers found that the process of washing a polycarbonate bottle leached between 0.2 and 0.3 milligrams of BPA for every liter of water. For context, this is hundreds of times less than the levels of calcium and sodium in drinking water.

Finding a replacement for BPA

BPA is an endocrine disruptor, meaning it disrupts hormones in the body. Given the negative health effects of BPA consumption and the fact that it breaks down on contact with water, chemists have been looking for a replacement for years.

The main problem with the development of new plastics is that replacing BPA with a different molecule may not eliminate negative health effects. In the same way that the chemical structure of BPA determines the properties of the material, the structure also causes negative biological effects. Endocrine disruptors such as BPA, due to their structure similar to natural hormones, can bind to and activate endocrine receptors.

Studies have shown that structurally similar chemical substitutes such as bisphenol F have the same health effects as BPA.

It is also not easy to replace a new molecule with a different chemical structure, because then the plastic will lose the desired characteristics of BPA polycarbonates. But there are some promising new studies. One avenue of research is focused on the production of polycarbonates by reacting bio-based rigid molecules with carbon dioxide gas.

Polycarbonates are an integral part of modern life. As researchers develop new materials, it’s important to consider not only the health risks, as the EPA does with BPA, but also the environmental impact.

World Nation News Desk
World Nation News Deskhttps://worldnationnews.com/
World Nation News is a digital news portal website. Which provides important and latest breaking news updates to our audience in an effective and efficient ways, like world’s top stories, entertainment, sports, technology and much more news.
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