Scientists remove 99% of "concerning" chemical BPA from water

03 August 2017
Posted by Alexandra Ashcroft.

A new method can extract more than 99% of a harmful compound from water, scientists at Carnegie Mellon University show.

Over 8 billion kilograms of bisphenol A, better known as BPA, is made each year through the manufacturing of plastics like water bottles and straws. Because BPA can travel everywhere “there’s not a living thing on this planet that can escape contamination”, warns Professor Terrence Collins, who led the work published this week in the journal Green Chemistry.

This statement is particularly alarming because BPA is an endocrine disruptor, which means it can behave like a hormone. “Hormones are the messenger molecules of [biological] development... if you have a hormone mimic, you have something that’s capable of altering development, at low concentrations”, explains Collins.

Studies on human cells, fish and mammals have shown that BPA adversely alters brain and nervous system development and harms growth, metabolism, and the reproductive system.

In June 2017, the EU listed BPA as a “Substance of Very High Concern”. Under this new ruling, producers of products with BPA may have to inform the EU if their product contains BPA. But because BPA is converted into longer compounds, called polymers, in most products, few manufacturers will be beholden by this.

However, Collins warns that “the polymers...  revert to BPA when they encounter water”. Ultimately, this resulted in large volumes of BPA leaching into our water systems where we have few options to remove it.

One way to remove BPA from water is to soak it up with a substance called activated carbon. Some countries, such as Switzerland, are adding activated carbon steps to their wastewater treatment plants to remove BPA and other pollutants from their waterways.

The main limitation with activated carbon and other BPA removal systems is the hefty price tag and the fact the process is reversible. The waste product ends up in a landfill site, where the BPA can eventually escape and leach back into the water.

This means there is a very real need for affordable and permanent BPA removal systems, which is where Collins and his team come into the picture. They developed a substance that works with hydrogen peroxide to convert the BPA in the water to a solid powder.

This powder form of BPA can then be filtered safely out of the water. Collins is particularly proud of his system because, as well as being permanent, it works “very easily, very effectively and with huge efficiency, greater than 99%” under pH conditions similar to those used in water treatment plants.

They’ve had a working substance since 2002 but Collins wanted to be sure they “weren’t getting out of the frying pan and into the fire, as you could, in theory, get a worse endocrine disruptor through this process”.

Collins has thus spent the last 15 years or so teaming up with various experts to develop a rigorous five-tier protocol that can be used to test whether a molecule can act like a hormone. The substance, the BPA powder and the leftover water have all been shown to have no endocrine disruptor activity.

This encouraging substance has only been tested in the lab. Although the pH used was similar that used in wastewater treatment facilities, wastewater is much dirtier than pure lab water. Going forward, they need to show it can work in real life conditions.

Collins believes the presence of BPA and other endocrine disruptors in our environment “is the most important problem that the chemical enterprise faces...we need to be very honest about the challenges and get on with solving them as quickly as possible.”

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