An ingredient commonly used in sunscreen and other cosmetics, avobenzone, can break down into dangerous toxins in poolside conditions, according to a study in Russia.

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An ingredient commonly used in sunscreen can break down into toxic chemicals when exposed to chlorinated water and sunlight, a team of Russian researchers found.
 
The chemical, avobenzone, was approved by the US Food and Drug Administration in 1988 and is listed among the ingredients of many sunscreens in the United States.
 
Avobenzone is used by millions of people in sunblocks, lipsticks, lip balms, and moisturizers due to its powerful capacity to block skin cancer-causing ultraviolet rays.
 
But new lab tests simulating conditions commonly found at a summer pool party showed the chemical can break down into dangerous toxins, researchers said.
 
Scientists from the Faculty of Chemistry of the Lomonosov Moscow State University used chromatomass spectrometry to probe how the chemical reacts in chlorinated water and sunlight, and discovered it can break down into an array of organic compounds including aromatic acids, aldehydes, phenols, and acetyl benzenes.
 
“It's known that acetyl benzenes and phenols, especially chlorinated ones, are quite toxic,” said chemist Albert Lebedev, one of the authors of the team’s paper, which is published in the journal Chemosphere.

Credit: Albert Lebedev

The class of acetyl benzenes includes chloroacetophenone — a chemical commonly used in the production of tear gas, according to the scientists.
 
“Avobenzone is found in nearly every non-mineral sunscreen in the United States,” said Sonya Lunder, a senior analyst at the non-profit health and environment watchdog Environmental Working Group (EWG), and author of group’s 2017 Guide to Sunscreens.
 
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Avobenzone “is one of the only ingredients that protects against UVA radiation, and critical for sun protection presently,” Lunder said. UVA refers to the type of UV rays that penetrate deep into the skin’s thickest layer, the dermis.
 
“Avobenzone is also well-known to be an unstable chemical. Sunscreen formulators have to add other ingredients to help keep it intact,” she said.
 
“What happens to sunscreens in pool water is still being investigated,” said David Andrews, a senior scientist at EWG. “We are following the issue and developments.”
 
EWG provides an online sunscreen guide, as well as lists of the best and worst sunscreens for children.

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