Chemicals used in sunscreen for blocking out the Sun’s cancer-causing ultraviolet (UV) rays have been shown to cause deformities in certain fish species, and researchers believe these chemicals could also have harmful effects on humans, according to a study published in Environmental Science & Technology.
Previous research suggested these chemicals were not found in high enough levels to threaten the health of humans or animals, but scientists testing the waters of Shenzhen, China, found that seven of the nine most common sunscreen chemicals were found to accumulate in waters surrounding popular beaches. Traces were also recorded in a reservoir and tap water.
To see the effects of exposure to these chemicals, scientists fed zebrafish brine shrimp exposed to three of these chemicals in the lab. Adult fish were largely unaffected, but the offspring exposed to elevated levels over a longer period of time showed abnormalities and birth defects.
“The evidence from our work with zebrafish and from studies with rats suggests this could be a vital issue for human beings,” wrote the authors, who continue that traces of these chemicals in drinking water could mean additional filtering systems are needed.
“This result showed us another possible exposure pathway for humans besides direct [skin] application and, considering the association between the human exposure of [these chemicals] and health outcomes, it raises concern,” wrote the authors.
Concerns over sunscreen’s effect on users have mostly been outweighed by its benefits in protecting against sunburns and cancer, but consuming it through water systems could be another story. Runoff from these care products has been found in sewage sludge and river environments, and it’s not just sunscreen we need to look out for – UV filters are also added to personal care products, including moisturizers and makeup.
Research has suggested that sunscreen can have damaging effects on the marine environment. Each year, about 14,000 tons of sunscreen winds up in the world's reefs. Oxybenzone, one of the most common chemicals, has been shown to negatively affect coral species in laboratory settings, while a single drop of oxybenzone per 4.3 million gallons of water can prove detrimental. Because of this, Hawaii became the first government in the world to vote earlier this year to ban coral-killing sunscreens by blocking the sale and distribution of sunscreens containing certain chemicals. The law will go into effect on January 1, 2021.