Is benzophenone safe in skin care? Part 2: Environmental effects

Although it has been used as an ingredient in sunscreens and other personal care products since the 1980s, benzophenone-3 (BP-3) or oxybenzone has emerged in recent years as a significant environmental and health contaminant. DiNardo and Downs point out that BP-3 has been linked to contact and photocontact allergies in humans and implicated as a potential endocrine disruptor. They add that it can yield deleterious by-products when reacting with chlorine in swimming pools and wastewater treatment plants and can cause additional side effects in humans who ingest fish.¹ This column will focus on recent studies, mainly on the role of benzophenones in sunscreen agents that pose considerable risks to waterways and marine life, with concomitant effects on the food chain.

Environmental effects of BPs and legislative responses

Various UV filters, including BP-3, octinoxate, octocrylene, and ethylhexyl salicylate, are thought to pose considerable peril to the marine environment.^2,3 In particular, BP-3 has been demonstrated to provoke coral reef bleaching in vitro, leading to ossification and deforming DNA in the larval stage.^3,4

According to a 2018 report, BP-3 is believed to be present in approximately two thirds of organic sunscreens used in the United States.³ In addition, several studies have revealed that detectable levels of organic sunscreen ingredients, including BP-3, have been identified in coastal waters around the globe, including Hawaii and the U.S. Virgin Islands.^4-8

^{M Swiet Productions/Moment/Getty Images}

A surfeit of tourists has been blamed in part, given that an estimated 25% of applied sunscreen is eliminated within 20 minutes of entering the water and thought to release about 4,000-6,000 tons/year into the surrounding coral reefs.^9,10 In Hawaii in particular, sewage contamination of the waterways has resulted from wastewater treatment facilities ill-equipped to filter out organic substances such as BP-3 and octinoxate.^10,11 In light of such circumstances, the use of sunscreens containing BP-3 and octinoxate have been restricted in Hawaii, particularly in proximity to beaches, since Jan. 1, 2021, because of their apparent environmental impact.¹⁰

The exposure of coral to these compounds is believed to result in bleaching because of impaired membrane integrity and photosynthetic pigment loss in the zooxanthellae that coral releases.^9,10 Coral and the algae zooxanthellae have a symbiotic relationship, Siller et al. explain, with the coral delivering protection and components essential for photosynthesis and the algae ultimately serving as nutrients for the coral.¹⁰ Stress endured by coral is believed to cause algae to detach, rendering coral more vulnerable to disease and less viable overall.¹⁰

In 2016, Downs et al. showed that four out of five sampled locations had detectable levels of BP-3 (100 pp trillion) with a fifth tested site measured at 19.2 pp billion.⁴

In 2019, Sirois acknowledges the problem of coral bleaching around the world but speculates that banning sunscreen ingredients for this purpose will delude people that such a measure will reverse the decline of coral and may lead to the unintended consequence of lower use of sunscreens. Sirois adds that a more comprehensive investigation of the multiple causes of coral reef bleaching is warranted, as are deeper examinations of studies using higher concentrations of sunscreen ingredients in artificial conditions.¹²

Dr. Leslie S. Baumann

In the same year, Raffa et al. discussed the impending ban in Hawaii of the two sunscreen ingredients (BP-3 and octinoxate) to help preserve coral reefs. In so doing, they detailed the natural and human-induced harm to coral reefs, including pollution, fishing practices, overall impact of global climate change, and alterations in ocean temperature and chemistry. The implication is that sunscreen ingredients, which help prevent sun damage in users, are not the only causes of harm to coral reefs. Nevertheless, they point out that concentration estimates and mechanism studies buttress the argument that sunscreen ingredients contribute to coral bleaching. Still, the ban in Hawaii is thought to be a trend. Opponents of the ban are concerned that human skin cancers will rise in such circumstances. Alternative chemical sunscreens are being investigated, and physical sunscreens have emerged as the go-to recommendation.¹³

Notably, oxybenzone has been virtually replaced in the European Union with other UV filters with broad-spectrum action, but the majority of such filters have not yet been approved for use in the United States by the Food and Drug Administration.³