Researchers have detected high levels of sunscreen chemicals in the waters of Shenzhen, China. These include beaches, a harbour, a reservoir and even tap water. In tests on zebrafish, the team showed that several of these UV ﬁlters are being transmitted through the food chain, and can have adverse effects on developing offspring.
Organic UV ﬁlters found in sunscreens, skin lotions and make-up, as well as textiles, plastics, and paints, are endocrine disruptors.
Risk assessments for single compounds have concluded that current levels of organic UV ﬁlters pose low risk, but they don’t account for interactions of mixtures and how these interactions develop over time.
Kelvin Sze-Yin Leung’s team at Hong Kong Baptist University analysed nine common organic UV ﬁlters in surface waters of Shenzhen, a city with more than 20 popular beaches. They found seven of the nine chemicals, including benzophenone derivatives BP-3, BP-8, and BP-1, as well as ethylhexyl methoxycinnamate (EHMC), at public beaches, a harbour, a reservoir and in tap water.
Total concentrations of UV ﬁlters were relatively high at three popular public beaches – ranging from 192 to 645ngL-1 – in the summer as expected. Shenzhen Reservoir showed UV ﬁlter pollution in both seasons, while tap water was contaminated by BP-3.
If inefficient water treatment processes are to blame, then research is needed into other ways to remove these ﬁlters to protect human health, says Sze-Yin Leung.
In further lab studies, the team exposed brine shrimp to BP-3, EHMC and octocrylene, both as single chemicals or in mixtures, and then fed them to adult zebrafish, a common model organism. They found that concentrations in both shrimp and zebrafish were up to four times higher when exposed to the mixtures than when exposed to only a single UV ﬁlter. But the fish had no visible problems.
Feeding the exposed shrimp to the fish for 25 days did not appear to signiﬁcantly inﬂuence early life stage development of the second generation of zebrafish. However, when this exposure period was extended to over 47 days, the team noticed signiﬁcant adverse effects on embryo development.
The researchers believe comprehensive evaluation of the effects of UV ﬁlters, and their mixtures, on aquatic environments as well as human health is needed.