Popular brands of sunscreen containing chemicals that can cause birth defects and infertility were found in fish in the sea off Hong Kong, according to the research conducted by the scientists from Baptist University. The five-year study was published in the scientific journal Environmental Science & Technology in August, showing a link between the chemicals and abnormalities or death in the offspring of zebrafish.
The research gathered seawater samples from 30 locations off the Hong Kong coast - including beach areas in Sai Kung, Southern Hong Kong Island, Tuen Mun, and at sewage treatment outfalls in Victoria Harbour, Tolo Harbour and West Tuen Mun. The research team discovered that Octocrylene (OC), Benzophenone-3 (BP-3), and Ethylhexyl methoxycinnamate acid (EHMC) were the three most abundant ultraviolet (UV) filters in the samples.
"Since more than 70 percent of the genetic structure of zebrafish resembles that of humans, the effect of these contaminants passing along the food chain to humans and the long-term impact on human fertility cannot be neglected," said Kelvin Leung Sze-yin, the associate professor from the Chemical Department of the university.
The team also fed the zebrafish with polluted shrimp, and after 47 days, the death rate of zebrafish embryos in 24 hours rose six times to almost 60 percent. The 72-hour hatching rate, on the other hand, significantly dropped from 80 percent to less than 30 percent.
"After human use, the organic or chemical UV filters in sunscreens are discharged into the sea, either directly by being washed off with seawater, or indirectly through discharge of wastewater," said Leung, who also led the research. "Eventually, they enter the sea, thereby posing a threat to the marine organism and the ecosystem."
The study also revealed that the combination of the three chemicals increased their accumulation than in the presence of every single one of them.
"It shows 'a mixture effect'. In simple words, one plus one, plus one, does not equal three. It's a multiplier effect," Leung said.
According to the South China Morning Post, the two most popular types of sunscreen among beachgoers are physical blockers which reflect or scatter UV radiation and commonly used; and the other one is the kind that absorbs radiation with chemicals.
Leung advised to only use natural, mineral-based sunscreen, or wear sun-protecting clothing. His team wanted to conduct further study in the future regarding the long-term impact of UV filters on humans and the ecosystem.
In a United States 2015 study, about 6,000 to 14,000 tons of sunscreen ends up in the world's oceans every year. The chemicals of which have shown adverse impact in the environment, including coral bleaching. Meanwhile, Hawaii already banned the use of sunscreen containing UV filters oxybenzone and octinoxate to protect coral reefs.
