Dr Kelvin Leung, director of the research team participating in the study. (Photo: RNewsfoto/Hong Kong Baptist University)
Sunscreen waste could harm fish embryos
Tuesday, October 09, 2018, 02:50 (GMT + 9)
A team of researchers working on the identification of the harm caused by sunscreen chemicals in seawater found these susbtances can cause abnormalities in and kill zebrafish offspring by entering the food chain.
These scientists, from Hong Kong Baptist University (HKBU), explain that the extensive amount of sunscreen chemicals in seawater also could pose a risk to human health as the genetic structure of zebrafish resembles that of humans.
The study also shows that these contaminants are commonly found in the coastal waters of Hong Kong.
As part of their work, the team, led by Dr Kelvin Leung Sze-yin, Associate Professor of the Department of Chemistry of HKBU, collected seawater samples from 30 locations off the Hong Kong coast. Seven commonly used organic UV (ultra-violet) filters, the active ingredients in sunscreens, were investigated.
The team also collected fish, shrimp, mussels and other wild organisms from seven local aquaculture farms around Hong Kong and found the presence of UV filters in concentrations ranging from 3.1 to 51.3 nanograms in each gram of the samples.
The findings indicated that the UV filters that accumulated in marine life could possibly pass up the food chain to humans and affect our health.
The researchers collected the samples at depths of two metres in the sea, extracted the samples using the "solid phase extraction" method followed by highly sensitive instrumental analysis, a process designed to obtain reliable environmental data of UV filters.
The team simulated the real aquatic environment in a laboratory where contaminated artemia were fed to zebrafish for 47 days. The contaminated watercontained three commonly used UV filters, namely benzophenone-3 (BP-3), ethylhexyl methoxycinnamate (EHMC) and octocrylene (OC).
After 47 days, none of the adult zebrafish appeared to be damaged, but several of their embryos were found to have malformations or abnormalities.
The embryos' 24-hour mortality rate increased dramatically, from 10 per cent to nearly 60 per cent, while the 72-hour hatching rate decreased significantly, from 80 per cent to less than 30 per cent.
"After human use, the organic/chemical UV filters in sunscreens are discharged into the sea either directly by being washed off with sea water or indirectly through discharge of wastewater. Eventually they enter the sea, thereby posing a threat to marine organisms and the ecosystem," pointed out Leung Sze-yin.
The study findings were published in the academic scientific journal Environmental Science & Technology.