Sunscreen chemical’s risk to humans

A study by Hong Kong Baptist University (HKBU) has detected an extensive amount of sunscreen chemicals in seawater that could pose a risk to human health. The study, a world-first in identifying the harm caused by a combination of polluting chemicals in sunscreen, found the chemicals can cause abnormalities in and kill the offspring of zebrafish by entering the food chain. As the genetic structure of zebrafish resembles that of humans, the results imply that these contaminants could pose a risk to humans. The study also revealed that these contaminants are commonly found in the coastal waters of Hong Kong.

The team was led by Dr Kelvin Leung, Associate Professor of the Department of Chemistry of HKBU. The team 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, shrimps, mussels and other wild organisms from seven local aquaculture farms around Hong Kong. The team 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. 
 

HKBU Research - Sunscreen chemical risks
Dr Kelvin Leung says that owing to the high similarity of the genetic structure of zebrafish and that of humans, the contamination of seawater caused by sunscreen chemicals poses a possible risk to human health via the food chain.
 

UV filters harmful to zebrafish embryos

The team 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 water contained 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 % to nearly 60%, while the 72-hour hatching rate decreased significantly, from 80% to less than 30%.

HKBU Research - Sunscreen chemical risks
The HKBU study finds the "mixture effect" of UV filters in sunscreens harms the development of fish embryos. The images show the various abnormalities and malformations in zebrafish embryos.
 

Mixture effect first proved

Dr Kelvin Leung said the study found that the combined presence of BP-3, EHMC and OC creates "a mixture effect" that increases their accumulation compared with the case when only one chemical is present. This increase was particularly marked in zebrafish. "Since more than 70% 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." he added.