Mercury levels in North Pacific waters were about 30 per cent higher in 2006 than in 1996. (Photo: Stock File/FIS)

Marine methylmercury levels in seafood rising: study

UNITED STATES
Wednesday, May 06, 2009, 02:30 (GMT + 9)

Mercury emissions originating in Asia and the atmosphere are absorbed into the food chain by fish such as tuna and are on the rise, a recent study devised by a team of US and Australian scientists has established.

The research is the first to record the development of methylmercury in North Pacific waters.

According to the study, the toxin forms in mid-depth waters with the help of dead algae that sink down, or “ocean rain.” Once at a lower depth, bacteria decompose the algae, a process that in the presence of mercury forms methylmercury.

US Secretary of the Interior Ken Salazar .(Photo: Doi.gov)

Eventually, it enters the bodies of small animals and works its way up to tuna, sharks and other underwater predators.

The study also examined mercury levels in the water from Hawaii to Alaska. Samples showed that in 2006, levels were about 30 per cent higher than a decade earlier.

A substantial amount of these levels originates in the atmosphere due to emission rates, scientists speculate. Within the next 30 years, if emissions continue to be released as calculations foresee, scientists expect a 50 per cent increase of mercury in the Pacific Ocean.

"This unprecedented study is critically important to the health and safety of the American people and our wildlife because it helps us understand the relationship between atmospheric emissions of mercury and concentrations of mercury in marine fish,” said US Secretary of the Interior Ken Salazar, Environmental Data Interactive reports.

"We have always known mercury can pose a risk, now we need to reduce the mercury emissions so we can reduce the ocean mercury levels."

Co-author of the study Elsie Sunderland, of Harvard University, said that 40 per cent of humans’ exposure to mercury in the US is through tuna consumption.

Related articles:

- Supreme Court greenlights suit against tuna giant
- FDA reverses policy on fish consumption

By Natalia Real
editorial@fis.com
www.fis.com 

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