Fish-eaters warned of mercury pollution dangers

Mercury pollution may be damaging the immune system of seals in the North Sea according to scientists at a Belgian university.

The study also raised concerns that the immune systems of people who eat lots of fish could be affected.

Researchers from the University of Liege wanted to find out the effects of methylmercury, the form of mercury most frequently found in marine mammals and people who consume fish on a regular basis.

Doses of the chemical were applied to seals’ white blood cells - the body’s natural defence against disease - and the effects of the mercury were carefully monitored.

The levels of mercury applied matched that found in harbour seals caught in the North Sea.

Test results found that methylmercury causes significant harm to T-lymphocytes, key cells in the seals’ immune system.

Similar tests on human blood cells had the same result.

Krishna Das, who led the study, said it has long been known that mercury damages the immune system of marine mammals, but the exact reasons for this were not known until now.

She added that the methods used in her research were not an exact replica of what happens when mercury enters the digestive system.

However, the research does give an important insight into the effects of mercury pollution and as to why the seal population has been particularly susceptible to viruses in recent years.

The EU recently banned exports of mercury because of its effects on the environment.

Mercury evaporates into the atmosphere during transportation and enters watersystems in rainfall.