Sea turns harmless form of mercury into potent neurotoxin

Alberta University-led researchers have confirmed that a relatively harmless inorganic form of mercury found worldwide in ocean water is transformed into a potent neurotoxin in the seawater itself.

After two years of testing water samples across the Arctic Ocean, the researchers found that relatively harmless inorganic mercury, released from human activities such as industry and coal burning, undergoes a process called methylation and becomes deadly monomethylmercury.

Unlike inorganic mercury, monomethylmercury is bio-accumulative, meaning its toxic effects are amplified as it progresses through the food chain from small sea creatures to humans. The greatest exposure for humans to monomethylmercury is through seafood.

The researchers believe that the methylation process happens in oceans all over the world and that the conversion is carried out by microbial life forms in the ocean.

Alberta University biological sciences PhD graduate Igor Lehnherr said that the conversion of inorganic mercury to monomethylmercury accounts for approximately 50 per cent of the neurotoxin present in polar marine waters and could account for a significant amount of the mercury found in Arctic marine organisms.

According to the researchers, this is the first direct evidence that inorganic mercury is methylated in seawater.