MEXICO: A paper published in the journal Environmental Toxicology and Chemistry this week stated that concentrations of mercury have increased in tuna by about 4 percent annually — bad news for a fish that is already one of the highest on the list of species that contain mercury, according to a Newsweek report.
Mercury levels are also found in carnivores that consume other animals, indicating the mercury bioaccumulates — or, moves up the food chain. As a result, smaller fish such as sardines or fish that eat mostly plankton, like salmon, may be preferably alternatives to tuna.
Scientists have been studying the issue for years, and even appeared to show evidence in a 2003 paper that mercury levels weren’t rising, but it was later determined that the finding was a result of the fact that fishermen were catching smaller fish due to overfishing.
Mercury can have a profound impact on humans, particularly in the development and function of the brain and nervous system. Foods that contain mercury are typically high on the list of foods that pregnant women should avoid, as it can stunt the development of the fetus and cause reduced IQs.
The high amount of mercury in the Pacific appears to come from heavy industrial development in Asia, particularly China, based on research from the University of Michigan. The most toxic form of the metal, methylmercury, is later absorbed by microbes in the ocean and in wetlands.
The study shows that mercury is rising in a variety of animals, according to Harvard University environmental health researcher Dr. Philippe Grandjean, who was involved in the study and was quoted in the report as saying that specimens from Beluga whales, peregrine falcons, and polar bears show that mercury concentrations have exploded to 10 times the level that they were before the industrial age.
The only way to get rid of mercury is for it to sink into the deep ocean or end up bound up in the soil, but that can take hundreds of years. However, there have been moves from countries like China to limit the use of mercury-containing products by 2020.
