Once These Chemicals Are Inside My Body, What Can Happen?
Research has now begun to conclusively link dioxin and organochlorine exposure to birth defects, cancer, and reproductive and developmental disorders (11). Many scientists believe that the recent reports of declining sperm counts among men in industrialized countries can be traced to organochlorines (8). Similar problems in wildlife populations have been definitively traced to this type of pollution, and we’re not as different from our friends in the animal kingdom as appearances first suggest. Many biologists now believe organochlorines are responsible for the strange mutations, sterility, immune system failures, and local extinctions they’ve been noticing for years in animals from the Great Lakes to the North Sea (12).
Methylmercury is formed from inorganic mercury by the action of anaerobic organisms that live in aquatic systems including lakes, rivers, wetlands,sediments, soils and the open ocean. This methylation process converts inorganic mercury to methylmercury in the natural environment
Because methylmercury is formed in aquatic systems and because it is not readily eliminated from organisms it is biomagnified in aquatic food chainsfrom bacteria, to plankton, through macroinvertebrates, to herbivorous fish and to piscivorous (fish-eating) fish. At each step in the food chain, theconcentration of methylmercury in the organism increases. The concentration of methylmercury in the top level aquatic predators can reach a level a million times higher than the level in the water. This is because methylmercury has a half-life of about 72 days in aquatic organisms resulting in itsbioaccumulation within these food chains. Organisms, including humans, fish-eating birds, and fish-eating mammals such as otters and whales that consume fish from the top of the aquatic food chain receive the methylmercury that has accumulated through this process. Fish and other aquaticspecies are the only significant source of human methylmercury exposure
Human health effects
Ingested methylmercury is readily and completely absorbed by the gastrointestinal tract. It is mostly found complexed with free cysteine and with proteins and peptides containing that amino acid. The methylmercuric-cysteinyl complex is recognized by amino acid transporting proteins in the body as methionine, another essential amino acid. Because of this mimicry, it is transported freely throughout the body including across theblood-brain barrier and across the placenta, where it is absorbed by the developing fetus. Also for this reason as well as its strong binding to proteins, methylmercury is not readily eliminated. Methylmercury has a half-life in human blood of about 50 days.
Several studies indicate that methylmercury is linked to subtle developmental deficits in children exposed in-utero such as loss of IQ points, and decreased performance in tests of language skills, memory function and attention deficits. Methylmercury exposure in adults has also been linked to increased risk of cardiovascular disease including heart attack. Some evidence also suggests that methylmercury can causeautoimmune effects in sensitive individuals.