Autoimmune Disease Linked to Mercury Exposure
Autoimmune diseases are among the ten leading causes of death for women. For reasons that remain unclear, women are more likely to be affected by autoimmune disease than men. That’s not to say men do not also suffer from autoimmune diseases, which include multiple sclerosis, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), rheumatoid arthritis, lupus, and Sjögren's syndrome.
These are all serious diseases characterized by a single defect: the body’s immune system incorrectly identifies a particular tissue as foreign and attacks it. In essence, autoimmune diseases involve the body warring against itself, at considerable cost to the patient’s health. While some genetic component or components are believed to play a role in some of these diseases, it’s long been suspected that a secondary factor, encountered in the environment, must also be present to trigger autoimmune activity.
Now researchers at the University of Michigan say they’ve discovered one likely culprit: mercury. "We don't have a very good sense of why people develop autoimmune disorders," says lead author Emily Somers, Ph.D., Sc.M, at the U-M Medical and Public Health Schools. “In our study, exposure to mercury stood out as the main risk factor for autoimmunity.” Previous research has suggested a link between exposure to mercury caused by the removal of old mercury-amalgam dental fillings and an increased risk of developing multiple sclerosis. Most dentists have abandoned the practice of installing mercury-laced fillings, however.
These days, people are most likely to ingest mercury by eating contaminated fish. Mercury is a potent neurotoxin, meaning it damages brain tissue and nerves. For this reason, pregnant women are advised to limit their intake of fish species that may harbor mercury. While shrimp, scallops and salmon are unlikely to contain any mercury, certain other species of seafood, including tuna, shark, king mackerel, swordfish, and tilefish, may contain problematic amounts of the toxic element.
While there are many health benefits of eating seafood, authorities caution that this new research underscores the importance of monitoring your exposure to problematic seafood. "For women of childbearing age, who are at particular risk of developing this type of disease, it may be especially important to keep track of seafood consumption.”
Even at levels generally considered safe, young women in the present study showed evidence of autoantibodies in their blood. Autoantibodies are proteins formed in the body when the immune system begins attacking the body’s own tissues. These proteins may appear years before any identifiable symptoms of autoimmune disease, suggesting that women are even more sensitive to mercury exposure than previously thought.
Emily C. Somers, Martha A. Ganser, Jeffrey S. Warren, Niladri Basu, Lu Wang, Suzanna M. Zick, Sung Kyun Park. Mercury Exposure and Antinuclear Antibodies among Females of Reproductive Age in the United States: NHANES. Environmental Health Perspectives, 2015; DOI: 10.1289/ehp.1408751