Emily Somers, Ph.D.; Sung Kyun Park, Sc.D.
University of Michigan
NIEHS Grants K01ES019909, P30ES017885
NIEHS grantees report an association between exposure to methylmercury — even at levels generally considered safe — and the development of autoimmunity, which can sometimes lead to an autoimmune disease such as inflammatory bowel disease, lupus, rheumatoid arthritis, or multiple sclerosis.
Autoimmunity occurs when the immune system begins treating normal proteins in the body as if they are foreign invaders. To study mercury’s affects on autoimmunity, the researchers analyzed data from 1,352 women ages 16 to 49 who participated in the National Health and Nutrition Examination Survey from 1999 to 2004. They assessed mercury levels based on hair and blood samples, which can be used to track organic mercury (methylmercury) exposure, as well as urine samples, which can be used to track inorganic mercury.
Tests revealed the presence of antinuclear antibodies (ANA), a marker of autoimmunity, in 16 percent of the study participants. The researchers found an association between ANA levels and mercury levels in hair and blood, but not urine, after adjusting for confounders. The association was strongest for the women with the highest ANA levels. However, even at low methylmercury levels — less than 0.37 parts per million hair mercury and less than one microgram per liter blood mercury — the researchers observed a dose-response relationship. The researchers note that these levels are in the range that regulatory agencies generally consider safe for women of childbearing age.
The new findings point to the need for further investigation into the relationship between methylmercury and autoimmune conditions.
Citation: Somers EC, Ganser MA, Warren JS, Basu N, Wang L, Zick SM, Park SK. 2015. Mercury exposure and antinuclear antibodies among females of reproductive age in the United States: NHANES. Environ Health Perspect; [Online 10 February 2015].