Mercury linked to immune changes seen in autoimmune disease.

Gardner, RM, JF Nyland, IA Silva, AM Ventura, JM deSouza and EK Silbergeld. 2010. Mercury exposure, serum antinuclear/antinucleolar antibodies, and serum cytokine levels in mining populations in Amazonian Brazil: A cross-sectional study. Environmental Research

Synopsis by Jennifer F. Nyland

Mercury increases the risk of developing autoimmune symptoms - similar to those seen with arthritis - in miners from Amazonian Brazil who work with the metal.

A study in people adds to the growing evidence and concern that mercury can alter the immune system in ways that may promote autoimmune diseases such as arthritis and lupus. The researchers report that mercury increased levels of key signaling and antibody markers measured in the blood of Brazilian gold miners who use the metal to extract the gold from river sediments.

This is the first time mercury has been shown to affect in people the immune signaling proteins that are responsible for inducing inflammation. The results support recent animal studies that find similar changes to rodent immune systems after mercury exposure. The study adds to the few other human studies on the subject, which are less consistent in their conclusions.

Mercury is a well known toxicant. Exposure to even small amounts can damage the brain and nervous system in ways that reduce motor, verbal and attention abilities. This is especially true for developing fetuses and children.

Its effects on the immune system are still being teased apart.

In the United States, most people are exposed to mercury – by eating certain species of fish – most notably large predators such as tuna, swordfish and tilefish. Federal fish advisories warn against eating too much of certain species or too much fish caught from contaminated waterways so as to limit exposure to the metal.

The researchers studied five separate populations: a gold mining camp where mercury is used to extract the gold and two diamond and two emerald mining camps where mercury is not used. Mercury exposure was determined through questionnaires, urine samples and hair samples. Overall, mercury levels and the ranges were higher than what is reported for people who live in the United States.

When blood from gold miners was compared to diamond and emerald miners, changes were found. Levels of certain antibodies and proteins called cytokines were increased only in the gold miners. These increased protein levels are often used to help diagnose some autoimmune diseases like lupus or rheumatoid arthritis.

Even though the miners were exposed through their work to periodic and relatively high levels of mercury, the findings apply to others since mercury exposure from multiple sources is a global problem. Importantly, these changes were not related to whether the miners had malaria, giving the findings a broader application worldwide.  Malaria is a common parasitic infection in many parts of the world, but not in the United States or Europe, and it too can cause changes in the immune system.  Since the immune changes observed in this study were unrelated to whether or not the miners were infected, the authors can conclude that the effects are most likely from mercury exposure.


Fuente: Environmenta lhealth news