Dangerous Chemicals in Your Life: Mercury

The inorganic element mercury (Hg) has always been present in nature and is often spewed into the atmosphere in smoke from volcanoes (University of Oxford) and forest fires (National Science Foundation). In addition to these sources, mercury also comes to us from human-made (anthropogenic) sources. The main sources of anthropogenic mercury emissions are gold mining operations, coal combustion, non-ferrous metals production and cement production (U.S. EPA, 2015-a). Mercury can also be present in a variety of products, from batteries to jewelry (learn more here). Click here for a map of Sierra Nevada abandoned mining sites, many of which have left a legacy of downstream mercury (Sierra Nevada Conservancy). Click here for a map of national mercury concentrations in precipitation as a result of factory emissions and other airborne sources (National Atmospheric Deposition Program) Mercury poisoning has been linked to impaired neurological development in fetuses, infants, and children. It can also impact thinking, memory, attention, language, and fine motor and visual skills (EPA, 2014-b). The greatest source of mercury poisoning for people comes from eating infected fish (EPA, 2014-c). The difference between tolerable, background levels of mercury and harmful levels in the environment is very small (Eisler), so whatever we can do to reduce emissions and minimize our exposure to this heavy metal might mean the difference between health and dangerous effects. Although mercury is unhealthy in any form, inorganic mercury can get significantly more toxic when it enters aquatic systems, such as lakes, rivers, wetlands, meadows, soils, and the open ocean, where anaerobic organisms convert inorganic mercury to organic methylmercury (Ullrich). Mercury accumulates in the tissues of each organism that eats infected prey, then magnifies in concentration as it travels up the food chain—a process known as biomagnification. What you can do.
  • Avoid eating fish high in mercury. This includes shark, swordfish, king mackerel, tilefish and larger tunas. Larger and more predatory fish tend to have higher levels of mercury. Fish with lower levels of mercury include shrimp, tilapia, canned light tuna, pollock and catfish. (NRDC-b).
  • Mercury levels in fish near you depend on the mining history in each specific watershed where the fish live. Click here for a map database of fish advisories where you live.
  • Buy Fairtrade Gold. This initiative supports and certifies mercury-free gold from small-scale, artisanal miners and their communities. To learn more about the initiative and where to buy mercury-free gold, login to www.fairgold.org.

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