page_title: Mercury in fish
section_title: United States
hierarchical_section_title: Mercury in fish / Legislation / United States
caption_attribution_description: English: Poster, "Advice about Eating Fish. What Pregnant Women &amp; Parents Should Know." Types of fish to eat categorized as "Best Choices," "Good Choices" and "Choices to Avoid", based on mercury levels found in fish and risk to human health.
context_page_description: Fish and shellfish concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organomercury compound. Fish products have been shown to contain varying amounts of heavy metals, particularly mercury and fat-soluble pollutants from water pollution. Species of fish that are long-lived and high on the food chain, such as marlin, tuna, shark, swordfish, king mackerel and tilefish contain higher concentrations of mercury than others.
  Mercury is known to bioaccumulate in humans, so bioaccumulation in seafood carries over into human populations, where it can result in mercury poisoning. Mercury is dangerous to both natural ecosystems and humans because it is a metal known to be highly toxic, especially due to its ability to damage the central nervous system. In human-controlled ecosystems of fish, usually done for market production of wanted seafood species, mercury clearly rises through the food chain via fish consuming small plankton, as well as through non-food sources such as underwater sediment.
  The presence of mercury in fish can be a particular health concern for women who are or may become pregnant, nursing mothers, and young children.
context_section_description: The United States has regulated mercury emissions under the authority of the Clean Air Act.
  The Environmental Protection Agency (EPA) first attempted to regulate power plant mercury emissions with the Clean Air Mercury Rule in 2005. The George W. Bush administration intended for the regulation to use a cap-and-trade system to control emissions across multiple industries. The rule was challenged in litigation, and in 2008 the U.S. Court of Appeals for the District of Columbia Circuit vacated the rule, stating that EPA had improperly excluded power plants from designation as emitting hazardous air pollutants.
  EPA subsequently classified mercury emissions from power plants as hazardous under section 112 of the Clean Air Act. The 2012 Mercury and Air Toxics Standards (MATS) regulation, issued by the Barack Obama administration, targets airborne mercury emissions from power plants and other stationary sources. Airborne mercury is dissolved in the oceans, where microorganisms convert waterborne mercury into methyl mercury, which enters the food chain and is stored in fish tissue.
  EPA stated that the MATS regulation would prevent about 90% of power plant mercury. The agency estimated the total expected health benefits are estimated at $37 billion–$90 billion by 2016. EPA estimated the economic cost at $9.6 billion annually.
  In 2020 the Trump administration attempted to weaken the MATS rule by disavowing EPA's previous calculations and justifications, thereby making the rule subject to legal challenges.
caption: Fish advisory chart issued by U.S. Environmental Protection Agency and Food and Drug Administration
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