Mercury in Food and Dietary Supplements
For Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1 - 11 Years
Mercury may be present in food because it is in the environment. Mercury may occur naturally in soil, air, and water, but levels can vary depending on the environmental makeup of local areas. For example, mercury can be distributed in the environment from natural sources such as volcanic activity and geological weathering. The levels of mercury in the environment are often higher because of pollution from human activities such as fossil fuel combustion, manufacturing, and small-scale gold mining.
Methylmercury, one type of mercury, is formed by microscopic organisms and is the most widespread form of mercury in the environment. It is also the most potentially harmful form of mercury and can be toxic to people of any age or health status.
The FDA monitors and regulates levels of mercury in foods, including dietary supplements, and cosmetics. While eating seafood is the most common way people in the U.S. are exposed to mercury, most types of seafood do not have levels of mercury that would result in health effects for adults. To help those who are or might become pregnant or are breastfeeding, as well as parents and caregivers choose fish that are nutritious and lower in mercury, the FDA and the Environmental Protection Agency (EPA) have issued advice on eating fish. This advice supports the recommendations of the Dietary Guidelines for Americans.
The FDA’s goal is to limit consumer exposure to mercury, with a focus on protecting the very young, through developing regulations, setting action levels, and issuing advice to consumers. The agency considers the health effects of the ‘whole food’, which includes the potential harmful health effects of specific contaminants that may be present, as well as the food’s nutrients that are vital to growth and development for babies and small children and help promote health and prevent disease throughout our lifespan.
For more information about our specific activities to reduce exposure to arsenic, lead, mercury, and cadmium from foods consumed by babies and young children please visit the FDA’s Closer to Zero page.
The most common way people in the U.S. are exposed to mercury is by eating seafood contaminated with methylmercury. Nearly all fish and shellfish contain trace amounts of methylmercury. While it is not possible to prevent or remove mercury entirely from foods, most types of seafood do not have levels of mercury that would result in health effects for adults.
Because the very young are more vulnerable to the harmful health effects of mercury exposure, and because there are significant differences in the levels of mercury between different types of seafood, the FDA and EPA have issued advice on eating fish. This advice can help those who are or might become pregnant or are breastfeeding, as well as parents and caregivers who are feeding children - choose types of seafood that are lower in mercury and provide key nutrients that support brain development, the spinal cord, and a child’s immune system. This advice supports the recommendations of the Dietary Guidelines for Americans.
The advice features a chart that makes it easy to choose dozens of healthy and lower mercury options and includes information about the nutritional value of fish. A set of frequently asked questions & answers provides more information on how to use the chart and additional tips for eating fish.
Resources from the FDA
- Advice About Eating Fish for Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1-11 Years.
- Technical Information on Development of FDA/EPA Advice about Eating Fish for Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1-11 Years.
- FDA Issues Recommendations for Certain High-Risk Groups Regarding Mercury-Containing Dental Amalgam
- To Help Protect Children from Environmental Contaminants, Healthy Food Choices for Your Baby Aged 6-12 Months
Resources from Other Federal Government Agencies
- United States Environmental Protection Agency - Mercury
- United States Centers for Disease Control and Prevention (CDC) - Mercury and Breastfeeding
- United States Centers for Disease Control and Prevention (CDC) - Mercury Fact Sheet
- Agency for Toxic Substances and Disease Registry
- National Institutes of Health, National Institute of Environmental Health Sciences
The Centers for Disease Control and Prevention (CDC) monitor mercury levels in the U.S. population and have found that people tested in the U.S. do not have levels of mercury in their blood that would be expected to result in health effects. However, understanding what levels of mercury exposure will result in specific health effects is an area of active research.
Methylmercury, the form of mercury found in seafood, is the most potentially harmful form of mercury and can be toxic to people of any age or health status.
- The long-term adverse health effects from consuming food contaminated with mercury vary depending on the amount consumed, length of time of exposure, age, and other exposures happening at the same time—either to mercury from other sources, other contaminants, or to beneficial nutrients.
- Fetuses, infants, and children are particularly vulnerable to the potential harmful effects from mercury exposure because of their smaller body sizes, metabolism, and rapid growth.
- Exposure to high levels of mercury during times of active brain development can lead to neurological effects such as decreased measures of intelligence, difficulty in memory and cognition, and problems with gross and fine motor skills. Evidence is also emerging that attention could be impacted.
- Adverse short-term health effects for adults from typical consumption usually require a level of mercury not generally found in seafood products.
- For adults exposed to harmful levels of methylmercury, symptoms of poisoning may appear over time or may develop suddenly. They may include a range of symptoms such as psychological issues (e.g., depression or memory problems), numbness or muscle weakness (e.g., difficulty walking); difficulty with speech, hearing, or vision; a “metallic” taste in the mouth; and issues with balance.
- Suspected methylmercury poisoning should be diagnosed by a physician after testing for the level of mercury in a person's blood or urine.
The FDA tests food for arsenic, lead, cadmium, and mercury to monitor the safety of the U.S. food supply, enforce FDA regulations, and inform agency guidance to industry and advice to consumers. Testing may be targeted to a specific category of food, such as foods commonly eaten by children under 2 years of age, or to a specific food or food group. Testing may also be conducted in response to reports of elevated contaminant levels in certain foods. Testing may occur at FDA laboratories, laboratories we contract with, or at state laboratories as part of our cooperative agreement with states.
The FDA tests for environmental contaminants, including mercury, through:
- the Total Diet Study;
- For the FDA’s most recent survey of foods measuring for mercury, and please visit: FDA Total Diet Study (TDS) FY2018-FY2020 Elements Report and Data (2022)
- the FDA’s Toxic Elements in Food and Foodware, and Radionuclides in Food compliance program; and
- Other surveys, which may be conducted annually or in response to reports of elevated contaminant levels in certain products or to focus on a specific food or food group.
The FDA has conducted routine surveillance and targeted surveys for arsenic, lead, cadmium, and mercury in foods, including those commonly consumed by babies and children under 2 years of age. Data on lead in the table below helped to inform the FDA’s action levels for lead in foods intended for babies and young children and were posted when the FDA issued draft guidance to industry. Data on arsenic, cadmium, and mercury will help inform the development of action levels.
- Analytical Results for Arsenic, Lead, Cadmium, and Mercury in Foods Intended for Babies and Young Children- TEP (FY2008-FY2021) in PDF, in XLSX
Sampled under the FDA’s Toxic Elements in Food and Foodware, and Radionuclides in Food – Import and Domestic Compliance Program, Posted March 2023
The FDA has been conducting research to optimize testing methods to measure increasingly smaller amounts of environmental contaminants in foods commonly eaten by babies and young children.
- For more information, please visit: A survey of toxic elements in ready to eat baby foods in the US market 2021 (2022).
To evaluate the scientific evidence regarding seafood and child growth and development to support a more holistic view of seafood consumption, the FDA launched an independent study by the National Academies of Sciences, Engineering, and Medicine (NASEM).
- For more information, please visit: FDA and Federal Partners Launch Study on the Role of Seafood Consumption in Child Growth and Development.
From 1990-2010, the FDA sampled and tested fish and other seafood for mercury. The results of this 20-year survey showed that mercury levels did not change significantly over time.
The FDA is currently developing an updated method for determining levels of mercury in fish and other seafood, as well as a sampling and analysis plan, to produce new data. This update is expected to begin in 2023. For data on mercury levels (concentrations) from 1990-2010, please visit:
- Mercury Concentrations in Fish: FDA Monitoring Program (1990-2010)
- Mercury Levels in Commercial Fish and Shellfish (1990-2012)
Net Effects Report on Fetal Neurodevelopment
In 2009, the FDA made available for public comment a draft report that mathematically modeled certain aspects of eating commercial fish on fetal neurodevelopment, fatal coronary heart disease, and fatal stroke. In 2014, after scientific reviews from experts and scientists, and consideration of over 460 public comments, the FDA published a revised report. Since that time, other published risk-benefit models, additional epidemiological evidence, and new analyses on omega-3 fatty acids, have raised concerns about the findings in the 2014 FDA net effects report. While our continued research has helped further the FDA’s understanding of mathematical modeling for neurodevelopmental effects from heavy metal exposure, the FDA has updated the FDA/EPA Advice About Eating Fish to further align with the Dietary Guidelines for Americans.
- Quantitative Assessment of the Net Effects on Fetal Neurodevelopment from the Eating Commercial Fish (As Measured by IQ and also by Early Age Verbal Development in Children)
- Peer Review Report on the Quantitative Assessment of the Net Effects from Eating Commercial Fish on Fetal Neurodevelopment (As Measured by IQ and also by Early Age Verbal Development in Children)
- Draft Report of Quantitative Risk and Benefit Assessment of Consumption of Commercial Fish, Focusing on Fetal Neurodevelopmental Effects (Measured by Verbal Development in Children) and on Coronary Heart Disease and Stroke in the General Population, and Summary of Published Research on the Beneficial Effects of Fish Consumption and Omega-3 Fatty Acids for Certain Neurodevelopmental and Cardiovascular Endpoints.
January 2009; 74 FR 3615 Page: 3615-3617
Other Past Research
- An Exposure Assessment for Methylmercury from Seafood for Consumers in the United States Risk Analysis October 2002, Vol 22, Issue 4
- An Intervention Analysis for the Reduction of Exposure to Methylmercury from the Consumption of Seafood by Women of Child-bearing Age Regulatory Toxicology Pharmacology, Dec. 2004 Vol. 40, Issue 3
- A Pooled Analysis of the Iraqi and Seychelles Methylmercury Studies Human and Ecological Risk Assessment: An International Journal 2000, vol. 6 issue 2
FDA regulations require industry to meet certain safety guidelines. It is the legal responsibility of companies that produce and grow foods and manufacture products sold in the U.S. and intended for food use to comply with FDA regulations and with the Federal Food, Drug and Cosmetic Act. The FDA issues guidance to industry to help them meet their legal responsibility.
Mercury, if present in food, is a contaminant. There are no FDA authorized uses of mercury as a color additive or food additive.
For some contaminants, the FDA has issued guidance to industry on action levels when a certain level of a contaminant is unavoidable. Guidance on action levels inform industry on the levels of contamination at or above which the FDA may regard certain foods as adulterated (i.e., that it violates the law). Action levels do not establish a permissible level of contamination. When the agency finds that the level of a contaminant causes the food to be unsafe, we take action, which may include working with the manufacturer to resolve the issue and taking steps to prevent the product from entering, or remaining in, the U.S. market.
Bottled Water Regulation
The FDA, through its regulatory authority under the Federal Food, Drug, and Cosmetic Act, limits the level of mercury (as well as other contaminants) in bottled water by establishing allowable levels in the quality standard for bottled water. For mercury, this level is set to 2ppb, the same amount allowed by the U.S. Environmental Protection Agency for public drinking water.
The FDA has also issued the following guidance to industry for action levels of methylmercury in fish and other seafood and mercury treated grain seed:
- For the seafood guidance, please visit: CPG Sec. 540.600 Fish, Shellfish, Crustaceans and other Aquatic Animals - Fresh, Frozen or Processed - Methyl Mercury
- For treated grain seed, please visit: CPG Sec 578.400 Treated Grain Seed - Mercury Residue
- Guidance for Industry: Action Levels for Poisonous or Deleterious Substances in Human Food and Animal Feed
International Scientific Activities
FDA experts participate in the international standard-setting body, Codex Alimentarius Commission (Codex). The purpose of Codex is to protect the health of consumers and promote fair trade practices by adopting scientifically based standards, guidelines, and codes of practice across all areas of food safety and quality. Its work includes reviewing the scientific data concerning contaminant levels in foods. These international discussions can lead to recommendations for standards individual countries may adopt and codes of practice to prevent or reduce the presence of contaminants in food.