Mercury in food
Mercury is a metal that is released into the environment from both natural and anthropogenic sources. Once released, mercury undergoes a series of complex transformations and cycles between atmosphere, ocean and land. Of the chemical forms of mercury, methylmercury is by far the most common form in the food chain.
The critical target for toxicity is the kidney. Other targets include the liver, nervous system, immune system, reproductive and developmental systems. Methylmercury is able to enter the hair follicle, and to cross the placenta as well as the blood-brain and blood-cerebrospinal fluid barriers, allowing accumulation in hair, the foetus and the brain.
Fish & other seafood, non-alcoholic beverages and composite food are the most important contributors to inorganic mercury dietary exposure in the European population. Fish meat is the dominating contributor to methylmercury dietary exposure for all age classes, followed by fish products. The mercury content in these commodities varies widely among different fish species, and is in general higher in predatory fish.
In general, the mean dietary exposure does not exceed the tolerable weekly intake (TWI) for methylmercury across age groups, with exceptions in all age groups that are close to or above the TWI. High consumers of fish meat may exceed the TWI by up to approximately six-fold. Unborn children constitute the most vulnerable group for developmental effects of methylmercury exposure, and pregnant women can be present in the group of high and frequent fish consumers.
Provisions for methods of sampling and analysis for the official control of lead, cadmium, mercury, inorganic tin, 3-MCPD and benzo(a)pyrene in foodstuffs are laid down in Commission Regulation (EC) No 333/2007.
Scientific Opinion on the risk for public health related to the presence of mercury and methylmercury in food
To achieve the benefits of fish consumption (effect of fish/seafood consumption during pregnancy on functional outcomes of children’s neurodevelopment and on cardiovascular diseases in adults), which are associated with 1–4 fish servings per week and at the same time protect against neurodevelopmental toxicity of methylmercury, the consumption of fish/seafood species with a high content of mercury in the daily diet should be limited: when consuming species with a high methylmercury content, only a few numbers of servings (<1–2) can be eaten on a weekly basis.
However, as the consumption patterns for fish and seafood vary considerably within the European Union and even within Member States, this consumption advice should typically be refined at national level.