Metals as contaminants in food
Metals such as arsenic, cadmium, lead and mercury are natural occurring chemical compounds. They can be present at various levels in the environment, e.g. soil, water and atmosphere. Metals can also occur as residues in food because of their presence in the environment, as a result of human activities such as farming, industry or car exhausts or from contamination during food processing and storage. People can be exposed to these metals from the environment or by ingesting contaminated food or water. Their accumulation in the body can lead to harmful effects over time.
Nickel is a naturally occurring metal that is sometimes present in food and water through environmental contamination, including as a result of human activity. Short-term (‘acute’) exposure to nickel causes allergic reactions in some individuals, both by touch and also from ingestion in food or water. The results of animal studies also indicate possible reproductive and developmental effects from long-term (‘chronic’) exposure to nickel.
In the European Union, there are currently no maximum levels for nickel in food. Nickel in drinking water intended for human consumption and in natural mineral waters should not exceed 20 micrograms per litre.
In February 2015, EFSA published a scientific opinion on the risks to human health from nickel in food, particularly in vegetables, and also in drinking water. EFSA set a safe level, known as the tolerable daily intake (TDI), of 2.8 micrograms per kilogram of body weight. Based on current mean and high exposures, EFSA’s experts concluded that current chronic dietary exposure to Nickel is of concern for the general population.
In January 2015, EFSA published a statement on the risks and benefits of seafood, specifically related to the presence of methylmercury in food. Limiting consumption of fish species with a high methylmercury content is the most effective way to achieve the health benefits of fish whilst minimising the risks posed by excessive exposure to methylmercury.
EFSA recommended that individual Member States consider their national patterns of fish consumption and assess the risk of different population groups exceeding safe levels of methylmercury while obtaining the health benefits of fish. This particularly applies to countries where fish/seafood species with a high mercury content – such as swordfish, pike, tuna and hake – are consumed regularly.
Two earlier EFSA scientific opinions looked respectively at the risks from mercury and methylmercury in food, and the health benefits of fish/seafood. The first opinion established a TWI for methylmercury of 1.3 micrograms per kg of body weight; the second recommended weekly intakes of fish of between 1-2 servings and 3-4 servings in order to realise health benefits such as improved neurodevelopment in children and reduced risk of coronary heart disease in adults respectively.
EFSA has received requests from the European Commission or Member States to provide risk assessments on several metals as contaminants, including arsenic, cadmium, chromium, lead, mercury, nickel and uranium. This work is carried out by the Panel on Contaminants in the Food Chain (CONTAM Panel). EFSA also works closely with Member States and other data providers to collect data on occurrence of metals in food and feed.
There are different forms of chromium. Chromium III occurs naturally and is an essential nutrient and the main form of chromium present in food. It aids normal glucose, protein, and fat metabolism. Another form, chromium VI is most commonly produced by industrial processes and is sometimes present in drinking water.
In March 2014, the CONTAM Panel published a scientific opinion on the risk to human health from chromium in food, particularly in vegetables and in bottled drinking water. EFSA’s experts established a tolerable daily intake (TDI) of 0.3 milligrams per kilogram of body weight per day for chromium III. Dietary exposure across all age groups is well below the TDI and therefore does not raise concerns for public health.
Animal studies indicate high levels of chromium VI can cause cancer; therefore, the Panel did not establish a safe level (‘TDI’) for chromium VI. However, EFSA’s experts concluded there is a concern regarding average chromium VI intake via drinking water for infants, but a low concern for all other age groups. Above average exposures for some groups, particularly infants, toddlers and other children, could be a concern but these estimates were limited by the availability of data.
Arsenic is a widely-occurring contaminant which occurs both naturally and as a result of human activity. Foodstuffs are the main source of exposure for the general population in Europe. The main sources of inorganic arsenic intake are cereal grains and cereal based products, food for special dietary uses (e.g. algae), bottled water, coffee and beer, rice and rice-based products, fish and vegetables.
In October 2009, the CONTAM Panel adopted an opinion on arsenic in food, mainly focused on inorganic arsenic, which is the more toxic form in which arsenic can appear. The Panel recommended that exposure to inorganic arsenic should be reduced. In March 2014, EFSA updated its analysis of the occurrence of arsenic in food in Europe. The Authority’s data specialists refined their estimates of long-term (‘chronic’) dietary exposure to inorganic arsenic, which were found to be lower than previously reported by EFSA.
Uranium is a naturally occurring radioactive metal, which can be found in varying concentrations in the environment, water and foodstuffs. In March 2009 the CONTAM Panel conducted a risk assessment on dietary exposure to uranium in foodstuffs, in particular mineral water, and advised on the Tolerable Daily Intake (TDI) for uranium. The opinion focused on the chemical toxicity of uranium. The radiological risks related to uranium are outside EFSA’s remit.
EFSA concluded that average dietary exposure to uranium for the general population and high consumers across Europe is currently below the TDI. In specific areas where uranium concentrations in drinking water are high, the exposure estimates are close, but still below the TDI. For infants fed with infant formula made up with water containing uranium, the Panel noted that exposure in relation to body weight may be up to three times higher than for adults, and concluded that such exposure should be avoided.
Foodstuffs are the main source of cadmium exposure for the non-smoking general population. In 2009, EFSA’s CONTAM Panel carried out a risk assessment on cadmium in food and established a tolerable weekly intake (TWI) of 2.5 micrograms per kilogram of body weight (µg/kg bw). Following an assessment of cadmium by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the CONTAM Panel reassessed the TWI in 2011 and concluded that the TWI of 2.5 µg/kg bw is still appropriate. The current average dietary exposure to cadmium for adults is close to the TWI and the exposure of some subgroups, such as children, vegetarians and people living in highly contaminated areas, could exceed the TWI. The risk of adverse effects for an individual at the current dietary exposure is low because the TWI is not based on actual kidney damage, but on an early indicator of changes in kidney function, suggesting possible kidney damage later in life. In its 2011 reassessment, however, the CONTAM Panel reaffirmed its previous conclusions that adverse effects are unlikely to occur in an individual with current dietary exposure but there is a need to reduce exposure to cadmium at the population level.
Lead is an environmental contaminant which occurs both naturally and through human activities such as mining. In an opinion published in April 2010 on possible health risks related to the presence of lead in food, the CONTAM Panel considered cereals, vegetables and tap water to contribute most to dietary exposure to lead for most Europeans. The Panel concluded that current levels of exposure to lead pose a low to negligible health risk for most adults but there is potential concern over possible neurodevelopmental effects in foetuses, infants and children.
The basic principles of EU legislation on contaminants in food are contained in Regulation 315/93/EEC:
- Food containing a contaminant to an amount unacceptable from the public health viewpoint and in particular at a toxicological level, is not to be placed on the market
- Contaminant levels must be kept as low as can reasonably be achieved following recommended good working practices
- Maximum levels must be set for certain contaminants in order to protect public health.
Regulation EC 1881/2006 lays down maximum levels for certain contaminants in foodstuff, including lead, cadmium, mercury and inorganic tin. This Regulation does not cover radioactive substances. Regulation EC 333/2007 covers the methods of sampling and analysis for the official control of the maximum levels of these metals. Surveillance for residues of chemical elements in foods of animal origin is specified in Council Directive 96/23/EC.
- EU legislation on contaminants – European Commission