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.
EFSA provides scientific support and advice to risk managers based on risk assessments. The European Commission and EU Member States make decisions on regulatory issues including the setting of maximum levels for metals in food – EFSA’s scientific advice helps inform such decisions.
Exposure to contaminants whilst not desirable may not be avoidable. Therefore, as part of its risk assessments of contaminants in food, when possible (i.e. when sufficient information is available), EFSA establishes a Tolerable Daily or Weekly Intake (TDI/TWI) for these substances. This is an estimate of the average quantity of a chemical contaminant that can be ingested daily or weekly over a lifetime without posing a significant risk to health. A TDI/TWI is usually expressed on a body weight basis in milligrams per kilogram of body weight per day or week (mg/kg bw/day or wk).
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
EFSA has received requests from the European Commission or Member States to provide risk assessments on arsenic, cadmium, mercury and uranium in food. This work is carried out by the Panel on Contaminants in the Food Chain (CONTAM Panel).
Mercury in food
In December 2012, EFSA updated its scientific advice on mercury in food. The Authority established Tolerable Weekly Intakes (TWIs) for the main forms of mercury found in food: methylmercury and inorganic mercury. Methylmercury is the predominant form of mercury in fish and other seafood, and is particularly toxic to the developing nervous system including the brain. Inorganic mercury is less toxic and can also be found in fish and other seafood as well as ready-made meals.
The CONTAM Panel considered new scientific information regarding the toxicity of these forms of mercury and established a TWI for inorganic mercury of 4 µg/kg body weight (bw) and a TWI for methylmercury of 1.3 µg/kg bw (lower than JECFA’s TWI of 1.6 µg/kg bw). Average exposure to methylmercury in food is unlikely to exceed the TWI, but the likelihood of reaching such a level increases for high and frequent fish consumers. This group may include pregnant women, resulting in exposure of the fetus at a critical period in brain development. Exposure to inorganic mercury through food is unlikely to exceed the TWI for most people, unless combined with other sources of exposure (mainly from fillings used in dental treatment).
Following publication of this opinion, EFSA received a request from the European Commission for a scientific opinion on the risks and benefits of fish/seafood consumption as regards methylmercury. EFSA accepted this mandate. The opinion is scheduled for publication by December 2013.
Arsenic in food
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.
In October 2009, the CONTAM Panel adopted an opinion on arsenic in food. This opinion mainly focuses on inorganic arsenic, which is the more toxic form in which arsenic can appear. The Panel compared amounts of arsenic that people could consume through food and drink to levels which may cause certain health problems. As there was little or no difference between the two, the Panel recommended that exposure to inorganic arsenic should be reduced. However, the Panel also highlighted considerable uncertainties in relation to its risk assessment. It stressed the need for more data on levels of organic and inorganic arsenic in different foodstuffs, as well as on the relationship between arsenic intake levels and possible health effects.
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.
Uranium in foodstuffs
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. Under the European Atomic Energy Community (EURATOM) Treaty, scientific advice on these aspects is the responsibility of a Group of experts attached to the European Commission’s Directorate-General for Energy and Transport.
- EURATOM Group of Experts – European Commission
The Panel did not identify any new data which would have called for a revision of the TDI for uranium of 0.6 µg/kg bw per day established by the World Health Organisation (WHO), and therefore it endorsed this TDI.
The Panel 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.
Cadmium in food
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 in food
Lead is an environmental contaminant which occurs both naturally and through human activities such as mining. In 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.