March 20 - The European Food Safety Authority's Panel on contaminants in the food chain has set a reduced tolerable weekly intake (TWI) for cadmium of 2.5 micrograms per kilogram of body weight (µg/kg bw), based on an analysis of new data.
The TWI is the level at which adverse effects are not expected. Average dietary exposure to cadmium for adults across Europe is around this level. Some population groups - vegetarians, children, smokers and people living in highly contaminated areas - can have a higher level of exposure up to twice the TWI. However, the Panel concluded that even for these groups the risk of adverse effects would be very low. The Panel concluded that current exposure to cadmium at the level of the population should be reduced.
EFSA was asked by the European Commission to assess the risks to human health related to the presence of cadmium in foodstuffs in order to support risk managers in reviewing the maximum permitted levels in food. EFSA was also asked to indicate the relative importance of other sources of exposure to cadmium and consider the exposure situation for specific groups of the population, including children.
Cadmium is a heavy metal which enters the environment from natural sources, such as volcanic emissions and the weathering of rocks, as well as from industry and agriculture. It is found in the air, soil and water and can subsequently accumulate in plants and animals.
Cadmium is primarily toxic to the kidney, but can also cause bone demineralisation, and has been classified as carcinogenic to humans by the International Agency for Research on Cancer[2] . Foodstuffs are the main source of cadmium exposure for the non-smoking population. Cereals and cereals products, vegetables, nuts and pulses, starchy roots and potatoes as well as meat and meat products contribute most to human exposure. High levels were also found in some other foodstuffs (e.g. seaweed, fish and seafood, food supplements, mushrooms, chocolate) but as they are consumed to a lesser extent, they were no major contributors to exposure.
The Panel carried out an analysis of a large number of studies looking at the relationship between urinary cadmium levels and beta-2-microglobulin, a protein excreted in the urine which is a biological indicator of kidney function. The Panel established the TWI of 2.5 µg/kg bw by applying the results of this analysis to a model translating levels of urinary cadmium into dietary exposure. The Panel concluded that the risk of adverse effects even for groups that have exposure at levels above the TWI was very low because the TWI was not based on actual kidney damage, but on an early indicator of changes in kidney function suggesting possible kidney damage later in life.
The Panel also analysed data on levels of cadmium in food from 20 different countries, alongside national dietary surveys and EU-wide consumption data collected by EFSA. This information indicated that average and high-level[3] exposure were 2.3 µg/kg bw and 3.0 µg/kg bw per week respectively.
Vegetarians – who eat relatively high amounts of foods containing cadmium, including cereals, nuts, oilseeds and pulses – were estimated to have an average weekly exposure of up to 5.4 µg/kg bw. The Panel also stated that locally-produced food in highly contaminated areas may lead to higher exposure levels. Furthermore, dietary exposure could be higher for children than adults, due to the greater amount of food consumed by children in relation to their bodyweight.
The Panel also stated that smoking can contribute to a similar internal exposure as the diet, and that house dust can be an important source of overall exposure to cadmium for children.