Adverse effects unlikely from heavy metal found in food products

Posted by Isobel Drake on 25th March 2009

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.

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.

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 not major contributors to exposure, according to the EFSA.

Average dietary exposure to cadmium for adults across Europe is around the TWI 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. The Panel concluded that, even for these groups, the risk of adverse effects would be very low. The Panel added, however, that current exposure to cadmium at the level of the population should be reduced.

The risk of adverse effects even for groups that have exposure at levels above the TWI was very low, according to the EFSA, 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.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.