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Heavy Metal Contamination of Foods is a World Wide Concern

Heavy Metal Contamination of Foods is a World Wide Concern

It is essential to carry put testing of raw materials for heavy metals as they can enter foods from the environment by natural means through weathering of the earth’s crust, mining, soil erosion, industrial discharge, urban runoff, sewage effluents, pesticides use air pollution fallout, etc. Heavy metals reach humans and animals through ingestion of contaminated foods. The more the intake of heavy metal contaminated foods, the more the increase in quantity of heavy metal intake. It is the FBOs that are responsible for the safety of food and animal feed that they produce, transport, store or sell. They partner with recognised chemical laboratories which ascertain that heavy metal content in foods is within regulatory limits so foods are safe.

Heavy Metals Affect Health

Heavy metals that produce the most harmful effects on health are mercury, lead, cadmium, tin and arsenic. The hazard comes from the metals accumulating in the tissues. Heavy metals can affect the brain, the nervous system and arrest the development of children. These metals cause damage to the kidneys, reproductive and immune systems and can even cause cancer. In order to protect human health FBOs partner with independent chemical testing laboratories to control their levels in foods. Recognised and accredited chemical testing laboratories have laid down criteria for determining heavy metals in foods.

Food Regulations have fixed the maximum levels for these metals in foodstuffs including milk, meat, fish, cereals, vegetables, fruit and fruit juices. In order to ensure that these maximum limits are not exceeded food testing labs carry out routine food testing. Any foods that have the potential to be contaminated are sampled and appropriately tested so heavy metals remain within regulatory limits. It is the responsibility of the FBO to test his products for content of mercury, lead, cadmium, tin or arsenic at the point of sale.

Foods can get contaminated in the following ways
  • Fish and fish products have the potential to be contaminated with mercury and methyl mercury from industrial discharge into their habitats
  • Canned food packed in metal tins can become contaminated with tin if the packing material is incorrect
  • Lead and cadmium can reach foods from certain ceramic dishes and other material when they come in contact with foods. Cadmium can also be ingested from edible plants like vegetables
  • Water supply testing is equally important to identify lead and arsenic contamination in water.
  • Arsenic contaminated water used for irrigation can reach agricultural produce like grains and vegetables as well as cooked food if it is use for food preparation

Chemical testing laboratories use several methods for testing the presence of heavy metals in various foods. The two important methods are sample digestion and detection method. Sample digestion includes
  • Dry ashing of the sample in a conventional oven
  • microwave digestion of the sample in a strong acid
  • acid digestion of the sample by heating in a pressure vessel
  • dissolving the sample directly into acid
  • Some testing laboratories also use AAS, HG and ICP, ICP-MS and ICP-OES methods



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