Metallic Contamination

Food Standard and Quality Control

Lesson 25 : Food Adulteration

Metallic Contamination

Toxic Metals:

Contamination of food products by heavy metals is becoming an unavoidable problem these days. Air, soil, and water pollution are contributing to the presence of harmful elements, such as cadmium, lead, mercury, and arsenic in foodstuff.

The occurrence of heavy metals-enriched ecosystem components, firstly, arises from rapid industrial growth, advances in agricultural chemicalization, or the urban activities of human beings. These agents have led to metal dispersion in the environment and, consequently, impaired health of the population by the ingestion of victuals contaminated by harmful elements.

For example, turmeric is coated sometimes with lead chromate. Cooking vessels could be a source of lead and cadmium contamination of foods. Lead is a toxic element and contamination of food with lead can interfere with a variety of body processes and is toxic to many organs and tissues including the heart, bones, intestines, kidneys, reproductive and nervous systems. It interferes with the development of the nervous system and is therefore particularly toxic to children, causing potentially permanent learning and behavior disorders. The common symptoms include abdominal pain, headache, anemia, irritability, and in severe cases seizures, coma, and death.

Fish grown in mercury contaminated water when caught contains large amounts of mercury. The methyl or dimethyl forms of organic mercury compounds are most toxic. The toxic effects of methyl mercury are mostly neurological. When the brain is affected, the subject becomes blind, deaf and paralysis of the various muscles makes him a cripple. The other elements which are toxic in small doses are cadmium, arsenic, antimony and cobalt.

Indian Council of Medical Research (ICMR) in a survey results also revealed high levels of pesticide residues in bovine milk and metals like arsenic, cadmium and lead in infant formula canned products and turmeric.

List of common chemical contamination in foods:

Chemical Foods commonly involved Toxic effects
Arsenic Fruits sprayed by lead arsenate, drinking water Dizziness, chills, cramps, paralysis leading to death.
Barium Foods contaminated by rat poison (barium carbonate). Violent peristalsis, muscular twitching and convulsions.
Cadmium Fruit juices and soft drinks that comes in contact with cadmium and plated vessels, crabs, oysters and kidneys. Excessive salivation, liver, kidney damage, prostate cancer, multiple fractures (painful ltaiĀ·ltai' disease reported from Japan due to cadmium poisoning.)
Cobalt Water, beer Cardiac failure.
Copper Acid foods in contact with tarnished copper ware. Vomiting, diarrhoea, abdominal pain.
Lead Some processed foods
Lead water pipes.
Paralysis, brain damage.
Mercury Mercury fungicide treated seed grains or mercury contaminated fish particularly pike, tuna and shell fish.
Paralysis, brain damage and blindness.
Tin Canned foods Colic, vomiting, photophobia.
Zinc Foods stored in galvanized iron ware. Dizziness, vomiting.
Pesticides All types of foods. Acute or chronic poisoning causing damage to liver, kidney, brain and nerves leading to death.
Diethyl stilbestrol Present in meat of stibestrol fed animals and birds. Teratogenesis, carcinogenesis.
Antibiotics Meat from animals fed antibiotics Drug resistance,
hardening of arteries,
heart diseases.

Source:Swaminathan M., 1987, Food Science Chemistry and Experimental Foods, The Bangalore Printing and Publishing Co., Ltd., Banagalore 560 018.

Packaging hazards

Last modified: Tuesday, 21 February 2012, 10:54 AM