Food Contaminants

=1 DEFINITION= Food contaminants are harmful chemicals and microorganisms found in food which have the potential to cause illness in consumers. In developing countries there is significant exposure of the general population to pesticide residues in food. Also mycotoxins and other naturally occuring toxins present acute and chronic health hazards and are a worldwide problem.

=2 SOURCES=

2.1 pesticides and weedkillers Pesticides are chemical substance that protect plants from other harmful plants or animals. The three basic groups are insecticides, fungicides and herbicides. -The most widely used group was and still is in some developing countries organochloride insecticides such as DDT. Ingestion of 1-5 g cause acute intoxication and the lehal dose is 5-10 g. It can persist for close to 7 years in soil and can be to meat and milk of farm animals. -carbamates and organophosphate pesticides are more toxic but less persistent hence are les sof a problem to consumers. Organophosphates mimic or block the action of natural estrogens therefore disrupt the endocrine systém platiny a role in regulating sexual and reproductive development.

2.2 antibiotics Antibiotics are used to treat infectious diseases in farm animals, they have been incorporated in foodstuff for growth promotion and preservation but are now banned because they lead to bacterial resistence and must not be given to milking cows.

2.4 industry Industrial poisons contaminate food by improper disposal of industrial waste, accidents and crime at a plant. -failure to dispose of mercury and cadmium in a safe way causes food contamination. Cadmium also through phosphate fertilizers, cigarettes and water. It then accumulates in the liver and kidneys with a biological half-life of 33 years. Acute intoxication was described in Japan as Itai-Itai disease manifesting as tubular proteinuria with osteomalacia and pseudofractures. Mercury in fish cause irreversable encephalopathy and leads to parakusis, incubation period is 2-5 weeks. Alkyl mercury poisoning occured in Iraq in 1972 due to use as fungicide in food grains. -Food lead may be associated with introduction of unleaded petrol and non-soldered can seams, rtecent data suggest that a threshold cannot be determined for impairment of mental deleterious effects noted at very low exposure levels. -Polychlorinated biphenyls were widely ussed in the past but are now banned in the food Chin due to their persistence.

2.5 Radioactive fallout the main potentially dangerous radioisotopes are iodine-131, strontium-90 and cesium-137. Anímal food is more dangerous to humans than plant animals sine milk and meat concentrates the materiál. strontium – 90 concentrated in milk so especially dangerous for infants, caesium – 137 concentrated in muscle and all meats may be contaminated

=3 REFERENCE=
 * 1) BENCKO, Vladimir, et al. Hygiene and Epidemiology : Selected Chapters. 2nd edition. Prague. 2008. ISBN 80-246-0793-X.
 * 2) Lener, J. et al. Medical Hygiene. Karolinum, Praha 1997.