PESTICIDES AND FOOD PRODUCTS

The use of a pair of identical metallic electrodes to establish the equivalence point in amperometric titrations offers the advantages of simplicity of equipment and elimination of the need to prepare and maintain a reference electrode. This type of system has been incorporated into equipment designed for the routine automatic determination of a single species, usually with a coulometric generated reagent. An example of this type of system is an instrument for the automatic determination of chloride in samples of serum, sweat, tissue extracts, pesticides, and food products. Here, the reagent is silver ion coulometrically generated from a silver anode. The indicator system consists of a pair of twin silver electrodes that are maintained at a potential of perhaps 0.1 V. Before the equivalence point in the titration of chloride ion, there is essentially no current because no easily reduced species is present in the solution. Consequently, electron transfer at the cathode is precluded and that... 

On-line LC-GC has frequently been used as a clean-up technique for the analysis of trace levels of contaminants (pesticides, plasticizers, dyestuffs and toxic organic chemicals) in water and food products. Several different approaches have been proposed for the analysis of contaminants by on-line LC-GC. Since pesticide residues occur at low concentration in water, soil or food, extraction and concentration is needed before GC analysis is carried out. 

Polarographic methods can be used to examine food and food products biological materials herbicides, insecticides and pesticides petroleum and petroleum products pharmaceuticals. The examination of blood and urine samples is frequently carried out to establish the presence of drugs and to obtain quantitative results. 

From this analysis it is clear that in addition to their benefits, the use of pesticides in food production not only causes serious public health problems but also considerable damage to vital agricultural and natural ecosystems in the United States and world. A conservative estimate suggests that the environmental and social costs of pesticide use in the United States total about 4 billion each year. Worldwide the yearly environmental and public health costs are probably at least 100 billion. This is several times the 18 bllllon/yr spent on pesticides in the world. 

This practice went on until recently. Four hundred eighty-one formulations and compounds were included in the official list of pesticides permitted for use in agriculture from 1986-90 [14]. In 1990, the MPC and other health protocols were developed for only 127 pesticides in food products, 105 pesticides in bodies of water used for hygiene and drinking, 78 pesticides in fishery reservoirs, 31 pesticides in farm animal feed, 81 pesticides in the soil, and 119 pesticides in work zone air [1]. There were no MPCs for the remainder of the pesticides permitted for use and, according to existing rules, they should not have been used. Nevertheless, they were. 

While before 1964 the main cause of poisoning was the violation of safety rules, more recently the causes of poisoning have been violating quarantine periods when returning to treated fields, violating health protection zones, and ingesting water and food products contaminated by pesticides (emphasis ours - authors). 

Blood was studied in a group of virtually healthy adolescents aged 14-17 from two localities in the Ukraine, where pesticide exposure differed by a factor of three, though the pesticide content in food products, drinking water, air and soil in the experimental zone was not higher than public health standards permitted. In Azerbaijan there was a difference of 100 times in the amounts of pesticides used in the experimental and control localities, while the pesticide contamination of elements of the environment and food products in the experimental zone was 2-50 times higher than acceptable levels [A97]. Table 3.6 shows the results. 

Research on pesticides in food products carried out in 1965-66 in Khersonsk Oblast (Ukraine) detected HCH in 80% of vegetable product samples, and DDT in 74.3%o (in products of animal origin, these figures were 10%o and 93.8%), respectively). The daily diet of subjects from Group I intensity work contained 2.31 mg of DDT [A77]. 

Table 3.15 gives some idea of the trends in pesticide contamination of different food products. As should have been expected, fatty dairy products, Table 3.15. Residual Pesticides in agricultural and food products in the USSR exceeding MPLs in 1988-89 [3]...

On the whole, 68.7% of 262 types of agricultural and food products that were studied in the USSR in 1988 were contaminated by pesticides in unacceptable quantities. The basic pesticide types led the list OCPs such as DDT (38.8% of 250 types of products studied) and HCH 37.3% of 255 products), OPPs such as methyl parathion (26.5% of 170 products) and trichlorfon (28.4% of 236 products), 2,4-D (43.8% of 144 products), and OMPs (31.0% of 129 products). 

A system of laboratory monitoring has been organized in the district which controls indications for pesticides and other chemical substances in objects of the environment, raw material supplies and food products. 

Approximately 55 different commercial formulations of chlordecone have been prepared since its introduction in 1958 (Epstein 1978). The major form of chlordecone, which was used as a pesticide on food products, was a wettable powder (50% chlordecone) (Epstein 1978). Formulations of chlordecone commonly used for nonfood products were in the form of granules and dusts containing 5% or 10% active ingredient (Epstein 1978). Other formulations of chlordecone contained the following percentages of active ingredient 0.125% (used in the United States in ant and roach traps), 5% (exported for banana and potato dusting), 25% (used in the United States in ant and roach bait), 50% (used to control mole crickets in Florida), and 90% (exported to Europe for conversion to kelevan for use on Colorado potato beetles in eastern European countries) (Epstein 1978). 

TESTING (Physiological). Determination of (lie toxicity of a substance or product by administering it to laboratory animals in controlled dosages, by mouth, skin application, or injection. Materials commonly subjected lo such evaluation are plianuaceuheals, pesticides, and foods. Extensive testing programs are required before such products are approved for human use. 

Panel 2 of the Committee for Analytical Methods for Residues of Pesticides and Veterinary Products in Foodstuffs of the Ministry of Agriculture, Fisheries and Food (1976) Analyst 101 386. 

In the environment, organisms including man are exposed to mixtures of chemicals rather than single compounds. Examples of mixtures are food and feedstuff, pesticide and medical products, dyes, cosmetics, and alloys. Many other commercial products, such as printing inks, contain a mixture of substances, possibly up to 60 individual chemicals in 1 formulation. Preparation of these chemicals may involve the use of several hundred other substances in upstream processes. 

Another major trend in performance chemicals is towards the development of products - pharmaceuticals, pesticides and food additives, etc. - that are more targeted in their action with less undesirable side-effects. This is also an issue which is addressed by green chemistry. In the case of chiral molecules that exhibit biological activity the desired effect almost always resides in only one of the enantiomers. The other enantiomer constitutes isomeric ballast that does not contribute to the desired activity and may even exhibit undesirable side-effects. Consequently, in the last two decades there has been a marked trend towards the marketing of chiral pharmaceuticals and pesticides as enantiomeri-cally pure compounds. This generated a demand for economical methods for the synthesis of pure enantiomers [127]. 

As the 1960s unfolded, other serious threats to public health and the workforce were revealed -toxic lead in paint and gasoline, asbestos in building insulation, food contaminated with mercury from pesticides and industrial products. 

The classic prototype chlorinated hydrocarbon pesticide is DDT (dichloro-diphenyltrichloroethane), a chemical which earned its discoverer, Dr. Paul Muller, a Nobel Prize in 1948. This honor was an event that partly reflected the tremendous beneficial impact that this class of compounds had on disease prevention and food production. Although this compound is not used any longer in the United States (see Chapter 3), it is still widely used throughout the world where the risk/benefit ratio favors continued pesticide use. This is because of its efficacy in agriculture and its ability to kill insect vectors of important human diseases such as malaria. It is thus monitored in the FDA food surveillance programs. 

Vanzetti, D. and E. Wynen (2002), Does it make sense to buy locally produced organic products in Hall, D. and J. Moffitt (eds) Economics of Pesticides, Sustainable Food Production and Organic Food Markets, Elsevier, pp. 195-208 www.elspl.com.au/abstracts/E2.htm. 

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