Distribution in Food Products

With the above discussion in mind, it may be assumed that chiral xenobi-otics are likely to be present in various foodstuffs, as human food comprises the meat of fish, birds and terrestrial animals, and of course vegetables. Many chiral pesticides are used to control insects in vegetables and cereals, and hence the presence of these pesticides in the food products is to be expected. Only a few reports are available dealing the presence of chiral pesticides in various foodstuffs. The cholinesterase inhibition activity of chiral organophosphorous pesticides, as well as that of toxic organophosphorous pesticides nerve gases, are enantioselective in nature. Scientists at the Microbiological and Chemical Exposure Assessment Research Division of NERL in Cincinnati, USA, have found the chiral insecticide permethrin, a pyrethroid insecticide, in spinach. Similarly, malathion has been observed in blackberry extract [146]. 

In 1965, Lichtenstein etal. [147] described the presence of aldrin and dieldrin pesticides in cucumber. In the same year, Thruston [148] reported chlordane in squash tissues. In 1991, Pylypiw etal. [149, 150] reported DDE, chlordane and heptachlor epoxide in squash and cantaloupe tissues. Furthermore, the same group [151] reported the presence of chlordane in summer and winter squash and sweet potato from different Connecticut, USA, farms. The authors also examined the market basket data from 1990 to 1997, and suggested that certain crops - cucumber, squash and pumpkin - contain some chiral agrochemicals in their edible portions. Recently, Martina eta/. [152] have detected chlordane residues in the edible tissues of carrot, beet, potato, spinach, lettuce, dandelion, zucchini, bush bean and eggplant. 

Chiral pollutants from various sources are contaminating our environment, as discussed above. The presence of chiral pollutants in sea water and sediment indicates the transportation of these pollutants from the point of origin (source) to the sea. There are many pesticides that have already been banned for a long time, but their presence in sea water shows their persistence in the environment These chiral pollutants, especially pesticides, have been reported in the various body parts of aquatic and terrestrial animals, including human beings, and have entered into the body through the food chain. A detailed search of the literature indicates that only a few reports on the detection of chiral pollutants are available. 

Therefore, water, sediment, soil and air samples should be analysed for these pollutants. Moreover, the detection of these notorious pollutants in biological samples - and especially in the blood, urine and other tissues and biological fluids of human beings - should be investigated. 

Aitken, D. Parker, R. J. Taylor, J. Gopal and R. N. Kilenyi, Asymmetric Synthesis, Blackie, New York, 1992. 

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