Insecticide poisoning food contamination

Minute amounts of arsenic are widely distributed in the common foods, in quantities that are more likely to be beneficial than toxic. However, poisoning may result from foods contaminated with excessive amounts of arsenic-containing sprays used as insecticides and weed killers. 

The OP and carbamate insecticides are relatively nonpersistent in the environment. They are applied to the crop or directly to the soil as systemic insecticides, and they generally persist from only a few hours to several months. Thus these compounds, in contrast to the organochlorine insecticides, do not represent a serious problem as contaminants of soil and water and rarely enter the human food chain. Being esters, the compounds are susceptible to hydrolysis, and their breakdown products are generally nontoxic. Direct contamination of food by concentrated compounds has been the cause of poisoning episodes in several countries. 

Endrin is more highly toxic than other organochlorine insecticides. The major target is the CNS. Major symptomatology is exemplified by rapid onset of violent epileptiform convulsions in severe poisoning cases. The onset may occur as rapidly as 0.5 h or delayed as much as lOh after ingestion of contaminated food. Other symptoms include headaches, dizziness, nervousness, confusion, nausea, and vomiting. 

There are many different cholinesterase inhibitors which find use, particularly as insecticides but also as nerve gases for use in chemical warfare. Organophosphorus insecticides are the most widely used and the most frequently involved in fatal human poisonings. They may be absorbed through the skin and there have been accidental poisoning cases arising from such exposure. Accidental contamination of food with insecticides such as parathion has led to a significant number of deaths. There are two types of toxic effects inhibition of cholinesterases and delayed neuropathy. 

The greatest danger from the use of DDT over wide areas arises if water is contaminated. Damage to many forms of life may also occur when aquatic pests are controlled by chlorinated hydrocarbons. This is due to several causes. First, fish are particularly susceptible to DDT poisoning, so that fish deaths due to direct poisoning may occur immediately or soon after the insecticide has been applied. They may extract DDT, present in a low concentration, from the immense amount of water, which is passed through the gills for purposes of respiration. Second, insects and other invertebrates, which are the main food of some fish, may be exterminated, so the fish are starved. Third, the invertebrates may take up amounts of DDT, which are not immediately lethal when fish eats these poisoned animals, the DDT may be retained in the bodies of the fish, which over a period obtain a toxic dose. 

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