United States pesticide poisoning

Pesticides are another class of chemicals capable of damaging the nervous system and, even at low levels, produce deficits detectable by psychological testing. The organophosphorus insecticides, which are chemical relatives of the most potent nerve gases, are notorious poisons and, carelessly handled, as often happens in underdeveloped countries, can prove lethal. Parathion, diazinon, and malathion are representatives of this class and are widely used in the United States. Acute poisoning episodes produce signs such as eye irritation, headache, dizziness, nausea, and visual... 

J., U.S. Environmental Protection Agency, personal communication, 1989). The United States has fewer recorded pesticide poisonings per unit weight of applied pesticide than in other countries. For Instance, the U.S. has only about l/50th the number of world poisonings but uses about one-fifth of all the pesticide used in the world. Thus, it appears that the U.S. program to regulate the use of pesticides is more effective than in most parts of the world. 

In addition to poisoning humans, pesticides affect agricultural ecosystems and spread beyond into surrounding terrestrial and aquatic ecosystems. As a result, detrimental environmental effects follow pesticide use in the United States. Some of these are delineated below ... 

Exposure Levels in Humans. Metabolism of endrin in humans is relatively rapid compared with other organochlorine pesticides. Thus, levels in human blood and tissue may not be reliable estimates of exposure except after very high occupational exposures or acute poisonings (Runhaar et al. 1985). Endrin was not found in adipose tissue samples of the general U.S. population (Stanley 1986), or in adipose breast tissue from breast cancer patients in the United States (Djordjevic et al. 1994). Endrin has been detected in the milk of lactating women (Alawi et al. 1992 Bordet et al. 1993 Dewailly et al. 1993), but no data from the United States could be located. Data on the concentrations of endrin in breast milk from U.S. women would be useful. No information was found on levels of endrin, endrin aldehyde, or endrin ketone in blood and other tissues of people near hazardous waste sites. This information is necessary for assessing the need to conduct health studies on these populations. 

The first chlordane-related mortality was of three wild birds and was recorded between 1978 and 1981 (Blus et al., 1983). The levels of chlordanes and heptachlor epoxide from the two adult male red-shouldered hawks (Buteo lineatus) and an adult female great horned owl (Bubo virginianus) were within the critical lethal range that has been defined by experimental studies (heptachlor epoxide in brain tissue 3.4-8.3 pg g-1 wet wt. oxychlordane in brain tissue 1.1 5.0 pg g-1 wet wt.). The chlordane poisoning of birds has been reported in several studies in the United States (Blus et al., 1983, 1985 Post, 1951 Stansley Roscoe, 1999). From 1986 to 1990, 122 cases of avian mortality due to chlordane and/or dieldrin were documented in New York, Maryland and New Jersey (Okoniewski Novesky, 1993). High pesticide concentrations were found in cyclodiene-resistant insect populations. These pesticide-tainted insects, when eaten by birds, caused mortalities in the avian populations (Okoniewski Novesky, 1993). 

The peak period for the use of aldrin and dieldrin was between the late 1960s and the early 1970s throughout various parts of the world (WHO, 1989). The use pattern of aldrin and dieldrin are quite similar. They act as effective contact and stomach poisons for insects. They are used to control soil insects (e.g. grasshoppers and corn rootworm), and protect crops and wooden structures from termites (WHO, 1989). The production of aldrin and dieldrin has decreased since the early 1960s. In the United States, the peak use of aldrin from 19 million pounds in 1966 decreased to 10.5 million pounds in 1970 (USEPA, 1980). During this same period (1966-1970), annual dieldrin use dropped from 1 million to 670,000 pounds. These decreases were primarily due to increased insect resistance to the aldrin and dieldrin, and to the development and availability of more effective and environmentally friendly pesticides (USEPA, 1980). 

Disparlure, the sex pheromone of the female gypsy moth, has been used to control the spread of the gypsy moth caterpillar, a pest that has periodically devastated forests in the northeastern United States by defoliating many shade and fruit-bearing trees.The active pheromone is placed in a trap containing a poison or sticky substance, and the male moth is lured to the trap by the pheromone. Such a species-specific method presents a new way of controlling an insect population that avoids the widespread use of harmful, nonspecific pesticides. Disparlure is synthesized by oxidation of an alkene using chemistry presented in Chapter 12. 

There is also a big gap between real and perceived risk. In Europe and the United States the public is mainly concerned about residues and food safety. With proper precautions, however, this is not a real problem, as residues in food are low and do not contribute significantly to our total intake of chemicals. Actually, there are no cases confirmed in which residues of modem pesticides in food were the cause of poisoning of humans. As there is a large overproduction of agricultural commodities in western countries, people worry about minor risks, like pesticide residues, as they do not have to worry about supply of food in principle. The picture is strikingly different in other parts of the world, where food production does not match the growth of the population and where malnutrition and famine are well known. 

Neem (also known as azadirachtin) is an insecticide extracted from the seeds of the neem tree (Azadirachta indica) common in most of Africa and India. It is closely related to the chinaberry tree (Melia azadarach), common in the southern and southeastern United States. Extracts of both trees have insecticidal properties. Neem is unique among pesticides since it has so many uses It acts as a broad-spectrum repellent, growth regulator, and insect poison. It discourages feeding by making plants unpalatable to insects if they still attack, it inhibits their ability to molt and lay eggs. 

Morgan DP. Recognition and management of pesticide poisonings, 4th ed., United States Environmental Protection Agency, EPA Publication No. EPA-540/9 88 001, Washington, DC, March 1989. 

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