Signs and Symptoms of Insecticide Poisoning

Acute CH poisonings manifest with numerous symptoms (see Table 4-2). Few psychiatric effects appear in the acute stages. Most symptoms, such as irritability and confusion, result from acute physical illness and shock. The cyclodienes, not DDT or its related derivatives, produce the most severe symptoms in Table 4-2. One case report described seizures resulting from the concomitant use of lindane for treatment of head lice with dextroamphetamine for treatment of at-tention-deficit/hyperactivity disorder (ADHD) (Cox et al. 2000). 

Organophosphorus and carbamate insecticides are the two classes of anticholinesterase insecticides. All anticholinesterases inhibit nervous tissue acetylcholinesterase, the enzyme that deactivates the neurotransmitter acetylcholine (Ecobichon 1996). Poisoning causes accumulation of acetylcholine in the synaptic cleft, resulting in continuous electrical stimulation (Chambers 1992 Costa 1988). Described best by Chambers (1992), the mechanism of acute symptoms of poisoning occurs through three pathways  

Stimulation of the somatic or voluntary muscles results in twitches, tremors, convulsions, or tetanic paralysis. 

Stimulation of the parasympathetic and sympathetic branches in the autonomic nervous system results in a wide array of symptoms, depending on which system is more stimulated (Table 4-2). The chemical, route of exposure, and dose determine the symptoms. 

Acetylcholine receptors control the primary central nervous system symptoms, including acute and chronic psychiatric symptoms (Costa 1988). The concept that OPs cause psychiatric symptoms developed concurrently with theories that postulated cholinergic involve- 

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APPENDIX 18 OBSERVATION OF SIGNS AND SYMPTOMS OF INSECTICIDE POISONING 539... 

TABLE 4-2. Signs and symptoms of insecticide poisoning Chlorinated hydrocarbon pesticides Acute Chronic... 

List the major signs and symptoms of (1) organophosphate insecticide poisoning and (2) acute nicotine toxicity. 

Most of the signs and symptoms resulting from diazinon poisoning are due to the inhibition of an enzyme called acetylcholinesterase in the nervous system. This enzyme is also found in your red blood cells and a similar enzyme (serum cholinesterase) is found in blood plasma. The most common test for exposure to many organophosphorus insecticides, including diazinon, is to determine the level of cholinesterase activity in the red blood cells or plasma. This test requires only a small amount of blood and is routinely available in your doctor s office. It takes time for this enzyme to completely recover to normal levels following exposure. Therefore, a valid test may be conducted a number of days following the suspected exposure. This test indicates only exposure to an insecticide of this type. It does not specifically show exposure to diazinon. 

The time of onset and severity of symptoms depend on the route of exposure, potency of the agent, and total dose received (see below). Toxic signs and symptoms develop most rapidly after inhalation or intravenous injection and slowest after skin contact. Anticholinesterase insecticides are absorbed through the skin, lungs, conjunctivae, and gastrointestinal tract. Severe symptoms can occur from absorption by any route. Within 6 hours, most patients are symptomatic, and without treatment, death may occur within 24 hours. Death typically is caused by respiratory failure owing to the combination of pulmonary and cardiovascular effects (Fig. 10-4). Poisoning may be complicated by aspiration pneumonia, urinary tract infections, and sepsis. ... 

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