ing animal. The principle has been established by several workers (22,52,55) in addition 
to the studies involving contamination of the ordinary daily diet. 
Symptoms of Poisoning 
Several workers have described the symptoms of insecticide poisoning (12,15,17,24, 
44,48,49,62,66,68,69,74,80,83,84,86,89,90,95,96,97,98,99,100,113,121). 
Chlorinated Hydrocarbons.--These insecticides stimulate the central nervous system, 
producing neuro-muscular symptoms of extreme variety. Initial symptoms are an in- 
creased awareness of the animal to its surroundings. Muscular twitching and spasms 
are then observed, usually beginning at the head and progressing posteriorly. 
In poisoning by DDT, TDE, and methoxychlor, the muscular spasms become si- 
multaneously generalized, causing the animal to appear to be shivering with cold. With 
other members of this group, the spasms are usually followed by convulsive seizures of 
a clonic-tonic type, with or without the intermediate trembling. The convulsions may 
last for a few seconds or several hours and may be continuous or repeated at intervals. 
Abnormal posturing is often seen. Occasionally an animal becomes belligerent. 
There is generally a flow of thick saliva and frequently dribbling of urine. Outcrying 
is common. 
During convulsive seizures, the body temperature may raise to 114° to 118°F. 
Certain poisoned animals fail to show the more active symptoms and are depressed 
and appear to be almost completely lost fromtheir environment. They fail to eat or drink, 
These animals usually live for afew more days than those violently affected, but the death 
rate is about the same. 
In certain cases, the symptoms alternate between violence and depression. 
The severity of symptoms ina given animal is difficult to translate into a prognosis. 
Some animals suffer a single convulsion and die, while others survive innumerable 
seizures. 
While the symptoms observed are rather definite, they are not definitive enough to 
be diagnostic. Many afflictions of the central nervous system can duplicate the symptoms 
of poisoning by these insecticides. 
Organic Phosphorus Compounds.--This group of compounds is generally considered 
to produce poisoning by inhibition or interference with the activity of the enzyme choli- 
nesterase, primarily in the nervous system. There is good evidence that poisoning may 
exist due to fractions of the molecules not having an affinity for the enzyme. 
When intoxication is primarily due to enzyme interference, the clinical symptoms 
are primarily cholinergic, including mild to profuse salivation, dyspnea, signs of ab- 
dominal pain, ataxia, diarrhea, and, occasionally, convulsions, 
Onset of symptoms may be within 5 to 6 minutes of treatment, or may be delayed 
for 2 to 3 days, according to the compound and dosage involved. The course of intoxi- 
cation is governed by the compound and dosage. Materials such as malathion, diazinon, 
Bayer L 13/59, parathion, and TEPP produce poisoning of short duration, resulting in 
death or recovery within 24 hours of exposure. Ronnel and Bayer 21/199 produce their 
effects over a much longer period of time and may show effects of the intoxication for 
30 days or more. 
These materials decrease the activity of cholinesterase in blood as well as in nerve 
tissue, and the blood is usually used as an indicator of the amount of the enzyme in the 
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