Toxicology of Parathion


categories -(11, 15, 24). One group of symptoms, which closely
resembles stimulation of the parasympathetic nervous system,
includes nausea, diarrhea and increased secretion of saliva, tears
and sweat. Another common symptom is the constriction of the
pupils of the eye. Faulty vision may accompany this condition.
Respiratory difficulty with a feeling of tightness in the chest is
another manifestation. This group of symptoms is known as the
muscarinic effects of phosphatic insecticide poisoning.
 A second set of symptoms is known as the nicotinic symp-
toms. These include twitching of the muscles in the eyelids and
the tongue which may be followed by generalized jerking of the
muscles of the entire body. At the same time, overall muscular
weakness develops. Muscular weakness may become so severe
that the muscles involved in breathing fail to respond normally
and artificial respiration is necessary.
 A third set of symptoms, known as the central nervous
system effects, includes most commonly a headache, which may
be accompanied by dizziness and a general feeling of uneasiness
and restlessness.
 If poisoning is severe, coma and death may result. Grob (9)
 has reported that the average time between the last exposure
 to parathion and death varies between 1 and 211/2 hours, with an
 average of 101/2 hours. There is a lapse of from 1 to 131/2 hours
 between the time of last exposure to parathion and the onset
 of poisoning symptoms, the average time being approximately
 9 hours. In general, it appears that symptoms follow exposure
 to parathion somewhat more slowly than in the case of some of
 the other organic phosphates.
 Parathion has caused the death of three people in the field
 during the course of spray operations, but only one of these was
 in Florida (1). Several other individuals have died in chemical
 plants while handling technical grade material. During the 1950
 spray season, in which over 1,000 tons of parathion were applied
 to Florida citrus groves, records were obtained on a number
 of cases of supposed parathion poisoning (7). Forty-eight cases
 were reported to the Citrus Experiment Station. Of these, 11
 were definitely not parathion poisoning, 12 were doubtful and
 25 could be considered to be relatively definite cases of parathion
 illness. Most cases occurred among men who were using hand
 spray guns. The next most hazardous job seemed to be mixing
 the spray material in the spray tank. Information was obtained
 which showed that Speed Sprayer drivers had a relatively high