Atrazine, human poisonings

There have been only 65 recorded cases of human poisonings among occupationally exposed workers during 1966-81 in the United States. One death was reported following extensive dermal exposure. Dermal exposure to atrazine can cause skin rash, erythema, blisters, and edema. Ocular irritation, chest pains, and a feeling of tightness in the chest, nausea, and dizziness have also been reported after dermal, oral, or inhalation exposures. 

Like most other classes of pesticides and herbicides, the degree of toxicity of triazines has been found to vary with compounds. Thus, the toxicity may not be solely attributed to the triazine ring. For example, while substances such as atrazine, metribuzin, and cyanazine are moderately toxic by all routes of exposure, compounds such as prometryn and propazine have a very low order of toxicity. However, no cases of human poisonings have been reported. A few selected triazine herbicides are discussed individually in the following sections. 

Acute oral toxicity of atrazine in experimental animals was found to be moderate. In humans, the acute and chronic toxicity is low. There is no reported case of poisoning. The toxic symptoms in animals include ataxia, dyspnea, and convulsion. Other symptoms are abdominal pain, diarrhea, vomiting and irritation of mucous membranes. The oral LD50 values in rats and rabbits are 672 and 750 mg/kg, respectively (NIOSH 1986). 

The amounts of atrazine ingested in two medically documented cases of intended suicide were enormous 500 g and 1000 g, respectively. These amounts are equivalent to a two- to four-fold LD50 in rats, but attending physicians reported no signs of poisoning due to atrazine. Therapeutic measures were required to control adverse effects of coformulants that under normal conditions are innocuous, or to neutralize inappropriate therapy. These cases suggest a virtually unlimited tolerance of the human system to atrazine. Were it not for the intercurrent reaction to accompanying substances, they would never have been reported. 

Very high doses of atrazine ingested in suicidal attempts had no acute clinical effect, suggesting that atrazine is virtually innocuous to humans. Sporadic reports on suspected acute poisoning leave too many questions open to be convincing they reflect coincidence rather than causality. 

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