Carbaryl breaks down readily and experience shows it readily de- composes on plants, and in soil and water to less toxic byproducts. Accumulation in animal tissues and biomagnification of residues in food chains with carbaryl and its metabolites does not occur.
Sevin is a mild to moderate cholinesterase inhibitor: cholinesterase is the enzyme that regulates the flow of nerve impulses in humans. Recovery in cases of accidental exposure is usually quite rapid. Atropine is the only antidote recommended and then only in more severe poisoning cases such as the accidental ingestion of carbaryl by a child. During the almost two decades of extensive carbaryl use in the United States, few cases of overexposure have occurred and no fatalities have been reported. Under most use situations, no special protective clothing is necessary to provide worker safety and no federal or state agencies require adult re-entry restrictions following the application of Sevin.
Toxicology/Toxicity
The toxicology of Sevin carbaryl insecticide has been extensively investigated by many different research groups, including universities, governmental agencies, and private research foundations. Laboratory tests to determine toxicological (tumor producing, birth defects, mutations, etc.) effects have been conducted on at least a dozen species of mammals. In addition, toxicity (how poisonous is the chemical) studies are known for at least 20 species of mammals, 50 species of birds, and 40 species of fish. Even some human exposure studies have been conducted.
We do know that carbaryl is quite toxic to honey bees, certain beneficial insects such as lady beetles, and parasitic wasps and bees, certain species of aquatic insects, and some forms of shellfish such as shrimp and crabs. Care must be taken when using carbaryl in areas where these organisms exist.
Extensive evidence indicates that carbaryl does not cause cancer or genetic changes in animals. Carbaryl has also been extensively tested for its effect on reproduction and the occurrence of birth effects (we call this teratogenic potential).
Experiments have been conducted on various strains of rats and mice, and on hamsters, gerbils, guinea pigs, rabbits, dogs, sheep, and monkeys. Adverse effects have occurred only in dogs.