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Aquatic Life Criteria - Carbaryl

EPA has published final ambient water quality criteria (AWQC) for the protection of aquatic life from the potential effects of carbaryl. Carbaryl is a pesticide used to control insects, slugs and snails and to thin fruit in orchards. It can enter water bodies and potentially harm aquatic life. Carbaryl is the second most frequently found insecticide in water, with detections in approximately 50 percent of urban streams. The criteria document will help states, territories, and authorized tribes add to their water quality standards, a concentration level for carbaryl, at or below which aquatic organisms will be protected.

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What is Carbaryl?

Carbaryl is a member of the N-methyl carbamate class of pesticides, which share a common mechanism of toxicity by affecting the nervous system in animals. Carbaryl also affects plant development and is used to thin fruit in orchards.

Where does Carbaryl Come From?

Carbaryl (Sevin®) is a pesticide used to control insects, slugs and snails and to thin fruit in orchards. It can enter water bodies through runoff and potentially pose risks to aquatic life. Carbaryl is the second most frequently found insecticide in water, with detections in approximately half of monitored urban streams.

How does Carbaryl affect Aquatic Life?

Carbaryl is an insecticide belonging to the N-methyl carbamate class of pesticides. After contact with or ingestion by aquatic organisms, the toxic mode of action of carbaryl is inhibition of the enzyme acetylcholinesterase (AChE) at synaptic junctions in the nervous system. AChE breaks down the neurotransmitter acetylcholine. Inhibition of AChE results in the accumulation of acetylcholine in the nerve synapses which leads to continual firing of nerve pulses throughout the nervous system.

This buildup results in uncontrolled movement, paralysis, convulsions, tetany, and possible death. Without proper nerve function, the respiratory, circulatory and other vital body systems will fail, ultimately causing death of the organism. The acetylcholinesterase inhibition effects of carbaryl are reversible with removal of exposure of the stressor chemical.

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