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What it means: Carbofuran is a systemic carbamate insecticide and nematicide used on crops including corn, rice, and soybeans. EPA regulatory action beginning in 2006 led to cancellation of most food uses by 2009 due to acute toxicity to birds and other wildlife. Carbofuran is water-soluble and mobile in soil and has been detected in groundwater near agricultural areas.

Health effects: Carbofuran is one of the most acutely toxic carbamate pesticides. It inhibits acetylcholinesterase, causing cholinergic toxicity at the nervous system. Short-term exposure above the MCL can cause nausea, headache, blurred vision, and in high doses respiratory failure. Children are most vulnerable to acute effects. EPA has not classified carbofuran as a human carcinogen.

Limit: 0.04 mg/L (40 ppb)

What it means: Oxamyl is a carbamate insecticide and nematicide sold under the trade name Vydate, used on potatoes, apples, citrus, and other crops. It remains in agricultural use in the United States. Oxamyl is water-soluble and mobile in soil, making it prone to leaching into groundwater and entering surface water through runoff.

Health effects: Short-term exposure above the MCL can cause nervous system effects including headache, blurred vision, muscle weakness, and nausea, consistent with acetylcholinesterase inhibition by carbamate compounds. Chronic effects include nervous system damage. Children are most susceptible to acute neurological effects. EPA has not classified oxamyl as a human carcinogen.

Limit: 0.2 mg/L (200 ppb)

What it means: Toluene is an aromatic hydrocarbon solvent found in gasoline, paints, adhesives, and chemical manufacturing. It is a BTEX compound (benzene, toluene, ethylbenzene, xylene) and enters drinking water through leaking underground fuel storage tanks, petroleum spills, and industrial discharge. It is highly volatile but can persist in groundwater at contamination sites.

Health effects: Short-term exposure above the MCL can cause nervous system effects including headache, dizziness, and impaired coordination. Chronic exposure is associated with kidney and liver damage and neurological effects. EPA has not classified toluene as a human carcinogen. Developing fetuses may be particularly sensitive to its neurotoxic effects.

Limit: 1 mg/L (1,000 ppb)