The Environmental Protection Agency is seeking comments on a proposal to revoke all tolerances for the insecticide chlorpyrifos.

Chlorpyrifos is an organophosphate insecticide, acaricide and miticide used primarily to control foliage and soil-borne insect pests on a variety of food and feed crops. In the tree fruit and grape industries, it is used during dormancy and pre-bloom to protect against certain pests.

The 9th Circuit Court of Appeals had ordered EPA to determine the health risk of chlorpyrifos by October 31, in response to a petition brought by the Pesticide Action Network North America and the Natural Resources Defense Council.

The agency says it was unable to make a safety finding by that deadline and instead proposed revoking all tolerances based on current science.

EPA’s assessment indicates that contributions to dietary exposures to chlorpyrifos from food and residential exposures are safe, the agency said.

However, safe levels of chlorpyrifos in the diet may be exceeded when dietary exposures are combined with estimated exposures from drinking water for people in certain vulnerable watersheds – primarily heavily cropped areas where chlorpyrifos may be widely used and drinking water is derived from small water systems.

The agency proposed a 60-day comment period for public input prior to any final decision. The agency also said it anticipates a final rule in December 2016.

At high enough doses, chlorpyrifos can inhibit the enzyme cholinesterase, which controls nervous system signals.

Comments can be submitted at in docket EPA-HQ-OPP-2015-0653.