EPA Releases Updates on Organophosphate Pesticides Dicrotophos, Dimethoate, and Tetrachlorvinphos

Understanding Organophosphate Pesticides

Organophosphates are a class of pesticides used extensively in both agricultural and non-agricultural settings. They work by affecting the nervous system of pests, making them effective against a variety of insects. However, they can also pose risks to mammals, including humans, depending on exposure levels. To mitigate these risks, the EPA conducts a registration review of each pesticide every 15 years to confirm that they do not pose unreasonable adverse effects to human health and the environment.

Comprehensive Evaluation Process

The EPA has thoroughly reviewed numerous studies to ensure that dicrotophos, dimethoate, and TCVP meet federal standards for safety. These studies include toxicity tests across major organ systems, evaluations of neurotoxicity through interaction with the acetylcholinesterase (AChE) enzyme, and assessments of developmental neurotoxicity (DNT). The data from animal studies, epidemiological studies, and in vitro assays are integrated using a weight of evidence (WOE) approach to assess the developmental risks and determine appropriate safety factors.

Dicrotophos: Mitigation Measures Proposed

Dicrotophos is primarily used on cotton to control various pests. The EPA's updated human health draft risk assessment (HH DRA) identified potential neurotoxicity risks for workers and bystanders. Consequently, the EPA proposes several mitigation measures, including:

• Decreasing the single maximum application rate for aerial applications
• Updating labels with current worker personal protective equipment (PPE) information
• Implementing drift and runoff mitigation measures
• Adding pollinator stewardship language on labels
• Providing links to EPA’s Bulletins Live! Two for endangered species protection

The public can comment on these proposed measures for 60 days following the publication of the Federal Register notice.

Dimethoate: Revised Safety Factor

Dimethoate is used on various agricultural crops. The updated HH DRA for dimethoate supports reducing the Food Quality Protection Act Safety Factor (FQPA SF) from 10X to 1X, based on evidence that developmental neurotoxicity occurs at much higher concentrations than those affecting AChE levels. The EPA proposes:

• Cancelling several agricultural and non-agricultural uses with low benefits
• Updating labels for worker PPE
• Implementing drift and runoff mitigation measures
• Adding pollinator stewardship language on labels
• Providing links to EPA’s Bulletins Live! Two

The updated HH DRA and other documents are available for public comment for 60 days.

TCVP: Enhanced Safety Measures

TCVP is used in livestock treatment and various other applications. The EPA’s Interim Registration Review Decision retains the 10X FQPA factor and outlines several mitigation measures to address risks, including:

• Prohibiting certain application methods such as foggers and misters
• Increasing PPE requirements
• Requiring label statements to protect non-target organisms and water
• Providing links to EPA’s Bulletins Live! Two

Additionally, the EPA is improving pet product incident reporting by requiring more detailed reports and annual sales information from pesticide registrants. The TCVP ID is available for review in the public docket, with the EPA encouraging feedback on these measures.

These updated decisions reflect the EPA’s commitment to safeguarding human health and the environment from potential risks posed by organophosphate pesticides. Stakeholders and the public are invited to review and comment on these proposed decisions to ensure a comprehensive evaluation process.