EPA Issues Interim Decisions on Key Pesticides Chlorothalonil, Thiophanate-Methyl, and Carbendazim

EPA's Action on Pesticides with Long-Standing Use

In a recent update, the EPA released interim decisions for chlorothalonil, thiophanate-methyl (TM), and carbendazim (MBC). These fungicides are valued for their broad-spectrum antifungal properties and low potential for resistance, playing a pivotal role in agriculture and other antimicrobial applications. While these pesticides remain indispensable, the EPA's decisions aim to address identified risks to human health, ecological systems, and endangered species.

The measures were developed after rigorous risk assessments and public feedback during the registration review process. These decisions integrate updated mitigation strategies, such as restrictions on application rates, enhanced labelling requirements, and new personal protective equipment (PPE) standards.

Chlorothalonil: Mitigating Health and Ecological Risks

Chlorothalonil, a fungicide used for over 60 years, is applied on crops like potatoes, peanuts, tomatoes, and ornamental plants, as well as in antimicrobial products such as paints and adhesives. However, EPA risk assessments highlighted concerns about its effects on human health, including developmental issues from acute exposure and kidney damage from chronic exposure through drinking water contamination.

To address these risks, the EPA introduced:

• Stricter application limits in vulnerable areas to reduce groundwater contamination.
• Increased PPE requirements, including respirators, for occupational handlers.
• Buffer zones near aquatic and conservation areas to protect wildlife.
• Rainfall restrictions in critical habitats of salmon and steelhead species.

The EPA also issued a Data Call-In to gather more information on chlorothalonil's impact on pollinators, underscoring its commitment to non-target species protection.

Thiophanate-Methyl and Carbendazim: Focus on Occupational Safety and Ecological Protection

Thiophanate-methyl, primarily used in agriculture on crops like citrus, nuts, and soybeans, degrades into carbendazim, a more stable and persistent compound. While these fungicides are crucial for cost-effective crop protection, their use poses cancer risks to workers, thyroid toxicity, and ecological hazards to fish, birds, and invertebrates.

Key mitigation measures include:

• Reduced application rates and restrictions on soil applications to minimise environmental contamination.
• Enhanced PPE standards, including closed mixing systems, to protect workers handling treated materials.
• Updated product labels with spray drift management measures and ecological protections for pollinators and endangered species.
• Phase-out of certain applications, such as polyvinyl chloride (PVC) uses, to eliminate potential risks to children from treated flooring.

Public Feedback Shapes Final Decisions

The EPA's decisions reflect public input and updates to its endangered species workplan. Stakeholders, including registrants, influenced changes such as the cancellation of specific uses and refinements to risk mitigation strategies.