The U.S. Environmental Protection Agency (EPA) has released an interim decision (ID) as part of its registration review of the herbicide paraquat dichloride (paraquat) that was initiated in 2011. With the release of the interim decision EPA will enforce additional mitigation measures it deems necessary to improve safety and prevent accidental ingestion and exposure during handling and application.
Paraquat is a commonly used herbicide first labeled for agricultural use in 1964. It is commonly used to control weeds in both agricultural and non-agricultural settings and is used also as a desiccant and as a harvest aid product in cotton to prepare the crop for harvest.
The latest paraquat usage and safety requirements were developed during the final stages of EPA’s latest registration review of paraquat dichloride process initiated in 2011. EPA typically reviews registered pesticide products on a 15-year cycle.
One of the cotton industry’s priority concerns during the registration review process for paraquat was the need to maintain full use of the product for cotton desiccation. In recognition of that need, the new EPA ID for paraquat includes specific allowances for paraquat use as a cotton harvest aid that is welcome news for cotton producers.
Following release of the interim decision the following additional, enforceable, mitigation measures have been authorized for the use and application of paraquat:
• Limit aerial applications to a maximum of 350 acres per applicator per 24-hr period for all uses except cotton desiccation.
• Require a 7-day restricted entry interval (REI) for cotton desiccation.
• Require a 48-hour REI for all crops and uses except cotton desiccation.
• Require a residential area drift buffer for all aerial applications.
• Prohibit use of human flaggers.
• Prohibit pressurized handgun and backpack sprayer application methods.
• Limit the maximum application rate for alfalfa to one pound of paraquat cation per acre.
• Require enclosed cabs if area treated in 24-hour period is more than 80 acres.
• Require enclosed cabs or PF10 respirators if area treated in 24- hour period is 80 acres or less; and
• Require mandatory spray drift management label language.
Prior to the release of the paraquat ID, several changes were made relative to the product beginning in 2016. At that time the EPA authorized new packaging requirements and other risk mitigation measures that were implemented between 2017 and 2020, including:
• Requiring new, closed-system packaging.
• Changes to the pesticide label and rules requiring distribution of supplemental warning materials.
• Restricting the use of paraquat to certified pesticide applicators only.
• Requiring additional, specialized, training for certified applicators.
The new label and training requirements were specifically designed to lessen the chances of the accidental ingestion of the product, which is a significant concern being addressed during the EPA review process.
Although the changes announced this week are final, the agency’s registration review is not yet complete. Still to be performed is an endangered species assessment and endocrine screening.