Acifluorfen, sodium salt

Acifluorfen was registered in the early 1980s for soybean use as a protoporphyrinogen oxidase (PPO) inhibitor — the same mechanism as lactofen and oxyfluorfen [1]. It is applied post-emergently and is one of the most effective broadleaf controls in soybeans [2]. EPA initiated a Special Review based on cancer bioassays showing hepatocellular carcinomas and nasal turbinate tumors in rodents [1]. Despite these concerns, it remained registered for specific uses. Acifluorfen is a persistent herbicide with a soil half-life of several months and has been detected in surface water runoff from soybean fields [2].

Agricultural workers applying acifluorfen to soybean fields face inhalation and dermal exposure [1]. Dietary residues on soybeans and soy products represent consumer exposure [2]. Environmental contamination through agricultural runoff [1].

Acifluorfen is converted to metabolites that form reactive intermediates causing oxidative stress and direct cellular injury [1]. Animal studies showed dose-dependent hepatocellular carcinomas and nasal cavity tumors. EPA Group B2 probable carcinogen classification [2]. The nasal cavity tumors are consistent with inhalation as a relevant exposure route [1].

Soybean farmworkers; consumers of soy products [1].

1. Farmworkers must use PPE during mixing, loading, and application [1]. 2. Choose organic soy products to avoid acifluorfen residues [2]. 3. Wash conventional soy-based produce [1].