Bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) is a contact herbicide registered for application as the octanoic and/or heptanoic acid esters for control of broadleaf weeds in various crops.
USEPA has completed a risk assessment of acute, chronic, and cancer aggregate dietary (food and drinking water) exposure and risk assessments for bromoxynil using the Dietary Exposure Evaluation Model DEEM-FCID™, Version 2.03. The model uses food consumption data from the U.S. Department of Agriculture’s Continuing Surveys of Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. This assessment was published March 22, 2011 and serves as an update to the 1998 dietary assessment for bromoxynil using current approaches and input data.
For surface waters, the first highest estimated drinking water concentration was found to be 11.5 ug/L based on application to sorghum. For an annual average first highest estimated drinking water concentration was 0.19 ug/L also based on application to sorghum.
For ground water, the highest estimated drinking water concentration was found to be 0.00326 ug/L based on cotton.
The DEEM-FCID ™ analysis assumes that all drinking water will contain bromoxynil at the highest chronic estimated drinking water concentration for groundwater or surface water.
Bromoxynil is classified as “Possible Human Carcinogen” based on male mouse hepatocellular tumors found in the long term cancer studies. The cancer analyses yielded an aggregate (food and water) risk estimate of 1.5 x 10-6 (1.5:1,000,000) for the general US Population.