Overview: WSDOT uses periodic application of herbicides on roadsides as part of an integrated vegetation management program. Because their herbicide use had changed and the state of science had advanced since they had last performed a risk assessment a decade earlier, WSDOT asked Intertox to update this prior analysis with new data and information. Intertox conducted an evaluation of the potential risks to the public, herbicide applicators, and ecological receptors from use of herbicide products for roadside vegetation management. As a follow-up to this evaluation, Intertox has produced fact sheets and presented in public forums for ongoing risk communication support.
Service Areas: Risk Assessment, Risk Communication
Chemicals of concern: 17 active ingredients in 24 herbicide products
Approach: Intertox performed an extensive scientific literature review of herbicide toxicity and exposure data, focusing on the most recent 10 years of available research. Our findings were used to update the data and approach of the previous risk assessment.
Outcome: Intertox presented risk estimates for each herbicide active ingredient in each route of exposure. Risks were categorized into different levels of priority for risk management purposes. Most active ingredient/exposure route combinations posed negligible or low priority risks, while few combinations required WSDOT to change products or reduce or alter application to reduce potential risks.
Project Successes: The Intertox risk assessment was reviewed and approved with minimal comments by a host of state and regional health and environmental agencies.
Benefits to client: WSDOT now has an up-to-date and sound herbicide risk assessment from which to make risk management decisions and communicate risks to the public. In addition, WSDOT uses Intertox on an ongoing basis to provide technical and risk communication support as needed.
