The Minnesota Department of Health (MDH) has completed a reevaluation of the existing water risk guidance for the metolachor, a widely used as an herbicide. The review included re-evaluation of the available data for existing health-based guidance values for metolachlor (s-metolachlor). As a result of the re-evaluation, the guidance values for metolachlor (s-metolachlor) were updated. The revised health based water guidance concentration is 300 µg/L for short-term exposure; the previous guidance value was 400 µg/L.
MDH re-evaluates all guidance developed since 2008 on a routine basis to keep existing health-based guidance values up to date with the most recent MDH risk assessment methodology and the available science. Incorporating new data and updating methodology can result in changes to existing guidance values or result in a recommendation for a more in-depth review.