Final Highway 36 Public Health Assessment

November 13, 2014

The Oregon Health Authority has issued the final Public Health Assessment (PHA) for the Highway 36 Corridor Exposure Investigation. This final version incorporates comments received on the draft report issued May 9, 2013.

Summary of the Highway 36 Exposure Investigation

Public comments - received during the public comment period (redacted)

Original Exposure Investigation Questions

Are residents in the Highway 36 Corridor being exposed to pesticides from local application practices?
If residents are being exposed:
- To what pesticides are they being exposed?
- To what levels are they being exposed?
- What are potential source(s) of the pesticides to which they are exposed?
- What are potential routes (pathways) of residents’ exposures?
- What health risks are associated with these exposures?

Highlights of Revisions, Reflected in the Final Public Health Assessment

This version summarizes public comments and explains how OHA responded to and addressed those comments (Appendix A).
This version includes a new analysis for pre- and post-pesticide application (community-collected) urine samples. This new analysis resulted in a new conclusion, which states: “There are additional sources of 2,4-D and atrazine in the investigation area that are not accounted for in the pesticide application records available to the investigation team.”
This version has clarified language throughout the report, specifically in describing the agency-collected data as an attempt to characterize baseline conditions. This is because the agency sampling occurred at a time of year when herbicide use was presumably at its lowest levels, which is reflected in the sampling results. The original EI plan was to conduct a complete round of sampling immediately post-application, to assess whether we observed different results – and thus exposure potential – in the sampling. That post-application sampling did not occur, for reasons that were beyond the investigation team’s control. Therefore, we do not know what the levels of herbicides may be in times or seasons other than the timeframe when agency samples were collected. This clarification is reflected in a modified conclusion (12), which now states: “Drinking water was eliminated as an exposure pathway for 2,4-D and atrazine in the fall of 2011,” and in a new conclusion (15), which states: “Concentrations of pesticides in drinking water, soil and homegrown foods in the spring of 2011 and other seasons and years are unknown.”
There is a new recommendation aimed at preventing human exposures to pesticides, recommending that, “State agencies continue to collaborate on determining best practices that would protect human populations from pesticide exposures.”

Data Analyzed

The report analyzed the following sets of information:

Community-collected urine sampling data from the spring of 2011;
Urine sampling data collected by the Agency for Toxic Substances and Disease Registry (ATSDR) and the Oregon Health Authority (OHA) in August 2011;
Environmental sampling data (soil, water, homegrown foods) collected by the U.S Environmental Protection Agency (EPA) & the Oregon Department of Environmental Quality (DEQ) in September of 2011;
Air and water data submitted by community members; and
2011 pesticide application record data provided by the Oregon Department of Agriculture (ODA) and the Oregon Department of Forestry (ODF).