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Title

Responsiveness Summary: Response to comments on Method B and C Target Cleanup Goals and Adjustment for Additive Risk and Hazard

 
Publication number Date Published
26-09-059October 2026
VIEW NOW Responsiveness Summary: Response to comments on Method B and C Target Cleanup Goals and Adjustment for Additive Risk and Hazard (Number of pages: 52) (Publication Size: 750KB)
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Author(s) Andy Kallus
Description Method B and C cleanup levels established under the Model Toxics Control Act (MTCA) may need to be lowered to account for exposure to multiple hazardous substances and/or exposure pathways (i.e., total site risk). This adjustment needs to be made only if, without the adjustment, the noncancer hazard index (HI) would exceed 1, or the total excess cancer risk would exceed one in one hundred thousand (1 x 10?5). The guidance gives instructions and practical examples for adjusting cleanup levels to meet MTCA’s additive risk-based goals for cancer (1 x 10?5) and noncancer (HI of 1) health endpoints. We shared the draft guidance for public review and comment. This document provides Ecology’s response to public guidance on its draft guidance.
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Contact Andy Kallus at 360-878-2952 or andrew.kallus@ecy.wa.gov
Keywords Site Cleanup, cleanup levels, Model Toxic Control Act, responsiveness summary, Public Comment, MTCA, Cleanup Levels and Risk Calculation (CLARC), Method B cleanup level, Method C cleanup level, additive risk, ARARs, calculating cleanup levels, cancer risk, CLARC, cleanup level adjustment, cumulative risk
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Method B and C Target Cleanup Goals and Adjustment for Additive Risk and Hazard