Dioxin/Furan Toxicity Equivalency Factors

The DEQ uses the most current toxicity data, including toxicity equivalency factors (TEFs), as much as possible. Because of this, the DEQ requires dioxin/furan calculations for soil samples to use the World Health Organization (WHO) 2005 TEFs. However, when the most recent changes were made to DEQ-7 water quality standards, the WHO 2005 TEFs had not been made available, and thus the WHO 1998 TEFs were referenced for the calculation of dioxins/furans. Therefore, until the water quality standards are changed, the WHO 1998 TEFs must be used to calculate dioxin/furan results for water samples.

World Health Organization (WHO) Toxicity Equivalency Factors
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1998 DEQ-7 TEF Dioxins/Furans Calculator for Water Samples


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2005 TEF Dioxins/Furans Calculator for Soil Samples


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