Comparison of Dioxin Exposure Guidelines Set By The World Health Organization (WHO) And Two U.S. Government Agencies

Source: Chlorine Chemistry Council

Also see Dioxin Exposure Guidelines Set By Various Countries and Government Agencies

ATSDR or the Tolerable Daily Intake Set by the UN/WHO

The draft dioxin reassessment of the US Environmental Protection Agency (US EPA) yields a theoretical reference dose (RfD) that is 100 to 1,000 times lower than current background exposure levels[1]. A reference dose is an estimate of a daily exposure to a chemical that is likely to be without appreciable risk of deleterious systemic effects during a human lifetime. In the US, the background level of exposure to dioxin is approximately 0.5 -1.0 pg TEQ/kg-body weight/day (USEPA, 2003). The US EPA's reference dose, here estimated at 0.001 pg TEQ/kg-body weight/day, is vanishingly small in comparison to either the Minimal Risk Level (MRL) of 1 pg TCDD/kg-body weight/day set by the US Agency for Toxic Substances and Disease Registry (US ATSDR), or the 2.3 pg TEQ/kg-body weight/day average tolerable daily intake (Avg.TDI) calculated from the monthly value set by the United Nations (UN) Food & Agriculture Organization/World Health Organization (WHO) Joint Expert Committee on Food Additives (JECFA).

^#picogram (pg) is one-trillionth of a gram, or 0.000000000001g

*TCDD is 2,3,7,8-Tetrachlorodibenzo-p-dioxin, the most toxic and the most intensively studied of all the dioxin-like chemicals.

            **Minimal Risk Level (MRL), according to the US ATSDR (2000), is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure.

            ***Toxic Equivalent (TEQ), a quantitative measure of the combined toxicity of a mixture of dioxin-like chemicals

****Average Tolerable Daily Intake (Avg.TDI) is calculated from the JECFA's provisional  tolerable monthly intake of 70 pg/kg-bw.

References:

Joint UN FAO/WHO Expert Committee on Food Additives, Fifty-seventh Meeting, Rome, 5-14 June, 2001.

US ATSDR (2000). Minimal Risk Levels (MRLs) for Hazardous Substances. [On-Line]. Available: http://www.atsdr.cdc.gov/mrls.html

USEPA (U.S. Environmental Protection Agency).  2003.  Exposure and Human Health Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds.  Part III: Integrated Summary and Risk Characterization. Office of Research and Development.  December. (DRAFT).

July 19, 2001
(Updated on December 10, 2007)

[1] "Background exposure level" of dioxin refers to the average level of exposure of humans to dioxin. It is thought that ninety-five percent of human exposure to dioxin occurs through the diet.