Is establishing a background dioxin concentration important?
Yes. Since dioxins are created by natural, industrial, and non-industrial manmade sources, assessing the amount of dioxins attributable to natural and non-industrial sources is a critical element in establishing an achievable cleanup goal for a site. This ensures that site-specific dioxins, in this case resulting from the industrial activity on the Fort Bragg mill property, are addressed. The background level is sometimes called the “ambient” level of dioxin. USEPA and others have determined that dioxins occur at ambient levels widely throughout the environment. As a result, they can be detected in pristine rural and urban soils, sediments, air, food, and water throughout the world. In its 2003 draft Exposure and Human Health Reassessment on TCDD and Related Compounds, USEPA states that 71% of manmade dioxins are a result of municipal waste incinerators, the burning of refuse in backyard barrels and medical waste incinerators. In the more recent 2006 report, backyard barrel burning of
