CONNECTICUT DIOXIN AMBIENT AIR-QUALITY STANDARD

Connecticut is the first state in the country to have adopted an ambient air quality standard for dioxins at 1 pg/m3, 2,3,7,8-TCDD equivalents, as annual average. This paper describes the scientific basis and the methodology used by the State Department of Health Services (the risk assessment agency) in assisting the Department of Environmental Protection (the risk management agency) to establish health-based dioxin standard. This standard protects the public health from the aggregate effect of all sources of dioxin emissions in the vapor and particulate phases. The risk assessment methodology included: a limit on total daily dioxin exposure from all media and sources based on reproductive effects; a multimedia nonsource-specific exposure assessment; and apportionment by media of the health-based limit (including background dosing rate); an evaluation of inhalation bioavailability and cancer risk based on a calculation of a range of upperbound cancer risk estimates using different potency, bioavailability, and particle phase assumptions.