Integrated Criteria Document Dioxins

Abstract

This report contains general information on mixtures of polychlorinated dibenzo-p-dioxins and -dibenzofurans (dioxins) considering standards, emissions, exposure levels and effect levels. The document also discusses the need and possibilities to reduce the risks related to this group of compounds. Dioxins includes 210 tricyclic chlorinated organic compounds in total. International Toxicity Equivalency Factors (-TEFs) are used to describe to toxicity of dioxins, expressed in toxic equivalents (I-TEQ) based on 2,3,7,8-TCDD, the most known compound. Information to quantify dioxin emissions is scarce ; they are not commercially produced nor applied, being formed in incineration and industrial processes. Based on 1990 figures, direct emissions to air, water and soil amount approximately 600, 4 and 3 g I-TEQ per year, respectively. Deposition and sludge application contribute significantly to the load of soil (approx. 330 g I-TEQ), whereas, the contamination of water bodies is largely determined by deposition and trans-boundary emissions (approx. 100-125 g I-TEQ). In total the amount of dioxins in the soil and sediment compartments has been increased in 1990 with approx. 330 and over 65-90 g I-TEQ, respectively. Information on the occurrence of dioxins in the environment is very limited. Based on estimated exposure levels (approx. 1-3 pg I-TEQ.kg-1 b.w. per day by food, which contributes 90-95% to the total exposure) dioxins are considered not to present a risk to humans, the TDI being 10 pg I-TEQ.kg-1 b.w. However, information is lacking to evaluate the risks for sucklings during breast-feeding. Generally the risks to ecosystems is limited and only locally ecosystems may be at risk. However, secondary poisoning can not be ruled out and foodchain effects may occur in both the aquatic and terrestric environment. As a result of policy measures emission to air will decrease to approx. 125 g I-TEQ per year by 2000, those to water and soil will be the same as in 1990. The yearly increase in dioxin content of the soil will then amount 0.1 ng I-TEQ.kg-1. Additional measures are possible.