Substance and perceptions of environmental impacts of dioxin emissions

EXECUTIVE SUMMARY The emission of dioxins is perceived widely as a major environmental impact of combustion processes. This paper reports the results of an extensive study of published data on a) the physical and chemical properties of dioxins and their environmental transport mechanisms; b) the measured impacts of dioxin emissions on the environment and on public health.; c) the rate of formation of dioxins from all U.S. and international sources; d) how the contribution of Waste-to-Energy (WTE) plants has changed with time; and e) the pre-MACT and post-MACT performance of individual Waste-to-Energy (WTE) plants in the U.S. Although dioxins are considered to be some of the most dangerous man-made substance, there is no conclusive evidence associating present background levels with carcinogenic, reproductive, developmental or immunologic effects. Even in the Seveso accidental release, no association between dioxin and adverse health effects on humans was observed. Unfortunately, there have been very few public health studies to document the exact composition and levels of dioxin among the studied populations. For that reason results are not comparable and therefore unreliable. Because of the unique environmental properties of dioxins and furans, such as resistance to photolytic, biological and chemical degradation, low water and high lipid solubility and tendency for bioaccumulation, they are categorized as Persistent Organic Pollutants (POPs). Dioxins can move long distances in the atmosphere before deposition, may persist in the environment for long periods of years and may bio-concentrate by factors of up to 70,000 fold. Their physical and chemical properties of high persistence and semi-volatility, coupled with other unique characteristics, have resulted in their being widely distributed through the global environment, even in regions where they have never been used. Further research is necessary in order to comprehend the various transfer processes by which dioxins move between the atmospheric, aquatic, terrestrial and biological environments, and the degradation processes and rates in each medium. Currently, few parameters are regularly monitored on a global scale and sampling procedures are not standardized and not frequent enough resulting to inconclusive results in most human health studies. The study has shown that during the last decades dioxin emissions have decreased significantly. This decrease is the result of an international effort to curb emissions from concentrated sources such as waste-to-energy (WTE) facilities, cement kilns and the pulp and paper industry. Emissions data from around the world presented in this study indicate a sharp reduction in dioxin emissions on …