An estimation of dioxin emissions in the United States

Abstract

Total annual US air emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans (PCDD/Fs) from all known sources are estimated to be about 400 kilograms as of 1989, almost entirely from combustion sources. Municipal solid waste incineration is the largest known source of PCDD/Fs, as of 1989. The next largest sources include hospital waste incineration, forest and agricultural fires, and residential wood burning. Anthropogenic emissions of PCDD/Fs are estimated to be an order of magnitude greater than emissions of PCDD/Fs from forest fires. Dioxin emissions are shown to generally increase with the chlorine content of the combusted material, in the absence of effective pollution control systems. Dioxin emissions from 1940 and 1970 are also estimated. The estimates are verified through analysis of the concentrations of dioxin in soil, air, and sediments.

Dioxin sources and industrial emissions control — a review

“…This trend was recently confirmed in figures for UK vehicles [61]. The dominant chlorine source is thought to be the organohalogen additives used to effect the post-combustion expulsion of lead from the engine [60], although 100 ppm of chlorine is also found in unleaded fuel [37]. Incomplete combustion and the presence of particles in the exhaust stream are implicated.…”

“…A statistical analysis of 1900 test runs at waste combustors indicated no correlation between feed chlorine and dioxin production [35]. The validity of these conclusions was questioned however [36] citing the types of incinerator studied and making reference to a study which established a link between chlorine input and dioxin output for a range of incinerator types [37].…”

“…Recent inventories of dioxin emissions in the UK [61,65] and US [37] are detailed in Table I. According to these studies MSW incineration in the UK contributes almost 70% of the annual industrial atmospheric emissions of dioxin.…”

Sources of Dioxin

“…We estimate that, in the United States, forest fires produce about 20 kilograms (kg) of "dioxin" [a term that includes polychlorinated furans as well as dioxins, all with equal weighting], that residential wood burning accounts for another approximately 20 kg, and agricultural fires for about 10 kg. The total annual dioxin production is estimated to be approximately 400 kg, most of it from incinerators (1). It is true that anthropogenic production has decreased, thanks largely to controls of municipal waste combustion and to the banning of formerly high-volume organochlorine pesticides and herbicides.…”

Relation of chlorine, copper and sulphur to dioxin emission factors

“…A number of laboratory and combustor-scale studies have shown that the addition of chlorine compounds increases the production of dioxin [3,4]. In 1995, one of us published a paper showing that average dioxin emission factors are correlated with the average chlorine content of the combusted material [5]. At about the same time, Rigo et al published an analysis concluding that there is no statistical relationship between dioxin emissions and feed stream chlorine content [6,7].…”