Waste Incineration and Public Health (2000) / Chapter Skim
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Environmental Transport and Exposure Pathways of Substances Emitted from Incineration Facilities
Environmental Transport and Exposure Pathways of Substances Emitted from Incineration Facilities
Pages 71-111
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From page 71... ...
This chapter provides a review of the environmental dynamics of substances emitted from waste-incineration facilities and the pathways that could result in human exposure to such contaminants. The chapter is not intended to provide a 71
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From page 73... ...
Most of the substances released from incineration facilities to air do not remain in air but are deposited to soil, vegetation, or surface water and can come into contact with humans through a series of complex environmental pathways that include transport through several environmental media (see Figure 4-1~. As discussed in the great detail in Chapter 5, understanding the potential health impacts of waste incineration requires an understanding of the relative contribution of indoor, local, and regional sources of many pollutants.
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From page 74... ...
For example, the deposition of a pollutant from air to vegetation may incorporate additional air compartments like a boundary layer of air around the vegetation, and a laminar flow layer of air above that, and so forth. Multiple pathways may intersect one another in various environmental compartments, although each pathway individually usually does not self-intersect.
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From page 75... ...
has shown that the spatial scale needed to characterize the multimedia dispersion of organic chemicals is chemical dependent and should address the competition among reaction, atmospheric dispersion, and deposition. It should also address the impact of chemical partitioning into soil, vegetation, and surface water on the effective dispersion velocity in the air.
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From page 76... ...
. The ISC models can provide specific estimates for any given location, and can also take account of simple, intermediate, and complex terrain; dry deposition; wet deposition; and plume depletion.
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. Particles in the surface layer can be transported mechanically in the horizontal direction by runoff to nearby surface waters or be blown by wind.
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Contaminants that are sorbed to suspended solids (including colloids) can also be entrained in water currents, but they might undergo additional transport processes that alter their effective residence time in surface waters; such processes include agglutination of the suspended particles, sedimentation and deposition of solids, and their scouring and resuspension.
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From page 79... ...
Efforts to assess human exposure to contaminants in multiple media date back to the 1950s when the need to assess human exposure to radioactive fallout and releases led to an assessment framework that included transport both through and among air, soil, surface water, vegetation, and food chains (USNRC 1975, 1977; Hoffman et al. 1979; Moore et al.
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From page 80... ...
Incineration facilities add some incremental amount to the total ambient concentrations in the environment for many pollutants, such as nitrogen oxides, sulfur dioxide, particulate matter, volatile organic compounds. For selected pollutants, such as dioxin, incinerators might collectively contribute major fractions of observed ambient concentrations as discussed later in this chapter.
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From page 81... ...
. The models nevertheless are extremely useful in identifying the major pathways of exposure, the major reservoirs for contaminants (e.g., PCBs in sediments)
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From page 82... ...
, and possible human exposures, to particulate matter, cadmium, arsenic, lead, dioxins and furans, carbon monoxide, and hydrogen chloride that are emitted from waste-incineration facilities, as well as other sources. After those subsections, studies are discussed that estimated environmental concentrations of contaminants contributed by waste-incineration facilities.
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From page 83... ...
Fine and coarse particles generally have distinct sources and formation mechanisms, although there may be some overlap. Fine particles are usually formed from gases in two ways: (1)
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From page 84... ...
Thus, ambient particles penetrate indoors and are available to be breathed into the lungs. Because they can be transported long distances, penetrate indoors readily, reach deep into the lung, and are the particles most enriched in toxic compounds, it is the fine particulate matter which is of the greatest human-health concern when considering particulate matter or its precursors emitted as a result of waste incineration.
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From page 85... ...
. Cadmium and its salts can be vaporized during waste incineration and emitted to the air as chlorides, oxides, or in elemental form.
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Cadmium metal and cadmium salts exist in ambient air primarily in fine suspended particulate matter. When inhaled, some fraction of this particulate matter is deposited in the lung airways and the rest is exhaled.
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Arsenic is released into the environment by human activities including arsenical pesticide and preservative use, metal smelting, waste incineration, and coal combustion. Behavior in the Environment, Pathways, and Exposure The metal arsenic is insoluble in water (Weast et al.
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From page 88... ...
Arsenic metal and arsenic compounds (with the exception of arsine gas) have low volatility and exist in air primarily incorporated as fine suspended particulate matter.
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EPA (1997b) estimated that waste incineration contributed about 33% of the national mercury emissions in 1994-1995.
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Studies of the dietary intake conducted by the Food and Drug Administration show an average daily intake for adults of 0.03,ug/kg of daily weight remarkably independent of age and sex, or 2.1,ug/day for a 70-kg adult (Cramer 1994~. Using a terrestrial food chain model, Travis and Blaylock (1992)
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Atmospheric deposition is an important source of lead found in soils. The strong absorption of lead to organic matter in soil tends to limit the bioavailability of lead and thus it tends not to bioaccumulate in aquatic and terrestrial food chains.
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92 Cal Cq an so ca C)
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, unidentified sources still might be dominant, because attempts at mass balances suggest that the observed deposition rates are greater than can be accounted for by known sources (Brzuzy and Hites 1996~. In addition, there are substantial differences between the homologue distribution of dioxins found in the environment and those emitted by incineratorsdifferences that cannot be explained by models of the environmental fate of dioxins from combustion sources.
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From page 94... ...
From the concentrations and fluxes in the different compartments, the human exposure models are developed using the correlation of Travis and Hattemer-Frey (1988) on the assimilation of the dioxins in dairy products, beef, and vegetation.
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~ 95 an' WAT ER /.0001 / AIR l / 0004 * K ng /day FIGURE 4-2 Estimated environmental compartment concentrations of and human exposures to T4CDD by various pathways in Southern Ontario.
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A Hattemer-Frey, "Human Exposure to 2,3,7,8-TCDD", Chemosphere, 16:2331-2342 (1987)
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cities, while the total chlorine are about 10-100 ,ug/m3. ENVIRONMENTAL POLLUTION CONCENTRATIONS ASSOCIATED WITH WASTE INCINERATION At large distances, the only emissions from incineration facilities which need to be considered are those which contribute significantly to the total regional emissions.
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From page 98... ...
Estimates of Ambient Air Concentrations of Various Pollutants from Waste Incineration Estimates of air pollutant concentrations associated with hazardous-waste incinerators and cement kilns that burn hazardous waste are provided here to give some idea of the contribution of an incineration facility to air quality. The estimates are not intended to represent the full range of air concentrations that might be associated with incineration facilities currently operating.
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for 20 commercial hazardous-waste incineration units and 30 cement kilns using hazardous waste as fuel. It should be kept in
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100 an ·- ¢ C)
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Due to the uncertainties associated with the air modeling as mentioned above, the results shown should not be used in an absolute sense; however, they might be useful in a relative sense to detect trends. In this calculation, the air concentrations attributable to cement kilns are somewhat higher than those for hazardous-waste incinerators, even after imposition of MACT.
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102 ad ·C)
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b PCDD/F is the toxic equivalent of the sum of the polycholorinated dibenzodioxins and polychlorinated dibenzofurans. Results from Environmental Monitoring Studies Around Incineration Facilities Mathematical models and calculations have utility as tools for prediction and correlation of measurements in the environmental sciences.
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, and total particulate matter.
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(1998) determined concentrations of PCCDs and PCDFs in 24 soil samples collected near a municipal solid-waste incinerator (Tarragona, Catalonia, Spain)
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(1998) analyzed levels of cadmium and lead in air and surfacesoil samples collected in an area around the Baldovie municipal-waste incinerator in Scotland.
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From page 107... ...
Thus, single-medium studies indicate that important dioxin and furan concentrations could not be detected in bovine milk, soil, or vegetation, but increases in lead could be found in soil and vegetation and increases in mercury could be found in moss and human hair samples collected near incinerators. In addition to the single-medium studies, there have been several multimedia studies around incinerators.
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From page 108... ...
The incinerator is a rotary kiln with a secondary combustion chamber, heat-recovery equipment, and five pollution-control devices. The study focused on particulate matter in ambient air and metals in soils.
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From page 109... ...
However, the authors concluded that despite the magnitude of the emissions, soil and air concentrations in the urban area of Columbus did not exceed urban air and soil concentrations of dioxins found around the world. Limitations of the studies cited above include reflection of a nonrandom set of facilities; inconsistency of methods, and problems with sampling and analytical techniques, detection limits, number and location of samples, duration of studies, contaminant contribution from other emission sources, and quality assurance and quality control.
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From page 110... ...
However, methodological limitations of the studies do not allow for general conclusions to be made about waste incineration' s contributions to environmental concentrations of those contaminants. They also do not allow for characterization of total human exposure.
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From page 111... ...
The models suggest that fish consumption is potentially the major pathway of human exposure to mercury and that meats, dairy products, and fish are potentially the major pathways of exposure to dioxins and furans. Because the food chain is potentially the primary path for exposure to dioxins and furans and toxic metals such as mercury, the correlation between total exposure and local emissions is expected to be low.
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