BIO 220 W3 Discussion Question 2
BIO 220 W3 Discussion Question 2
Consider the most recent oil spill in the Gulf of Mexico. Describe the various mechanisms and pathways that transport toxins to the environment. Note: Avoid only talking about the oil spill affecting people in Mexico.
The main pathway for pollutants to get into the environment from a waste-incineration facility is, as for many other sources, through emission to the atmosphere. A large number of substances have been detected—most of them at very low concentrations—in the gaseous and particulate emissions from waste incineration. Among the emitted pollutants are metals and other noncombustible matter; acid gases; and products of incomplete combustion that include a large number of organic compounds as well as oxides of nitrogen, sulfur, and carbon. These pollutants are partitioned among the gas and particulate phases of the stack emissions from an incineration facility. As the pollutants disperse into the air, facility workers and people close to a facility might be exposed directly through inhalation or indirectly through consumption of food or water contaminated by deposition of the pollutants to soil and vegetation.
Other people can be exposed through a different mix of environmental pathways after the pollutants travel some distance in the atmosphere; go through various chemical and physical transformations; or pass through soil, water, or food. As part of estimating the amount of incineration-released contaminants that people are exposed to and the patterns of such exposure, investigators seek to track the concentration and movement of, and changes that occur in, the contaminants as they move through the environment from the incineration facility to a point of contact with people. Such information is also helpful in determining the contribution of incineration to the mix of environmental contaminants from all sources.
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 comprehensive examination of the many aspects considered because such an examination is beyond the committee’s task. To illustrate some of the important considerations with respect to environmental dynamics and exposure, particular attention is given to the main substances of concern that are discussed in Chapter 5 from a health-effects perspective.
The chapter also examines approaches for estimating environmental concentrations that are used to estimate human exposures. As an illustration of how incineration facilities contribute to environmental concentrations at different geographical scales and for different agents, information is provided on particulate matter, various metals (cadmium, arsenic, mercury, and lead), dioxin-like compounds, carbon monoxide, and hydrogen chloride.