Pollution-Related Studies

Pollution is part of contemporary hydrology, a topic discussed in Chapter 16. Let us stress here only that pollution-related studies may address a specific environmental problem and/or apply contaminants as tracers to understand flow paths in the natural system. The pollution-related aspect has a bearing on the planning stages of a study. The following information has to be collected first  

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Asthma rates in children in Southern California are high and oxidant pollution levels are likewise high. It is important to determine the relationship between the two. It is also important to determine whether there are chronic pulmonary effects produced by either these oxidants and/or particulate pollution. Since children spend more time outdoors than adults and since they exercise more while outdoors, the added assault from increased ventilation may be of importance. The studies feature a comprehensive exposure assessment that has led to a better understanding of the relationship between exposure and effects. It is also important to identify sub-populations of children and adults who are more susceptible to air pollution-related respiratory effects if they exist. Altered susceptibility could be based on genetic or non-genetic mechanisms (nutritional status for example). Both the epidemiologic and chamber studies provide opportunities to examine issues of hypersusceptibility and to determine the reasons for it if it exists. 

If the results from these studies are interpreted literally, the annual number of deaths in the United States attributed to fine particulate air pollution levels over background levels can be estimated. The National Resources Defense Council estimated that approximately 64,000 deaths per year were attributable to fine particulate air pollution in 239 U.S. cities, with a range of estimates between approximately 28,000 and 124,000 deaths per year (85). Although these studies do not allow air pollution-related deaths to be estimated with much precision, they suggest long-term exposure to air pollution continues to be an important contributor to early mortality. 

The study of the relations between diesel fuel composition and pollution caused by the diesel engine is the focus of considerable attention, particularly in Europe where this line of thought has been rapidly developing in recent years. 

Chemiluminescence has been studied extensively (2) for several reasons (/) chemiexcitation relates to fundamental molecular interactions and transformations and its study provides access to basic elements of reaction mechanisms and molecular properties (2) efficient chemiluminescence can provide an emergency or portable light source (J) chemiluminescence provides means to detect and measure trace elements and pollutants for environmental control, or clinically important substances (eg, metaboHtes, specific proteins, cancer markers, hormones, DNA) and (4) classification of the hioluminescent relationship between different organisms defines their biological relationship and pattern of evolution. 

It is also clear that it is difficult to relate cause and effect to any specific chemical since, with the exception of point source effluents, many waterways contain a multitude of chemicals, of which the active endocrine disruptor may not be that which has been measured in the water or tissue. For such reasons, many studies have used in vitro experiments in which isolated tissue, either from a control animal or one captured in a polluted water system, is exposed to a single pollutant in the laboratory. Such experiments have shown significant disruption to testicular activity by a wide range of xenobiotics, including cadmium, lindane, DDT, cythion, hexadrin and PCBs. ... 

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

Martin, D. J., and Michaelis. (1992). Research and Technology Strategy to Help Overcome the Environmental Problems in Relation to Transport Global Pollution Study. Luxembourg EEC. 

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