Environmental Exposure At The Individual Level example essay topic

Human exposure to pollutants in the air, water, soil and food-whether in the form of short-term, high-level, or long-term, low-level exposure-is a main cause of increased morbidity and death. However, the disease burden attributable to these exposures is not known with any degree of certainty because levels of general environmental pollution fluctuate greatly, methods for analyzing the relationships are incompletely developed, and the quality of available data is generally poor. Precise measures of the association between pollution levels and health outcomes are therefore rare. Exposure to environmental pollution is also usually involuntary. People may be unaware of this and / or its possible effects; as a result they may exert little control over their risk of exposure.

Biological and chemical agents in the environment are nevertheless responsible for the premature death or disablement of millions of people worldwide every year (WHO cited in Wainwright & Thornes, 2004, p. 17). It has recently been estimated that almost one quarter of the global burden of disease is attributable to environmental factors (WHO cited ibid. ). This estimate, which is based on published data, was made by attributing an environmental causal fraction to each disease category with a known environmental link.

The ability to link health and environmental data, and thereby to determine the relationship between levels of exposure and health effects, is clearly vital to control exposure and protect health. Standards and guidelines against which to assess levels of environmental pollution are now widely available. For example, the World Health Organization (WHO) has developed environmental quality guidelines for various pollutants in the air, drinking-water, food and workplace (Tibbetts, 2004, p. 472). These guidelines are based on epidemiological and toxicological studies and indicate the maximum environmental levels, or the maximum levels of human exposure, considered acceptable in order to protect human health. Nevertheless, individual susceptibility to pollution varies, to the extent that it is possible that some individuals may experience adverse effects at levels below the maximum recommended levels. Moreover, in many areas of the world these levels are frequently exceeded, in some places by as much as several times the recommended levels, and reduction of human exposure may be difficult or very costly (Rupp, 2001, p. 22).

Adverse effects on human health are therefore likely to continue to be observed in these areas. In such situations, analysis of data on human health and the environment provides a valuable tool for obtaining estimates of the health impact of pollution, which can be used to set priorities for action. Many epidemiological studies have been undertaken to analyze the relationship between specific forms of environmental pollution and health effects. Most of these studies have been conducted in developed countries, and the methods used may not be applicable to other settings, especially if high quality data are unavailable or too expensive to collect. Major problems often exist in obtaining data on health and particularly on environmental exposure at the individual level. As a consequence, it is normally necessary to rely on so-called "ecological" methods, in which the statistical unit of observation is a population rather than an individual (Harry et al., 2000, p. 19).

A serious limitation in conducting epidemiological studies concerns the measurement of exposure in individuals. Routinely collected environmental data are widely available in most countries and, where relevant, can be used as a proxy for exposure data. For example, monitoring networks provide data on pollution levels at specific sites, which can be used to characterize average exposures for geographical regions. Environmental data are also often compared with guideline values or maximum recommended levels in order to determine levels of compliance with prevailing policies.

The data are, however, rarely used to quantify the potential health effects. Equally, although many countries routinely collect data on health outcomes in the form of morbidity and mortality statistics, attempts are rarely made to link the data to environmental or other factors in order to attribute outcomes to their cause (Linsey, 2001, p. 29).