Disparities in Disease Patterns

NIEHS is considering discontinuing sponsorship of Environmental Health Perspectives, which currently is offered as an open source journal. So, I’ve been trolling through the back issues to download interesting papers and catch up on anything I’ve missed.

An interesting constellation of articles is in the September 2005 issue. Illnesses such as cardiovascular disease, diabetes, high blood pressure, and cancers of the breast and prostate have been observed to affect certain population groups disproportionately. Observation of these health disparities (defined as differences in incidence, prevalence, mortality, and burden of disease among specific population groups) led the NIH to fund eight different research centers with a total of $60.5 million over five years to study what factors might mediate the onset or outcomes of these common diseases. This research conducted by the Centers for Population Health and Health Disparities (CPHHDs) has been addressing how the combination of biological, social, cultural, environmental, and economic factors influence disease occurrence in certain populations. These studies are investigating the disparities affecting breast, prostate and cervical cancers, multiple disease burden in a single population, mental stress-related disabilities, and ethnic homogeneity and disease incidence.

The most interesting study conducted by the RAND CPHHD provides an overlay of multiple data types (census, cost of living, census, air quality and land use) that can be used to evaluate how neighborhood variables affect mental and physical health. The results from this study might be used to identify ways these neighborhood variables could be affected by policy. Neighborhood variables investigated include the relationship between built environment factors and obesity (for example, bike paths, sidewalks, parks), physical and social factors affecting quality of life in the elderly, and impacts of outdoor air quality (particulate matter and ozone) on asthma occurrence. The news blurb doesn’t say anything about a GIS component, but it makes sense there would be one for this application.

Another study published in the same issue assessed the effect of diet on arsenic metabolism. Many individuals in the Western U.S. who get their drinking water from private wells are exposed to arsenic concentrations higher than the 10 ug/L primary drinking water standard. Arsenic is naturally occurring in groundwater, with higher levels observed in Western U.S. aquifers. The primary metabolic pathway of ingested is methylation to monomethyl arsenic (MMA) and dimethyl arsenic (DMA). Recent evidence suggests that those who excrete high proportions of ingested arsenic as MMA are more susceptible than others to arsenic-caused cancer. Diet might be one factor that affects arsenic methylation. This study examined dietary intakes and urinary arsenic methylation patterns in volunteers from two high-arsenic regions in the western United States. The results indicated that subjects with lower protein, niacin, iron and zinc intakes excreted a higher proportion of ingested arsenic as MMA and a lower proportion as DMA than did subjects with higher nutrient intakes. These associations were observed even when adjusted for age, sex, smoking, and total urinary arsenic. The investigators concluded these findings are consistent with the theory that people with diets deficient in protein and other nutrients are more susceptible to arsenic-related cancers.

The lesson from these examples is that sustaining environmental health isn’t simply a matter of reducing or preventing hazardous exposures, but making sure that a range of environmental factors are properly balanced. Making sure that you eat properly to reduce your risks from arsenic in drinking water may be a cost-effective alternative, with collateral benefits, to costly drinking water treatment. Having a built environment that promotes exercise may be a better investment that expensive prescriptions for cholesterol-lowering drugs.