Epidemiologic studies demographics

Descriptive epidemiologic studies do not have a temporal component like case-control or cohort studies. Rather, this type of study evaluates factors that may influence the incidence of a disease, such as demographic or socioeconomic characteristics. It is not possible to determine causality from a descriptive epidemiologic study. Rather, this type of study is often used to generate a hypothesis that can be tested in case-control or cohort studies. 

Epidemiological studies provide another means of indicating a cause/effect relationship. In retrospective studies it is often not possible to characterize the exposure which may have occurred many years previously. In prospective studies, however, data are kept on a number of variables including the primary exposures of interest and what may be secondary exposure variables and demographic variables. In this way, one can perform regressions to determine significant correlations between exposure and effect. It is extremely critical that epidemiology studies be carefully constructed so that sufficient variables are considered to assure that the exposure correlations are not disputed. 

This chapter deals with epidemiological studies of human Pb exposure using biomarkers of such exposure. These studies deal with various parameters and correlates of human Pb exposure from demographic and environmental measurements. While much of the available data has been generated in the United States, illustrative international studies are also presented where relevant. Later chapters deal with epidemiological studies of dose—response relationships for Pb and an array of toxicity outcome measures addressing organ and tissue toxicides. 

The most commonly used demographic variables in epidemiology are age, race, and gender. Because these variables are relatively easy to study, a considerable amount of data has been amassed on these factors as they relate to cancer risk. 

Several studies have been initiated to investigate how demographic and epidemiologic factors correlate with the receptor properties of carcinomas of the breast (A3, L2, 01, R9). Many of the factors analyzed are significantly related to breast cancer risk. The results obtained are of interest because, with the exception of analyses of age and menopausal status, the relationships reported here have received little attention. No significant relationship of age of menarche to ERP... 

Four main sources can be used to provide epidemiological data. The first of these is the Population Studies System maintained by EPA at Research Triangle Park, NC, to contain demographic data in support of their Community Health... 

A Swiss study examined the epidemiology and costs of work-related bums [18]. These authors found that 4.6 % of all accidents in Switzerland were bums and that 3 % of all work-related accidents were bums. Based on population demographics, they estimated approximately 36,000 bum injuries per year with 5 % of these requiring hospital admission and one-third of those reqniring treatment in a specialized bum center. Of 6,814 bum injuries in 1984, 58 % (3,952) were work related. The total cost for bum care was 17.7 million Swiss Francs, with 19 % for medical care and the rest for other compensation. These anthors did not separate chemical skin injuries from other bum etiologies [18]. 

Survey and screening epidemiological data include the various population and subpopulation surveys and screenings of socioeconomic and demographic strata carried out in the United States and elsewhere over the past several decades. Additional cumulative aspects of these studies addressed here are the epidemiological and public health messages for Pb exposure... 

The ability of various epidemiological methods to tease out the persistence of developmental neurotoxic effects in humans will arguably depend on the Pb exposure and demographic/socioeconomic profiles of study cohorts. Differences seen across studies in terms of identified persisting effects do not rule out effects being present (see Mushak, 1993, for differences in outcomes across studies). 

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