Water and Soil Pollution: Ecological Environmental Study Methodologies Useful for Public Health Projects. A Literature Review.

Health risks at population level may be investigated with different types of environmental studies depending on access to data and funds. Options include ecological studies, case-control studies with individual interviews and human sample analysis, risk assessment or cohort studies. Most public health projects use data and methodologies already available due to the cost of ad-hoc data collection. The aim of the article is to perform a literature review of environmental exposure and health outcomes with main focus on methodologies for assessing an association between water and/or soil pollutants and cancer. A systematic literature search was performed in May 2019 using PubMed. Articles were assessed by four independent reviewers. Forty articles were identified and divided into four groups, according to the data and methods they used, i.e.: (1) regression models with data by geographical area; (2) regression models with data at individual level; (3) exposure intensity threshold values for evaluating health outcome trends; (4) analyses of distance between source of pollutant and health outcome clusters. The issue of exposure assessment has been investigated for over 40 years and the most important innovations regard technologies developed to measure pollutants, statistical methodologies to assess exposure, and software development. Thanks to these changes, it has been possible to develop and apply geo-coding and statistical methods to reduce the ecological bias when considering the relationship between humans, geographic areas, pollutants, and health outcomes. The results of the present review may contribute to optimize the use of public health resources.