Epidemiological association between water salinity and blood pressure in coastal populations: ambient temperature’s role as a confounder

Due to global climate change and anthropogenic activities, many low-lying coastal communities experience high sodium in drinking water as a result of saltwater intrusion, an emerging environmental health problem in many coastal regions. Drinking saline water is associated with higher sodium intake and hypertension. Exposure to higher ambient temperatures is common in many regions affected by saltwater intrusion, particularly in tropical and subtropical regions. Little attention has been given to the role of ambient temperature in the epidemiological association between drinking saline water and population blood pressure. We argue that high ambient temperatures increase water salinity and influence communities' sodium intake, urinary sodium excretion, and blood pressure. Hence, we hypothesize that ambient temperature is a potential confounder for the relationship between drinking saline water and population blood pressure. Testing the hypothesis requires a detailed measurement of urinary, blood, and sweat biomarkers (e.g., sodium), the population's blood pressure, and their drinking water’s salinity. An increasing number of coastal regions and islands will face the dual burden of high ambient heat exposure and saltwater intrusion in the future. Future studies are needed to determine the association between drinking saline water and blood pressure after adjusting for ambient temperature in saltwater intrusion-affected regions

A review of exposure assessment methods for epidemiological studies of health effects related to industrially contaminated sites

BACKGROUND: this paper is based upon work from COST Action ICSHNet. Health risks related to living close to industrially contaminated sites (ICSs) are a public concern. Toxicology-based risk assessment of single contaminants is the main approach to assess health risks, but epidemiological studies which investigate the relationships between exposure and health directly in the affected population have contributed important evidence. Limitations in exposure assessment have substantially contributed to uncertainty about associations found in epidemiological studies. OBJECTIVES: to examine exposure assessment methods that have been used in epidemiological studies on ICSs and to provide recommendations for improved exposure assessment in epidemiological studies by comparing exposure assessment methods in epidemiological studies and risk assessments. METHODS: after defining the multi-media framework of exposure related to ICSs, we discussed selected multi-media models applied in Europe. We provided an overview of exposure assessment in 54 epidemiological studies from a systematic review of hazardous waste sites; a systematic review of 41 epidemiological studies on incinerators and 52 additional studies on ICSs and health identified for this review. RESULTS: we identified 10 multi-media models used in Europe primarily for risk assessment. Recent models incorporated estimation of internal biomarker levels. Predictions of the models differ particularly for the routes 'indoor air inhalation' and 'vegetable consumption'. Virtually all of the 54 hazardous waste studies used proximity indicators of exposure, based on municipality or zip code of residence (28 studies) or distance to a contaminated site (25 studies). One study used human biomonitoring. In virtually all epidemiological studies, actual land use was ignored. In the 52 additional studies on contaminated sites, proximity indicators were applied in 39 studies, air pollution dispersion modelling in 6 studies, and human biomonitoring in 9 studies. Exposure assessment in epidemiological studies on incinerators included indicators (presence of source in municipality and distance to the incinerator) and air dispersion modelling. Environmental multi-media modelling methods were not applied in any of the three groups of studies. CONCLUSIONS: recommendations for refined exposure assessment in epidemiological studies included the use of more sophisticated exposure metrics instead of simple proximity indicators where feasible, as distance from a source results in misclassification of exposure as it ignores key determinants of environmental fate and transport, source characteristics, land use, and human consumption behaviour. More validation studies using personal exposure or human biomonitoring are needed to assess misclassification of exposure. Exposure assessment should take more advantage of the detailed multi-media exposure assessment procedures developed for risk assessment. The use of indicators can be substantially improved by linking definition of zones of exposure to existing knowledge of extent of dispersion. Studies should incorporate more often land use and individual behaviour