Water and health: what is the risk and visible burden of the exposure to environmental contaminations? Insights from a questionnaire-based survey in Northern Thailand

Understanding and measuring the consequences of environmental pollution on human health remains a challenge. Several barriers arise, with the difficulty in identifying uncommon pathologies but also with the limited knowledge of the real health status of populations that depends on the supply and use of care. In an effort to assess these barriers, we chose a study area severely affected by agricultural intensification to investigate the potential and visible impact of water pollution on human health. Located in northern Thailand, the study area includes a watershed, its reservoir and the irrigated area downstream. A questionnaire-based survey was conducted to assess the exposure of 297 households to potential water pollutions and understand their behaviour regarding the use of water and recourse to health services. The observations are discussed in the light of the epidemiological records provided by the Ministry of Public Health for the same area. The study shows the heterogeneity of the epidemiological data and the difficulty to assess the sanitary risk. Despite the small size of the study area, inequalities are observed, with remote populations having a poorer access to water with occasional shortage and a limited use of health services. In this context, the intensification of agriculture and the massive use of pesticides and fertilizers are likely to have serious consequences on human health. However, the impact of potential environmental pollution is not visible from the epidemiological records, because of a difficult diagnosis, a lack of consultation when symptoms are reversible and the long latency before clinical symptoms are apparent (example of cancers). Prevention and incentive from health authorities should help in reducing this risk.