HEALTH-PROBLEMS RELATED TO IRRIGATION WIT H WASTE-WATER IN MEXICO

Over 85 000 hectares in the Mezquital Valley of central Mexico are irr igated with wastewater. The main crops are fodder and cereal crops. A two cross-sectional survey was carried out to test the impact of expos ure to raw wastewater and from storage of that wastewater in reservoir s. The main outcomes were diarrhoeal disease and parasitic infections in farmworkers and their families. The total study population in the d ry season included 2 049 households. The study population was classifi ed in households where the farmworker is exposed to untreated wastewat er (exposed group), households exposed to reservoir water (semi-expose d group), and households where the farmworker practices rain-fed agric ulture (control group). Preliminary analysis of the data has been carr ied out. Current information indicates that the risk of Ascaris lumbri coides infection is much higher in the exposed group than in the contr ol group (95% CL=4.0-67.3 and 4.7-78.8). According to the procedures e mployed, exposed children from exposed households were at higher risks of diarrhoeal disease than controls (95% CL = 1.03-2,03). The final r esults of this study are expected to aid decisions within the reuse pr ogrammes in developing countries.