[Quality of potable water and incidence of gastroenteritis in 2 cities in the state of Sonora, Mexico]. / Calidad del agua potable e incidencia de gastroenteritis en dos ciudades del estado de Sonora, México.

Based on the fact that drinking-water is of great significance in the transmission of infectious diseases, the incidence of diarrheal disorders was examined in two cities similar in their demographic composition and in their use of health services, but not in the quality of the drinking-water supply. In Navojoa, a city with high incidence of diarrheal diseases (116/1000 pop. in 1985), high rates of drinking-water contamination with fecal coliforms were found (43% of water samples); on the contrary, in Ciudad Obregón, a city with lower rates of diarrheal diseases (49/1000 pop. in 1985), drinking-water contamination with fecal coliforms was also comparatively lower (only 6% of water samples). These data illustrate the need to promote the implementation of drinking-water treatment in those places with signs of fecal contamination and high incidence of diarrheal diseases. To this regard, the General Direction for Research and Technological Development of the Ministry of Health has promoted the development of a chlorination equipment, useful mainly in rural areas, where biological contamination is usually high. These and similar procedures for water treatment should be considered as effective means to decrease the incidence of diarrheal diseases.

[Removal of arsenic from water for human consumption in homes in rural communities in the Comarca Lagunera, Mexico]. / Remoción del arsénico del agua para consumo humano en domicilios de comunidades rurales de la Comarca Lagunera, México.

This paper presents the results of an intradomiciliary procedure for arsenic removal from water, by means of flocculation with ferric sulphate. The reaction was carried out in a specifically designed tank with a manual agitator (reactor) installed in a vertical support. The salts to flocculate were handed in two small envelopes, whose contents were added independently, agitating the water and letting it settle for two to three hours. Water is decanted by opening a faucet connected to the inferior part of the recipient. Ten families of the states of Durango and Coahuila (the Comarca Lagunera) were selected. Samples of water were taken before and after the treatment. In 70 percent of these samples the arsenic removal was total, and in the remaining 30 percent the removal was superior to 93 percent. The arsenic removal of water in the domicile was very effective, for which it is suggested as a palliative method for those groups with higher levels of exposition.