Uso de cloro na desinfecção de aguas

ARTIGO / ARTICLE

O Uso de Cloro na Desinfecção de Águas, a Formação de Trihalometanos e os Riscos Potenciais à Saúde Pública Chlorine Use in Water Disinfection, Trihalomethane Formation, and Potential Risks to Public Health
Sheila T. Meyer1 MEYER, S. T. Chlorine Use in Water Disinfection, Trihalomethane Formation, and Potential Risks to Public Health. Cad. Saúde Públ., Rio de Janeiro, 10 (1): 99-110, Jan/Mar, 1994. Before the development of the germ theory — relating microorganisms with disease transmission (1880) — people believed that diseases were transmitted by odours. Water and sewage disinfection emerged as a method for elimination of odours. There are many disinfecting agents, but chlorine is the main product used to disinfect water. Organic compounds present in water that is chlorinated can result in the formation of trihalomethanes. The latter are basically one atom of carbon, one of hydrogen, and three of a halogen (chlorine, bromine, or iodine). These are considered carcinogenic compounds and their presence in drinking water should therefore be avoided. Epidemiological research has shown an association between trihalomethane concentration and cancer morbidity and mortality for some types of carcinoma. Nevertheless, there may be more risk than benefit involved in replacing chlorine with other disinfecting agents, since the incidence of water-borne diseases only dropped after water chlorination became a routine procedure. Key words: Water Treatment; Chlorine; Trihalomethanes

INTRODUÇÃO A desinfecção da água tem sido praticada por milênios, embora os princípios envolvidos no processo não fossem conhecidos. Existem indícios de que o uso de água fervida já era recomendado em 500 a.C., mas alguns historiadores julgam que esta prática era adotada desde o começo da civilização (Iabusch, 1971). Até que a teoria dos microorganismos fosse estabelecia (Louis Pasteur, 1880), havia a crença de que as doenças eram transmitidas através de odores. A desinfecção da