ABSTRACT
Coagulation technology has been used since 1970 in northern Chile for removing arsenic from drinking-water. This experience suggests that coagulation is an effective technology for the removal of arsenic. It is currently possible to reduce arsenic from 400 microg/L to 10 microg/L at a rate of 500 L/sec, assuming pH, oxidizing and coagulation agents are strictly controlled. The Chilean experience with the removal of arsenic demonstrates that the water matrix dictates the selection of the arsenic-removal process. This paper presents a summary of the process, concepts, and operational considerations for the use of coagulation technology for removal of arsenic in Chile.
Subject(s)
Arsenic/chemistry , Arsenic Poisoning/prevention & control , Chile , Environmental Exposure , Fresh Water/chemistry , Humans , Iron/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Water SupplyABSTRACT
The problem of arsenic in Chile was reviewed. In Chile, the population is exposed to arsenic naturally via drinking-water and by air pollution resulted from mining activities. The sources of arsenic were identified to estimate the exposure of population to arsenic through air, water, and food. Health effects, particularly early effects, observed in children and adults, such as vascular diseases (premature cardiac infarct), respiratory illnesses (bronchiectasis), and skin lesions have been described. Chronic effects, such as lung and bladder cancers, were reported 20 years after peak exposure and persisted 27 years after mitigation measures for removing arsenic from drinking surface water were initiated. Although the effects of arsenic are similar in different ethnic and cultural groups (e.g. Japanese, Chinese, Indian, Bangladeshi, American, and Taiwanese), variations could be explained by age at exposure, the dose received, smoking, and nutrition. Since health effects were observed at arsenic levels of 50 microg/L in drinking-water, it is advised that Chile follows the World Health Organization's recommendation of 10 microg/L. The Chilean experience in removal of arsenic suggests that it is feasible to reach this level using the conventional coagulation process.
Subject(s)
Arsenic/adverse effects , Arsenic Poisoning/epidemiology , Cardiovascular Diseases/chemically induced , Cause of Death , Chile/epidemiology , Chronic Disease , Cocarcinogenesis , Environmental Exposure/adverse effects , Environmental Monitoring , Health Services Needs and Demand , Health Status , Health Surveys , Humans , Maximum Allowable Concentration , Neoplasms/chemically induced , Nutritional Status , Politics , Population Surveillance , Public Health/statistics & numerical data , Respiratory Tract Diseases/chemically induced , Risk Factors , Skin Diseases/chemically induced , Smoking/adverse effectsABSTRACT
En algunas ciudades de Chile, entre 1950 y 1970, los niveles de arsénico (As) en el agua potable alcanzaron los 800 µg/l, estando hoy en 40µg/l; para evaluar el rol de esta exposición, se llevó a cabo este estudio de casos de cáncer de pulmón y controles en las Regiones I, II y III. Entre 1994 y 1996, se ingresaron casos de cáncer de pulmón y dos controles hospitalarios: un control, un paciente con cáncer y el otro, un paciente sin cáncer, ambos diagnósticos no relacionados con arsénico. Los controles fueron pareados grupalmente por edad y sexo con los casos. A cada sujeto, se le aplicó una encuesta estandarizada sobre residencia, empleo y salud. La información sobre niveles de As en el agua provino de registros de las compañías de agua. Se ingresaron 151 casos de cáncer pulmonar y 419 controles (167 con cáncer y 242 sin cáncer). La mediana de As en el agua potable a lo largo de la vida fue significativamente mayor entre los casos, con una clara relación dosis-respuesta entre el promedio de As y el riesgo, con OR (95 por cento IC) de 1, 1,7 (0,5-5,1), 3,9 (1,2-13,4), 5,5 (2,2-13,5), y 9,0 (3,6-22) para los estratos 1 al 5, respectivamente. Provee nueva evidencia sobre el rol causal del As en el agua potable en cánceres internos y sobre la forma de la relación entre exposición y riesgo de cáncer.