Ana María Sancha

Lung cancer and arsenic concentrations in drinking water in Chile

Cities in northern Chile had arsenic concentrations of 860 &mgr;g/liter in drinking water in the period 1958–1970. Concentrations have since been reduced to 40 &mgr;g/liter. We investigated the relation between lung cancer and arsenic in drinking water in northern Chile in a case-control study involving patients diagnosed with lung cancer between 1994 and 1996 and frequency-matched hospital controls. The study identified 152 lung cancer cases and 419 controls. Participants were interviewed regarding drinking water sources, cigarette smoking, and other variables. Logistic regression analysis revealed a clear trend in lung cancer odds ratios and 95% confidence intervals (CIs) with increasing concentration of arsenic in drinking water, as follows: 1, 1.6 (95% CI = 0.5–5.3), 3.9 (95% CI = 1.2–12.3), 5.2 (95% CI = 2.3–11.7), and 8.9 (95% CI = 4.0–19.6), for arsenic concentrations ranging from less than 10 &mgr;g/liter to a 65-year average concentration of 200–400 &mgr;g/liter. There was evidence of synergy between cigarette smoking and ingestion of arsenic in drinking water; the odds ratio for lung cancer was 32.0 (95% CI = 7.2–198.0) among smokers exposed to more than 200 &mgr;g/liter of arsenic in drinking water (lifetime average) compared with nonsmokers exposed to less than 50 &mgr;g/liter. This study provides strong evidence that ingestion of inorganic arsenic is associated with human lung cancer.

Lung cancer and arsenic exposure in drinking water: a case-control study in northern Chile

In some Chilean cities, levels of arsenic (As) in drinking water reached 800 (micrograms/L between 1950 and 1970, while current levels are 40 (micrograms/L. To evaluate the causal role of this exposure in lung and bladder cancers, we conducted a case-control study in Regions I, II, and III of the country. From 1994 to 1996, cases diagnosed as lung cancer and two hospital controls were entered in the study; one control was a patient with a cancer, while the other was a patient without cancer, both conditions unrelated to As. Controls were matched with cases by age and sex. A standard survey containing questions about residence, employment, health history, was administered to study subjects. Data on As concentrations in water were obtained from records of the municipal water companies. A total of 151 lung cancer cases and 419 controls (167 with cancer and 242 without cancer) were enrolled. Median level of lifetime As exposure was significantly higher among cases, with a clear dose-response relationship between mean As exposure levels, with an OR (95% CI) of: 1, 1.7 (0.5-5.1), 3.9 (1.2-13.4), 5.5 (2.2-13.5), and 9.0 (3.6-22) for strata one to five respectively. This study provides new evidence that As in drinking water can cause internal cancers and gives an estimate of the form of this relationship.

Managing Hazardous Pollutants in Chile: Arsenic

Chile is one of the few countries that faces the environmental challenge posed by extensive arsenic pollution, which exists in the northern part of the country. Chile has worked through various options to appropriately address the environmental challenge of arsenic pollution of water and air. Because of cost and other reasons, copying standards used elsewhere in the world was not an option for Chile. Approximately 1.8 million people, representing about 12% of the total population of the country, live in arsenic-contaminated areas. In these regions, air, water, and soil are contaminated with arsenic from both natural and anthropogenic sources. For long periods, water consumed by the population contained arsenic levels that exceeded values recommended by the World Health Organization. Exposure to airborne arsenic also occurred near several large cities, as a consequence of both natural contamination and the intensive mining activity carried out in those areas. In rural areas, indigenous populations, who lack access to treated water, were also exposed to arsenic by consuming foods grown locally in arsenic-contaminated soils. Health effects in children and adults from arsenic exposure first appeared in the 1950s. Such effects included vascular, respiratory, and skin lesions from intake of high arsenic levels in drinking water. Methods to remove arsenic from water were evaluated, developed, and implemented that allowed significant reductions in exposure at a relatively low cost. Construction and operation of treatment plants to remove arsenic from water first began in the 1970s. Beginning in the 1990s, epidemiological studies showed that the rate of lung and bladder cancer in the arsenic-polluted area was considerably higher than mean cancer rates for the country. Cancer incidence was directly related to arsenic exposure. During the 1990s, international pressure and concern by Chiles Health Ministry prompted action to regulate arsenic emissions from copper smelters. A process began in which emission standards appropriate for Chile were set; this process included careful evaluation of risks versus mitigation costs for abatement options. Such options were developed and implemented. More recently, local communities have pressed for more significant reductions of arsenic in air and water. Considerable experience was gained with the arsenic experience on how to manage this type of hazardous pollutant, in a context of trade-offs among production, jobs, income, and health. In this review article, we cover arsenic levels in Chiles air, water, and soils and discuss health impacts and patterns of exposure. We also describe the process followed to set arsenic regulatory standards, as well as abatement options for air and water and the associated costs.

Full-scale Application of Coagulation Processes for Arsenic Removal in Chile: A Successful Case Study

Publisher Summary The presence of arsenic (As) in some drinking water supplies in the North of Chile has a natural origin due to the hydrogeologic characteristics of the area, which has a predominance of quaternary volcanism. The impacts on the health of the population supplied with this water during the sixties pushed the Chilean authorities to study the problem and develop a solution. In 1970 the first of the four water treatment plants for As removal presently in operation was built. The As is removed with coagulation processes. Coagulation converts soluble As into insoluble reaction products facilitating their subsequent removal from water by sedimentation and filtration. The general treatment process involves oxidation (pre- and posttreatment), pH adjustment and ferric or effluent turbidity, and filter run length. Turbidity removal is a prerequisite for efficient As removal. The As level in finished water is 0.04 mg/L. The surface raw water is characterized by high hardness, salinity, and alkalinity, and a low turbidity. Orthophosphate and natural organic matter (NOM) have not been currently detected. As occurs mainly in the As(V) and As(III) oxidation states with As(V) dominant. Organic species (methylated As) are rarely present and are considered of little significance compared with inorganic species. The As concentration in the raw water is in the range 0.40–0.60 mg/L. The new WHO guidelines for As, 0.01 mg/L, presents several challenges to Chile. This chapter highlights and analyzes the background and key issues in the Chilean As removal technology including some technical details of Chilean water utilities.

Chapter 36 – Removing arsenic from drinking water: A brief review of some lessons learned and gaps arisen in Chilean water utilities

Publisher Summary Arsenic (As) removal from water can be achieved using different technologies. Application at full scale of each might not be as successful as at laboratory tests. At full scale, some variables are difficult to control and these may interfere in the removal process. These interferences may not be detected when working at laboratory tests with analito (As) solutions in distilled water. The selection of the best available technology for arsenic removal should be based on some key factors, such as removal goals, quality of the water matrix, water quantity, operator skill requirements, operational water treatment costs, arsenic speciation, availability of analytical methods, sludge management, and others. Some of these issues may play an important role in the feasibility of arsenic removal practices and therefore must be considered and assessed before the selection of any arsenic removal technology. Small water utilities may face more challenges than larger systems. The situation for family systems is even worse.