An overview of environmental arsenic issues and exposure risks in Uruguay.

Evidence for low-dose health effects of Arsenic (As) in humans is still controversial and presents a major public health issue in several countries worldwide. It is not clear yet, whether there is a lower safe threshold for arsenic in drinking water among other possible sources such as food, below which, exposures are not harmful. In Uruguay, safe drinking water is supplied to 94% of the population by a state company (OSE) and As levels in workplaces and food are officially regulated. This paper aims to present and discuss the issues regarding arsenic exposure risks to the environment and human population, which are being addressed in a multidisciplinary manner in Uruguay since 2007. An overview is given on both the background and the current situation, presenting reports and research studies conducted on these problems by various academic, state, and private institutions that deal with regulations, surveillance, and health care. Scientific research on geogenic As levels in groundwater indicates As levels above those recommended by the WHO for drinking water (10 µg L-1) in different Uruguayan aquifers. There is a lack of baseline studies concerning Uruguayan residents that are exposed to As in drinking water over time. Furthermore, there is a need for data on environmental chemical exposure that could be associated with disease or death in the country. In addition, only a few As risk exposure assessment studies in children, adults, and workers using biomarkers in urine are available. Furthermore, this paper presents As levels in a rice growing region and the spatial distribution of groundwater arsenic data compared to a national cancer atlas database as ongoing research advances. Multidisciplinary research projects and local future actions are also described. This contribution constitutes a first attempt to develop a feasible health risk assessment of low-dose arsenic exposure in this Latin-American country.

Comparative study of blood lead levels in Uruguayan children (1994-2004).

Lead does not fulfill any physiological function in the human body. It is generally accepted that the blood lead level (BLL) is the best exposure index, as there is an excellent correlation between the actual exposure of the individual and the concentration of lead in blood. In Uruguay, lead contamination becomes a matter of public concern in 2001, giving rise to a sensitization in the population, which in many cases brought about a change in hygienic and dietary habits of the children. In 2004, after the leaded gasoline phasing out process in Uruguay was completed, we studied non-exposed children to correlate BLL with variables such as age, sex, area of residence, and available environmental lead data and compared these results with those from our similar screening studies 10years ago. The main result of this comparison is that BLL from children in our country had a significant decrease between 1994 and 2004.

Pesticides in Uruguay.

This is a review, from an independent and scientific point of view, of the different aspects involved in the issue of pesticides in Uruguay. In its preparation, the University, responsible official institutions, nongovenment environmental organizations, and independent experts have been consulted. As to the legal framework, the responsibilities of the institutions are described and evaluated. The earlier and current regulations for the registration and sale of pesticides are presented, as well as the available information on the active ingredients most used in Uruguay. Official control is evaluated in reference to pesticide residues in food, drinking water, and the environment and to final waste disposal. Maximum allowed residue limits and the responsibilities of the corresponding governmental institutions are presented. Emphasis is placed on the fact that there are no publicly available data. Several research programs are presented, mainly from academia, and usually are not completed due to lack of financial support. In the conclusions the most problematic aspects are pointed out, emphasizing the need to improve national regulations for the country to establish an effective system of control. The importance of financial support to achieve this control and to conduct interdisciplinary studies to determine the real situation is discussed. All compounds are listed in Table 19.

Lead contamination in Uruguay.

Uruguay is a developing country of South America with about 3 million people, half of whom live in its principal city, Montevideo. This city has several lead pollution sources as emitting industries, most of them surrounded by residential neighborhoods, some still using lead pipes in drinking water systems of old buildings, and has areas of heavy traffic with cars that are still fueled with leaded gasoline. The toxic effects of this heavy metal are well known. Children are a very sensitive population and their early symptoms of intoxication are not always taken into account. Blood lead is a good indicator of recent exposure to lead influenced by inhalation and ingestion. The systematic data assessment of lead pollution and people exposure in Uruguay was not well known when the Department of Toxicology and Environmental Hygiene of the Faculty of Chemistry began to analyze lead in biological samples, first from exposed workers and next from children and the general population, including sensitive animal species like dogs. Several described studies were carried out analyzing for blood lead to assess lead uptake and to obtain reference values for Uruguayan populations. Since 1986, that Department is the only laboratory where blood lead analyses are done, and the analytical method has been controlled by an interlaboratory quality control program of the Ministry of Labour of Spain and confirmed by experts from the Laboratory of Occupational and Environmental Medicine of Lund, Sweden. Financial and technical support was obtained from Sweden (SAREC) and also from the University of the Republic of Uruguay. Uruguayan lead workers have always been the principally studied population because their lead exposure assessment as well as their health protection education is not always done properly. Uruguay has adopted ACGIH reference values (150 micrograms/m3 in total lead dust, 50 micrograms/m3 respirable lead dust, 300 micrograms/L blood), and the high blood lead levels indicate significant adverse health risks effects and show a lack adequate controls for working conditions. A surveillance of children living in the surroundings of lead processing factories and in different neighborhoods was conducted because no data were available for blood lead in children before 1992. Also, general populations living in those areas or in areas of heavy traffic were assessed. Blood lead levels were always compared with those of control populations sampled at the same time answering a questionnaire. Workplace influence as well as atmospheric, soil, and water pollution were always considered to explain the obtained results. Some studies were carried out in dogs as a sensitive population, showing their higher exposure. The described studies included internal and external quality controls for the analytical methods and data processing. All blood lead analyses were done by atomic absorption spectrometry (AAS) after adding complexing agent and extraction. Samples taken together with Swedish researchers were analyzed in Lund (Department of Occupational and Environmental Medicine University Hospital), at 283.3 nm after electrothermal atomization (ETA). There was good correlation (r = 0.96) among 28 samples shared between Montevideo and Lund laboratories. The authors recommend more systematic clinical examination of workers, children, and the general population to determine the potential health risks for Uruguayan populations so as to improve their health conditions and to officially recognize lead pollution as an environmental problem.

Blood lead in Uruguayan children and possible sources of exposure.

Blood samples and questionnaire background data were collected from 96 children (age 2-14 years) living in urban, suburban, or rural areas with varying traffic intensity and industrial lead pollution in Uruguay. Spot samples of tap water were collected from the homes of 44 children, and samples of top soil were taken from seven areas. Samples of air-borne dust were collected in central and suburban Montevideo. Blood lead concentrations (B-Pb) in children ranged between 47 and 191 (mean 96) micrograms/L and exceeded in 36% of the children 100 micrograms/L, the intervention level adopted by the United States Centers for Disease Control. Lead in tap water ranged from 0.2 to 230 (mean 15) micrograms/L and exceeded in 39% of the samples the maximum level recommended by WHO, 10 micrograms/L. Lead pipes were used in parts of the water supply systems. Lead in air varied between different locations from 0.15 to 1.7 micrograms/m3, highest in the very center of Montevideo. The median soil lead ranged from 6 to 2100 micrograms/g and was highest in industrially polluted areas. At multiple regression analysis, B-Pb was significantly associated only with age (P = 0.032) and traffic intensity at school (P = 0.045). No significant impact on B-Pb of lead in water or soil could be established.