We present a review of these experiences in Uruguay, focusing on the development of a multidisciplinary and transdisciplinary approach. Available data concerning lead pollution as well as other research issues with regards to metals and metalloids like selenium, copper and arsenic are reviewed. We describe the Medical Geology field in Uruguay with some examples such as environmental lead exposure in children and selenium and copper deficiency in human and cattle populations and their related factors, in addition to recent studies on distribution, mobility and exposure to arsenic from ground water. These examples are described as follows:
The lead contamination in Uruguay, as in other countries in the region, is mainly due to its industrial sources (metallurgies, manufacture and recycling of batteries, foundries etc
.). Generally, non-occupational lead exposure is caused by living in manufacturing areas or by the improper handling of lead-containing materials and solid waste, which poses an important health risk, with children being the most affected population [2
]. Lead and other heavy metal exposure in Uruguayan populations has been studied at the Faculty of Chemistry for a long time with QA/QC analytical results [3
]. Those scientific research publications turned out to be the only background data available for the whole country from when lead pollution first received official attention in 2001 [4
], when the “La Teja neighborhood case” arose.
The first instance was a child from La Teja who showed blood lead levels (BLL) higher than 20 ug/dL, after which, several other cases of even higher values appeared in that neighborhood, as well as in other areas of Montevideo and throughout the whole country. The worst situation was in the slum settlements of La Teja, where the ground showed more than 3,000 ppm of lead in the soil due to scrap land fillings. This was later found in those areas because, foundries and metallurgical manufacturing industries had settled down during the last century, but most of them were no longer active due mainly to economic reasons, leaving their solid waste behind [5
The community affected by lead contamination began a broad mobilization demanding solutions from the health and environmental authorities. As a response, the Health Ministry established an interinstitutional and multidisciplinary committee, including delegates from health, environmental, labor, educational, and social security institutions and community NGOs, among others. The University of the Republic was the main institution responsible for technical advice and support.
Lead pollution in Uruguay was then considered a Medical Geology issue, which highlighted the importance of the multidisciplinary, transdisciplinary and interinstitutional approach to provide solutions for the management of the health risks faced by thousands of affected children who were exposed to lead mainly due to the contaminated soil.
As a consequence of this approach, blood lead screening programs and lead protocols were implemented for Uruguayan children, specialized children health care centers were created and most blood lead levels determinations for health controls were confirmed at the Faculty of Chemistry. Moreover, many laws were approved, as well as several research projects which were being carried out [6
The severity of the discovered lead pollution required official governmental actions, in order to reduce sources of lead contamination as well as to assess health impact on children who had been exposed to environmental or industrial lead pollution.
As those actions to reduce public exposure to lead, became consistent, lead studies performed by the toxicology team at the Faculty of Chemistry were reviewed to compare BLLs changes in Uruguayan populations, after the leaded gasoline was phased out in 2003 [7
]. This report included comparisons of similar populations (children, exposed and unexposed adults, and lead workers) that were sampled within a 10-yr period. BLL determinations were all performed using atomic spectrometry at the Faculty of Chemistry using appropriate quality controls. The studies reviewed by the report, which were carried out in 2004, involved the sampling of children (n
= 180), nonoccupationally exposed adults (n
= 714), and lead workers (n
= 81). A framework was established to correlate BLL with variables such as age, sex, area of residence, available environmental lead data, and possible lead exposure sources. To assess the change in risk, analytical results were statistically compared with similar screening studies results that were performed in 1994 by the same team.
Children in 1994 showed a positive relationship between BLL and traffic intensity, and 40% of their BLL exceeded 10 ug/dL, while in 2004, only 7% were above that intervention level. Results showed significantly lower BLL levels in children (5.7 ug/dL) and non occupationally exposed adults (5.5 ug/dL) than similar populations sampled in 1994 (9.9 ug/dL and 9.1 ug/dL, respectively). However, workers occupationally exposed to lead did not show significant BLL differences between 1994 and 2004, and their mean BLL values were still high (49.0 Pb ug/dL vs. 42.0 Pb ug/dL, respectively). In order to improve this, new laws have also been approved to address lead occupational exposure which required BLL assessment to be periodically monitored as part of the workers health certificate protocol.
It was shown that significant improvements in preventing nonoccupational lead exposure have been made and that this outcome can presumably be attributed to the phase-out of leaded gasoline and to improvements in nutrition, hygiene, and related habits for children as well as a favorable response to the official multidisciplinary actions. These changes suggest that the contribution of environmental lead to the overall exposure of children and non occupationally exposed adults in Uruguay is decreasing.
Recent studies have also demonstrated that there has been a significant change in preventing lead exposure due to the public’s sensitization, along with the integration of multidisciplinary actions promoted. As a conclusion, the problem of lead contamination in Uruguay has been considered an important and unique experience in Medical Geology development [6
Arsenic in ground water
A thesis project and a multidisciplinary project have been carried out by environmental geologists and chemical toxicologists to look for Arsenic and other toxic metals in groundwater from the Raigon Aquifer in southwest Uruguay [11
]. The groundwater quality has been the target of multiple studies in Uruguay. In particular, the Raigón Aquifer is of special interest because of its importance as a hydro-resource in the southern zone of Uruguay and for being responsible for a great part of the dairy farm water supply. Thus, little attention has been paid to the presence of toxic elements in the water. Preliminary research work done by this team has determined that arsenic levels were higher than 0.01 mg/L in water samples from this aquifer. This issue leads to the supposition that the population, as well as industrial and agricultural activities, could be consuming water with arsenic concentrations over the international maximum recommended limits of 0.01 mg/L. As it is fully described, these arsenic water levels may contribute to health problems over a long-term exposure [12
]. The sampling campaign was done in fall 2007 and almost a hundred wells, with lithological profile available, were sampled with standard protocols, as representative of the aquifer.
The analysis were performed by ICP-MS and the results showed 80% samples with arsenic levels exceeding 0,01 mg/L ranging from 0,001 mg/L to an arsenic maximum concentration of 0.03 mg/L [13
]. Therefore, this project is facing a typical interactive problem between geology and health (Medical Geology) and it requires a systematic evaluation of the toxicological interest, geological materials (chemical laboratory analyses) and the risks to the exposed population (human and animal ones) to characterize the water supply in connection with its toxic metal and metalloids contents. This research contributed to the assessment of exposure risks to human and animal populations, and eventually to the management and/or specific treatment of these resources to prevent long-term epidemiological problems.
In addition, since 2006, this arsenic Uruguayan working team, has been taking part in an Iberoamerican network project [14
] regarding arsenic distribution, analytical methodologies development and remediation, and it is now developing feasible analytical methodologies for arsenic speciation.