Abstract
Elevated arsenic concentrations in ground and surface water sources have been reported world-wide. Furthermore, arsenic exposure has been associated with several health disorders including type-2 diabetes. However, research in Argentina is limited and is typically confined to a few provinces (e. g. Santiago del Estero; Cordoba and Buenos Aires). This research aimed to evaluate the relationship between arsenic exposure in water and levels in human hair, fingernail and toenail samples from four locations in Argentina, General Roca (Rio Negro), Los Menucos (Rio Negro), Eduardo Castex (La Pampa) and Copahue-Caviahue (Neuquen). Furthermore, it aimed to establish whether a link exists between type-2 diabetes and arsenic levels in human hair, fingernail, toenail, urine and blood (whole and serum) samples. The secondary aim of the research was to evaluate methods for the removal of arsenic from water, namely the use of solid phase material (iron oxide and hydroxide) and electrocoagulation. Ground, surface and tap water samples were collected from each of the four locations. This study found that the exposure of residents to total arsenic in water from each of the locations increased in the order: General Roca < Los Menucos < Eduardo Castex. Copahue-Caviahue is a unique location and was selected due to the potential exposure to arsenic from the volcanic rio Agrio (upper rio Agrio: 179 -359 μg/l AsT). However, the drinking water from glacial sources for the towns of Copahue and Caviahue contained arsenic levels (< 0. 2 - 0. 98 pg/l AsT) below that of General Roca (< 0. 2 to 7. 6 μg/l AsT). Hair, fingernail and toenail samples were also collected from each location, and arsenic levels were found to increase in the order: Copahue-Caviahue < General Roca < Los Menucos < Eduardo Castex. Furthermore, a positive relationship (Pearson Correlation) was found between arsenic exposure in water and levels in these samples. Residents from Eduardo Castex had the highest arsenic levels in hair (< 0. 03 - 4. 24 mg/kg AsT), fingernail (< 0. 05 - 10. 7 mg/kg AsT) and toenail (0. 09 - 13. 8 mg/kg AsT) samples. This town was selected to establish a link between arsenic and type-2 diabetes. A Mann-Whitney U-Test found significantly lower arsenic levels in finger and toenail samples (p < 0. 01), whereas significantly higher arsenic levels where found in urine and blood serum samples from type-2 diabetic individuals (p < 0. 01). This study, has highlighted the requirement to evaluate the impact a health disorder, such as type-2 diabetes, has on the distribution of arsenic in the human body. The arsenic exposure studies highlighted the possible requirement for a low-cost arsenic removal method. Iron oxide/hydroxide and electrocoagulation were evaluated and high arsenic removal percentages were found in laboratory studies. Electrocoagulation was evaluated further in field-based tests in Argentina (Eduardo Castex, La Pampa; San Cristobel, Santa Fe) and high arsenic removal (96 to 97 %) was achieved after 2 hours. Overall, this research, for the first time, provides data on arsenic exposure in water and the relationship with levels in human samples from several regions of Argentina. Furthermore, this study has evaluated a wide range of biological sample types with regards to the potential link between arsenic and type-2 diabetes and has found no conclusive evidence that the arsenic levels represent cause and effect.