[Risk analysis of nitrate contamination in wells supplying drinking water in a rural area of Chile].
OBJECTIVE
To assess the risk associated with nitrate contamination of wells that supply drinking water in the rural, Parral region of central Chile.


METHODS
The nitrate concentration levels were determined using water samples from 94 wells. An analysis of the distribution of nitrate concentration levels was performed in order to assess possible geographic correlations. For the risk analysis, two exposure situations were identified among the population (for adults and for infants), and the health risks were mapped.


RESULTS
Fourteen percent of the wells studied had nitrate concentration levels greater than what the Chilean health standards allow for drinking water. There was no geographic correlation for the nitrate concentration levels. The mean hazard quotient (HQ) for adults in the study area was 0.12, indicating an absence of risk for this population group. For infants, the HQ values had a maximum value of 3.1 in some locations, but the average was 0.69 (still below 1.0), indicating that the well water in the study area was generally not hazardous for infants.


CONCLUSIONS
In the Parral region of Chile, nitrate contamination of wells is primarily linked to certain factors such as construction practices and the proximity of livestock. These factors affect the quality of drinking water in isolated cases. There was no risk found for the adult population, but there was for infants fed on formula mixed with water coming from the contaminated wells.
Arumi
José Luis
JL
Universidad de Concepción, Departamento de Recursos Hídricos, Chillán, Chile. jarumi@udec.cl
Núñez
Jorge
J
Salgado
Luis
L
Claret
Marcelino
M
D000328:Adult; D002677:Chile; D006801:Humans; D007223:Infant; D009566:Nitrates / Q000032:analysis*; D018570:Risk Assessment; D012423:Rural Health; D014877:Water Pollution, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
D009566:Nitrates