Heavy metal contamination in the Cotopaxi and Tungurahua rivers: a health risk

Abstract

The objective of our study was to evaluate if there is heavy metal contamination in the water of rivers and irrigation canals of the Cotopaxi and Tungurahua provinces in Ecuador and assesing the health risk of this contamination in the neighboring population. To date no study has been done on contaminant health risk in Ecuador. For this purpose, 21 water samples collected along the Cutuchi, Pumacunchi and Ambato Rivers, the Latacunga-Salcedo-Ambato irrigation canal, tap water and water from a tannery were analyzed by atomic absorption spectrophotometry. The metals analyzed were Cd, Cr, Pb, Ni, Hg and As. At all points tested at least one of these metals surpassed the permissible limits under the Ecuadorian law or the Environmental Protection Agency. Cr had the highest level of toxicity, with critical values (8.3E + 03; 2.2E + 04; 1.8E + 06; 99.6, for non-carcinogenic risk; and 1.17; 0.63; 217.06, for carcinogenic risk) followed by Cd, Pb, As and Hg. Regarding health risk analyses, there was high risk, both carcinogenic and non-carcinogenic, for all metals analyzed; the most harmful was Cr followed by As. The most damaging exposure route was inhalation, followed by the dermal and ingestion routes. Children were the most vulnerable population for non-carcinogenic risk, while for carcinogenic risk; the population most likely to suffer some type of cancer was the adult one. So, it is clear that the populations living close to these rivers have a high probability of having different diseases and cancer, due to the high heavy metal contamination that exists in these waters.