Assessment of risk to human health associated with the consumption of contaminated groundwater in the Western Brazilian Amazon

Abstract

The present study evaluates the risk to human health associated with the consumption of groundwater in municipalities in the Western Brazilian Amazon (Jaru, Ouro Preto do Oeste, Ji-Paraná and Presidente Médici, all in the state of Rondônia). Water was collected directly from wells with an underground collector and PET bottles between 2017 and 2019, in periods (low water, high water, Transition high water/low water). Nitrite and nitrate analyses were carried out using spectrophotometry (APHA, Standard methods for the examination of water and wastewater, Washington, 2017; EPA, Technical Resource Document, EPA/600/4-79/020 Disponívelem, 1971). Trace elements were detected by inductively coupled plasma-optical emission spectrometry. The hazard quotient was obtained from the ratio between the exposure level and the acceptable level for each substance present in the samples, and the hazard index resulted from the sum of the hazard quotients found for each substance. We found that the groundwater in the study areas is improper for human consumption in accordance with Brazilian regulations. Concentrations were found above the maximum values permitted by the Edict on Potability of Water for Human Consumption (PRC Edict 5/2017, as amended by GM/MS Edict 888/2021), and the World health organization standard for 2017 for Al (< 200 µg L^-1), As (< 10 µg L^-1), Ba (< 700 µg L^-1), Fe (< 300 µg L^-1), Mn (< 100 µg L^-1), Pb (< 10 µg L^-1), Zn (< 5,000 µg L^-1), and nitrate (< 10,000 µg L^-1). The results of the risk assessment indicated that the values were above the recommended levels (< 1) in 75.3% of the samples analyzed, meaning that people in the areas studied are highly exposed to contaminants that are harmful to human health.

Keywords: Amazônia; Hazard index; Hazard quotient; Trace elements.