Chemometrics and Human Health Risk Assessment Associated with BTEX Compounds in Groundwater at Gas Stations

Abstract

Benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes (BTEX) are classified as priority environmental pollutants due to their high toxicity and mobility, being used as indicators of groundwater contamination by petroleum derivatives. Thus, the objective of this study was to assess the human health risks considering the lifetime carcinogenic (LCR) and non-carcinogenic (as hazard quotient—HQ) risks for 3 different age groups exposed to BTEX compounds by ingestion and dermal absorption routes, as well as applying chemometric methods to obtain correlations between BTEX concentrations and physicochemical parameters in groundwater samples obtained from gas stations (GS) in the city of Salvador, Brazil. Principal component analysis (PCA) and hierarchical analysis (HCA) showed a high negative correlation between BTEX compounds, and the physicochemical parameters monitored, being the variables pH and dissolved oxygen that most influenced the BTEX levels in groundwater, as well as showing a strong positive correlation between the BTEX compounds, thus confirming a common source for these compounds as being mainly accidental leaks from the underground fuel storage tanks in the GS. According to a probabilistic health risk assessment with Monte Carlo simulation, the HQ values ​​for BTEX compounds were below the limit established by United States Environmental Protection Agency—USEPA (HQ = 1) for all groups, considering both routes of exposure. For the three population groups, the ingestion route was the one with the highest LCR values and, in the case of ethylbenzene, most of the values were above the acceptable limit by USEPA (1.0 × 10^–6), therefore indicating risks to human health.