Human Health Risk Assessment of Heavy Metals and Nitrates Associated with Oral and Dermal Groundwater Exposure: The Poirino Plateau Case Study (NW Italy)

Abstract

The Poirino Plateau (northwestern Italy) presents high contamination of the shallow aquifer due to intense agricultural practices and industrial activities. Many inhabitants have exploited shallow wells for personal purposes, coming into contact with contaminants. The aims of this study were to characterize groundwater contamination by heavy metals and nitrates, assess the noncarcinogenic and carcinogenic health risks for oral and dermal exposure in different receptor groups (children, adults, workers) and compare the noncarcinogenic and carcinogenic risk results with the regulatory limits and, therefore, if the actual regulatory limits are able to detect all potential situations of risk. For this purpose, 18 monitoring wells were collected in July 2022, and chemical–physical parameters and heavy metals were detected. The chemical data confirm a relevant anthropogenic contamination by nitrate and heavy metals. The estimated health risks are much higher in children, for oral exposure rather than dermal exposure for all the substances. The comparison between the results of the human health risk assessment and those in respect of threshold values confirms the existence of a transition condition. This condition, with concentrations below regulatory limits and above the noncarcinogenic or carcinogenic limits, reveals that the regulatory limits are not able to identify all the potential risk situations for the population.