Public health risk assessment of ambient PM2.5-bound toxic heavy metals

Abstract

<p>Rapid industrialization and urbanization has caused significant increments in concentrations of particulate matter (PM) bound heavy metals which have adverse effects on human health due to their carcinogenicity. Their exposure may affect reproduction and overall development and may lead to cardio-, haemo-, and neurotoxicity in humans. Despite this, previous studies have not captured the regional differences in air pollution and warrant regional level health effect studies.</p> <p>To this end, this study aims to assess the health risk assessment of particulate matter (PM<sub>2.5</sub>) bound heavy metals in the ambient air. Samples are collected from Bikaner for the period of January 2019 to December 2019 during alternate days. Approximate 25 samples of metals are collected from Bikaner city using PM<sub>2.5</sub> sampler on an 8-h basis. Samples were analyzed gravimetrically for determining mass content and chemically for determining metal content using Energy Dispersive X-Ray Fluorescence (ED-XRF). PM<sub>2.5</sub> exposure assessment is conducted using metal values and associated hazard quotient (HQ). Risk estimates were reported in terms of hazard quotient (defined as ratio of daily inhaled dose to daily acceptable inhaled dose) for exposures of non-carcinogenic metals or lifetime excess risk of cancer (ECR) for exposures of carcinogenic metals. These risks are compared for three contrasting sites including Bikaner, Mohali and Srinagar with Srinagar representative of Himalayan region while Bikaner is indicative of desert region. Dose-response parameters for all metals are adopted from the US EPA database. </p> <p>The potential risk due to hypothetical exposure of adults and children to four carcinogenic metals of PM<sub>2.5</sub> are expected to be greater than 10<sup>-7</sup> showing probability of cancer risks. Among metals, exposure to PM-associated Cd resulted in exposure to PM-associated Cd resulted in consistent cancerous risk in both seasons, whereas exposures to PM-associated Cr resulted in HQ>1 indicating chance of non-carcinogenic risk. This study provides meaningful information about the seasonal variation of PM<sub>2.5</sub>-linked metals and also explains these in terms of diverse geographical variability of selected sites. Finally, this study provides meaningful insights to design and influence public health policy interventions for PM<sub>2.5</sub>-borne heavy metal exposures of adults and children for selected sites in India.</p>