Occurrence, non-carcinogenic and carcinogenic risk assessment of trace elements in rainwater in the vicinity of a cement factory in northeastern Nigeria

Rapid industrialization and urbanization result in atmospheric pollution with trace elements precipitated and deposited by rain, affecting human health. This study determined the concentrations and non-carcinogenic and carcinogenic risks associated with trace elements in rainwater in the vicinity of the Ashaka cement factory. Samples were collected using a bulk sampler fitted with a high-density polythene funnel. A total of 140 samples were collected in 2020 and analyzed for 15 trace elements using ICP-OES. Multivariate analysis was used to identify the sources of the rainwater trace elements. The results show that the abundance of trace elements in the collected samples was in the following order: Fe > Sb > Cu > Ba > V > Sc > Sr > Mn > Zn > Ti > Hg > Al > Mo > Co. Crustal enrichment factors (EFc) indicated that the samples were extremely enriched with Hg, Sb, Cu, and Mo, moderately enriched with Zn, Ba, V, Co, Sr, Cr, and Sc, and unenriched with Fe, Mn, Ti, and Al. Chronic daily intake (CDI) for both the ingestion and dermal pathways was in the order Fe > Cu > Ba > Cr > V > Mn > Zn > Hg > Mo. The hazard index (HI) was > 1 through the ingestion pathway, indicating a likely non-carcinogenic advertising effect. Similarly, the carcinogenic risk (CR) exceeded the (1.0 × 10–4—1.0 × 10–4) acceptable limit for children and adults, indicating the likely development of cancer among consumers. This revealed that the elements present in rainwater are anthropogenic and are brought about by cement production.