Health Risk Assessment of Heavy Metals in Microplastics in Sediments, a case study of selected Rivers, South-South, Nigeria

Abstract

This study investigates the health risks associated with heavy metals adsorbed onto microplastics in sediments (MCPS) in the brackish water estuaries of Woji, Elelenwo, and Okujagu Creeks in Port Harcourt, Rivers State, Nigeria. Monthly sediment samples were collected following standard procedures from December 2020 to May 2021, and the levels of metals including Ni, Cr, Fe, and Hg were analysed via GBC Avanta PM A6600 Flame Atomic Absorption Spectrophotometer (FAAS) for their potential health impacts on humans, particularly through ingestion and dermal contact. Results show that during the dry season, the concentrations of Ni, Cr, and Fe in microplastic-associated sediment (MCPS) were significantly (P< 0.05) higher compared to the wet season, with concentrations exceeding sediment quality guidelines. The risk assessment revealed non-carcinogenic health risks, particularly for children, with Hazard Quotients (HQ) above 1 for Fe and Hg, indicating significant exposure. The Incremental Lifetime Cancer Risk (ILTCR) for Ni and Cr exceeded the threshold of 1.0E-06, suggesting potential long-term cancer risks due to chronic exposure. Ingestion and dermal contact with contaminated sediment were the primary exposure pathways for heavy metals. The seasonal variations highlighted that the dry season presented higher contamination levels, leading to greater health risks, while the wet season diluted the contaminants, reducing the potential risks. The study emphasizes the urgent need for better waste management practices along these creeks, to mitigate the health risks posed by heavy metal contamination in microplastics. This study focuses on the environmental and public health challenges facing communities near polluted water bodies in the Niger Delta, particularly in Port Harcourt.