Assessment of health risks associated with potentially toxic element contamination of soil by end-of-life ship dismantling in Bangladesh

Abstract

Ship breaking and recycling industry (SBRI) loops back scarce ferrous and non-ferrous materials from dismantled ships and also renews the global shipping fleet by treating the end-of-life (EoL) ships. Currently, SBRIs in Bangladesh, India, and Pakistan are dismantling the majority of the EoL ships by open beaching method. Accordingly, ship dismantling carries the blame of releasing potentially toxic elements (PTEs) to the coastal and marine environment risking the food chain through potential bioaccumulation and biomagnification. Health risk assessment associated with PTEs from open beach ship dismantling is scarce. This study aimed at assessing concentrations and seasonal variations of PTEs in soils exposed to the activities of SBRIs for their source apportionment by using contamination factor (CF) and multivariate statistical analysis, while carcinogenic and non-carcinogenic health risks due to the PTEs have also been determined. Soil samples were collected twice—during pre-monsoon and post-monsoon seasons—from three working zones of each of the 15 different ship breaking yards spanning the entire SBRI zone in Bangladesh. Soil contamination was assessed by using the CF, and inverse distance weighting interpolation mapping showed the spatial distribution of metals at SBRI zone in Bangladesh. Multivariate statistical analysis, principal component analysis, and correlation matrix yielded the source apportionment of PTEs. Subsequently, carcinogenic and non-carcinogenic health risks were assessed following the approach recommended by the United States Environmental Protection Agency (USEPA) with uncertainty estimation through Monte Carlo simulation. Contamination levels of PTEs followed Cd > Zn > Cr > Cu > Pb > Ni > Mn > As. Concentrations of Cd, Cr, Mn, and Zn were higher than the maximum allowable regulatory limits at storage zone and also higher as compared with the beaching and cutting zones in general. The contamination index indicated extreme Cd contamination in the area with elevated levels in pre-monsoon. Two principal components (PC) were identified—PC1 (Cd, Cu, Mn, Pb, Zn) and PC2 (As, Cr, Ni) inferring their source segmentation. Indirect soil ingestion is the major possible exposure path to PTEs. The health index indicated the absence of any obvious health effects on the people active at SBRI yards in Bangladesh. The carcinogenic risk was for 6 to 7 persons per 100,000 people which was within the USEPA acceptable range.