A case study on heavy metal contamination and sediment texture at Kolatoli Beach, Cox’s Bazar, Bangladesh: implications for ecological and human health risks

Rapid industrial growth and urban expansion have exacerbated the pollution of coastal beach sediments with heavy metals (HMs), particularly in developing countries such as Bangladesh, where the persistence and toxicity of these pollutants pose significant environmental and human health risks. Thus, this study investigated the contamination of HMs (Cu, Zn, Mn, Fe, Cd, Pb) to evaluate their associated risks at Kolatoli Beach, Cox’s Bazar, Bangladesh. Additionally, sediment texture analysis was performed to assess grain size distribution, which influences the mobility of these metals. The ecological risk (ER) was assessed through multiple indices, including the geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), ecological risk, and potential ecological risk index (PERI). Moreover, human health risk assessment (HHRA) was conducted for children and adults to determine non-carcinogenic and carcinogenic risks (CRs) through ingestion, inhalation, and dermal exposure. The sediment was predominantly sandy (93.72%), with lower clay (0%-2.51%) and silt (3.77%-6.28%) contents. The mean HM concentration in the sediment samples followed the descending order of Fe > Mn > Cu > Zn > Pb > Cd. The Igeo, CF, and PLI values indicated anthropogenic Cu and Pb accumulation in beach sediments, while Zn, Mn, and Fe remained at background levels. The PERI values ranged from 29.24 to 42.37, categorizing all samples under the ‘low ER’ classification (PERI < 150), though Pb and Cu had higher ER values. The overall hazard index (HI) values were below 1 for both age groups, indicating no significant non-carcinogenic risk (NCR). Total carcinogenic risk (TCR) values (5.99 × 10-6 for children, 3.99 × 10-6 for adults) remained within safe limits, though children posed higher CR. The statistical analyses revealed that HM contaminations were influenced by multiple factors. Overall, the study showed low to moderate HM contamination in the beach sediments, with tolerable ecological and human health risks.