Assessment of trace metal concentrations in the giant mud crab Scylla olivacea and sediments from the coast of Pakistan

The Pakistani coast holds economic potential through its rich marine resources, including a thriving mud crab fishery. However, it faces increasing trace metal contamination from both anthropogenic and natural sources. Coastal sediments act as reservoirs for these pollutants, facilitating their spread and endangering marine ecosystems, marine life, and human health. Hence, effective and continuous monitoring is essential to detect potential problems and ensure the safety of mud crab ( Scylla olivacea ) consumption. In order to provide baseline data, concentrations of 14 trace metals were measured in 24 sediment samples from eight sites and 50 mud crab claws from five sites at the Pakistani coast using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The Metal Pollution Index (MPI) was highest in Sandspit (75) and Keti Bandar (60). The Ecological Risk Index (RI) highlights elevated risks in Khor Kalmat, Sandspit, and Gwadar, with values exceeding 60. The Biota Sediment Accumulation Factor (BSAF) indicates bioaccumulation, with Zn (10.5) and As (5.5) in Ibrahim Hyderi and Sonmiani exceeding the threshold of 1, signalling ecological concerns. Total Hazard Index (THI) values were below 1 for all trace metals but were close to 1 for Hg (0.7) and Cu (0.7). A THI value >1 indicates potential hazard to health from trace metal ingestion through consumption of mud crabs. Lifetime cancer risk (CR) exceeded the 10 −5 threshold for As at all sites and for Cd at Ibrahim Hyderi, indicating non-negligible lifetime cancer risk.