Determination of heavy metals in selected fish species and seawater from the South Durban Industrial Basin, KwaZulu-Natal, South Africa

The South Durban Industrial Basin (SDIB), South Africa, an economic hub that spans a long coastline, is a disaster management hotspot, which threatens the sustainability of the fishing industry in this region. This study investigated the elemental concentrations in fish and seawater from a mini-ecosystem in the SDIB, to determine if a direct relationship exists between these two matrices, and to assess for metal toxicities. The results showed As and Cr to be above the maximum permissible limits (MPLs) of the World Health Organization (WHO) for all fish species (blacktail, karanteen, five finger, mullet, and pompano), while fish from Isipingo Beach exceeded the WHO MPLs for Pb, As, and Cr. Fish did not display signs of metal toxicity indicating either a harmless form of metals or high tolerance levels. Typical concentrations of metals in seawater (mg L-1) at (Isipingo Beach, Cuttings Beach, and Amanzimtoti Beach) were found to be for Al (3, 2.7, and 16.4), As (0.17, 0.11, and 0.19), Cr (0.16, 0.17, and 0.23), Cu (0.15, 0.13, and 0.24), Fe (2.7, 3.45, and 33.9), and Zn (2, 2.1, and 2.12). Except for As, estimated daily intakes, target hazard quotients, and carcinogenic risks indicated no associated health risks due to consumption of the fish from the SDIB. However, due to target hazard quotients and carcinogenic risks for As being above 4 and 0.0001, respectively, fish from the SDIB should be consumed in moderation or not consumed to prevent long-term toxic effects of As.

Automated summary

The study found elevated levels of arsenic and chromium in fish and seawater in the South Durban Industrial Basin (SDIB), but determined that there are currently no significant health risks for consumers. However, due to higher levels of arsenic, it is recommended to consume fish from the SDIB in moderation or avoid those with high arsenic content to prevent long-term toxic effects.