A study of contaminants in fish in South Africa : linking science, management and society

Contaminants in fish is a concern globally and locally. Fish have the propensity to accumulate contaminants to levels that may pose a threat to human health and disrupt ecosystem function. The purpose for investigating contaminants in this study for fish provides the public with information on the potential human health risks from the contaminated fish we consume. This study also investigated contaminants in estuarine fish and sediment, and is important to monitor as these components of ecosystems can indicate contamination in estuaries. Effective methods to determine contaminants in fish and sediment included the Direct Mercury Analyser 80 for mercury, Gas Chromatography for fatty acids and polychlorinated biphenyls and Inductively Coupled Plasma for aluminium, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, vanadium and zinc. Basic statistical tools, geochemical techniques, a bioaccumulation model and human health risk assessment tools provided by the United States Environmental Protection Agency were used to interpret the data. Ultimately consumption advice was developed from the risk assessment results and showed predatory fish such as swordfish and bluenose species are recommended to be avoided while yellow tail, red roman, mackerel, fish fingers and canned tuna are some of the fish that can be eaten 10-14 times per month that would not cause potential health risks. It was found that estuarine ambassid fish investigated in this study were not suitable for contaminant monitoring. There were no clear spatial and seasonal trends observed in the estuaries suggesting that ambassid fish efficiently assimilate contaminants. There was little evidence that contaminants were transferred from sediment to ambassid fish in the eThekwini estuaries. Therefore, their use is limited as a cost-effective estuarine contaminant monitoring tool. Each estuary investigated is unique and requires its own management plan