Evaluation of Trace Element and Metal Accumulation and Edibility Risk Associated with Consumption of Labeo umbratus from the Vaal Dam, South Africa

Abstract

With the occurrence of recreational and small scale subsistence fishing activities at the Vaal Dam, South Africa, consumption of fish from this dam may result in health risks associated with trace elements and metals. The Vaal Dam is one of the largest dams in South Africa, located between the Gauteng Province and Orange Free State, and supplies water to approximately 11.6 million people. A total of 38 specimens of the benthic cyprinid fish Labeo umbratus were collected from the Vaal Dam during two surveys, in 2011 and 2016. Samples of muscle, liver, kidney, gill and spinal cord were analysed, along with sediment samples collected during the same surveys. Thirteen trace elements were analysed in the samples by Inductively Coupled Plasma–Optical Emission Spectrometry, Inductively Coupled Plasma–Mass Spectrometry, Atomic Absorption Spectroscopy and Total Reflection X-ray Fluorescence spectroscopy. This is the first survey on trace element and Hg accumulation in this fish species from the Vaal Dam and target hazard quotients (THQ) indicated that there is a risk for consumers of fish for As and Hg (THQ = 1.43 and 1.14 respectively). Although levels of trace elements in this impoundment have shown little change for a number of years and are lower than global background levels, studies detailing the accumulation of metals by fish inhabiting the Vaal Dam have indicated that trace elements in muscle tissue are above food safety guidelines. Trace element levels in L. umbratus are lower compared to other species inhabiting the Vaal Dam and further indicate that risks for consumers can be decreased if humans relying on fish from the Vaal Dam preferentially consume this species over others.

Trace Elements in Crustaceans, Mollusks and Fish in the Kenyan Part of Lake Victoria: Bioaccumulation, Bioindication and Health Risk Analysis

“…In our study, the value was below the LOD (0.040 mg/kg dw) in muscle tissue of O. niloticus in three of the sampling sites (KM, KK, MN) but was detected in the rest of the samples, albeit at low levels. In the rather unpolluted Vaal Dam in South Africa, similar levels were reported from cyprinid fish (Gilbert et al 2017). Much higher Ni concentrations were reported from the polluted Olifants Rivers System (South Africa): 14.2 and 19.4 mg/kg dw in muscle tissue, and 16.6 and 26.1 mg/kg dw in liver tissue of C. gariepinus and L. umbratus, respectively (Coetzee et al 2002).…”

Trace metal concentrations in the abiotic and biotic components of River Rwizi ecosystem in western Uganda, and the risks to human health

“…(2017) , Mataba et al. (2016) , Gilbert et al. (2017) the order of Hg concentration was muscle > liver > gills.…”

“…If trace metals are deposited into aquatic ecosystems, they dissolve or adsorb to suspended particles or sediment (Mataba et al, 2016), rendering the benthic habitats a sink and source for secondary contamination in the ecosystem (Onyari and Wandiga, 1989). From the sediment or water, metals may be taken up by biota such as fish, plants or invertebrates (Goodyear and Mcneill, 1999;Nabulo et al, 2008), and potentially posing human health risks via the consumption of contaminated water and food (Rice et al, 2014).…”

Spatial changes in trace element and strontium isotope water chemistry in a temperate river system with application to sturgeon movement

“…Trace elements vary greatly with changes in geological and geographical factors and are defined as any element having an average concentration of less than 100 parts per million (ppm) (McNaught and Wilkinson 1997;Richir and Gobert 2016). Trace elements have been shown to accumulate in the liver, gills, otoliths, and calcified structures of many fish species, and incorporation can vary based on individual physiology as well as environmental factors (Gilanders 2001;Gilbert et al 2017;Pracheil et al 2019).…”

“…Analysis of incorporated trace elements can be applied in a variety of ways, such as stock identification and bioindication of toxins (Gilanders 2001;Pracheil et al 2014;Gilbert et al 2017). Additionally, trace element analyses of calcified structures are used to retrace life history changes in anadromous fish species, and are particularly useful for understanding movements and life history characteristics of rare or endangered species when validated by reference samples (Secor et al 1995;Elsdon and Gillanders 2003;Allen et al 2009).…”