Risk of heavy metal ingestion from the consumption of two commercially valuable species of fish from the fresh and coastal waters of Ghana.

The need to evaluate the human health safety of fishery resources remain urgent in the mist of the ever-increasing fear of heavy metal toxicity from the consumption of Ghana's fisheries resource, as a consequence of pollution from several anthropogenic activities including artisanal gold mining. Nevertheless, the bigeye grunt (Brachydeuterus auritus) and Bagrid catfish (Chrysichthys nigrodigitatus) remain commercially valuable fish species in West Africa and continue to attract high patronage.Forty-five specimens each of C. nigrodigitatus and B. auritus collected from the Weija Dam and the Tema Fishing Habour in Ghana, between June and September 2016, were analysed for seven heavy metals using Atomic Absorption Spectrometry.Lead and Cadmium were below detection in all samples while Cu was not detected in B. auritus. Levels of the remaining metals (mg kg-1) were below FAO/WHO maximum permissible limits in fish and occurred in the rank order Se (3.5) > Zn (2.34) > Cu (0.59) > As (0.37) > Hg (0.19) in C. nigrodigitatus and Se (2.97) > Zn (2.28) > Hg (0.31) > As (0.21) in B. auritus. Only As in C. nigrodigitatus recorded Estimated Weekly Intake (EWI) greater than FAO/WHO Provisional Tolerable Weekly Intake (PTWI). Also, As in C. nigrodigitatus and Hg in B. auritus had Targeted Hazard Quotient (THQ) greater than 1 for individuals consuming the fishes on daily basis and therefore, raising concerns. However, for both species of fish, cancer risk of As was 1 in 10,000,000,000 and modified Health Benefits values of Se (HBVSe) were positive indicating the health risks that might accompany Hg exposure would be negated. Since toxicity depends on the concentration and quantity of a pollutant consumed, safe maximum consumption rate of C. nigrodigitatus based on As concentrations was 0.21 mg per day and that of B. auritus was 0.058 mg per day for Hg. With an average of 0.227 kg fish per meal of an adult human, these translated into not more than 24 C. nigrodigitatus and nine (9) B. auritus meals in a month but because fish is consumed at 0.0685 kg per person per day in Ghana, these values respectively translates to 93 and 30 safe days of consumption per month.At the rate of 0.0685 kg fish per person per day that fish is consumed in Ghana, the consumption of the two species of fish in Ghana would essentially be of little or no consequence to consumers

Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.

<p>Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.</p

Comparison of heavy metals concentrations between the muscle tissues of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> from the waters of Ghana.

<p>Note: <i>Mean ± SD with different letters in columns are significantly different (Mann–Whitney U test</i>, <i>p > 0</i>.<i>05)</i>.</p

Weight of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.

<p>Weight of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.</p

Standard length of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.

<p>Standard length of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.</p

Map of Ghana showing the Weija Dam and the Tema fishing harbour where fish specimens were collected.

<p>Map of Ghana showing the Weija Dam and the Tema fishing harbour where fish specimens were collected.</p

Trends in the concentration of heavy metals in the muscle tissues of <i>Brachydeuterus auritus</i> from the coastal waters of Ghana.

<p>Note: Pb, Cd and Cu were below detection limits in B. auritus. Also, pairwise comparison indicates concentration of all metals were significantly different except As and Hg (Kruskal-Wallis test with Fisher’s LSD post hoc, H_3,0.05 = 129.618, p < 0.05.</p

Frequency distribution of metal concentrations in the muscle tissues of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> from the waters of Ghana.

<p>Note: Pb, Cd and Cu were excluded from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194682#pone.0194682.g001" target="_blank">Fig 1</a> because Pb and Cd were below detection in all samples while 96% of the C. nigrodigitatus and 100% of the B. auritus samples had Cu levels below detections.</p

Trends in the concentration of heavy metals in the muscle tissues of <i>Chrysichthys nigrodigitatus</i> from the Weija Dam of the Densu River in Ghana.

<p>Note: Pb and Cd were below detection limits in C. nigrodigitatus. Note: Concentrations of As and Se, As and Zn, Hg and Se, as well as Hg and Zn were significantly different (Kruskal-Wallis Test with Fisher’s LSD post hoc, H_3,0.05 = 118.779, p < 0.05).</p