Risk assessment of mercury in sharks (Rhizoprionodon longurio) caught in the coastal zone of Northwest Mexico

Bioaccumulation of cd and hg in Muscle of Juvenile Pacific Sharpnose Shark Rhizoprionodon longurio from the SE Gulf of California

In this study, the concentrations of Cd and Hg were measured in muscle of juvenile individuals at an importan fishing ground in southeastern Gulf of California to assess the health risk to human consumers considering elemental levels and rate of shark consumption in NW Mexico. Twenty-eight individuals were sampled in September 2019. Quantification of Hg was made by cold vapor-atomic absorption spectrophotometry, analyses of Cd were made by graphite furnace atomic absorption spectrophotometry. In general, average Hg (1.27 µg g^-1 dry weight) concentrations were higher than Cd (0.059). In comparison to results of Cd and Hg in muscle of several species of genus Rhizoprionodon sp., our reported concentrations were comparable. Maximum permissible limits (Cd 0.5 and Hg 0.5 µg g^-1 wet weight) in fish products for human consumption were not exceeded. Health risk assessment to shark consumers indicated that Hg is of more concern than Cd but no hazards exist.

Mercury concentrations in coastal Elasmobranchs (Hypanus guttatus and Rhizoprionodon porosus) and human exposure in Pernambuco, Northeastern Brazil

Elasmobranchs are long-lived predatory fish that show high Hg concentrations generally reflecting environmental levels, notwithstanding they are widely consumed in Brazil increasing Hg exposure to humans. This study reports on Hg concentrations in largely consumed sharks (Rhizoprionodon porosus) and rays (Hypanus guttatus) from the Pernambuco coast, NE Brazil and the risk associated with their consumption. Muscle tissue concentrations of Hg in H. guttatus and R. porosus varied from 40 to 1,020 ng.g-1 w.w. (median = 125; mean = 124 ± 48 ng.g-1 w.w.) in sharks and from 129 to 2,130 ng.g-1 w.w. (median = 976; mean = 919 ± 139 ng.g-1 w.w.) in rays. Concentrations of Hg positively correlated with size in sharks, but not in rays. Concentrations reflect the local environmental contamination of a large urban center and industrial park concentrated in a short extension of mangrove-dominated coastline (50 km) and are higher compared to other Brazilian sites where Hg concentrations in these species have been reported. Sharks had a risk coefficient (HQ) range of 0.04 to 1.1, not surpassing the reference level of exposure. On the other hand, rays' HQ ranged from 0.14 to 2.3, and exceeds the reference level of exposure and suggests adverse effects to consumers.