A pilot in vivo evaluation of Sb(III) and Sb(V) genotoxicity using comet assay and micronucleus test on the freshwater fish, silver perch Bidyanus bidyanus (Mitchell, 1838)

Abstract

Antimony (Sb) is a priority water pollutant known to be toxic to aquatic organisms at high concentrations. Environmental exposure, however, occurs most often at sub-lethal concentrations but very limited information is available on effects of sub-lethal, chronic exposure to Sb, which hinders reliable risk assessment and the setting of protective guidelines. In this pilot study, <i>in vivo</i> screening for Sb genotoxicity in the erythrocytes of the freshwater fish, silver perch (Bidyanus bidyanus) was conducted where fish were exposed to environmentally relevant and sub-lethal Sb concentrations of 0.4, 0.9 and 1.8 mg L⁻¹ Sb(III), and 0.9, 2 and 5 mg L⁻¹ Sb(V), for 14 d. Genotoxicity was assessed by both a single cell gel electrophoresis (SCGE) assay and a micronucleus (MN) test. The SCGE assay showed that all Sb(III) exposure concentrations induced a statistically significant non-dose-related increase in DNA damage after 2 d of exposure after which there was no further increase in DNA damage evident in relation to the control. Mortality of fish was 100 % in all Sb(III) exposures by 14 d. Clastogenic and/or aneugenic effects were not observed. The 1.8 mg L⁻¹ Sb(III) exposure was the only Sb concentration at which a significant increase in the cytotoxicity index as measured by the ratio of polychromatic erythrocytes (PCEs) to normochromatic erythrocytes (NCE) was induced at 2 d exposure. For Sb(V) exposures, no significant genotoxic effects were observed using either assay, nor was the PCE/NCE altered. This pilot investigation has indicated that sub-lethal waterborne Sb(III) exposure manifests in genotoxic effects in freshwater fish species, which may have consequences for resilience and survival. Further study is needed for deeper insight into the relationship between Sb(III) and genotoxicity and the multiple biomarker responses that need assessment to evidence effects.