Journal
ENVIRONMENTAL POLLUTION
Volume 272, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2020.116027
Keywords
Cadmium; Benzo[a]Pyrene; Mixture toxicity; Acute exposure; Gene expression; Body burden
Categories
Funding
- NSERC
- SK Innovation and Opportunity Scholarship
- University Graduate Scholarship through the University of Saskatchewan
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The study revealed a significant increase in tissue accumulation and modulation of gene expression when two environmental toxicants were co-exposed. However, this did not result in additive or more-than-additive toxic effects (oxidative stress) in zebrafish.
Environmental water quality guidelines often work under the assumption that the toxicity of environmental pollutants is identical when present in isolation or in a complex chemical mixture. Thus, there is a crucial gap in our knowledge regarding how these toxicants interact and alter the toxicological effects in aquatic organisms. The present study examined the effects of acute (72-hr) aqueous exposures of Cadmium (Cd), a highly toxic non-essential trace metal, and Benzo[a]Pyrene (B[a]P), a prototypical polycyclic aromatic hydrocarbon (PAH) in adult zebrafish. Following a range-finding series of individual single-toxicant exposures, a second series was carried out using select concentrations in binary mixture exposures (using 5.8 or 22 mu g/L for Cd; 0.44 or 1.07 mu g/L for B[a]P). Our results demonstrated that tissue accumulation of both toxicants increased significantly in the presence of the second toxicant relative to single-toxicant exposures. Cd-only and B[a]P-only single toxicant exposures caused a significant downregulation of cytochrome p4501a (CYP1A1) and metallothionein-2 (MT2) mRNA in the gills, respectively, however binary co-exposures using both toxicants resulted in strong up-regulation of CYP1A1 and MT2. Additionally, co-exposures caused a strong induction of SOD1 and CAT mRNA transcript levels in the gill. The observed increase in body burden and transcript modulation did not translate into additive or more-than-additive toxic effects (oxidative stress) in zebrafish. (C) 2020 Elsevier Ltd. All rights reserved.
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