Analysis of Sublethal Toxicity in Developing Zebrafish Embryos Exposed to a Range of Petroleum Substances

Abstract

The Organisation for Economic Co‐operation and Development (OECD) test guideline 236 (fish embryo acute toxicity test; 2013) relies on 4 endpoints to describe exposure‐related effects (coagulation, lack of somite formation, tail‐bud detachment from the yolk sac, and the presence of a heartbeat). Danio rerio (zebrafish) embryos were used to investigate these endpoints along with a number of additional sublethal effects (cardiac dysfunction, pericardial edema, yolk sac edema, tail curvature, hatch success, pericardial edema area, craniofacial malformation, swim bladder development, fin development, and heart rate) following 5‐d exposures to 7 petroleum substances. The substances investigated included 2 crude oils, 3 gas oils, a diluted bitumen, and a petrochemical containing a mixture of branched alcohols. Biomimetic extraction–solid‐phase microextraction (BE–SPME) was used to quantify freely dissolved concentrations of test substances as the exposure metric. The results indicated that the most prevalent effects observed were pericardial and yolk sac edema, tail curvature, and lack of embryo viability. A BE–SPME threshold was determined to characterize sublethal morphological alterations that preceded embryo mortality. Our results aid in the understanding of aquatic hazards of petroleum substances to developing zebrafish beyond traditional OECD test guideline 236 endpoints and show the applicability of BE–SPME as a simple analytical tool that can be used to predict sublethal embryo toxicity. Environ Toxicol Chem 2019;38:1302–1312. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

The Appropriateness of Using Aquatic Snails as Bioindicators of Toxicity for Oil Sands Process-Affected Water

“…The results showed that the relative species sensitivity of Lymnaea stagnalis (log CTLBB = 1.83 µmol/g lipid) is close to the mean of 14 tested aquatic species (log CTLBBs = 1.85 µmol/g lipid), including invertebrates, algae, and bacteria [30]. A biomimetic extraction method by solid-phase microextraction (BE-SPME) has been developed to predict toxicity during exposure to complex organic mixtures [31]. Pairing BE-SPME analysis results with toxicity response/endpoints of snails could validate this screening tool for estimating the toxicity of OSPW in the future.…”

Interlaboratory Comparison of a Biomimetic Extraction Method Applied to Oil Sands Process–Affected Waters

“…The key to establishing nondepletive extraction conditions is to employ a low PDMS to water ratio (Redman, Butler, et al, 2018). The BE‐SPME method has the potential to simplify aquatic hazard assessments of petroleum substances and aid in establishing water quality criteria in receiving waters because the total moles of hydrocarbons sorbed into the fiber can be related to toxicity thresholds in target lipid of aquatic organisms (Hedgpeth et al, 2019).…”

Sublethal Effect Concentrations for Nonpolar Narcosis in the Zebrafish Embryo

“…In the present study, we looked at a broader range of organismal sublethal effects that can be plausibly linked to narcosis and are potentially more sensitive than the ones used in previous studies: general morphological malformations (Hedgpeth et al, 2019; Vignet et al, 2014), oxygen consumption (Raftery et al, 2017), heart rate (Incardona et al, 2004; Raftery et al, 2017), and swimming performance (Vignet et al, 2014). We exposed zebrafish embryos in an adapted fish embryo acute toxicity (FET) test, Organisation for Economic Co‐operation and Development (OECD) test guideline 236 (Organisation for Economic Co‐operation and Development, 2013) to 3 well‐known nonpolar NICs (phenanthrene [PHN], 1,3,5‐trichlorobenzene [TChB], and pentachlorobenzene [PChB]) with varying octanol–water partition coefficients (log K OW , describing lipophilicity, range 4.0–5.2).…”

“…Narcosis‐inducing chemicals (NICs) exert their toxicity by accumulating in the organism's lipid compartments and disrupting the molecular interactions in cellular membranes, resulting in depressed respiratory–cardiovascular activity, lethargy, loss of equilibrium, and, finally, death of the organism (Ankley et al, 2010; Geier et al, 2018; Incardona et al, 2004; McKim et al, 1987; Raftery et al, 2017; van Wezel & Opperhuizen, 1995). Exposure to NICs can be harmful to various aquatic species and may lead to a decrease in population fitness (Escher & Hermens, 2002; Hedgpeth et al, 2019). Mortality resulting from exposure to NICs has been well described and discussed for different aquatic organisms, and acute toxicity data have been extensively used to develop quantitative structure–activity relationship models that predict mortality for aquatic organisms based on the lipophilicity of chemicals (Adhikari & Mishra, 2018; Di Toro et al, 2000; Finizio et al, 2020; Klüver et al, 2016).…”

“…A better understanding of the nature and incidence of such sublethal effects following exposure to NICs would thus be valuable in a risk-assessment context. For example, Hedgpeth et al (2019) recently drew attention to the importance of sublethal effects caused by petroleum substances (anthropogenic or natural mixtures), exerting toxicity mainly through narcosis. These authors focused on overt developmental abnormalities that are easily observable in zebrafish embryos and showed that morphological malformations occurred at approximately 2.8 times lower exposure concentrations compared to lethal effect concentrations.…”