Re‐evaluation of target lipid model–derived HC5 predictions for hydrocarbons

McGrath, Joy A.; Fanelli, Christopher J.; Toro, Dominic M. Di; Parkerton, Thomas F.; Redman, Aaron D.; Paumen, Miriam Leόn; Comber, Mike; Eadsforth, C. V.; Haan, Klaas den

doi:10.1002/etc.4100

Cited by 65 publications

(105 citation statements)

References 46 publications

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“…3A. This procedure yielded an acute 4 d CTLBB estimate for Atlantic Cod of 42 μmol/g octanol, which falls within the range reported for other pelagic species (9 to 327 μmol/ g octanol, N = 79 species) based on acute effect endpoints for single hydrocarbons (McGrath et al, 2018). This value is a factor of two lower than the CTLBB of 81 μmol/g octanol derived from 5-d zebrafish Table 2 Survival and growth effects of Troll Oil on cod larvae.…”

Section: Estimating Ctlbb From Observed Toxicity and Predicted Tus Fosupporting

confidence: 74%

“…Organism specific CTLBBs for a defined endpoint are estimated by fitting the TLM to toxicity datasets for individual hydrocarbons or related substances. A compilation of CTLBBs for both acute and chronic in-vivo endpoints across different aquatic species is provided by McGrath et al (2018). The utility of using TUs (derived using this approach) to successfully describe toxicity of different oils and dosing methods across species has been demonstrated (Kang et al, 2014;Redman et al, 2016;Redman et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Modeling the toxicity of dissolved crude oil exposures to characterize the sensitivity of cod (Gadus morhua) larvae and role of individual and unresolved hydrocarbons

Hansen

Parkerton

Nordtug

et al. 2019

Marine Pollution Bulletin

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Toxicity of weathered oil was investigated using Atlantic cod (Gadus morhua) larvae. A novel exposure system was applied to differentiate effects associated with dissolved and droplet oil with and without dispersant. After a 4-day exposure and subsequent 4-day recovery period, survival and growth were determined. Analytical data characterizing test oil composition included polyaromatic hydrocarbons (PAH) based on GC/MS and unresolved hydrocarbon classes obtained by two-dimensional chromatography coupled with flame ionization detection was used as input to an oil solubility model to calculate toxic units (TUs) of dissolved PAHs and whole oil, respectively. Critical target lipid body burdens derived from modeling characterizing the sensitivity of effect endpoints investigated were consistent across treatments and within the range previously reported for pelagic species. Individually measured PAHs captured only 3-11% of the TUs associated with the whole oil highlighting the limitations of traditional total PAH exposure metrics for expressing oil toxicity data.

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Section: Estimating Ctlbb From Observed Toxicity and Predicted Tus Fosupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Modeling the toxicity of dissolved crude oil exposures to characterize the sensitivity of cod (Gadus morhua) larvae and role of individual and unresolved hydrocarbons

Hansen

Parkerton

Nordtug

et al. 2019

Marine Pollution Bulletin

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“…Several test species for which chronic data were available do not have established critical body burdens (CBB) within the TLM model framework. For these species, the mean value for the CBB TLM re‐evaluation (McGrath et al, ) was used (

\overset{CBB}{true}

= 70.8 mmol kg −1 ). For all species, the average ACR value (

\overset{ACR}{true}

= 5.22) was used.…”

Section: Resultsmentioning

confidence: 99%

“…):

{CE}_{i, j} = \frac{italicLC 50_{i, j}}{{italicACR}_{i}}

where CE i , j is the chronic effect predicted by the TLM (comparable to an NOEC or EC10) for organism “i” and chemical “j,” LC 50 i , j is the acute 50% effect level predicted in Eq. for chemical “j,” and ACR i is the acute to chronic ratio for organism “i.” While individual acute to chronic ratios can vary considerably between studies, an average value for each organism (for predicting chronic effects) or an overall average value E [ ACR i ] (for extrapolating down to HC5‐predicted effects levels) can be used (McGrath et al, ). It should be noted that predicted chronic effects levels (CE) do not correspond uniquely to a single chronic toxicological endpoint (i.e., NOEC, EC10) but are instead meant to be representative of either of these endpoints (McGrath et al, ).…”

Section: Methodsmentioning

confidence: 99%

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Biodegradation and Ecotoxicity of Branched Alcohol Ethoxylates: Application of the Target Lipid Model and Implications for Environmental Classification

Bragin

Davis

Kung

et al. 2019

J Surfact & Detergents

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With the advent of global regulations for safer detergent and an emphasis on a shift toward more environmentally friendly formulations, the environmental profile of surfactant chemistries have moved to the forefront of product formulation and design. The two cornerstones of surfactant environmental profiles are the ability to biodegrade in the natural environment and the ecological hazard profile. The objectives of this article are to describe biodegradation and aquatic toxicity data for a series of branched oxo‐alcohol ethoxylate (AEO) surfactants; to apply the target lipid model (TLM) for deriving model‐based threshold hazard concentrations (HC5) of AEO; and, finally, to accurately determine aquatic classifications for AEO surfactants for use in regulatory classification frameworks. Biodegradation results indicate a high level of biodegradability of branched AEO, with C8–C13‐rich oxo‐alcohols with 1–20 mol of ethoxylate meeting the readily biodegradable criteria. Results from acute and chronic toxicity tests indicated comparable or lesser aquatic toxicity versus linear AEO structures previously reported in the literature. The TLM model, applied a priori, resulted in good agreement with acute toxicity data (RMSE = 0.49) and is comparable to the root mean square errors (RMSE) previously determined for other narcotic chemicals (RMSE = 0.46–0.57). Model errors for invertebrates and fish were smaller than those for algae, with the TLM systematically overpredicting acute and chronic classification of two of seven branched AEO. Furthermore, TLM‐predicted HC5 values were determined to be sufficiently conservative, with 100% of observed chronic data (N = 79) falling above the HC5 threshold values, providing a useful tool for the risk assessment of AEO.

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Recommendations for Improving Methods and Models for Aquatic Hazard Assessment of Ionizable Organic Chemicals

Escher

Abagyan

Embry

et al. 2020

Enviro Toxic and Chemistry

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Ionizable organic chemicals (IOCs) such as organic acids and bases are an important substance class requiring aquatic hazard evaluation. Although the aquatic toxicity of IOCs is highly dependent on the water pH, many toxicity studies in the literature cannot be interpreted because pH was not reported or not kept constant during the experiment, calling for an adaptation and improvement of testing guidelines. The modulating influence of pH on toxicity is mainly caused by pHdependent uptake and bioaccumulation of IOCs, which can be described by ion-trapping and toxicokinetic models. The internal effect concentrations of IOCs were found to be independent of the external pH because of organisms' and cells' ability to maintain a stable internal pH milieu. If the external pH is close to the internal pH, existing quantitative structure-activity relationships (QSARs) for neutral organics can be adapted by substituting the octanol-water partition coefficient by the ionization-corrected liposome-water distribution ratio as the hydrophobicity descriptor, demonstrated by modification of the target lipid model. Charged, zwitterionic and neutral species of an IOC can all contribute to observed toxicity, either through concentration-additive mixture effects or by interaction of different species, as is the case for uncoupling of mitochondrial respiration. For specifically acting IOCs, we recommend a 2-step screening procedure with ion-trapping/QSAR models used to predict the baseline toxicity, followed by adjustment using the toxic ratio derived from in vitro systems. Receptor-or plasmabinding models also show promise for elucidating IOC toxicity. The present review is intended to help demystify the ecotoxicity of IOCs and provide recommendations for their hazard and risk assessment. Environ Toxicol Chem 2020;39:269-286. /ETC FIGURE 1: Speciation in relation to the pH and acid dissociation constant, pK a , for (A) monoprotic acids and (B) monoprotic bases. The experimentally accessible pH range is marked by blue (fish) and green (daphnia, algae) boxes. Further discussion on the experimentally accessible pH range is provided in the section Testing guidelines.

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Re‐evaluation of target lipid model–derived HC5 predictions for hydrocarbons

Cited by 65 publications

References 46 publications

Modeling the toxicity of dissolved crude oil exposures to characterize the sensitivity of cod (Gadus morhua) larvae and role of individual and unresolved hydrocarbons

Modeling the toxicity of dissolved crude oil exposures to characterize the sensitivity of cod (Gadus morhua) larvae and role of individual and unresolved hydrocarbons

Biodegradation and Ecotoxicity of Branched Alcohol Ethoxylates: Application of the Target Lipid Model and Implications for Environmental Classification

Recommendations for Improving Methods and Models for Aquatic Hazard Assessment of Ionizable Organic Chemicals

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