Modeling Time‐Dependent Aquatic Toxicity of Hydrocarbons: Role of Organism Weight, Temperature, and Substance Hydrophobicity

Abstract

Oil spill exposures are highly dynamic and are not comparable to laboratory exposures used in standard toxicity tests. Toxicokinetic-toxicodynamic (TKTD) models allow translation of effects observed in the laboratory to the field. To improve TKTD model calibration, new and previously published data from 148 tests were analyzed to estimate rates characterizing the time course of toxicity for 10 fish and 42 invertebrate species across 37 hydrocarbons. A key parameter in the TKTD model is the first-order rate that incorporates passive elimination, biotransformation, and damage repair processes. The results indicated that temperature (4-26 °C), organism size (0.0001-10 g), and substance log octanol-water partition coefficient (2-6) had limited influence on this parameter, which exhibited a 5th to 95th percentile range of 0.2-2.5 day −1 (median 0.7 day −1 ). A species sensitivity distribution approach is proposed to quantify the variability of this parameter across taxa, with further studies needed for aliphatic hydrocarbons and plant species. Study findings allow existing oil spill models to be refined to improve effect predictions.

Changes in Temperature Alter the Toxicity of Polycyclic Aromatic Compounds to American Lobster (Homarus americanus) Larvae

“…These results with whole‐oil exposure suggested that the single PAC results of our study also apply to complex PAC mixtures (Scovil et al, 2023), but our results highlight that not all PACs exhibit a predictable change in toxicity with temperature. We did find that PACs with higher log K OW values (>4) were more likely to exhibit an effect at higher test temperatures, while differences in toxicity between temperatures for lower log K OW (<4) PACs were apparent in the short term (e.g., 3–12 h of exposure), which was generally resolved within 48 h, as was also observed in Redman et al (2022). The temperatures tested in Scovil et al (2023) and the present study are within the optimal range of larval lobster performance described by Quinn (2017) of 8 to 20 °C, and it is probable that at temperatures outside this optimal range, but within the critical temperature limits (4 and 26 °C), there may be other physiological processes that could exacerbate exposure to PACs (Quinn, 2017).…”

“…Similarly, with the phenanthrene, exposure effects were first observed at the higher temperature after 2.25 h of exposure, whereas it took 24 h of exposure (note that there were no assessments between 4.25 and 24 h) for the responses at the two temperatures to become equal. Redman et al (2022) concluded that temperature has only a minor influence on modulating toxicity, specifically on the elimination rate, but there can be differences in the rate at which effects are observable in the short term (Redman et al, 2022). A study with a conventional heavy crude oil found that larval American lobster exposed for 24 h to the highest dilution of WAF at 15 °C exhibited significantly more mortality than those exposed at 12 and 9 °C (Scovil et al, 2023).…”

“…Previous work on 15 marine copepod species found that higher temperatures, which are typically found in summer, led to increased sensitivity to water‐accommodated fractions (WAFs) of crude oil (Jiang et al, 2012). In a study by Redman et al (2022), rainbow trout ( Oncorhynchus mykiss ), daphnids ( Daphnia magna ), and blackworm ( Lumbriculus variegatus ) were exposed under flow‐through conditions to 2‐methylnaphthalene at 10 and 18 °C. By conducting their experiments within similar time frames, with the same test methods, they were able to focus on the role of test temperature and determined that it had limited influence on the overall toxicokinetics and toxicodynamics.…”

Temperate Versus Arctic: Unraveling the Effects of Temperature on Oil Toxicity in Gammarids

“…A larger body weight implies a longer time needed before a critical oil mass has partitioned into the cell membranes to reach the CBR and produce narcotic effects. Still, in a recent modeling study, only a limited influence of body weight (or size) on the final hydrocarbon concentrations in organisms was found; however, it should be noted that this conclusion was drawn based on pooled data from different literature sources (Redman et al, 2022).…”

“…A toxic effect level is reached when internal concentrations exceed the CBR. In the case of a general acutely toxic, narcotic effect, the concentration of organic contaminants within the lipid bilayer of the cell membranes of an organism exceeds a certain molar threshold concentration (Redman et al, 2022; van Wezel & Opperhuizen, 1995). Petroleum hydrocarbons generally exert such a nonpolar narcotic mode of action (De Laender et al, 2011).…”