Wageningen Environmental Research, P.O. Box 47, 6700, AA Wageningen, the Netherlands; Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700, AA Wageningen, the Netherlands.
Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700, AA Wageningen, the Netherlands.
Chemosphere. 2024 Aug;361:142511. doi: 10.1016/j.chemosphere.2024.142511. Epub 2024 May 31.
Environmental ambient temperature significantly impacts the metabolic activities of aquatic ectotherm organisms and influences the fate of various chemicals. Although numerous studies have shown that the acute lethal toxicity of most chemicals increases with increasing temperature, the impact of temperature on chronic effects - encompassing both lethal and sublethal endpoints - has received limited attention. Furthermore, the mechanisms linking temperature and toxicity, potentially unveiled by toxicokinetic-toxicodynamic models (TKTD), remains inadequately explored. This study investigated the effects of environmentally relevant concentrations of the insecticide imidacloprid (IMI) on the growth and survival of the freshwater amphipod Gammarus pulex at two different temperatures. Our experimental design was tailored to fit a TKTD model, specifically the Dynamic Energy Budget (DEB) model. We conducted experiments spanning three and six months, utilizing small G. pulex juveniles. We observed effects endpoints at least five times, employing both destructive and non-destructive methods, crucial for accurate model fittings. Our findings reveal that IMI at environmental concentrations (up to 0.3 μg/L) affects the growth and survival of G. pulex, albeit with limited effects, showing a 10% inhibition compared to the control group. These limited effects, observed in both lethal and sublethal aspects, suggest a different mode of action at low, environmentally-relevant concentrations in long-term exposure (3 months), in contrast to previous studies which applied higher concentrations and found that sublethal effects occurred at significantly lower levels than lethal effects in an acute test setting (4 days). Moreover, after parameterizing the DEB model for various temperatures, we identified a lower threshold for both lethal and sublethal effects at higher temperatures, indicating increased intrinsic sensitivity. Overall, this study contributes to future risk assessments considering temperature as a crucial factor and exemplifies the integration of the DEB model into experimental design for comprehensive toxicity evaluations.
环境环境温度显著影响水生变温动物的代谢活动，并影响各种化学物质的命运。尽管许多研究表明，大多数化学物质的急性致死毒性随温度升高而增加，但温度对慢性影响（包括致死和亚致死终点）的影响受到的关注有限。此外，潜在的由毒代动力学-毒效动力学模型（TKTD）揭示的温度和毒性之间的机制尚未得到充分探索。本研究调查了环境相关浓度的杀虫剂吡虫啉（IMI）对两种不同温度下淡水片脚类动物沼虾（Gammarus pulex）生长和生存的影响。我们的实验设计适合 TKTD 模型，特别是动态能量预算（DEB）模型。我们进行了为期三个月和六个月的实验，使用小型 G. pulex 幼体。我们至少五次观察了效应终点，采用了破坏性和非破坏性方法，这对于准确的模型拟合至关重要。我们的研究结果表明，环境浓度（高达 0.3μg/L）的 IMI 会影响 G. pulex 的生长和生存，尽管影响有限，与对照组相比，抑制率为 10%。这些在致死和亚致死方面观察到的有限影响表明，在长期暴露（3 个月）中，在低浓度（环境相关浓度）下，作用方式不同，与之前应用更高浓度并发现亚致死效应在急性测试环境（4 天）中发生在显著低于致死效应的水平的研究不同。此外，在为不同温度参数化 DEB 模型后，我们确定了致死和亚致死效应的较低阈值在较高温度下，表明内在敏感性增加。总的来说，这项研究有助于在未来的风险评估中考虑温度作为一个关键因素，并例证了将 DEB 模型集成到实验设计中进行全面毒性评估。
