Can short-term data accurately model long-term environmental exposures? Investigating the multigenerational adaptation potential of Daphnia magna to environmental concentrations of organic ultraviolet filters

Organic ultraviolet filters (UVFs) are contaminants of concern, ubiquitously found in many aquatic environments due to their use in personal care products to protect against ultraviolet radiation. Research regarding the toxicity of UVFs such as avobenzone, octocrylene and oxybenzone indicates that these chemicals may pose a threat to invertebrate species; however, minimal long-term studies have been conducted to determine how these UVFs may affect continuously exposed populations. The present study modeled the effects of a 5-generation exposure of Daphnia magna to these UVFs at environmental concentrations. Avobenzone and octocrylene resulted in minor, transient decreases in reproduction and wet mass. Oxybenzone exposure resulted in > 40% mortality, 46% decreased reproduction and 4-fold greater reproductive failure over the F0 and F1 generations; however, normal function was largely regained by the F2 generation. These results indicate that Daphnia are able to acclimate over long-term exposures to concentrations of 6.59 μg/L avobenzone, ~0.6 μg/L octocrylene or 16.5 μg/L oxybenzone. This suggests that short-term studies indicating high toxicity may not accurately represent long-term outcomes in wild populations, adding additional complexity to risk assessment practices at a time when many regions are considering or implementing UVF bans in order to protect these most sensitive invertebrate species.

有机紫外过滤剂（UVFs）是备受关注的污染物，由于被用于个人护理产品以抵御紫外线辐射，它们广泛存在于各类水生环境中。针对阿伏苯宗（avobenzone）、奥克立林（octocrylene）和羟苯酮（oxybenzone）等UVFs的毒性研究显示，此类化学品可能对无脊椎动物类群构成威胁，但目前针对这类UVFs如何影响持续暴露种群的长期研究仍十分有限。本研究以环境浓度下的上述UVFs对大型溞（Daphnia magna）开展5代暴露实验，并构建了相应的效应模型。结果表明，阿伏苯宗与奥克立林仅会导致繁殖率与湿重出现轻微且短暂的下降；羟苯酮暴露则会在F0及F1代造成超过40%的死亡率、46%的繁殖率下降，以及4倍之多的繁殖失败率，但F2代基本恢复了正常生理功能。上述结果显示，大型溞可在长期暴露于6.59 μg/L阿伏苯宗、约0.6 μg/L奥克立林或16.5 μg/L羟苯酮的环境中产生适应性。这意味着，显示出高毒性的短期研究或许无法准确反映野生种群的长期效应，在诸多地区正考虑或推行UVFs禁令以保护这类敏感无脊椎动物的当下，这一发现为风险评估实践增添了额外的复杂性。