The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd, Brisbane, Qld 4108, Australia.
Sci Total Environ. 2011 Nov 15;409(24):5268-76. doi: 10.1016/j.scitotenv.2011.08.056. Epub 2011 Oct 1.
Persistent organic pollutants (POPs) are persistent, toxic and bioaccumulative anthropogenic organic chemicals, capable of undergoing long range environmental transport to remote areas including the Antarctic. p,p'-dichlorodiphenyl dichloroethylene (p,p'-DDE) has been identified as a dominant POP accumulating in Antarctic krill (Euphausia superba), which is a key Southern Ocean species. This study examined the developmental toxicity of p,p'-DDE via aqueous exposure to Antarctic krill larvae. p,p'-DDE exposure was found to stimulate developmental timing in the first three larval stages of Antarctic krill, while extended monitoring of larvae after a five day exposure period had ended, revealed delayed inhibitory responses during development to the fourth larval stage. Stimulatory responses were observed from the lowest p,p'-DDE body residue tested of 10.1±3.0 μmol/kg (3.2±0.95 mg/kg) preserved wet weight, which is comparable to findings for temperate species and an order of magnitude lower than the exposure level found to cause sublethal behavioural effects in Antarctic krill. The delayed responses included increased mortality, which had doubled in the highest p,p'-DDE treatment (95±8.9% mortality at 20 μg/L p,p'-DDE) compared to the solvent control (44±11% mortality) 2 weeks after end of exposure. Development of surviving metanauplius larvae to calyptopis 1 larvae was delayed by 2 days in p,p'-DDE exposed larvae compared with untreated larvae. Finally, the developmental success of surviving p,p'-DDE exposed larvae was reduced by 50 to 75% compared to the solvent control (100% developmental success). The lowest observed effect concentration for all delayed effects was 1 μg/L, the lowest exposure concentration tested. These findings demonstrate the importance of delayed and indirect effects of toxicant exposure. Further, the findings of this study are important for environmental risk assessment of POPs in the Southern Ocean ecosystem and strongly highlight the significance of developmental endpoints for ecotoxicological testing.
持久性有机污染物（POPs）是持久性、毒性和生物累积性的人为有机化学品，能够进行长距离环境传输，到达包括南极在内的偏远地区。p,p'-二氯二苯二氯乙烯（p,p'-DDE）已被确定为在南极磷虾（Euphausia superba）中积累的主要 POP，南极磷虾是南大洋的关键物种。本研究通过对南极磷虾幼虫的水暴露来研究 p,p'-DDE 的发育毒性。研究发现，p,p'-DDE 暴露会刺激南极磷虾前三个幼虫阶段的发育时间，而在为期五天的暴露期结束后对幼虫进行的扩展监测显示，在第四幼虫阶段的发育过程中出现了延迟的抑制反应。在测试的最低 p,p'-DDE 体残留物 10.1±3.0 μmol/kg（3.2±0.95 mg/kg）湿重时观察到刺激反应，这与温带物种的发现相当，比在南极磷虾中发现的引起亚致死行为效应的暴露水平低一个数量级。延迟反应包括死亡率增加，在最高 p,p'-DDE 处理（20μg/L p,p'-DDE 时 95±8.9%死亡率）中与溶剂对照（暴露结束后 2 周时 44±11%死亡率）相比增加了一倍。与未处理的幼虫相比，暴露于 p,p'-DDE 的幼虫发育到 calyptopis 1 幼虫的时间延迟了两天。最后，与溶剂对照相比（100%发育成功率），幸存的 p,p'-DDE 暴露幼虫的发育成功率降低了 50%至 75%。所有延迟效应的最低观察到的效应浓度为 1μg/L，是测试的最低暴露浓度。这些发现表明了有毒物质暴露的延迟和间接效应的重要性。此外，本研究的发现对于评估南大洋生态系统中 POP 的环境风险非常重要，并强烈强调了发育终点在生态毒理学测试中的重要性。
