RSMAS, University of Miami, Miami, FL 33149, United States.
Aquat Toxicol. 2013 Mar 15;128-129:60-6. doi: 10.1016/j.aquatox.2012.11.020. Epub 2012 Dec 7.
The freshwater pulmonate snail, Lymnaea stagnalis, is the most sensitive freshwater organism tested to date for several metals (Co, Cu, Pb, Ni) based on 28 d early life-stage (ELS) tests in which growth was the most sensitive endpoint. The United States Environmental Protection Agency (USEPA) has expressed concern that growth in 28 d ELS tests with mollusks may overpredict toxicity because of the potential for recovery in a full life-cycle (LC) test. Consequently, the USEPA only accepts the survival endpoint for these tests in establishing water quality criteria (WQC). To address this concern, the current study aimed to test the sensitivity of L. stagnalis to Pb in a 56 d full LC test evaluating survival, growth, reproductive and embryonic growth endpoints and compare the estimated effect levels to those established using the 28 d ELS test design. The most sensitive endpoints in this study were 28 d growth and 56 d egg mass production, both with a NOEC of <1.0 μg L(-1) and a LOEC of 1.0 μg L(-1), showing that the ELS growth endpoint is predictive of the 56 d reproduction endpoint. Snails exposed to 1.0 and 2.7 μg L(-1) Pb showed full and partial recovery from growth inhibition between 28 and 56 d. While this recovery supports the USEPA's concern about the 28 d growth endpoint; considering the reproductive lifespan of L. stagnalis and the recovery dose-response, we conclude that the 28 d growth endpoint will be within a factor of 3 of full LC endpoints. This is consistent with the level of precision previously determined for fish ELS tests, which the USEPA accepts for WQC derivation, and suggests that tests using 28 d ELS growth endpoint for L. stagnalis may be acceptable for inclusion in WQC derivation.
淡水圆田螺是迄今为止对几种金属（钴、铜、铅、镍）最敏感的淡水生物，其基于 28 天早期生命阶段（ELS）测试，在这些测试中，生长是最敏感的终点。美国环境保护署（USEPA）表示关注，由于在全生命周期（LC）测试中可能会恢复，因此 28 天 ELS 测试中贝类的生长可能会过高预测毒性。因此，USEPA 仅在制定水质标准（WQC）时接受这些测试的生存终点。为了解决这一问题，本研究旨在使用 56 天全 LC 测试评估存活、生长、繁殖和胚胎生长终点，测试 Lymnaea stagnalis 对 Pb 的敏感性，并将估计的效应水平与使用 28 天 ELS 测试设计建立的水平进行比较。本研究中最敏感的终点是 28 天生长和 56 天卵质量产生，两者的无观测效应浓度（NOEC）均<1.0μg/L，且 10%效应浓度（LOEC）均为 1.0μg/L，表明 ELS 生长终点可预测 56 天繁殖终点。暴露于 1.0 和 2.7μg/L Pb 的蜗牛在 28 天至 56 天之间从生长抑制中完全和部分恢复。虽然这种恢复支持了 USEPA 对 28 天生长终点的担忧；但考虑到 Lymnaea stagnalis 的繁殖寿命和恢复剂量反应，我们得出结论，28 天生长终点将与全 LC 终点相差 3 倍以内。这与 USEPA 接受用于 WQC 推导的鱼类 ELS 测试之前确定的精度水平一致，并表明使用 28 天 ELS 生长终点的 Lymnaea stagnalis 测试可能可被接受用于 WQC 推导。
