Cowgill U M, Milazzo D P, Landenberger B D
Environment Toxicology and Chemistry Research Laboratory, Dow Chemical Company, Midland, Michigan 48674.
Arch Environ Contam Toxicol. 1990 Jul-Aug;19(4):513-7. doi: 10.1007/BF01059069.
The three brood Ceriodaphnia dubia test was carried out three nonconsecutive times, each period being separated by the previous one by three weeks. The toxicant studied was sodium lauryl sulfate (SLS) which bacterially degrades completely by the end of the third day of the test. The mean LC50 based on survival was 41 +/- 3.2 (CV = 7.8%) mg/L for day 3 through day 6. The mean EC50 based on progeny confirmed the LC50 and was 36 +/- 0.49 (CV = 1.4%) mg/L for the ultimate day of the test. The close reproducibility among successive tests is due in part to the use of pure SLS, the use of a mixed algal diet and in part to reducing handling to a minimum. Data failed to indicate any chronic effect exhibited by C. dubia populations since no statistically significant differences were noted between 48 hr (acute) and 144 hr values (chronic). Calculations of brood size for the first four broods clearly indicate a chronic effect of SLS on C. dubia by showing a progressively greater spread between the highest mean brood size and the lowest mean brood size as the brood number increases. It is suggested that calculations of this kind become part of the Ceriodaphnia test methodology so that any chronicity can be better identified.
对杜氏仙女溞进行了三次非连续的三代试验，每次试验间隔三周。所研究的毒物是十二烷基硫酸钠（SLS），在试验的第三天结束时可被细菌完全降解。基于存活情况的第3天至第6天的平均半数致死浓度（LC50）为41±3.2（变异系数=7.8%）mg/L。基于后代数量的平均半数效应浓度（EC50）证实了LC50，在试验的最后一天为36±0.49（变异系数=1.4%）mg/L。连续试验之间的高度可重复性部分归因于使用了纯SLS、混合藻类食物，以及将操作减少到最低限度。数据未能表明杜氏仙女溞种群表现出任何慢性效应，因为在48小时（急性）和144小时（慢性）的值之间未发现统计学上的显著差异。对前四代幼体数量的计算清楚地表明，随着幼体代数的增加，最高平均幼体数量和最低平均幼体数量之间的差距越来越大，这表明SLS对杜氏仙女溞有慢性影响。建议这种计算成为杜氏仙女溞试验方法的一部分，以便能更好地识别任何慢性影响。
