ISO 20666:2008规定了一种基于48小时内种群生长抑制测定对轮虫萼花臂尾轮虫慢性毒性的方法。 该方法适用于:a)在试验条件下可溶或可保持稳定悬浮液或分散液的化学物质；b)经处理或未经处理的工业或污水流出物，如果合适的话，在倾析、过滤或离心之后；c)淡水；d)水提取物。 ISO 20666:2008不适用于水中不稳定化学品（水解、吸收等）的检测，除非测量暴露浓度，也不适用于河口或海洋环境水生样品的检测。

ISO 20666:2008 specifies a method for the determination of the chronic toxicity to rotifer Brachionus calyciflorus, based on population growth inhibition in 48 h. The method is applicable to: a) chemical substances which are soluble or which can be maintained as stable suspensions or dispersions under the conditions of the test; b) industrial or sewage effluents, treated or untreated, if appropriate after decantation, filtration or centrifugation; c) fresh waters; d) aqueous extracts. ISO 20666:2008 is not applicable to the testing of unstable chemicals (hydrolysing, absorbing, etc.) in water unless exposure concentration is measured, nor to the testing of aquatic samples from the estuarine or marine environment.