Ready biodegradability is a key property for studying the environmental and ecological risks posed by chemicals, and a reference substance is used to check the reliability of the test results. Traditional reference substances such as aniline, sodium benzoate, and ammonium acetate rapidly degrade even in test systems without inoculum. In this study, 4‐isopropylphenol was investigated as a reference candidate. Aerobic biodegradation of 4‐isopropylphenol was studied using different methods, and repeatability tests were performed in multiple laboratories. 4‐Isopropylphenol met the ready biodegradability passing level in a closed bottle test (OECD 301D) and manometric respirometry test (OECD 301F). No obvious toxicity was found in activated sludge respiration inhibition and biodegradable toxicity control tests. The results of 301F tests performed in 15 Chinese laboratories were compared using statistical robustness analyses and Z‐scores. The robust average 28‐d biodegradability rate for 4‐isopropylphenol was 80.3%, and the relative standard deviation was 9.20%. The data from the 15 laboratories consistently indicated that 4‐isopropylphenol was readily biodegradable, except for an “unsatisfactory” outlier result from 1 laboratory. The degradation kinetics of 4‐isopropylphenol were derived from a logistic model, which had a good fit for the degradation curve. The biodegradation lag phase was 2.3 d (range 2–5 d), and the pass level was attained at 6.5 d on average (range 2–9 d), which met the 10‐d window requirement. The biodegradation rate at 28 d was 75.3% (range 64.0%–95.1%). The ready biodegradability of 4‐isopropylphenol indicates that it will be more appropriate as a reference chemical than other reference compounds used for investigating the biodegradability of chemicals. Integr Environ Assess Manag 2021;17:562–572. © 2020 SETAC

中文翻译：

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在不同实验室中对4-异丙基苯酚进行现成的生物降解性环测试，可对可生物降解的参考物质进行关键评估

易生物降解性是研究化学物质造成的环境和生态风险的关键属性，并且参考物质用于检查测试结果的可靠性。传统的参考物质，例如苯胺，苯甲酸钠和乙酸铵，即使在没有接种物的测试系统中也会迅速降解。在本研究中，对4-异丙基苯酚作为参考候选物进行了研究。使用不同的方法研究了4-异丙基苯酚的好氧生物降解，并在多个实验室中进行了重复性测试。4-异丙基苯酚在密闭瓶测试（OECD 301D）和测压呼吸法测试（OECD 301F）中均已达到可生物降解的合格水平。在活性污泥呼吸抑制和可生物降解的毒性控制试验中未发现明显的毒性。ž分数。4-异丙基苯酚的稳健的28 d平均生物降解率为80.3％，相对标准偏差为9.20％。来自15个实验室的数据一致表明，4-异丙基苯酚易于生物降解，除了1个实验室的“异常令人满意”的异常结果。4-异丙基苯酚的降解动力学来自对数模型，该模型非常适合降解曲线。生物降解滞后阶段为2.3 d（范围为2到5 d），通过水平平均为6.5 d（范围为2到9 d），满足10 d窗口要求。28 d时的生物降解率为75.3％（范围64.0％–95.1％）。整合环境评估管理2021; 17：562-572。分级为4 +©2020 SETAC