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Short-term toxicity to aquatic invertebrates

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Description of key information

The acute toxicity of N-(1,3-dimethylbutyl)-N'-phenylbenzene-1,4-diamine to invertebrates (Dapnia magna) was conducted under Flow-through immobilisation test according OECD Guideline 202. After 48 hours of exposure an EC50 of 0.23 mg/L (measured) is obtained (MITI, Ed. by CITI, 
Ministry of International Trade & Industry Japan, 1999). A lower effect value is known from the secondary hydrolysis product p-hydroquinone which was used as a key value.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.13 mg/L

Additional information

Short-term tests have been performed with 6PPD as well as with other similar PPDs yielding EC50-values in the range of 0.2 to 1.7 mg/L. The result of the study performed with 4-HDPA (0.69 mg/L) is within this range.

N-(1,3-dimethylbutyl)-N'-phenylbenzene-1,4-diamine (6PPD) is hydrolytically unstable at pH 7 and 4-hydroxydiphenylamine (CAS 122-37-2) was identified as the most sensitive (secondary) hydrolysis product.

The lowest effect value in acute tests was found for p-Hydroquinone (0.13 mg/L) which is close to the values for the PPDs (0.2 to 1.9 mg/L) and 4-HDPA (0.69 mg/L).Although p-Hydroquinone is a secondary hydrolysis product of 6PPD, it was chosen as a source of key value as it shows the lowest effect concentrations of all PPDs and their degradation products and therefore represents the worst case.

For 4-HDPA and, N-Phenylbenzoquinone-imine calculated values are available. These calculated values should only be used only for a rough estimation due to the high uncertainty of the method. However they show a trend: The effect values of these three intermediate compounds to daphnids are at a higher level and there is no sign for a higher toxicity than found for the PPDs or any of their degradation products.