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Toxicity to microorganisms

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Description of key information

The inhibition of the degradation activity of activated sludge in a STP is not anticipated when introduced in appropriate low concentrations.

Key value for chemical safety assessment

Additional information

No experimental data are available for 4,4'-diamino-3,3',5,5'-tetramethyldicyclohexylmethane (CAS 65962 -4 -50). Therefore a read across approach to structurally similar substances was made to assess the toxicity to microorganisms. The selected substances were 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) (CAS 6864 -37 -5) and 4,4'-methylenebis(cyclohexylamine) (CAS 1761 -71 -3).

As key study a short-term respiration inhibition test on the analogous substance 4,4 -methylenebis[2 -methyl-]cyclohexanamine (CAS 6864 -37 -5) according to ISO 8192 with domestic activated sludge was identified (BASF 1990).The 30 -min EC20 was determined to be 160 mg/L.

The following results support this finding:

- CAS 6864 -37 -5: BASF AG (1987). Report no. 9/0787/87. DIN 38412, part 8 (P. putida, growth inhibition): 17 -h EC50 = 96 mg/L (nominal)

- CAS 1761 -71 -3: BASF AG (1987). Report no. 87/0792. DIN 38412, part 27 (draft; P. putida respiration inhibition): 30 -min EC0 = 80 mg/L (nominal)

- CAS 1761 -71 -3: BASF AG (1986). Report no. 01.114/86. ISO 8192 (industrial act. sludge, respiration inhibition): 30 -min EC20 > 1000 mg/L; 180 -min EC20 < 100 mg/L (nominal)