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Toxicity to microorganisms

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Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when the substance is introduced in appropriately low concentrations.

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No sufficiently reliable data are available for 1,1'-(methylimino)dipropan-2 -ol (CAS 4402 -30 -6); therefore, a weight-of-evidence approach including data from two structurally similar substances was performed to assess the toxicity to microorganisms.

In a short-term respiration inhibition test performed according to ISO 8192 B, activated sludge from a wwtp treating predominantly industrial wastewater was exposed to 1,1'-(methylimino)dipropan-2 -ol (CAS 4402 -30 -6) for 30 minutes. No inhibition of the respiration activity was observed. The 30 -min EC 20 was determined to be greater than 719 mg/L (nominal; BASF AG, 1987).

The structurally similar substance 1,1',1''-nitrilotripropan-2 -ol (CAS 122 -20 -3) was tested under similar conditions. The 30 -min EC20 was determined to be > 1995 mg/L (nominal; BASF AG, 1981). No inhibiting effect of the test substance on the respiration activity of the activated sludge was observed, instead the substance stimulated the respiration.

The other structurally similar substance 1,1'-iminodipropan-2 -ol (CAS 110 -97 -4) was also tested under similar conditions and gave a 30 -min EC20 of > 1995 mg/L (nominal; BASF AG, 1981). The effect of the substance on microorganisms was also tested according to German Industrial Standard DIN 38412, Part 8 (draft). In this growth inhibition test with Pseudomonas putida as test organism, a toxicity threshold concentration of 15000 mg/L after 17 h of exposure was determined (equivalent to EC3; nominal; BASF AG, 1988).

It can be concluded that the inhibition of the degradation activity of activated sludge is not anticipated when 1,1'-(methylimino)dipropan-2 -ol (CAS 4402 -30 -6) is introduced in appropriately low concentrations.