Dimethyl(propyl)amine

Toxicity to microorganisms

Description of key information

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

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

73 mg/L

Additional information

To assess the toxicity of dimethylpropylamine (CAS 926-63-6) to microorganisms, experimental data from the target substance as well as from two structurally analogous substances are used.

The key study is a growth inhibition test according to Bringmann-Kuehn with Pseudomonas putida, conducted with the structurally similar substance dimethylethylamine (CAS 598-56-1) by BASF AG (1988, report no. 9/0015/88). The 17-h EC10 was determined to be 73 mg/L; the 17-h EC50 was 100 mg/L. This value was used for deriviation of PNEC STP sinceit is the most sensitive value among the eligible studies of this approach.

 The key study is supported by a ready biodegradability test performed with dimethyl(propyl)amine (CAS 926-63-6) according to OECD 310 using non-adapted activated sludge from a wwtp treating predominantly domestic sewage. The test concentration was 29 mg/L. The substance was assessed to be readily biodegradable (78% after 28 d). The inhibition control containing aniline as reference substance and the test substance itself, showed no inhibiting effect of the test substance regarding the degradation rate of 77% after 28 d. A 28-d NOEC can be derived to be greater than or equal to 29 mg/L (BASF SE, 2012; report no. 27G0302/10G091). 

 For the structural analogue dimethyl-n-butylamine (CAS 927-62-8), a supporting growth inhibition test according to DIN 38412 (Pseudomonas putida) is available (BASF AG 1991, report no. 1/91/0974/70/1). The EC values determined were 292 mg/L (EC10) and 480 mg/L (EC50), respectively. These results apply to not neutralised pH conditions. After neutralisation, dimethyl-n-butylamine (CAS 927-62-8) did not inhibit growth at a concentration of 1000 mg/L.

There are further experimental data on the read-across substance triethylamine (CAS 121-44-8) from a study according to DIN 38412-8. However, considering molecular structure with regard to the length of the alkyl chain, the test substance dimethyl(propyl)amine (CAS 926-63-6) is to be settled between the read-across substances N,N-dimethyl-ethylamine (CAS 598-56-1) and N,N-dimethyl-n-butylamine (CAS 927-62-8). Substances of similar molecular structure show a tendency to increase toxicity in correlation to the length of attached alkyl-chains. The assessment is based on this trend and, therefore, on the available data of N,N-dimethyl-ethylamine (CAS 598-56-1) and N,N-dimethyl-n-butylamine (CAS 927-62-8) representing the structurally most similar analogues. The assessment of classification and labelling according to DSD - DPD and GHS-EU is thereby not affected.

 Based on the results from mentioned analogous test substances N,N-dimethyl-ethylamine (CAS 598-56-1) and N,N-dimethyl-n-butylamine (CAS 927-62-8) and supported with available data from the target substance, it can be concluded that inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriate low concentrations.