1,2-dichloroethane

Toxicity to microorganisms

Description of key information

Single micro-organism
In a cell multiplication inhibition test the toxicity threshold for the model organism Pseudomonas putida for 1,2-dichloroethane was determined to be 135 mg/L.
Activated sludge
Based on the results of the key study the IC50 of 1,2-dichloroethane on activated sludge is 2.78 g/L.

Key value for chemical safety assessment

EC50 for microorganisms:

2 780 mg/L

EC10 or NOEC for microorganisms:

135 mg/L

Additional information

Single micro-organism

In a cell multiplication inhibition test (Bringman & Kuehn, 1976) the toxicity threshold for the model organism Pseudomonas putida for 1,2-dichloroethane was determined to be 135 mg/L. This study was designed to determine the effect of 1,2-dichloroethane on micro-organisms in aequous solution by measuring the inhibition of cell growth after exposure of 16 h. The study was taken as key study, as it was the best documented study, therefore it was considered as most reliable study.

Activated sludge

The key study for a multi-species inhibition test ( Tang, Blum & Speece, 1990) was designed to determine the effects of 1,2-dichloroethane on sewage sludge micro-organisms by measuring the respiration rate after exposure to the test substance after a 3 h contact time. Two protocols were assayed: the regular OECD 209 and a serum bottle, aimed to prevent losses of volatiles. Based on the results of this study the IC50 of 1,2-dichloroethane on activated sludge is 35.5 g/L in the regular test and 2.78 g/L in the serum bottle design. The study is selected as the key study for microbial multispecies toxicity.

According to the Guidance (R.7.8.18), "In case of multiple microbial inhibition data, the PNECstp is usually derived from results obtained for the most sensitive test system available, regardless of whether this is a test with activated sludge, relevant single bacterial spicies or ciliated protozoa". Consequently, the study on Pseudomonas putida NOEC = 135 mg/L should normally be used to determine the PNECstp. However, table R.10 -6 in Guidance recommends to use Bringmann & Kuehn data only if no other test is available (it is known that volatile substances were not properly addressed by their test procedure). Finally, the IC50 = 2.78 g/L will be used for PNECstp derivation.

 

Following additional information on toxicity to microorganism is available:

 

 

Species	EC50	Author
Phaenobacterium phospherum	158 mg/L (5 min)	Qureshi, A.A. (1982)
Phaenobacterium phospherum	1000 mg/L (15 min)	Hermens, J. et al. (1985)
Pseudomonas putida	5300 mg/L TT (30 min)	Niemitz, W. & Trenel, J. (1979)
Pseudomonas putida	583 mg/L EC10 (30 min)	Trenel, J. & Kuehn, R. (1982)
Entosiphion sulcatum	1127 mg/L TT	Bringmann, G. & Kuehn, R. (1980)
laboratory sewage sludge	50 mg/L (4 d)	Stuckey,et al.(1980)

 

Reference list

 

Bringmann, G. & Kuehn, R. (1980): Water Research 14, 231 - 241.

Hermens, J. et al. (1985): Ecotoxicol. Environ. Safety 9, 17-25.

Niemitz, W. & Trenel, J. (1979): Inst.Wasser-, Boden-, Lufthyg. Bundesgesundheitsamt, Berlin, 1 - 10.

Qureshi, A.A. et al. (1982): ASTM Spec. Techn. Publ. 766,|179 - 195.

Stuckey,et al.(1980): J. Water Pollut. Control Fed. 52, 720 - 729.

Trenel, J. & Kuehn, R. (1982): Inst. Wasser-, Boden-, Lufthyg. Bundesgesundheitsamt, Juli 1982, 12 - 14, 25 - 27, Anlage 2 (23 - 28), Anlage 4 (1 - 5).