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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

No test results according to standards are available but the biodegradability of 1,2-dichloroethane was assessed according to a variety of test designs in aerobic and anaerobic conditions. It was concluded in SIAR 521002: "it could be shown that the material is not biodegradable when non-adapted, non-acclimated conditions were used. In contrast biodegradation occurred when adapted or induced micro-organisms were used. Under (aerobic) conditions biodegradation of 1,2-dichloroethane is too slow to be an important environmental fate process".

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, fulfilling specific criteria

Additional information

Different investigations have been undertaken to study the biodegradability of 1,2-dichloroethane. However, there are no standardized screening studies on ready or inherently biodegradation available. In the various non-guideline studies which were mostly conducted according to generally acceptable principles it could be shown that the material is not biodegradable when non-adapted, non-acclimated conditions were used. In contrast biodegradation occurred when adapted or induced micro-organisms were used. However, under environmental conditions ready biodegradation is not likely to occur. Under aerobic conditions biodegradation of 1,2-dichloroethane is too slow to be an important environmental fate process.

 

The key study is in line with this assumption. The biodegradability of 1,2-dichloroethane was assessed over a 30-day period by mixed bacterial culture growing on methane. The nominal test concentration was 200 - 300 µg/L. The degradation after 30 days was higher than 90 %. These results indicate that, 1,2-dichloroethane can be regarded as biodegradable under test conditions. However, the low concentration tested indicates that degradation of 1,2-dichloroethane is too slow to be an important environmental fate process.

 

Further on, the following additional information on biodegradation in water is available:

 

Test System

Result

Author

Activated sludge

Little or no biodegradation in aerobic systems

No degradation in an acclimated anaerobic system after 4 months

HSDB literature search

Standard procedures for water and waste water examination

Determination of COD: DCE is only minimally oxidisable.

Janicke, W. (1983)

Laboratory investigation under anaerobic conditions

No degradation after 7 days

Wilson, J.T.et al.(1983)

Aerobic fixed bed bioreactor

DCE is enzymatically degraded by strain DE 2

Stucki, G.et al.(1983

Batch Experiment

Under methanogenic conditions 63 % of the initial amount of DCE were transformed

Bouwer, E.J. & McCarthy, P.L. (1983)

Biodegradation with inoculum gained from groundwater

95 % degradation after 35 days

Stucki, G.et al.(1992)

Pseudomonas fluorescens (adapted conditions)

Degradation of 100 µg dichloroethane/ml to 10 µg/ml within 24 h.

Vandenbergh, P.A. & Kunka, B.S. (1988)

BOD

Biodegradability (% Bio-Oxidation) in synthetic salt water:

15 % after 20 days

Price, K.S.et al.(1974)

Bacteria isolated from subsurface sediment

73 % degradation of 18-23 µg/L after 21 days

Phelps, T.J.et al.(1991)

flask-screening procedure according to Bunch and Chambers (modified)

After stepwise adaptation degradation of 63 and 53 % was observed after 28 days with 1,2-dichloroethane concentrations of 5 and 10 mg/l, respectively.

Tabak, H.H.et al.(1981)

 

 

Reference list

 

Bouwer, E.J., McCarty, P.L. (1983): Appl. Environ. Microbiol. 45, 1286 - 1294.

HSDB literature search on 1,2-dichloroethane, on-line via STN.

Janicke, W. (1983): WaBoLu Ber. 1, 3, 5, 7 - 26, 30 - 31, 36.

Phelps, T.J.et al.(1991): Environ. Sci. Technol. 25, 1461 - 1465.

Price, K.S., Waggy, G.T. & Conway, R.A. (1974): Brine shrimp bioassay and seawater BOD of petrochemicals; J. Water Pollut. Control. Fed. 46, 63-77.

Stucki, G., Krebser, U. and Leisinger T. (1983): Bacterial growth on 1,2-dichloroethane; Experientia 39, 1271-1273.

Stucki, G.et al.(1992): Water Res. 26, 273 - 278.

Tabak, H.H.et al.(1981) J. Water Pollut. Control Fed. 53, 1503-1518.

Vandenbergh, P.A., Kunka, B.S. (1988): Appl. Environ. Microbiol. 54, 2578 - 2579.

Wilson J.T.et al.(1983), Ground Water, 21(2), 134-42.