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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The substance has a BOD5/ThOD ratio of 0.50, and is therefore considered to be readily degradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The BOD5 (non-adapted), BOD5 (adapted) and COD of the substance were reported by Bridié et al. (1979) to be 1.19 g O2/g, 1.72 g O2/g and 2.23 g O2/g, respectively.  The BOD test was conducted in accordance with the standard dilution method (APHA "Standard Methods" No. 219 (1971)) at 20 ± 1ºC for a period of 5 days. The only deviation from the APHA standard was the addition of 0.5 mg/l allylthiourea in each test to prevent nitrification. 500 ml test solutions were seeded with a filtered 10 ml volume of the effluent from a biological sanitary waste treatment plant. The authors reported that in some cases an adapted seed was prepared and used, although in no case was inducement of adaptation tried exhaustively. Duplicate tests were run on a mixture of glucose and glutamic acid, as recommended in the APHA method, as a means of checking the activity of the inoculum. The COD test was conducted in accordance with the standard potassium dichromate method described in ASTM D 1252 -97 (reapproved 1974). The BOD5/COD ratios from these results are 0.53 (non-adapted) and 0.77 (adapted). As indicated in the REACH Endpoint Specific Guidance section R.7.9.5.1; where no other measured degradability data are available,BOD5 datacan be used for classification purposes, but where the chemical structure is known, a calculated theoretical oxygen demand (ThOD) value should be used instead of the COD. According to Annex IV of OECD 301, the ThOD of this substance can be calculated to be 2.40 g O2/g, which gives BOD5/ThOD ratios of 0.50 (non-adapted) and 0.72 (adapted). The value for non-adapted seed equals 0.5, at which level or above a substance can be considered to be readily degradable.