Phenol, sulfonated

Biodegradation in water: screening tests

Description of key information

Not readily biodegradable.

Key value for chemical safety assessment

Type of water:

freshwater

Additional information

The ready biodegradability of Phenol sulphonated (EC: 277-962-5; CAS: 74665-14-8) sold under the commercial name SELLATAN P was determined in a closed bottle test in accordance with OECD 301D at a concentration of 3 mg/L in mineral medium inoculated with secondary effluent from a treatment plant (1 mL/L). Sodium benzoate was used as a reference substance to check the validity of the method. Mineral medium with inoculum (1 mL/L) without test item and reference substance served as an inoculum blank/test blank. Separate test solutions were maintained in parallel (in duplicate) for test, reference, and control samples for observation on day 0, 7, 14, 21, and 28.
During the experiment, the residual concentration of oxygen in test bottles on day 28 was 6.52 mg/L (guideline limit >0.5 mg/L at all times). The depletion of dissolved oxygen in the blank control sample on day 28 was 0.84 (guideline limit ≤ 1.5 mg/L), respectively. The maximum degradation of the test item was 24.76% on day 28.
The per cent degradation in the toxicity control was greater than 25% after 14 days.

The biological degradation of the test item with time is given in the below table:

Treatment	% Degradation (Based on ThOD) on day
	7	14	21	28
Procedure Control	54.80	70.65	83.25	91.24
Test solution	2.62	7.24	16.39	24.76
Toxicity Control	53.34	66.80	-	-

The ThOD value for the test and reference item was 1.147 mg O2/mg and 1.666 mg O2/mg, respectively.
The percentage of biodegradation of the test item in test solution and toxicity control, revealed that the test
item was not readily biodegradable and not inhibitory to microbial activity in the inoculum.