Registration Dossier
Registration Dossier
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EC number: 203-402-6 | CAS number: 106-48-9
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
4-chlorophenol can be judged inherently ultimately biodegradable.
Key value for chemical safety assessment
- Biodegradation in water:
- inherently biodegradable
Additional information
One study and two publications investigating the biodegradability of 4-chlorophenol (CAS No. 106-48-9) are available and are used in a "weight-of-evidence approach" to assess the biodegradability of the test substance.
The available study assessed the ready biodegradability of the test substance according to OECD guideline 301C (MOE, 1979). After 14 days a biodegradation of only 0.7 - 2.0% was reached, which clearly indicate that the test substance is not readily biodegradable.
The two available publications assessed the inherent biodegradability of the test substance. One study was conducted according to OECD guideline 302 B using activated sludge from an industrial waste water treatment plant (Wellens, 1990). Adapted inoculum in a concentration of 1.1 g/L dry weight and test item concentration of 50 – 400 mg/L based on DOC were applied. The DOC was removed to 100% within 17 days, which demonstrate that the test substance is inherently biodegradable by pre-adapted microorganisms. The second study did not follow a specific guideline; however, was conducted similar to OECD guideline 302C, but using a higher test substance concentration of 200 mg/L based on COD (Pitter, 1976). Pre-adapted activated sludge was used as inoculum. The oxygen demand was measured until there was no further decrease of COD measurable. Biodegradation of 96% was reached within 9 days using pre-adapted microorganisms, which confirmed inherent biodegradability of the test substance under suitable conditions.
Together, these results show that 4-chlorophenol can not be termed as readily biodegradable; however, can be judged inherently biodegradable and therefore is not considered to be persistent in the environment.
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