p-cresol

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Aerobic batch laboratory microcosm experiments using different soils to determine the loss rate of p-cresol

GLP compliance:

not specified

Test type:

laboratory

Oxygen conditions:

aerobic

Soil classification:

other: natural soils

Soil no.:

#1

Soil type:

other: Typic Paleudults

% Clay:

8.6

% Silt:

23.4

% Sand:

68

% Org. C:

0.94

pH:

4.8

CEC:

6.4 meq/100 g soil d.w.

Soil no.:

#2

Soil type:

Mollisol

% Clay:

7.4

% Silt:

31.1

% Sand:

61.5

% Org. C:

3.25

pH:

7.8

CEC:

10.8 meq/100 g soil d.w.

Details on soil characteristics:

Texture of soil no.1 is a sandy loam; Texture of soil no. 2 is a sandy silt loam

Soil No.:

#1

Duration:

64 d

Soil No.:

#2

Duration:

64 d

Soil No.:

#1

Initial conc.:

100 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#2

Initial conc.:

45 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Soil No.:

#1

Temp.:

20°C

Humidity:

80% of field capacity

Soil No.:

#2

Temp.:

20°C

Humidity:

80% of field capacity

Key result

Soil No.:

#1

% Degr.:

139

Parameter:

other: rate constant (% per day)

Sampling time:

1 d

Key result

Soil No.:

#1

DT50:

0.5 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Remarks on result:

other: r²=0.93

Key result

Soil No.:

#2

DT50:

> 1 d

Type:

other: substance not detectable after 1 d

Temp.:

20 °C

Transformation products:

not measured

The recovery efficiencies for p-cresol of the soils were 78% and 97%. The chemical concentrations were corrected by the recovery efficiencies.

Conclusions:

The degradation behaviour of p-cresol was investigated in two different soils. The first soil (acidic) was a sandy loam with an organic carbon content of 0.94%. The second was a sandy silt loam with an organic carbon content of 3.25%. The loadings of the soils and the degradation were monitored by an HPLC method. Maintained in the dark at 20°C, p-cresol degraded with half-live times of <1d for the sandy loam and 0.5 d for the sandy silt loam.

Executive summary:

The degradation behaviour of p-cresol was investigated by Loehr et al. (1992) in two different soils. The first soil (acidic) was a sandy loam with an organic carbon content of 0.94%. The second was a sandy silt loam with an organic carbon content of 3.25%. The loadings of the soils and the degradation were monitored by an HPLC method. Maintained in the dark at 20°C, p-cresol degraded with half-live times of <1d for the sandy loam and 0.5 d for the sandy silt loam.

Description of key information

p-Cresol degraded with half-live times of <1 d for the sandy loam (basic soil) and 0.5 d for the sandy silt loam (acidic soil).

Key value for chemical safety assessment

Half-life in soil:

0.5 d

at the temperature of:

20 °C

Additional information

The substance is readily biodegradable and no biodegradation simulation test has to be performed for soil according to REACH Annex IX column 2.

The degradation behaviour of p-cresol was investigated in two different soils. The first soil (acidic) was a sandy loam with an organic carbon content of 0.94%. The second was a sandy silt loam with an organic carbon content of 3.25%. The loadings of the soils and the degradation were monitored by an HPLC method. Maintained in the dark at 20°C, p-cresol degraded with half-live times of < 1d for the sandy loam and 0.5 d for the sandy silt loam.