p-cresol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Principles of method if other than guideline:

Degradation test under anaerobic conditions

GLP compliance:

no

Oxygen conditions:

anaerobic

Inoculum or test system:

anaerobic sludge

Initial conc.:

50 mg/L

Based on:

DOC

Parameter:

% degradation (CH4 evolution)

Value:

96

Sampling time:

60 d

Details on results:

RS-Freetext:
lag time 7 days
net total gas production was 96 +/- 4.3 % of the theoretical production (CH4 + CO2)

Degradation products: yes
Degradation products (CAS No./EC No./EINECS Name): 74-82-8 200-812-7 methane

RS-Freetext: lag time 7 days net total gas production was 96 +/- 4.3 % of the theoretical production (CH4 + CO2) Degradation products: yes Degradation products (CAS No./EC No./EINECS Name): 74-82-8 200-812-7 methane

Validity criteria fulfilled:

not specified

Interpretation of results:

other: mineralized

Conclusions:

p-Cresol is mineralized under methanogenic conditions by anaerobic sludges from wastewater treatment plants.

Executive summary:

p-Cresol is mineralized under methanogenic conditions by anaerobic sludges from wastewater treatment plants.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

yes

Remarks:

minor deviations

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

100 mg/L dry weight

Initial conc.:

200 mg/L

Based on:

COD

Details on study design:

Test compound was sole source of carbon

Parameter:

other: COD removal

Value:

96

Sampling time:

5 d

Details on results:

Initial degradation rate: 55.0 mg COD/g/h

Validity criteria fulfilled:

not specified

Interpretation of results:

inherently biodegradable

Conclusions:

p-Cresol is inherently degradable as shown by a test according to the OECD guideline 302 B with a removal of 96 % after 5 days of incubation.

Executive summary:

p-Cresol is inherently degradable as shown by a test according to the OECD guideline 302 B with a removal of 96 % after 5 days of incubation.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: method development for ASTM anaerobic biodegradation

Deviations:

not specified

GLP compliance:

no

Oxygen conditions:

anaerobic

Inoculum or test system:

anaerobic sludge

Details on inoculum:

primary anaerobic sludge from 12 treatment plants receiving mainly domestic waste water were diluted to 10% in a mineral salts medium: test substance concentration 30 mg/l;
secondary anaerobic sludge from 2 treatment plants diluted to 10% in a mineral salts medium: test substance 50 mg/l

Initial conc.:

>= 30 - <= 50 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CH4 evolution

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

35 °C, due to storage of sludges before incubation, lag phase of  methanogenesis could be increased in some sludges

Parameter:

% degradation (CH4 evolution)

Value:

62 - 101

Sampling time:

8 wk

Remarks on result:

other: primary sludges

Parameter:

other: methane and CO2 production

Value:

51 - 121

Sampling time:

8 wk

Remarks on result:

other: secondary sludges

Details on results:

primary sludges:
degradation ranged from 62 to 101% in 11 sludges (lag times for approx. 20% of theoretical CH4 production: 2-5 weeks; insufficient data for 1 sludge
secondary sludges:
degradation was 51% after 4 weeks lag-phase with the first sludge and 121% after 3 weeks lag-phase with the second (degradation related to theoretical methane and CO2 production)
Degradation products (CAS No./EC No./EINECS Name): 74-82-8 200-812-7 methane

Validity criteria fulfilled:

not specified

Interpretation of results:

other: anaerobically biodegradable

Conclusions:

p-Cresol is also anaerobically biodegradable. As measured from methane release and carbon dioxide formation, p-cresol is mineralized under methanogenic conditions by anaerobic sludges from wastewater treatment plants.

Executive summary:

p-Cresol is also anaerobically biodegradable. As measured from methane release and carbon dioxide formation, p-cresol is mineralized under methanogenic conditions by anaerobic sludges from wastewater treatment plants.

Reference 4

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

no

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial, adapted

Details on inoculum:

acclimatization 2 d

Duration of test (contact time):

10 d

Initial conc.:

>= 50 - <= 400 mg/L

Based on:

DOC

Initial conc.:

>= 200 - <= 1 000 mg/L

Based on:

COD

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

10 d

Details on results:

90 % degradation during the log-phase (8 d)

Validity criteria fulfilled:

not specified

Interpretation of results:

inherently biodegradable

Conclusions:

p-Cresol is inherently degradable as shown by a test according to the OECD guideline 302 B where 100 % of the added p-cresol were degraded within 10 days after a lag-period of 2 days.

Executive summary:

p-Cresol is inherently degradable as shown by a test according to the OECD guideline 302 B where 100 % of the added p-cresol were degraded within 10 days after a lag-period of 2 days.

Reference 5

Endpoint:

biodegradation in water: ready biodegradability

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:

Method: other: batch culture study in seawater

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: marine bacteria

Parameter:

% degradation (test mat. analysis)

Value:

50

Sampling time:

13.5 d

Details on results:

t1/2 = 295 h (100 µg/l)
t1/2 = 215 h (500 µg/l)
t1/2 = 325 h (1000 µg/l)
Doubling time of population
85 h (100 µg/l)
40 h (500 µg/l)
31 h (1000 µg/l)

Degradation products: not measured

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

p-Cresol is readily biodegradable in seawater.

Executive summary:

p-Cresol is readily biodegradable in seawater.

Reference 6

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study comparable to OECD Guideline 301C

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

Voith sapromat B12

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Minicipal sewage sludge with initial cell concentration: 30 mg/l

Duration of test (contact time):

20 - 40 d

Initial conc.:

100 mg/L

Based on:

test mat.

Reference substance:

aniline

Remarks:

100 mg/L

Parameter:

% degradation (O2 consumption)

Value:

80 - 95

Sampling time:

40 d

Remarks on result:

other: readily biodegradable

Details on results:

The oxygen uptake curves are not reported. However, the authors state that all test compounds revealed the lag phase, biodegradation phase and the plateau region within a period of 10 days, indicating that the 10-day window criteria is met.
first order biodegradation constant (hr-1): ln k = -5.87
maximum specific substrate uptake rate per unit biomass km = 18.5 / day (Aniline 16.1, Phenol 16.9)
p-Cresol is slightly better biodegradable than phenol and aniline

Results with reference substance:

degradation of reference substance aniline >=60 % within 28 days

Incubation period 20-40 days; no oxygen uptake curve given

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In a test according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)), 80 to 95 % of p-cresol were degraded within 40 days. p-Cresol was slightly better biodegradable than phenol and aniline supporting the conclusion that it is readily biodegradable

Executive summary:

In a test according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)), 80 to 95 % of p-cresol were degraded within 40 days. p-Cresol was slightly better biodegradable than phenol and aniline supporting the conclusion that it is readily biodegradable.

Description of key information

p-Cresol is readily biodegradable under aerobic conditions in freshwater. It is inherently biodegradable, and anaerobically biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Serveral experiments on biodegradability are available for p-cresol.

In tests according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)), 80 to 95 % of p-cresol were degraded within 40 d.

Biodegradation of p-cresol was also tested in seawater where it was biodegradable as well.

The inherent degradability of p-cresol was studied in two different tests. Using an adapted activated sludge, p-cresol degraded to 96 % within 5 days and 100% after within 10 days.

p-Cresol is also anaerobically biodegradable. As measured from methane release and carbon dioxide formation, and m- and p-cresol are mineralized under methanogenic conditions by anaerobic sludges from wastewater treatment plants.

Although the substance is readily biodegradable and no biodegradation simulation test has to be performed for sediments, there are studies available on biodegradation in sediments. p-Cresol is biodegraded in aquifer sediment under anaerobic conditions and by anoxic river sediment within 3-4 weeks.