4-(1,1,3,3-tetramethylbutyl)phenol

Biodegradation in soil

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Read-across from Nonylphenol (-> similar chemical structure and similar degradation behaviour in ready biodegradability tests and simulation tests (water, sediments)). Nonylphenol study comparable to guideline without detailed documentation. No measurement of transformation products.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

yes

Remarks:

No measurement of transformation products, only one soil type used

GLP compliance:

no

Test type:

laboratory

Radiolabelling:

no

Oxygen conditions:

aerobic

Soil classification:

other: artificial compost-sandstone mixture

Soil no.:

#1

Soil type:

other: artificial sandstone-compost mixture

% Org. C:

11

pH:

6.8

CEC:

22.1 meq/100 g soil d.w.

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Soil preparation (e.g., 2 mm sieved; air dried etc.): compost was 5 mm sieved, sandstone was 2 mm sieved

PROPERTIES OF THE SOILS (in addition to defined fields)
- Composition: 1/3 d.m. mature sewage sludge compost and 2/3 d.m. sandstone
- Water-holding (field) capacity (%): 51
- Total N (%): 0.5
- C/N: 20
- Total P (%): 1

Soil No.:

#1

Duration:

40 d

Soil No.:

#1

Initial conc.:

>= 100 - <= 1 000 ppm

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

test mat. analysis

Soil No.:

#1

Temp.:

25 °C

Humidity:

60 % field moisture capacity

Microbial biomass:

not determined

Details on experimental conditions:

1. PRELIMINARY EXPERIMENTS:
no preliminary experiments conducted

2. EXPERIMENTAL DESIGN
- Soil condition: compost-sandstone mixture at 60 % field capacity
- Soil (g/replicate): 60
- Control conditions, if used: control sample treated with ethanol
- No. of replication controls, if used: 3
- No. of replication treatments: 3
- Test apparatus: The incubator was a multipurpose assembly, with intermittent aeration (Parr and Smith 1969)
- Details of traps for CO2 and organic volatile, if any: The cells were flushed periodically with a stream of CO2-free air to remove accumulated CO2 and restore the O2 content, the effluent air being bubbled in 15 ml 0.1 N NaOH. The absorbed CO2 was determined by a conductivity method (Wollum and Gomez 1969)
- Identity and concentration of co-solvent: ethanol

Sterile controls:
- Six replicates were sterilized by gamma irradiation (5 megarads), then spiked with 100 ppm nonylphenol and compared with six non-irradiated spiked (100 ppm) replicates.
- The cells were incubated for 24 days under the conditions outlined above except that a simpler static aeration system was used, in an aseptic room.
Test material application
- Volume of test solution used/treatment: Technical-grade nonylphenol was dissolved in ethanol at 0.4 ml/g spiked compost
- Application method (e.g. applied on surface, homogeneous mixing etc.):
* The dissolved substances were mixed with part of the compost (4 g d. m.) and the ethanol was left to evaporate.
* The spiked compost was then mixed thoroughly in an incubation cell with the rest of the 60-g sample (16g d.m. compost + 40 g d.m. sandstone)
- Is the co-solvent evaporated: yes

Experimental conditions (in addition to defined fields)
- Continuous darkness: Yes

3. OXYGEN CONDITIONS (delete elements as appropriate)
- Methods used to create the aerobic conditions: The cells were flushed periodically with a stream of CO2-free air to remove accumulated CO2 and restore the O2 content

4. SAMPLING DETAILS
- Sampling intervals: 0, 5, 10, 20 and 40 days of incubation
- Sampling method for soil samples: On removal from the incubator, the replicates were mixed thoroughly and half the quantity was freeze-dried. After freeze-drying, three samples of each treatment were analysed for residual nonylphenol. Only 4-NP concentrations were measured.
- Method of collection of CO2 and volatile organic compounds:
> CO2 traps
> Volatilization of 4-NP was studied concurrently, using phenol traps made of polyvinylpirrolydone (Andersen and Sower 1968). The phenol traps replaced CO2 traps on six extra cells of the 1000-ppm treatment, and were analysed for 4-NP at 10, 20 and 40 days
- Sampling intervals/times for:
> Residual 4-NP: 0, 5, 10, 20 and 40 days of incubation (sterile controls: 0, 15 and 24 days)
> ATP: 0, 5, 10, 20 and 40 days of incubation (sterile controls: 0, 15 and 24 days)
> pH: 0, 5, 10, 20 and 40 days of incubation
> Moisture content: 0, 5, 10, 20 and 40 days of incubation

Soil No.:

#1

% Degr.:

>= 62 - <= 89

Parameter:

test mat. analysis

Sampling time:

40 d

Transformation products:

not measured

Details on transformation products:

No details

Evaporation of parent compound:

yes

Volatile metabolites:

not measured

Residues:

yes

Details on results:

ANALOGUE APPROACH JUSTIFICATION:
The read-across approach for biodegradation on soil is based on the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.”

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances.

From tests for ready biodegradability both substances can be classified as inherently biodegradable.

In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range.

Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour. Thus, read-across can be used to fill the existing data gap for PTOP biodegradation in soil (IUCLID 5.2.3).



DECREASE OF 4-NP CONCENTRATION:
- 11 % of the initial 4-NP was recovered after the 100-ppm treatment after 40 days of incubation
- 38 % of the initial 4-NP was recovered after the 1000-ppm treatment after 40 days of incubation

VOLATILIZATION OF 4-NP
- Insignificant, with only 0.22 % 4-NP volatilized over 40 days at 1000 ppm

STERILE TREATMENTS (if used)
- The sterilization proved to be incomplete, as CO2 was detected within 2 days of irradiation.
- Respiration remained, however, depressed by 48 % on average throughout the first 2 weeks

Results with reference substance:

Not applicable

4-NP degradation:

- In both treatments, 4-NP concentrations did not begin to fall until after the 5th day.

- Following this initial lag phase, two more phases were recorded:

* First phase: 4 -NP concentrations fell quickly

* Second phase: 4 -NP disappearance processes either slowed down (100 ppm) or stopped (1000 ppm).

- The concentrations stabilized at 403 ppm for the 1000-ppm treatment and at 8 ppm for the 100-ppm treatment.

- Apparently, 4-NP is degraded microbiologically after induction of the microorganisms.

Correlation between NP degradation and NP concentration:

- 4 -NP is more persistent at high concentrations (1000 ppm) or under semi-sterile conditions.

- In both cases persistence can be related to the level of biological activity.

- At 1000 ppm, 4-NP ceased to disappear once CO2 production dropped below 20 µg C/g C per h.

- At 100 ppm, 4-NP disappeared readily, and biological activity did not differ from that of the control treatment.

- These observations indicate that biological processes are responsible for the disappearance of 4-NP.

- Biodegradation is evident through the presence of a lag phase. Such periods of adaptation have been observed during the biodegradation of many pesticides of different chemistries (Audus 1964; Hiltbold 1976).

The lack of transformation under the 1000-ppm treatment or under semi-sterile conditions seems to indicate that different processes, such as residue binding, may take place.

NP toxicity:

- After an initial increase in ATP content, concentrations stabilized around 400 ng/g in the control and 100-ppm treatment.

- In the 1000-ppm treatment, a progressive decrease in ATP content was observed from the 5th day on. The difference between values on days 10 and 40 was significant (t < 0.01).

- These results suggest that nonylphenol does not have a sudden lethal action on global biomass, since the ATP content directly reflects the active soil biomass (Maire 1984). It does not, however, reveal qualitative changes in the microflora. The biomass-ATP measure may also be insufficiently sensitive to show fine but significant biomass fluctuations.

Conclusions:

The test substance 4-NP (technical grade) was degraded under aerobic conditions at 25 °C in soil. Degradation rates were dependent on the initial test substance concentration (89 % and 62 % degradation within 40 days at 100 ppm and 1000 ppm initial 4-NP, respectively).

The results for biodegradation of 4-NP in soil are adequate for the purpose of classification and labelling and/or risk assessment under REACH.

Executive summary:

The persistence and biotoxicity of nonylphenol, a mixture of monoalkyl phenols that is found in relatively high concentrations in sewage sludge, were studied in a 40 day incubation experiment (25 °C, darkness) with a reconstituted soil system (compost + sandstone).

The effect of nonylphenol (100 and 1000 ppm) on CO2 evolution and biomass ATP were monitored. Nonylphenol depressed CO2 production significantly only at high concentrations [1000 ppm 4-nonylphenol (4-NP)]. Biomass ATP declined progressively after the 5th day. At 100 ppm no toxic effects were detected.

After a lag phase, nonylphenol disappeared readily upon incubation at the lower concentration (100 ppm, 89 % degradation after 40 days), but persisted at high levels (1000 ppm, 62 % degradation after 40 days). The persistence of 4-nonylphenol increased under aseptic conditions.

The lack of transformation under the 1000-ppm treatment or under semi-sterile conditions seems to indicate that different processes, such as residue binding, may take place.

Reference 2

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:

other: Read-across from Nonylphenol (-> similar chemical structure and similar degradation behaviour in ready biodegradability tests and simulation tests (water, sediments)). Nonylphenol study comparable to Guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

yes

Remarks:

incubation at 30 °C; storage of soil of up to six month at -5 °C prior to experiments

GLP compliance:

no

Test type:

laboratory

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil no.:

#1

Soil type:

silt loam

% Clay:

32

% Silt:

52

% Sand:

15.5

% Org. C:

2.9

pH:

6.7

Soil no.:

#2

Soil type:

sandy loam

% Sand:

> 90

% Org. C:

0.8

pH:

5.8

Soil no.:

#3

Soil type:

loam

% Clay:

27

% Silt:

36

% Sand:

37

% Org. C:

4.6

pH:

5.9

Soil no.:

#4

Soil type:

loam

% Clay:

15

% Silt:

45

% Sand:

40

% Org. C:

3.2

pH:

7.4

Soil no.:

#5

Soil type:

Organic

% Org. C:

26.2

pH:

7.4

Soil no.:

#6

Soil type:

loam

% Org. C:

4.4

pH:

6.4

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Geographic location: for details see Table 1
- Storage conditions: -5 °C
- Storage length: up to six month

SEWAGE SLUDGE USED IN THE STUDY:
- Obtained from a municipal sewage treatment plant (London, Ontario, Canada) serving about 60,000 residents and having negligible industrial input

Soil No.:

#1

Duration:

40 d

Soil No.:

#2

Duration:

40 d

Soil No.:

#3

Duration:

40 d

Soil No.:

#4

Duration:

40 d

Soil No.:

#5

Duration:

40 d

Soil No.:

#6

Duration:

40 d

Soil No.:

#1

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#2

Initial conc.:

>= 1 - <= 250 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#3

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#4

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#5

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Soil No.:

#6

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

test mat. analysis

Soil No.:

#1

Temp.:

30 °C

Humidity:

field capacity, air-dried, and two intermediate values

Microbial biomass:

not determined

Soil No.:

#2

Temp.:

4-30 °C

Humidity:

field capacity, air-dried, and two intermediate values

Microbial biomass:

not determined

Soil No.:

#3

Temp.:

30 °C

Humidity:

not reported

Microbial biomass:

not determined

Soil No.:

#4

Temp.:

30 °C

Humidity:

not reported

Microbial biomass:

not determined

Soil No.:

#5

Temp.:

30 °C

Humidity:

not reported

Microbial biomass:

not determined

Soil No.:

#6

Temp.:

30 °C

Humidity:

not reported

Microbial biomass:

not determined

Details on experimental conditions:

1. PRELIMINARY EXPERIMENTS: no


2. EXPERIMENTAL DESIGN
- Soil condition: fresh
- Soil (g/replicate): 10 or 100 g dry weight
- In some experiments, the microcosms were incubated with agitation on a rotary shaker at 115 rev/min
- Test apparatus (Type/material/volume):
> incubation in 150 ml baby jars
> the baby food jars were placed in sealable 1L Mason jars containing a scintillation vial with water to provide moisture and a scintillation vial with NaOH as CO2 trap
- Details of traps for CO2: 7 ml of 1M NaOH
- Sterile controls:
> sterile sewage sludge supernatant was prepared by centrifuging (12,000 g, 15 min) and filter sterilizing (0.2 µm) recovered supernatant
> sterile soil was prepared by autoclaving twice (45 min at 120 °C), the second following a 24-h room temperature incubation

Test material application
- Volume of test solution used/treatment: 20 µl
- Application method (e.g. applied on surface, homogeneous mixing etc.): Hexane solutions (20 µl) of [ring-U-14CJ4-nonylphenol and nonradiolabeled nonylphenol were added to fine sand, and the solvent was allowed to evaporate
- Is the co-solvent evaporated: yes
- Samples of moist soil (100 or 10 g dry wt; as indicated) added to 150-ml baby foot jars were supplemented with nonylphenol by thoroughly incorporating 100 mg of sand containing the aliquot of chemical required to achieve the desired final concentration (5 mg/kg dry wt, unless otherwise indicated)
- In experiments examining the possible retention and reduction in bioavailability of 4-nonylphenol by sewage solids: 100 mg of dried sewage solids were used as the carrier rather than sand.

Sewage solids:
- obtained by centrifuging sewage sludge (12,000 g, 15 min)
- recovered cake was air-dried and grinded to fine powder with mortar and pestle

Investigationof potential rate-controlling parameters
1) Moisture content
- Effect of moisture on mineralization was examined in soil #1 and soil #2
- for each soil the moisture content was adjusted to 4 values (water holding capacity, air-dried, and two intermediate values)
2) Temperatre:
- Range: 4 - 30 °C

Any indication of the test material adsorbing to the walls of the test apparatus:

Experimental conditions (in addition to defined fields)
- Moisture maintenance method:
- Continuous darkness: no data

Other details, if any:

3. OXYGEN CONDITIONS
- Methods used to create the an/aerobic conditions: no specific methods used


4. SUPPLEMENTARY EXPERIMENTS:
Experiments to determine the possible retention and reduction in bioavailability of 4-nonylphenol by sewage solids: 100 mg of dried sewage solids were used as the carrier rather than sand.


5. SAMPLING DETAILS: no details reported

Soil No.:

#2

% Recovery:

10

Remarks on result:

other: 50 % of the initially applied radioactivity remained bound

Soil No.:

#1

% Degr.:

ca. 42

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#2

% Degr.:

>= 42 - <= 48

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#3

% Degr.:

>= 42 - <= 45

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#4

% Degr.:

ca. 37

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#5

% Degr.:

ca. 35

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#6

% Degr.:

ca. 38

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#5

DT50:

4.5 d

St. dev.:

0.05

Type:

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

Remarks on result:

other: minimum half-life of all six soils analysed

Soil No.:

#3

DT50:

16.27 d

St. dev.:

2.28

Type:

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

Remarks on result:

other: Maximum half-life of all six soils examined

Transformation products:

yes

No.:

#1

Details on transformation products:

No details reported

Evaporation of parent compound:

not measured

Volatile metabolites:

yes

Residues:

yes

Details on results:

ANALOGUE APPROACH JUSTIFICATION:
The read-across approach for biodegradation on soil is based on the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.”

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances.

From tests for ready biodegradability both substances can be classified as inherently biodegradable.

In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range.

Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour. Thus, read-across can be used to fill the existing data gap for PTOP biodegradation in soil.



EXTRACTABLE RESIDUES (soil #2)
- % of applied amount at end of study period: 10

NON-EXTRACTABLE RESIDUES (soil #2)
- % of applied amount at end of study period: 50

STERILE TREATMENTS (if used)
- No mineralization

RESULTS OF SUPPLEMENTARY EXPERIMENT (if any):
- Sorption of 4-nonylphenol to sewage solids did not limit biodegradation
> Rates of mineralization were comparable in soils that received 4-nonylphenol added with sand or with dried solids as carrier
> Carrier mass (100 mg) small in comparison to amount of soil (100 g)
- Large amount of sewage sludge (50 %m v/v) or sewage sludge added directly: only very slow mineralization of 4-nonylphenol in static incubations
- Agitation of microcosms (oxygen transfer): 4-nonylphenol was mineralized at comparable rates in soil supplemented with sewage sludge (50 % v/v) and unsupplemented soil control in a 10-d experiment
=> Taken together the results suggest that slow 4-nonylphenol mineralization in soil heavily amended with sewage sludge or in sewage sludge directly was due to oxygen limitation promoted by high biological oxygen demand and restricted gaseous diffusion; furthermore, the sewage sludge readily mineralized 4-nonylphenol in the presence of sufficient oxygen

DISSIPATION OF TECHNICAL NONYLPHENOL IN AN AGRICULTURAL SOIL (soil #2):
- Investigation of the various GC-detectable nonylphenol isomers
- All detectable compounds of technical nonylphenol are degraded in this soil

INFLUENCE OF MOISTURE CONTENT (soil #1 and #2):
- Maximal mineralization at intermediate moisture content

EFFECT OF TEMPERATURE (soil #2):
- Increasing lag phase to detectable mineralization with decreasing temperature

Results with reference substance:

Not applicable

Conclusions:

The 4-nonylphenol was readily mineralized in soils that varied widely in their physical properties, sampling location, and management. The soils tested included three cultivated soil, a noncultivated temperate soil, and two soils from the Canadian Far North; which were presumably pristine with respect to exposure to 4-nonylphenoI through agricultural or other sources. The results suggest that the ability to mineralize 4-nonylphenol is widespread, if not ubiquitous, in soil microbial population. The absence of mineralization in sterile controls confirmed the microbial basis for degradation of this compound.
The biodegradability of 4-nonylphenol in the Arctic soils further suggest that the biochemistry required for 4-nonyphenol metabolism was present without anthropogenic exposure to this chemical.
The results for biodegradation of 4-NP in soil are adequate for the purpose of classification and labelling and/or risk assessment under REACH.

Executive summary:

The biodegradation of 4 -nonylphenol was studied in agricultural, noncultivated temperate and Arctic soil in laboratory microcosm incubations for 40 days.

At 30 °C, [U-ring-14C]4 -nonylphenol was rapidly mineralized without a lag in the six soils tested. A sandy loam agricultural soil was chosen for more detailed study. The 4 -nonylphenol mineralization did not occur in autoclaved soil. The response of 4 -nonylphenol mineralization to variation in temperature and moisture content was consistent with an aerobic biological mechanism of degradation. Mineralization of [U-ring-14C]4 -nonylphenol was rapid in the concentration range of 1 to 250 mg/kg soil dw. Sludge solids did not inhibit 4 -nonylphenol mineralization, although sewage sludge at high concentrations was inhibitory, apparently because of high BOD. GC-MS analyses of extracts prepared from soil incubated with commercial nonylphenol indicate that all detectable isomers were degraded.

In summary, these results indicate that microorganisms that can metabolize 4 -nonylphenol are found in a wide variety of soils, including two originating from the Canadian Far North, which presumably have not been exposed anthropogenically to this chemical. It can be concluded that 4 -nonylphenol should be generally biodegradable in well-aerated arable soils.

Reference 3

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Read-across from Nonylphenol (-> similar chemical structure and similar degradation behaviour in ready biodegradability tests and simulation tests (water, sediments)). Nonylphenol study meets generally accepted scientific standards.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The degradation and possible uptake of Nonylphenol (NP) in agricultural plants was studied in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated in sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napus L. ev Hyola 401) was sown in the pots and harvested after 30d. In order to investigate the influence of plant growth in the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight.

GLP compliance:

no

Test type:

laboratory

Radiolabelling:

no

Oxygen conditions:

aerobic/anaerobic

Soil classification:

not specified

Soil no.:

#1

Soil type:

sandy loam

Soil no.:

#2

Soil type:

other: sandy loam with anaerobic sludge

Soil type:

other: sandy loam with aerobic sludge

Soil no.:

#4

Soil type:

other: sandy loam with compost

Soil no.:

#5

Soil type:

other: sandy loam with pig manure

Soil no.:

#6

Soil type:

other: sandy loam + spike (NP)

Soil no.:

#7

Soil type:

other: sandy loam + pig manure + spike (NP)

Soil no.:

#8

Soil type:

other: sandy loam + aerobic sludge + spike (NP)

Soil no.:

#9

Soil type:

other: sandy loam + compost + spike (NP)

Details on soil characteristics:

SOIL
- Soil origin: Danish experimental station
- Pesticide use history at the collection site: the soil had not received any pesticides, sludge or other domestic waste products.
- Soil preparation: 5 mm sieved, dried prior to addition of waste products
- Before the experiments N, P, K, Mg, Cu, and Mn were added to the soil to avoid deficiency of these elements
- For details see table 2

Soil No.:

#1

Duration:

30 d

Soil No.:

#2

Duration:

30 d

Soil No.:

#3

Duration:

30 d

Soil No.:

#4

Duration:

30 d

Soil No.:

#5

Duration:

30 d

Soil No.:

#6

Duration:

30 d

Soil No.:

#7

Duration:

30 d

Soil No.:

#8

Duration:

30 d

Soil No.:

#9

Duration:

30 d

Initial conc.:

>= 0 - <= 246 other: ppb dry weight

Based on:

other: concentration of NP in soil amended with waste products (Soil #1 - #5; see table 2)

Initial conc.:

>= 320 - <= 534 other: ppb dry weight

Based on:

other: concentration of NP in spiked soil (Soil #6 - #9; see table 2)

Parameter followed for biodegradation estimation:

test mat. analysis

Soil No.:

#1

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#2

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#3

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#4

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#5

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#6

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#7

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#8

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Soil No.:

#9

Temp.:

no data

Humidity:

60 % of water holding capacity

Microbial biomass:

no data

Details on experimental conditions:

1. SLUDGE APPLICATION:
- Anaerobic sludge was added to soil comparable with 10 t sludge/ha dry weight
- During this application, about 2,075 kg C/ha was added to the soil


2. WASTE APPLICATION:
- Application was made to achieve the same level of carbon as with sludge application
- Application of aerobic sludge, compost and pig manure were added to soil comparable with 7.8, 15.2, and 6.5 t dry matter/ha, respectively


3. EXPERIMENTAL DESIGN
- Soil condition: fresh
- Soil (kg/replicate): 3.5
- Humidity: pots were not drained, and moisture in them was kept at 60 % of water holding capacity
- No. of replication treatments: three replicates per (waste) treatment - three pots with rape and three plant-free pots
- Additional experiments with NP spiked soil (NP in water solution) -> NP was added to:
* Control soil
* Soil with the addition of aerobic sludge
* Soil with the addition of compost
* Soil with the addition of pig manure
* Addition of NP in quantity to achieve a concentration of 100 ppm dry weight -> because of of different addition of waste, the initial concentration varied (see table 2)

Soil No.:

#2

% Degr.:

>= 74 - <= 87

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#3

% Degr.:

>= 82 - <= 91.7

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#8

% Degr.:

99.1

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#9

% Degr.:

97.8

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#8

% Degr.:

84

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#9

% Degr.:

64

Parameter:

test mat. analysis

Sampling time:

30 d

Transformation products:

not measured

Evaporation of parent compound:

not measured

Volatile metabolites:

not measured

Residues:

yes

Details on results:

ANALOGUE APPROACH JUSTIFICATION:
The read-across approach for biodegradation on soil is based on the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.”

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances.

From tests for ready biodegradability both substances can be classified as inherently biodegradable.

In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range.

Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour. Thus, read-across can be used to fill the existing data gap for PTOP biodegradation in soil.



- For both aerobic (soil #2) and anaerobic (soil #3) sludge treatments, there were significantly lower NP concentrations in the soil from planted pots compared with unplanted pots.
- The NP degradation in spiked treatments was more complete
- The spiked (linear) NP degraded more rapidly than the (branched) NP from the waste products:
* When NP was added as spike, only 1 to 2 % was measured in the soil after 30 days
* The addition of NP as a water solution was a more bioavailable form as compared with the waste application
* In spike experiments, the plant growth did not have any influence in the degradation
- Results with soil where both waste and spike were added:
* Tendency to a more complete degradation of spiked NP
- NP degradation in soil amended with compost was not so complete as compared with sludge (aerobic and anaerobic) amended soil:
* Sewage sludge may favour degradation because microorganisms capable of degrading NP may already be present
* Compost has a higher C/N ratio and therefore microorganisms give less favourable conditions in the compost

Conclusions:

When NP was added to soil with waste application and homogenous mixtures were established, plant growth stimulated the degradation process of NP. The degradation of NP in soil was affected by waste type and application form. More complete degradation of NP was observed in soil amended with sludge compared with compost-treated soil. When NP was added as spike in an unbranched from, the degradation of the spiked NP was nearly complete and only about 2 % remained in the soil after 30 d.
The results for biodegradation of 4-NP in soil are adequate for the purpose of classification and labelling and/or risk assessment under REACH.

Executive summary:

The degradation and possible uptake of Nonylphenol (NP) in agricultural plants was studied in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated in sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napusL. ev Hyola 401) was sown in the pots and harvested after 30 d. In order to investigate the influence of plant growth in the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight.

When NP was added to soil with waste application and homogenous mixtures were established, plant growth stimulated the degradation process of NP. In experiments with anaerobic and aerobic sludge, respectively, 13 and 8.3 % of NP remained in the soil from pots planted with rape compared with 26 and 18 % in soil without plant growth.

When NP was added as spike to soil, the degradation was more complete and plant growth did not influence the degradation. Percentages of 2.2 and 1.8 were still in the soil after 30 days for planted and plant-free pots, respectively.

The degradation of NP in soil was affected by waste type and application form. More complete degradation of NP was observed in soil amended with sludge compared with compost-treated soil.

Reference 4

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Read-across from Nonylphenol (-> similar chemical structure and similar degradation behaviour in ready biodegradability tests and simulation tests (water, sediments)). Nonylphenol study meets generally accepted scientific standards, well documented and acceptable for assessment.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Lysimeter study (45-cm soil columns): Anaerobically digested sewage sludge was incorporated in the top 15-cm to an initial content of 0.56 mg Nonylphenol (NP) kg-1 dry weight. Spring Barley (Hordeum vulgare L.) was sown onto the columns. The lysimeters were placed outdoors and therefore received natural precipitation, but were also irrigated to a total amount of water equivalent to 700 mm of precipitation. Leachate and soil samples from three soil layers were collected continuously during a growth period of 110 d. Leachate samples and soil extracts were concentrated by solid-phase extraction (SPE) and analyzed for NP using HPLC with fluorescence detection.

GLP compliance:

no

Test type:

other: lysimeter experiment (outdoor)

Radiolabelling:

no

Oxygen conditions:

aerobic

Soil classification:

not specified

Soil no.:

#1

Soil type:

other: Askov loamy sand soil (Typie Hapludalf) obtained from a Danish agricultural research station (Askov)

% Clay:

10.8

% Silt:

18.2

% Sand:

71

% Org. C:

1.3

pH:

5.6

Bulk density (g/cm³):

1.1

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Sampling depth (cm): 0-20 cm (Ap horizon)
- Soil preparation: 1cm sieved

PROPERTIES OF THE SOILS (in addition to defined fields)
- Water content: 16 %
- Water holding capacity: 0.47 L/kg

Soil No.:

#1

Duration:

110 d

Soil No.:

#1

Initial conc.:

0.56 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Soil No.:

#1

Temp.:

not measured

Humidity:

16 %

Microbial biomass:

not measured

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Lysimeter: * PVC plastic column
* Surface area: 0.0779 m²
* Depth: 50 cm
* Placed on top of a PVC funnel mouthed into a leachate collection bottle
- Soil incubation conditions (duration, temperature if applicable): outdoors, underground (surface of lysimeter at same level as surrounding ground
- Soil condition: fresh
- Soil (kg/replicate): 39 kg (lysimeters with sludge application: 26 kg soil + 13 kg of sludge (420 g) amended soil)
- Control conditions: three lysimeters without sludge application
- No. of replication controls: 3
- No. of replication treatments: 3 replicates for 5 sampling days (15 lysimeters altogether)
- Sampling depths: 0-15 cm, 15-30 cm, 30-45 cm (three soil laysers)
- Sampling days: 10, 20, 30, 50, and 110
- Storage until analyses: -18 °C

Sampling of leachate:
- Sampling days: 0, 10, 20, 30, 50, 70, and 110
- Since three lysimeters were taken out of the experiment at each day of soil sampling, the number of replicates declined during the experimental period from 15 replicates on Days 0 and 10 to 3 replicates on Days 70 and Day 110
- Storage until analyses: -18 °C

Soil No.:

#1

% Degr.:

45

Sampling time:

10 d

Soil No.:

#1

% Degr.:

99

Sampling time:

110 d

Soil No.:

#1

DT50:

37 d

Type:

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

Remarks on result:

other: 95 % confidence level: 31-46 days

Transformation products:

not measured

Evaporation of parent compound:

not measured

Volatile metabolites:

not measured

Residues:

yes

Details on results:

ANALOGUE APPROACH JUSTIFICATION:
The read-across approach for biodegradation on soil is based on the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.”

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances.

From tests for ready biodegradability both substances can be classified as inherently biodegradable.

In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range.

Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour. Thus, read-across can be used to fill the existing data gap for PTOP biodegradation in soil.



DEGRADATION KINETICS:
- Two phases of degradation: * First phase: Days 0-10 (rapid degradation with loss of 55 % of NP; data not used for estimation of half-life)
* Second phase: continuous but slower decline
- Degradation rate constant for NP: 0.00812/day


ANALYSIS OF LEACHATE SAMPLES:
- NP was not detected in concentrations above the detection limit in any of the samples


ANALYSIS OF SOIL SAMPLES:
- NP was not detected in concentrations above the detection limit in any of the samples taken from soil layers below the depth of sludge incorporation (15 cm) => negligible downward transport

Conclusions:

In the top layer of the soil an initial rapid degradation was observed, followed by a slower but continuous degradation. After ten days 55 % of NP were degraded. At the end of the experiment, the concentration of NP was below the analytical detection limit.
The results for biodegradation of 4-NP in soil are adequate for the purpose of classification and labelling and/or risk assessment under REACH.

Executive summary:

Nonylphenol (NP) was added with sewage sludge to lysimeters to an initial concentration of 0.56 mg NP/kg dry weight. The lysimeters were packed with loamy sand soil and grown with barley to mimic field conditions. The lysimeters were placed outdoors and therefore received natural precipitation, but were also irrigated to a total amount of water equivalent to 700 mm of precipitation.

Leachate and soil samples from three soil layers were taken after 0, 10, 20, 30, 50, 70, and 110 days and 10, 20, 30, 50, and 110 days, respectively. Leachate samples and soil extracts were concentrated by solid-phase extraction (SPE) and analyzed for NP using HPLC with fluorescence detection.

In the top layer of the soil an initial rapid degradation was observed, followed by a slower but continuous degradation. After ten days 55 % of NP were degraded. At the end of the experiment, the concentration of NP was below the analytical detection limit. Assuming first-order degradation kinetics, a half-life of 37 days for NP was estimated.

Reference 5

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:

other: Read-across from Nonylphenol (-> similar chemical structure and similar degradation behaviour in ready biodegradability tests and simulation tests (water, sediments)). Nonylphenol study comparable to Guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

yes

Remarks:

only one soil tested; incubation period of 150 days; incubation at 16:8 h light:dark photoperiod because of planted microcosms

GLP compliance:

no

Test type:

laboratory

Radiolabelling:

yes

Oxygen conditions:

aerobic/anaerobic

Soil classification:

USDA (US Department of Agriculture)

Soil no.:

#1

Soil type:

other: Loamy sand soil with biosolids (99.5 % : 0.05 %)

% Org. C:

1.8

pH:

7.11

Bulk density (g/cm³):

1.3

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Geographic location: no data
- Pesticide use history at the collection site: no data
- Collection procedures: no data
- Sampling depth (cm): no data
- Storage conditions: no data
- Storage length: no data


PROPERTIES OF THE SOIL/BIOSOLIDS MIX (in addition to defined fields)
- Available P (mg/kg): 15.4
- Available K (mg/kg): 240
- N as NO3 (mg/kg): 30
- Fe (mg/kg): 605
- Zn (mg/kg): 48.4
- Cu (mg/kg): 16.3
- Mn (mg/kg): 322
- S (mg/kg): 29
- Sodium absorption ratio: 0.95
- Organic matter (%): 1.8
- Nonylphenol (mg/kg): 5 (Calculated from measured biosolids concentration)

Soil No.:

#1

Duration:

150 d

Soil No.:

#1

Initial conc.:

>= 6 - <= 47 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

test mat. analysis

Soil No.:

#1

Temp.:

day/night temperature of 20/16 +/- 1°C

Humidity:

60 - 80 % of field capacity

Details on experimental conditions:

1. PRELIMINARY EXPERIMENTS:
- Prestudy soil testing and two preliminary 60-d plant growth studies


2. EXPERIMENTAL DESIGN
- Soil condition: fresh
- Soil: 2-kg mixture of soil/biosolids (95.5:0.5 w/w) per replicate
- No. of replication treatments: Triplicate planted, unplanted, and unplanted poisoned column microcosms were used for each of the three compounds and concentrations.
- Test apparatus: Column microcosms (diameter, 7.5 cm, length, 36 cm), containing a mixture of soil/biosolids (99.5:0.5 w/w) planted with crested wheatgrass (Agropyron cristatum)
- Details of traps for CO2 and organic volatile, if any: see below (Microcosm design)

Microcosm design:
- Column microcosms were constructed with polyvinyl chloride (PVC) pipe (length, 36 cm; diameter, 7.5 cm; wall thickness, 3.18 mm)
- Bottom: covered with a PVC cap fitted with a 6.35 mm stainless-steel bulkhead union (Swagelok, Solon, OH, USA) filled with glass wool
- The union connected the bottom of the column to a vacuum pump through a series of four traps (40-ml glass volatile organic analysis vials) using stainless-steel tubing (diameter, 3.18 mm) through a reducing ferrule
- First trap: used to collect any column leachate
- Three subsequent traps: filled with 30 ml of 1 M KOH solution to capture [14C]CO2
- Needle valves were used to regulate the flow through the traps at 10 ml/min

Biosolids:
- Origin of biosolids: municipal WWTP receiving industrial, commercial, and domestic wastewater
- Spiked with uniformly ring-labeled [14C]NP and mixed with a recently collected, loamy sand soil to yield three initial nominal soil/biosolids concentrations of 6, 24, and 47 mg/kg dry weight (concentrations include the amount of compound originally in the biosolids and the amount of spiked 14C-labeled compound)
- The unspiked microcosms contained 5 mg/kg dry weight (calculated) of NP derived from the original biosolids

Sterile controls:
- Microcosms received 500 mg/kg dry weight of HgCl2 based on the biosolids/soil mix

Reference compound:
- [14 C]Phenol
- Readily degradable
- Single nominal concentration of 22 mg/kg

Plants:
- Crested wheatgrass seeds (n 10–15 seeds) obtained from the U.S. Department of Agriculture–Agricultural Research Service facility located at Utah State University were added to each column
- The number of crested wheatgrass plants in each column was thinned to six after 14 d

Test material application: no details reported

Experimental conditions (in addition to defined fields)
- Moisture maintenance method: Soil moisture was maintained at 60 to 80% of field capacity by weighing the columns and adding tap water as needed
- Continuous darkness: No > 16:8-h light:dark photoperiod
- Temperature: day/night temperature of 20/16 +/- 1°C


3. OXYGEN CONDITIONS (delete elements as appropriate)
- Methods used to create the aerobic conditions: vacuum at the bottom at the microcosms -> constant flow (10 ml/min) of ambient air through soil column


4. SUPPLEMENTARY EXPERIMENTS: none


5. SAMPLING DETAILS
1) CO2 traps:
- Sampling intervals: weekly throughout the study
- Method of collection of CO2 and volatile organic compounds: an aliquot of KOH from each trap was added to 5 ml of scintillation cocktail and analyzed by liquid scintillation counting (LSC). The amount of 14 CO 2 was then calculated by multiplying the activity of the aliquot by the volume of the KOH solution in each trap

2) Leachate
- Sampling intervals: visual daily inspections; if any leachate was collected, the volume was recorded before the leachate was returned to the top of
the soil column with the daily water
- Leachate was collected in less than 1% (111 of 13,725) of the daily samples from the 96 reactors, with an average volume of 30 ml/incident

3) 14C analysis in soil
- Sampling method for soil samples:
> Soil cores were extruded from each of the columns and separated into five equal sections (length, 6.5 cm each)
> In the nonplanted columns, each section of soil was homogenized, placed into plastic bags, sealed, and frozen after collecting a 5-g aliquot for soil moisture determination.
> In the planted columns, bulk roots and soil were separated from each section by gentle agitation and washing with deionized water. After separation, the roots from each section were homogenized, placed in aluminum foil, air-dried, and frozen. Soil was treated as described previously for the unplanted columns.
- Determined using a combustion/LSC method
- The amount of 14 C associated with the soil as bicarbonate was determined by adding excess 10% HCl to a soil/water slurry. The evolved 14CO2 was trapped and analyzed in a method identical to that for the combustions.

Soil No.:

#1

% Recovery:

98.5

Remarks on result:

other: mean value; range: 67-130 % recovery

Soil No.:

#1

% Degr.:

90

Parameter:

CO2 evolution

Sampling time:

150 d

Soil No.:

#1

DT50:

>= 31 - <= 51 d

Type:

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

Remarks on result:

other: Assuming first-order disappearance kinetics, half-lives for NP averaged from 31 to 51 d in the various planted, unplanted, and unplanted poisoned systems.

Transformation products:

yes

No.:

#1

Details on transformation products:

No details reported

Evaporation of parent compound:

no

Volatile metabolites:

yes

Residues:

yes

Details on results:

ANALOGUE APPROACH JUSTIFICATION:
The read-across approach for biodegradation on soil is based on the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.”

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances.

From tests for ready biodegradability both substances can be classified as inherently biodegradable.

In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range.

Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour. Thus, read-across can be used to fill the existing data gap for PTOP biodegradation in soil.


14C RECOVERIES AND DISTRIBUTION:
- Most of the 14C activity recovered from the system at the end of the study was associated with the soil (60–70%)
- The second largest percentage of 14C was found in the 14CO2 traps
- Less than 0.5% of the total activity added to the system was found in the plant tissue


MINERALISATION
- % of applied radioactivity present as CO2 at end of study: 7.2% +/- 1.0% for the nonpoisoned microcosms
- final percentage mineralization was not significantly affected by differences in the initial concentrations (6–47 mg/kg) of the compounds in the biosolids/soil mixture (one-way ANOVA: NP, p 0.548)
- The addition of mercuric chloride was not completely effective in preventing mineralization, but it did significantly reduce the extent and rate to below that of the nonpoisoned reactors.
- No measurable 14 HCO 3 was found in the soil at the end of the study
- No enhancement in the final percentage mineralization was observed in the planted reactors
- slight reduction in mineralization in the planted systems, probably due to nutrient deficiency (reddened foliage in the plants, including the controls, during the final weeks of the study (130 d). Analysis of one of the control plants yielded a phosphorus concentration of 1,100 mg/kg (dry wt), compared with 1,800 to 1,900 mg/kg in the 60-d preliminary study.)


DEGRADATION OF NP:
- Triplicate measurements at the end of the study for treatments with 47 mg/kg initial concentration
- final NP soil concentration decreased by approximately 90%, to 4.5 +/- 3.3 mg/kg (mean 95% CI of triplicate column microcosms) for the planted, 1.5 +/- 1.0 mg/kg for the unplanted, and 5.26 +/- 3.84 for the unplanted poisoned.
- The lack of statistical difference between treatments (planted, unplanted, and unplanted poisoned) indicates either that the mercuric chloride poisoning was not effective in significantly slowing down biodegradation or that abiotic loss mechanisms, such as volatilization, hydrolysis, or decrease in extractability associated with nonequilibrium sorption processes, played a role in the 90 % reduction in NP concentration
- As volatilization is unlikely (see below) and NP is resistant to hydrolysis, biotransformation or decreasing extractability because of nonequilibrium sorption processes are the most likely mechanism associated with the reduction of NP concentrations in the soil.


VOLATILIZATION
- Based on the 14C mass recovery and hydrophobic nature of the NP (strongly sorbs to soil), however, large losses from volatilization are unlikely

Results with reference substance:

The reference compound phenol was 53 +/- 1.9 % (average 95 % CI) mineralized after 75 d.

Conclusions:

The extent of mineralization varied with compound, ranging from 7% (NP) to 53% (phenol), but was independent of the initial exposure concentration of 6 to 47 mg/kg. The presence of crested wheatgrass did not enhance the percentage mineralization. Degradation of NP in soil based on test material analyses was 90 % at the end of the study. Calculated half-lives for NP averaged from 31 to 51 d in the various planted, unplanted, and unplanted poisoned systems. The results for biodegradation of 4-NP in soil are adequate for the purpose of classification and labelling and/or risk assessment under REACH.

Executive summary:

Microcosm experiments (duration, 150 d) were conducted to evaluate the mineralization and plant uptake of [14C]nonylphenol (NP) in a soil/biosolids (99.5:0.5 w/w) environment planted with crested wheatgrass (Agropyron cristatum) under aerobic conditions.

Three initial nominal concentrations (6, 24, and 47 mg/kg dry wt) of NP were examined along with unplanted and unplanted poisoned controls. Phenol (22 mg/kg) also was evaluated as a more degradable reference compound. The biosolids were obtained from a municipal treatment plant, and the loamy sand soil was freshly collected. Incubation was conducted at a day/night temperature of 20/16 +/- 1°C and a 16:8-h light:dark photoperiod.

Mineralization ranged from 7% for NP to 53% for phenol, but was independent of the initial exposure concentration of 6 to 47 mg/kg. The presence of crested wheatgrass did not enhance the percentage mineralization.

Degradation of NP in soil based on test material analyses was 90 % at the end of the study.

Calculated half-lives for NP averaged from 31 to 51 d in the various planted, unplanted, and unplanted poisoned systems.

Reference 6

Endpoint:

biodegradation in soil, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

In accordance with Regulation (EC) 1907/2006 Annex XI (1.5) and the relevant ECHA guidance documents, the substances detailed in the table below are grouped for the purposes of read across to reduce the need for unnecessary repeat testing on the basis that the substances are similar on the basis of a common functional groups.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Soil No.:

#9

% Degr.:

64

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#8

% Degr.:

84

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#9

% Degr.:

97.8

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#8

% Degr.:

99.1

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#3

% Degr.:

>= 82 - <= 91.7

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#2

% Degr.:

>= 74 - <= 87

Parameter:

test mat. analysis

Sampling time:

30 d

Soil No.:

#1

% Degr.:

99

Parameter:

test mat. analysis

Sampling time:

110 d

Soil No.:

#1

% Degr.:

45

Parameter:

test mat. analysis

Sampling time:

10 d

Soil No.:

#6

% Degr.:

ca. 38

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#5

% Degr.:

ca. 35

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#4

% Degr.:

ca. 37

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#3

% Degr.:

>= 42 - <= 45

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#2

% Degr.:

>= 42 - <= 48

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#1

% Degr.:

ca. 42

Parameter:

radiochem. meas.

Remarks:

14CO2

Sampling time:

40 d

Soil No.:

#1

% Degr.:

90

Parameter:

CO2 evolution

Sampling time:

150 d

Soil No.:

#1

% Degr.:

>= 62 - <= 89

Parameter:

test mat. analysis

Sampling time:

40 d

Soil No.:

#1

DT50:

>= 31 - <= 51 d

Type:

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

Remarks on result:

other: Assuming first-order disappearance kinetics, half-lives for NP averaged from 31 to 51 d in the various planted, unplanted, and unplanted poisoned systems.

Soil No.:

#5

DT50:

4.5 d

Type:

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

Remarks on result:

other: minimum half-life of all six soils analysed

Soil No.:

#3

DT50:

16.27 d

Type:

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

Remarks on result:

other: Maximum half-life of all six soils examined

Soil No.:

#1

DT50:

37 d

Type:

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

Remarks on result:

other: 95 % confidence level: 31-46 days

Transformation products:

yes

No.:

#1

No.:

#1

Conclusions:

The read across for 4-tert-octylphenol (CAS: 140-66-9); is based upon the analogous substances to which basic form, degree of substitution of functional groups is not considered to effect the proposed read across for the endpoint of biodegradation in soil. Based on the information available for the read across substances, the substance is likely to be biodegradable in soils with rapid degradation in well-aerated soils.

Description of key information

As no data for biodegradation in soil of 4-tert-Octylphenol (PTOP) are available, read-across was performed using 4-Nonylphenol (NP) as source substance. 

Additional information

The read-across approach for biodegradation in soil is based on the structural similarity: both substances consist of a branched alkyl chain attached to hydroxybenzene in the para-position. In contrast to NP, which has nine carbon atoms in the variably branched alkyl chain, PTOP consist of eight carbon atoms in the alkyl chain and has only one isomer. Besides the branched chain isomers, there exist also linear isomers for NP as well as for PTOP (4-n-NP and 4-n-PTOP, respectively). 

NP and PTOP have only one functional group which is in both substances the same hydroxyl group. Therefore, the reliability of a read-across is not negatively influenced by this functional group.

With respect to their physico-chemical properties NP and PTOP have, apart from the melting point and therefore physical form at room temperature, similar properties regarding molecular formula and weight, water solubility, boiling point, relative density, vapour pressure, and n-octanol/water partition coefficient. Both substances have a log Kow > 3 and <6.

In conclusion PTOP and NP are in very good agreement with regards to their physico-chemical properties and should therefore show similar behaviour in the environment.

A read-across approach for biodegradation in soil is supported by the UK “Environmental Risk Evaluation Report 2005: 4-tert-Octylphenol”, 2005, which states (p. 41): “Although the release pattern of 4-tertoctylphenol is generally less widespread than that of nonylphenol, its similar chemical structure combined with the fact that it can be a significant impurity in nonylphenol probably means that some degree of general acclimation of microbial populations has occurred.” Therefore, it can be assumed that NP and PTOP can be degraded similarly.

Moreover, the read-across is based on the comparison of the study results for IUCLID sections 5.2.1 (Biodegradation in water: screening tests) and 5.2.2 (Biodegradation in water and sediments: simulation tests) of both substances (see Table 2).

From tests for ready biodegradability both substances can be classified as inherently biodegradable. In simulations tests for Biodegradation in water and sediments PTOP and NP are both not biodegradable in marine sediments and river bed sediments under anaerobic conditions. In contrary both chemicals are biodegradable in marine sediments, river bed sediments, and in the water column under aerobic conditions. Reported half-lives of PTOP and NP in the respective compartments are within the same range (see Table 3 for result summary). Therefore, it can be concluded that PTOP and NP show very similar degradation behaviour.

Table 1: Physico-chemical properties of PTOP and NP

	PTOP (Information from ERA 2005)	NP (Information from EU RAR 2002)
Identification of the substance	CAS number: 140-66-9 EINECS number: 205-426-2 IUPAC name: 4-tert(iary)-Octylphenol EINECS name: 4-(1,1,3,3-Tetramethylbutyl)phenol Molecular formula: C14H22O Structural formula: HO-C6H4-C8H17, where C6H4is a benzene unit substituted at the 1,4-position.	CAS Number: 84852-15-3 and 25154-52-3 EINECS Number: 284-325-5 and 246-672-0 IUPAC Name: 4-Nonyl phenol (branched) and Nonylphenol Molecular formula: C15H24O Structural formula:
Molecular weight	206.33 g/mole	220.34 g/mole
Purity	99.2 % (SIDS, 1994)	90 % (w/w) Impurities: 2-Nonylphenol 5% w/w                    2,4-Dinonylphenol 5% w/w
Additives	No reported additives	No reported additives
Physical state	Solid at 20 °C and 101.3 kPa (SIDS, 1994) ; Exists as white or light pink flakes	Commercially produced nonylphenol is a clear to pale yellow viscous liquid with a slight phenolic odour.
Melting Point	79 – 82 °C Intermediate value: 80.5 °C	-8 °C
Boiling Point	281.5 °C (intermediate value considered representative)	Studies conducted to GLP (Roy F. Weston Inc., 1990a) suggest that some thermal decomposition occurs before the boiling point (>300°C) is reached and hence this material may not have a specific boiling range.   The boiling range has been quoted as 290-302°C (Hüls, 1994); 287-306°C, with decomposition (Industrial Chemicals, 1975); 293-297°C(Merck Index, 1989); and 295°C (ICI, 1995). Other values include 295°C(Dutch Institute for the Working Environment, 1991) and 310°C (Kirk- Othmer, 1993).    The actual boiling/decomposition range will depend on the purity and origin of the material and the values quoted here can be considered representative of the commercially available material.
Relative density	The relative density at 20°C has been quoted as 0.95 (Hüls AG cited in SIDS, 1994 and IUCLID, 2000), but no method was specified. Waern (2000) gives a value of 0.92, but no information on the method or temperature was provided and it was not possible to determine the original reference for this value.	0.95 at 20 °C
Vapour pressure	0.21 Pa (this is the value which was preferred in the ERA 2005)	0.3 Pa at 25°C
Water solubility	19 mg/L (very low water solubility)	6 mg/l at 20 °C (very low water solubility)
n-Octanol/Water partition coefficient	Log Kow= 4.12 at 20.5 °C (determined according to OECD 107)	Log Kow = 4.48

 

Table 2: Summary of Ready Biodegradability of Octylphenol and Nonylphenol

Compound (CAS Number)	Purity [%]	Test Method	Result	10-Day Window?	Biodegradability Classification	Reference
Octylphenol
Octylphenol (140-66-9)	98.97	OECD 302C (MITI (II)) non-GLP	0 % degradation in 28 d	n.a.	Not inherently biodegradable (distinctive and unnatural inoculum used => result should not be used for categorization of the persistence of PTOP	Sewell (1991)
Octylphenol (140-66-9)	99.64	OECD 301B (CO2Evolution Test) GLP	62 % degradation in 28 d	Failing	Ready biodegradable	Gledhill (1999) Staples (2001)
Octylphenol (27193-28-8)	95.6	BOD Test for Insoluble Substances (O2Consumption) GLP	20 % degradation in 28 d	n.a.	Inherently biodegradable	Scholz (1991)
Nonylphenol
Nonylphenol (84852-15-3)	Reagent grade	OECD 301B (CO2Evolution Test) GLP	47.5 % degradation in 28 d	n.a.	Inherently biodegradable	Gledhill (1999) Staples (2001)
Nonylphenol (84852-15-3)	95.6	OECD 301F (Ready Biodegrad-ability: Manometric Respirometry Test) GLP: no data	62 % degradation in 28 d	Failing	Ready biodegradable	Staples (1999)

n.a. = not applicable

Table 3: Summary of Biodegradation in Water and Sediments

Compound (CAS Number)	Purity [%]	Test Method	Result	Medium	Experimental Conditions	Reference
Octylphenol
Octylphenol (4-tert-Octylphenol; CAS No. not reported)	97	Water: Similar to OECD 309 (Aerobic Minerali-sation in Surface Water - Simulation Biodegradation Test)   Sediment: Similar to EPA OPPTS 835.5154 (Anaerobic Biodegradability in the Subsurface)   non-GLP	River water, aerobic: Half-lives: 8 – 50 d   Bed sediments, anaerobic: No biodegradation	Freshwater and bed sediment	Temperature: 20 °C Oxygen: aerobic / anaerobic	Johnson (2000)
Octylphenol (4-tert-Octylphenol; CAS No. not reported)	Not reported	EPA OPPTS 835.3180 (Sediment / Water Microcosm Biodegradation Test); non-GLP	Seawater, aerobic: Half-life = 60 d;   Marine sediment, aerobic: Half-life > 20 d;   Marine sediment, anaerobic: No degradation	Seawater and marine sediment	Temperature: 20 °C Oxygen: aerobic / anaerobic	Ying (2003)
Nonylphenol
Nonylphenol (CAS No. not reported)	98	Similar to EPA OPPTS 835.5154 (Anaerobic Biodegradability in the Subsurface) non-GLP	Degradation rate constant: 0.010 – 0.015 d^-1­   Half-life: 46.2 – 69.3 d	Freshwater sediment	Temperature: 30 °C Oxygen: anaerobic	Chang (2004)
Nonylphenol (CAS No. not reported)	98	Similar to EPA OPPTS 835.3180 (Sediment / Water Microcosm Biodegradation Test) non-GLP	Degradation rate constant: 0.0007 – 0.051 d^-1­   Half-life: 13.6 – 99.0 d (deceleration of degradation caused by heavy metal application)	Freshwater sediment	Temperature: 20 - 50 °C Oxygen: aerobic	Yuan (2004)
Nonylphenol (4-n-nonylphenol; linear isomer)	> 99	EPA OPPTS 835.3180 (Sediment / Water Microcosm Biodegradation Test) non-GLP	Oxic conditions: > 90 % in 32 d;   Anoxic conditions: No biodegradation within 154 d	Freshwater sediment	Temperature: 23 °C Oxygen: aerobic / anaerobic	Bradley (2008)
Nonylphenol (CAS No. not reported)	> 94	Microcosm experiments with NP polluted river sediments; non-GLP	> 95 % degradation in 8 d   Half-life: 1.1 - 1.9 d	Freshwater sediment	Temperature: 30 °C Oxygen: aerobic	DeWeert (2009)
Nonylphenol (mixture of different branched isomers)	No data	Similar to OECD 309 (Aerobic Minerali-sation in Surface Water - Simulation Biodegradation Test); non-GLP	Seawater: 50 % degradation in 58 d   Seawater + sediment: 44 % degradation in 58 d (lack of oxygen)	Seawater and marine sediment	Temperature: 11 °C Oxygen: aerobic	Ekelund (1993)
4-n-Nonylphenol	No data	Similar to EPA OPPTS 835.3180 (Sediment / Water Microcosm Biodegradation Test), and similar to OECD 309 (Aerobic Minerali-sation in Surface Water - Simulation Biodegradation Test); non-GLP	Seawater, aerobic: Half-life = 5 d;   Marine sediment, aerobic: Half-life = 5.8 d; > 98 % degradation within 1 week   Marine sediment, anaerobic: No degradation	Seawater and marine sediment	Temperature: 20 °C Oxygen: aerobic / anaerobic	Ying (2003)

 

The available Nonylphenol data indicate that nonylphenol undergoes biodegradation in soil systems. The mineralization of NP is not dependent of the initial concentration except for very high concentrations (e.g. 1000 mg/kg, Trocmé et al., 1988) which inhibit biodegradation of NP because of toxicity to micro-organisms.

Moreover, NP degradation in soils is dependent on soil temperature and soil moisture conditions (Topp et al., 2000) as well as on oxygen conditions. NP degradation was limited due to lack of oxygen because of high BOD of high concentrations of sewage sludge.

A factor that is important for NP biodegradation is that the nonylphenol supplied is a mixture of compounds with differing degrees of branching/isomers in the nonyl chain. In general increased branching in alkyl chains reduces biodegradability and so it may be expected that linear NP isomers degrade faster than branched NP isomers. In the degradation results of Trocmé et al. (1988) some direct evidence for this was found in the chromatographic analysis of nonylphenol at various times during the test (some nonylphenol peaks decreased faster than others). According to the UK Risk Assessment Report on 4-nonylphenol (branched) and nonylphenol, p. 60, “such an effect may explain why in many of the tests the degradation of nonylphenol appears to follow two or more “phases”, with an initial relatively rapid removal of nonylphenol followed by one or more slower phases of removal, although there are many other possible explanations for such behaviour (e.g. a reduction of viability of micro-organisms with time)”. 

Test with ring-labeled [¹⁴C]nonylphenol demonstrate that not only the alkyl chain is subject to degradation but also the aromatic ring.

The overall conclusion from the nonylphenol data is that nonylphenol is biodegradable in soils and would be rapidly dissipated in well-aerated soils following application of sewage sludge. Reported half-lives for NP degradation in soil were between 4.5 and 51 d.

For Octylphenol it can therefore be concluded by read-across from nonylphenol, that this substance is likely to be biodegradable in soils with rapid degradation in well-aerated soils.