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

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants, 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

Species:

Lolium perenne

Duration:

15 d

Dose descriptor:

EC10

Effect conc.:

738.9 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Fresh weight of seedling

Remarks on result:

other: (49.6, 11011.2)

Species:

Brassica rapa

Duration:

15 d

Dose descriptor:

EC10

Effect conc.:

574.8 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Fresh weight of seedling

Remarks on result:

other: (279.9, 1180.4)

Species:

Lactuca sativa

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

625 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Species:

Lactuca sativa

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

559 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

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 Toxicity to terrestrial plants. Based on the information available for the read across substances, the substance is expected to be toxic to terrestrial plants.

Reference 2

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions which do not impair the overall conclusion from the data.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No Data

Analytical monitoring:

yes

Details on sampling:

The concentrations of most compounds were analysed at the start of the tests to verify the added concentrations, and at the end of the test to detect any decrease in concentration due to degradation or volatilisation.

Vehicle:

not specified

Details on preparation and application of test substrate:

No Data

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

-Common Name: Lettuce
- Variety: Ravel R2

Test type:

early seedling growth toxicity test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

14 d

Post exposure observation period:

No Data

Test temperature:

21 °C +/- 4 °C

pH:

7.5

Moisture:

25% to 30% moisture content

Details on test conditions:

TEST SYSTEM
- Duplicates: Duplicate vessels were used for the control and for at least 3 test concentrations
- Test volume per vessel: 0.25 L containing 400 g of soil
- No. of seeds per vessel: 10

TEST MEDIUM PARAMETERS
- Evaporation of water was compensated daily by adding demineralised water
- Water content and pH of soil were checked at the start and end of the test
- Storage Conditions: Plants were cultured in climatic chambers to maintain a test temperature of 21 °C
- Humidity: Varied between 40% and 80%

SOURCE AND PROPERTIES OF SUBSTRATE
- Geographic location: An orchard, although exact geographic location is not provided.
- Collection procedures: Two collections of soil were made although the characteristics of the soils differed between collections. Soils from the first collection agreed with the specification of OECD Guideline 208.
- Soil texture (if natural soil) of the first collection:
- % organic matter content: 1.4%
- % clay: 12%
- pH: 7.5

- Soil texture (if natural soil) of the second collection:
- % organic matter content: 1.8%
- % clay: 24%
- pH: 7.5

- Pretreatment of soil: Soils were 4-mm sieved before the start of the tests.

NUTRIENT MEDIUM (if used)
- Description: K2HPO4 had to be added to the second soil collection to achieve good plant growth.

Nominal and measured concentrations:

Nominal concentrations in mg/kg dry soil were spaced by a factor of 3.2

Reference substance (positive control):

not specified

Species:

Lactuca sativa

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

625 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

No Data

Results with reference substance (positive control):

No Data

Reported statistics and error estimates:

The concentration at which growth was 50% of the control (EC50) was calculated by applying a logistic model according to Haanstra (1985). Haanstra, Doelman L.P and Oude Voshaar J.H (1985) The use of sigmoidal dose response curves in soil ecotoxicological research, Plant Soil 82: 293-297.

Validity criteria fulfilled:

yes

Conclusions:

In general, the EC50 values in soil decreased rather than increased between days 7 and 14 of exposure. The authors also compared the soil and nutrient water exposures concluding that effect levels determined in nutrient solution cannot directly be related to soil concentrations.

Executive summary:

In a 14-day chronic toxicity study, lettuce (Lactuca sativa) were exposed at control, and at least three test concentrations spaced by a factor of 3.2 in natural soil. The EC₅₀based on plant growth was 625 mg nonylphenol/kg. Based on the results of this study, nonylphenol would be considered to have adverse effects on the growth of Lactuca sativa.

This study is classified as acceptable and is similar in methodology to the requirements of the OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test).

Reference 3

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions which do not impair the overall conclusion from the data. The study meets the requirements of the REACH Endpoint 9.4.3.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No Data

Analytical monitoring:

yes

Details on sampling:

The concentrations of most compounds tested were analysed at the start of the tests to verify the added concentrations, and at the end of the test to detect any decrease in concentration due to degradation or volatilisation.

Vehicle:

not specified

Details on preparation and application of test substrate:

No Data

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

-Common Name: Lettuce
- Variety: Ravel R2

Test type:

early seedling growth toxicity test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

7 d

Post exposure observation period:

No Data

Test temperature:

21 °C +/- 4 °C

pH:

7.5

Moisture:

25% to 30% moisture content

Details on test conditions:

TEST SYSTEM
- Duplicates: Duplicate vessels were used for the control and for at least 3 test concentrations
- Test volume per vessel: 0.25 L containing 400 g of soil
- No. of seeds per vessel: 10

TEST MEDIUM PARAMETERS
- Evaporation of water was compensated daily by adding demineralised water
- Water content and pH of soil were checked at the start and end of the test
- Storage Conditions: Plants were cultured in climatic chambers to maintain a test temperature of 21 °C
- Humidity: Varied between 40% and 80%

SOURCE AND PROPERTIES OF SUBSTRATE
- Geographic location: An orchard, although exact geographic location is not provided.
- Collection procedures: Two collections of soil were made although the characteristics of the soils differed between collections. Soils from the first collection agreed with the specification of OECD Guideline 208.
- Soil texture (if natural soil) of the first collection:
- % organic matter content: 1.4%
- % clay: 12%
- pH: 7.5

- Soil texture (if natural soil) of the second collection:
- % organic matter content: 1.8%
- % clay: 24%
- pH: 7.5

- Pretreatment of soil: Soils were 4-mm sieved before the start of the tests.

NUTRIENT MEDIUM (if used)
- Description: K2HPO4 had to be added to the second soil collection to achieve good plant growth.

Nominal and measured concentrations:

Nominal concentrations in mg/kg dry soil were spaced by a factor of 3.2

Reference substance (positive control):

not specified

Species:

Lactuca sativa

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

559 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

- In soil, the analysed concentrations of the compounds, including nonylphenol, at t=0 were generally in agreement with the nominal concentrations, mostly 70 to 150%, although the lower values were considered to relate to the volatilisation of chlorobenzenes also tested in this study.

Results with reference substance (positive control):

No Data

Reported statistics and error estimates:

The concentration at which growth was 50% of the control (EC50) was calculated by applying a logistic model according to Haanstra (1985).

Haanstra, Doelman L.P and Oude Voshaar J.H (1985) The use of sigmoidal dose response curves in soil ecotoxicological research, Plant Soil 82: 293-297.

This study provides the only reliable short-term data available for the REACH endpoint 9.4.3 (Short-Term Toxicity to Terrestrial Plants). Long-term results from the same study are reported in this IUCLID dossier.

Validity criteria fulfilled:

yes

Conclusions:

In general, the EC50 values in soil decreased rather than increased between days 7 and 14 of exposure. The authors also compared the soil exposures with nutrient water exposures concluding that effect levels determined in nutrient solution cannot directly be related to soil concentrations.

Executive summary:

In a 7-day chronic toxicity study, lettuce (Lactuca sativa) were exposed at control, and at least three test concentrations spaced by a factor of 3.2 in natural soil. The EC₅₀ based on plant growth was 559 mg nonylphenol/kg. Based on the results of this study, nonylphenol would be considered to have adverse effects on the growth of Lactuca sativa.

This study is classified as acceptable and is similar in methodology to the requirements of the OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test).

Reference 4

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Spring 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is comparable to a guideline study.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data

Analytical monitoring:

no

Details on sampling:

- Concentrations: The test concentrations were selected following a preliminary assay consisting of 0, 1, 10, 100, 1000 and 10000 mg of nonylphenol per kg of soil. The range of concentrations showing an inhibition between 10% and 90% were selected for the main study.

Vehicle:

yes

Details on preparation and application of test substrate:

- Controls: Two control soils were prepared; one negative control and one solvent control to which the same volume of acetone was added as was used in the test substance concentrations.
- Chemical name of vehicle (solvent): Nonylphenol was applied to soils dissolved in acetone (95%, Panreac, Barcelona, Spain).
- Evaporation of vehicle before use: To prepare the concentrations of test substance, the amount of soil to be used for each concentration was moistened with a fixed volume of acetone solution containing the appropriate quantity of nonylphenol. Acetone was then left to evaporate for 24 hours in a fume hood.

Species:

Lolium perenne

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

- Common name: Ryegrass

Test type:

seedling emergence toxicity / vegetative vigour test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

15 d

Remarks:

Plants were incubated for 15 days following 50% of the plants having germinated in the controls.

Post exposure observation period:

No data

Test temperature:

21 °C

pH:

6.2 +/- 0.5 (as per OECD Artificial Soil) adjusted using calcium carbonate

Moisture:

- Water holding capacity: 44.8%
- Water content adjusted to 60% of maximum water holding capacity

Details on test conditions:

TEST SYSTEM
- Testing facility: Universitat Autonoma de Barcelona
- Test container (type, material, size): Each replicate consisted of a 250-ml polyethylene cup
- Amount of soil: 100 g of soil (dry weight)
- Method: Seeds were planted at 0.5 cm depth
- No. of seeds per container: 10 seeds per replicate
- No. of plants (retained after thinning): 5 seedlings were retained per replicate
- No. of replicates per treatment group: 5 replicates per concentration were prepared
- No. of replicates per control: Five replicates per control
- No. of replicates per vehicle control: Five replicates per vehicle control

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): OECD Artificial Soil
- Organic carbon (%): 3.45
- Maximum water holding capacity (in % dry weight): 44.8% adjusted to 60% WHC
- CEC: 8.94

GROWTH CONDITIONS
- Photoperiod: 16/8 hours (light/dark)
- Light source: Growth chamber at a constant 21 °C
- Relative humidity (%): 70%

Nominal and measured concentrations:

Nominal concentrations: The test concentrations were selected following a preliminary assay consisting of 0, 1, 10, 100, 1000 and 10000 mg of nonylphenol per kg of soil. The range of concentrations showing an inhibition between 10% and 90% were selected for the study.

Reference substance (positive control):

no

Species:

Lolium perenne

Duration:

15 d

Dose descriptor:

EC10

Effect conc.:

738.9 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Fresh weight of seedling

Remarks on result:

other: (49.6, 11011.2)

Details on results:

SEED GERMINATION
- Percent seed germination: 95.5% in the OECD soil controls

SEEDLING EMERGENCE
- Fresh weight of OECD controls: Mean of 219 mg with standard deviation of +/- 22 mg.
- Other effects: No signs of nutrient deficiency were observed.

No differences in the outcomes between controls with and without the addition of acetone were found in any of the assays.

Results with reference substance (positive control):

No data

Reported statistics and error estimates:

EC10 and EC50 (with 95% confidence intervals) were derived using Statistica 6.0 (StatSoft Inc., Tulsa, OK, USA).

This study (Domene et al., 2009) also reports results for another plant species, Brassica rapa (Key Study for this endpoint), also springtail, enchytraeid and earthworm species. Results for the other species are included in this IUCLID dossier. The EC₁₀ for the monocotyledon Lolium perenne is less sensitive when compared to the effects on plant weight to B. rapa (EC₁₀ of 738.9 mg/kg). The same trend was seen when the EC₅₀s for seed germination and plant weight were compared; L. perenne was consistently less sensitive than B. rapa (see table below).

Unlike the other species tested, no additional plant tests were carried out using the two natural soils because the authors stated that in plants nonylphenol generally showed inhibitory effects over 1 g/kg in OECD soil in the preliminary test. This is the concentration above which a pollutant is not considered to be toxic according to the OECD protocol used in the study, so no further testing was undertaken.

Additional Results

Toxicity values for EC₁₀ and EC₅₀s for germination and fresh weight, also for other species, are provided in the table below. Each species is entered into the IUCLID database.

Species	Endpoint	Soil	EC10	EC50
B. rapa	Freshweight	OECD	574.8 (279.9, 1,180.4)	1,449.1 (785.0, 2,674.7)
	Germination		695.9 (286.3, 1,691.6)	8,159.2 (5,904.0, 11,276.0)
L. perenne	Freshweight	OECD	738.9 (49.6, 11,011.2)	4,011.6 (862.2, 18,664.5)
	Germination		1,385.8 (696.5, 2,757.3)	7,500.7 (6,031.2, 9,328.3)
E. andreii	Survival	OECD	343.9 (160.6, 736.4)	625.5 (427.9, 914.1)
		PRA	182.4 (157.6, 211.2)	290.7 (272.0, 310.7)
		UAB	498.2 (439.2, 565.2)	622.0 (592.3, 653.2)
	Reproduction	OECD	55.8 (13.7, 227.7)	82.0 (47.6, 141.1)
		PRA	43.1 (26.9, 69.0)	69.6 (57.7, 83.9)
		UAB	63.6 (46.5, 87.1)	124.3 (110.5, 139.9)
	Biomass	OECD	88.3 (50.0, 155.8)	309.1 (240.4, 397.3)
		PRA	121.2 (93.6, 156.9)	240.2 (218.0, 264.8)
		UAB	289.4 (219.1, 382.4)	523.2 (474.5, 576.9)
E. crypticus	Survival	OECD	663.5 (444.9, 989.5)	906.7 (786.5, 1,045.3)
		PRA	214.5 (171.3, 268.6)	316.2 (284.9, 350.9)
		UAB	227.0 (89.5, 575.3)	615.2 (431.9, 876.3)
	Reproduction	OECD	24.0 (5.2, 110.7)	225.8 (134.8, 378.4)
		PRA	455.8 (311.2, 667.5)	641.7 (554.2, 742.9)
		UAB	197.2 (97.9, 397.3)	212.8 (194.6, 232.8)
F. candida	Survival	OECD	102.0 (69.7, 149.3)	138.7 (129.4, 148.7)
		PRA	52.3 (47.0, 58.1)	69.8 (65.8, 74.1)
		UAB	89.1 (70.0, 113.5)	116.3 (104.2, 129.8)
	Reproduction	OECD	63.2 (47.3, 84.5)	92.8 (83.8, 102.8)
		PRA	45.0 (27.5, 73.7)	64.4 (54.6, 75.9)
		UAB	54.8 (23.9, 125.7)	88.0 (79.9, 96.9)

Validity criteria fulfilled:

yes

Conclusions:

The authors considered nonylphenol to be more toxic than the nonylphenol ethoxylates mixture and considered the results to be in agreement with existing published literature. Nonylphenol presented low phytotoxicity but moderate toxicity to invertebrates, reproduction being clearly the most sensitive endpoint. Nonylphenol generally affected the invertebrates reproduction at lower concentrations than those affecting growth or survival. Earthworms and collembolans were more sensitive taxa compared to enchytraids.

Executive summary:

In a 15-day chronic toxicity study, monocotyledonous plants (Lolium perenne) were exposed to control, solvent control and nonylphenol at a range of concentrations showing inhibition between 10% and 90% from an initial range-finding test. The EC₁₀ based on fresh weight of the emergent seedling was 738.9 mg nonylphenol/kg, using an artificial soil test medium. Based on the results of this study, nonylphenol is not considered to be phytotoxic at the EC₅₀ level (4,011.6 mg/kg is greater than the 1 g/kg threshold of toxicity in the OECD protocol).

This study is classified as acceptable and is similar in methodology to the requirements of the OECD Guideline 208 (OECD, 2006).

Reference 5

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Spring 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is comparable to a guideline study.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data

Analytical monitoring:

no

Details on sampling:

- Concentrations: The test concentrations were selected following a preliminary assay consisting of 0, 1, 10, 100, 1000 and 10000 mg of nonylphenol per kg of soil. The range of concentrations showing an inhibition between 10% and 90% were selected for the main study.

Vehicle:

yes

Details on preparation and application of test substrate:

- Controls: Two control soils were prepared; one negative control and one solvent control to which the same volume of acetone was added as was used in the test substance concentrations.
- Chemical name of vehicle (solvent): Nonylphenol was applied to soils dissolved in acetone (95%, Panreac, Barcelona, Spain).
- Evaporation of vehicle before use: To prepare the concentrations of test substance, the amount of soil to be used for each concentration was moistened with a fixed volume of acetone solution containing the appropriate quantity of nonylphenol. Acetone was then left to evaporate for 24 hours in a fume hood.

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

- Common name: Field mustard or turnip mustard

Test type:

seedling emergence toxicity / vegetative vigour test

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

yes

Total exposure duration:

15 d

Remarks:

Plants were incubated for 15 days following 50% of the plants having germinated in the controls.

Post exposure observation period:

No data

Test temperature:

21 °C

pH:

6.2 +/- 0.5 (as per OECD Artificial Soil) adjusted using calcium carbonate

Moisture:

- Water holding capacity: 44.8%
- Water content adjusted to 60% of maximum water holding capacity

Details on test conditions:

TEST SYSTEM
- Testing facility: Universitat Autonoma de Barcelona
- Test container (type, material, size): Each replicate consisted of a 250-ml polyethylene cup
- Amount of soil: 100 g of soil (dry weight)
- Method: Seeds were planted at 0.5 cm depth
- No. of seeds per container: 10 seeds per replicate
- No. of plants (retained after thinning): 5 seedlings were retained per replicate
- No. of replicates per treatment group: 5 replicates per concentration were prepared
- No. of replicates per control: Five replicates per control
- No. of replicates per vehicle control: Five replicates per vehicle control

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Composition (if artificial substrate): OECD Artificial Soil
- Organic carbon (%): 3.45
- Maximum water holding capacity (in % dry weight): 44.8% adjusted to 60% WHC
- CEC: 8.94

GROWTH CONDITIONS
- Photoperiod: 16/8 hours (light/dark)
- Light source: Growth chamber at a constant 21 °C
- Relative humidity (%): 70%

Nominal and measured concentrations:

Nominal concentrations: The test concentrations were selected following a preliminary assay consisting of 0, 1, 10, 100, 1000 and 10000 mg of nonylphenol per kg of soil. The range of concentrations showing an inhibition between 10% and 90% were selected for the study.

Reference substance (positive control):

no

Species:

Brassica rapa

Duration:

15 d

Dose descriptor:

EC10

Effect conc.:

574.8 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Fresh weight of seedling

Remarks on result:

other: (279.9, 1180.4)

Details on results:

SEED GERMINATION
- Percent seed germination: 97.5% in the OECD soil controls

SEEDLING EMERGENCE
- Fresh weight of OECD controls: Mean of 854 mg with standard deviation of +/- 119 mg.
- Other effects: No signs of nutrient deficiency were observed.

No differences in the outcomes between controls with and without the addition of acetone were found in any of the assays.

Results with reference substance (positive control):

No data

Reported statistics and error estimates:

EC10 and EC50 (with 95% confidence intervals) were derived using Statistica 6.0 (StatSoft Inc., Tulsa, OK, USA).

No tests were carried out using the two natural soils (unlike in the earthworm, collembola and enchyraeid tests in the Domene et al., 2009 study) because in plants nonylphenol generally showed inhibitory effects over 1 g/kg in OECD soil in the preliminary test. This is the concentration above which a pollutant is not considered to be toxic according to the OECD protocol used in the study.

 

Validity criteria fulfilled:

yes

Conclusions:

The authors considered nonylphenol to be more toxic than the nonylphenol ethoxylates mixture and considered the results to be in agreement with existing published literature. Nonylphenol presented low phytotoxicity but moderate toxicity to invertebrates, reproduction being clearly the most sensitive endpoint. Nonylphenol generally affected the invertebrates reproduction at lower concentrations than those affecting growth or survival. Earthworms and collembolans were more sensitive taxa compared to enchytraids.

Executive summary:

In a 15-day chronic toxicity study, dicotyledonous plants (Brassica rapa) were exposed to control, solvent control and nonylphenol at a range of concentrations showing inhibition between 10% and 90% from an initial range-finding test. The EC₁₀ based on fresh weight of the emergent seedling was 574.8 mg nonylphenol/kg, using an artificial soil test medium. Based on the results of this study, nonylphenol is not considered to be phytotoxic at the EC₅₀ level (1,449.1 mg/kg is greater than the 1 g/kg threshold of toxicity in the OECD protocol).

This study is classified as acceptable and is similar in methodology to the requirements of the OECD Guideline 208 (OECD, 2006).

Description of key information

A 7-day short-term toxicity test using Lactuca sativa reported an EC50 for growth of 559 mg nonylphenol/kg (Hulzebos et al., 1993). The key information for long-term effects to plant relates to the Domene et al., (2009) study where the most sensitive endpoint was a test on Lolium perenne with an EC10 based fresh weight of 574.8 mg nonylphenol/kg.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

559 mg/kg soil dw

Long-term EC10, LC10 or NOEC for terrestrial plants:

574.8 mg/kg soil dw

Additional information

There were three reliable toxicity studies relating to six different species of terrestrial plants. Only one reliable short-term study was available where a 7-day test using Lactuca sativa reported an EC₅₀for growth of 559 mg nonylphenol/kg (Hulzebos et al., 1993). However, this result is more sensitive than the extended 14-day test in the same study where an EC₅₀of 625 mg/kg is reported. The Key Study is provided by Domeneet al., (2009) as this study was highly reliable (Klimisch 1) and fulfilled the information requirements for a Robust Study Summary. The 50% effect concentrations in the Hulzeboset al., (1993) study are similar to the EC₁₀results reported by Domeneet al., (2009). Effects on fresh weight inBrassica rapaandLolium perenneover a 15-day period resulted in calculated EC₁₀s of 574.8 and 738.9 mg nonylphenol/kg, respectively. This suggests that dicotyledonous plants are more sensitive than monocotyledons to nonylphenol toxicity. A number of factors differ between the long-term exposures in the Hulzebos and Domene studies including (i) the species, (ii) the effect levels and (iii) the soil type. In particular, Domeneet al., (2009) used artificial soils (the preferred test medium for REACH testing) whereas Hulzeboset al., (1993) employed natural soil with the potential to introduce further uncertainty due to the variation in natural soil properties to the Hulzebos experiment. It is difficult to make direct comparisons between the two studies due to these variations but the results do suggest that plants are likely to be affected by nonylphenol in soils where concentrations exceed 559 mg nonylphenol/kg. Domeneet al,. (2009) also reports EC₅₀values for seed germination in B. rapa and L. perenne of 8159.2 and 7500.7 mg/kg, respectively.

In summary, the reliable data present an inconsistent trend of the toxicity of nonylphenol to terrestrial plants, although the NOEC is expected to be around the 0.5g/kg level or more. Based on the arguments of data reliability, adequacy and sensitivity of test species, the key value for long-term plant exposure to nonylphenol and further hazard assessment is theL. perenneEC₁₀of 574.8 mg/kg. These results indicate that nonylphenol is slightly toxic to some plants at the EC₁₀protection level but not toxic at the EC₅₀level. More generally, plants are less sensitive to nonylphenol than soil invertebrates. These data are suitable for use in the octylphenol assessment.