Xylene

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Original study not reviewed but data taken from a reliable secondary source

Principles of method if other than guideline:

The Draft Screening Assessment Report (Environment Canada 2014) was prepared by Health Canada and Environment Canada and has undergone external written scientific peer review/consultation.

GLP compliance:

not specified

Remarks:

Record is a review of experimental evidence

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Analytical monitoring:

not specified

Details on sampling:

No data reported

Vehicle:

not specified

Details on preparation and application of test substrate:

Reported as coarse sandy loam soil recalculated for fine clay loam soil

Species:

other: Agropyron dasystachyum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Northern wheatgrass, Agropyron dasystachyum

Species:

other: Medicago sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Alfalfa, Medicago sativa

Test type:

other: root wet mass reduction

Substrate type:

not specified

Total exposure duration:

14 d

Remarks:

N/A

Post exposure observation period:

No data reported

Test temperature:

No data reported

pH:

No data reported

Moisture:

No data reported

Details on test conditions:

No data reported

Nominal and measured concentrations:

No data reported

Reference substance (positive control):

not specified

Key result

Species:

other: Agropyron dasystachyum

Duration:

14 d

Dose descriptor:

EC25

Effect conc.:

3 mg/kg soil dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Wet root mass reduction

Remarks on result:

other: Coarse sandy loam soil

Species:

other: Agropyron dasystachyum

Duration:

14 d

Dose descriptor:

EC25

Effect conc.:

218 mg/kg soil dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Wet root mass reduction

Remarks on result:

other: Fine clay loam soil

Species:

other: Medicago sativa

Duration:

14 d

Dose descriptor:

EC25

Effect conc.:

462 mg/kg soil dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Wet root mass reduction

Remarks on result:

other: Coarse sandy loam soil

Species:

other: Medicago sativa

Duration:

14 d

Dose descriptor:

EC25

Effect conc.:

316 mg/kg soil dw

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Wet root mass reduction

Remarks on result:

other: Fine clay loam soil

Details on results:

In terms of soil toxicity to plants, the ESG and Komex studies reported the most sensitive endpoint for northern wheatgrass, Agropyron dasystachyum, to be significantly reduced root wet mass, with 14-day IC25 values of 3 mg/kg dw for coarse sandy loam soil and 218 mg/kg dw for fine clay loam soil (ESG International, Inc. 2002; Komex International Ltd. 2002, see original data source for reference). The most sensitive endpoint for alfalfa, Medicago sativa, was a significant reduction in root length, with 14-day IC25 values of 462 and 316 mg/kg dw for coarse sandy loam and fine clay loam, respectively.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Reported as coarse sandy loam soil recalculated for fine clay loam soil

N/A

Validity criteria fulfilled:

not applicable

Conclusions:

The Draft Screening Assessment Report (Environment Canada 2014) presents results from ESG International (2002) for the toxicity of ethylbenzene to Northern wheatgrass of 14 day EC25 of 3 mg/kg dw (coarse sandy loam).

Executive summary:

The Draft Screening Assessment Report (Environment Canada 2014) presents results from ESG International (2002) for the toxicity of ethylbenzene to Northern wheatgrass of 14 day EC25 of 3 mg/kg dw (coarse sandy loam). The Northern Wheatgrass value was taken by Environment Canada as the critical toxicity value for ethylbenzene toxicity to terrestrial species. The ESG and Komex studies reported the most sensitive endpoint for northern wheatgrass, Agropyron dasystachyum, to be significantly reduced root wet mass, with 14-day EC25 values of 3 mg/kg dw for coarse sandy loam soil and 218 mg/kg dw for fine clay loam soil (ESG International, Inc. 2002; Komex International Ltd. 2002). The most sensitive endpoint for alfalfa, Medicago sativa, was a significant reduction in root length, with 14-day EC25 values of 462 and 316 mg/kg dw for coarse sandy loam and fine clay loam, respectively.

The Draft Screening Assessment Report (Environment Canada 2014) was prepared by the Existing Substances programs at Health Canada and Environment Canada and has undergone external written scientific peer review/consultation. Data was taken from literature searches up to December 2009 for ecological sections, and review and assessment documents. When available and relevant, information presented in hazard assessments from other jurisdictions was considered. The key studies were critically evaluated, with the screening assessment presenting the most critical studies and lines of evidence pertinent to the conclusion.

Reference 2

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Detailed information covering the calculation model, compositional data used as input, validity, applicability and adequacy of the result are in the attached document (Attached justification).
The Target Lipid Model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM have been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (Koc) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The registered substance is within the scope of the TLM and EqP frameworks.
The data source is used as part of a weight of evidence approach. Please refer to the 'Attached justification' section for a detailed weight of evidence document.

Qualifier:

no guideline required

Principles of method if other than guideline:

The endpoint calculated is the LL50, EL50, and NOELR -
The narcosis TLM was developed to predict the toxicity of chemicals to aquatic organisms that act via narcosis. It is based on the hypothesis that target lipid is the site of toxic action within the organism, that octanol is the appropriate surrogate, and that target lipid has the same physical–chemical properties in all organisms.
The approach describes:
• The theory and how to predict the acute toxicity to these organisms;
• Development of an Acute to Chronic ratio [ACR] for only hydrocarbons and for 29 data points.


The logkow used for calculation:
m- xylene= 3.20

GLP compliance:

no

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on preparation and application of test substrate:

N/A

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

N/A

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

N/A

Remarks:

N/A

Post exposure observation period:

N/A

Test temperature:

N/A

pH:

N/A

Moisture:

N/A

Details on test conditions:

N/A

Nominal and measured concentrations:

N/A

Key result

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

56.759 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

10.873 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Key result

Species:

Brassica rapa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

36.646 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Brassica rapa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

7.02 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Validity criteria fulfilled:

yes

Conclusions:

The TLM-EqP predicted effect values for m-xylene were 36.636 and 7.020 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively to Brassica rapa, and 56.759 and 10.873 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively to Avena sativa. The target substance is a hydrocarbon acting via baseline toxicity, and falls within the parametric, structural and mechanistic domain of the model.

Executive summary:

The registered substance is highly volatile which complicates environmental testing. Therefore, a modeling framework is needed to account for the bioavailability of the substance to perform read-across and data gap filling. The TLM-EqP modeling has been validated as a suitable method for predicting effect values in terrestrial plants. The TLM-EqP predicted effect values for m-xylene were 56.759 and 10.873 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Avena sativa, respectively. The TLM-EqP predicted effect values for m-xylene were 36.646 and 7.020 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Brassica rapa, respectively.

Reference 3

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Detailed information covering the calculation model, compositional data used as input, validity, applicability and adequacy of the result are in the attached document (Attached justification).
The Target Lipid Model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM have been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (Koc) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The registered substance is within the scope of the TLM and EqP frameworks.
In addition, the data source is used as part of a weight of evidence approach. Please refer to the 'Attached justification' section for a detailed weight of evidence document.

Qualifier:

no guideline required

Principles of method if other than guideline:

The endpoint calculated is the LL50, EL50, and NOELR -
The narcosis TLM was developed to predict the toxicity of chemicals to aquatic organisms that act via narcosis. It is based on the hypothesis that target lipid is the site of toxic action within the organism, that octanol is the appropriate surrogate, and that target lipid has the same physical–chemical properties in all organisms.
The approach describes:
• The theory and how to predict the acute toxicity to these organisms;
• Development of an Acute to Chronic ratio [ACR] for only hydrocarbons and for 29 data points.

The logkow used for calculation:
o-xylene= 3.12

GLP compliance:

no

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on preparation and application of test substrate:

N/A

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

N/A

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

N/A

Remarks:

N/A

Post exposure observation period:

N/A

Test temperature:

N/A

pH:

N/A

Moisture:

N/A

Details on test conditions:

N/A

Nominal and measured concentrations:

N/A

Key result

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

104.095 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

19.942 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Key result

Species:

Brassica rapa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

67.21 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Brassica rapa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

12.875 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Validity criteria fulfilled:

yes

Conclusions:

The TLM-EqP predicted effect values for m-xylene were 104 and 19.942 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively to Avena sativa, and 67.210 and 12.875 mg/kg soil dw for short term (14-day LL50) and long-term effects (21-day NOELR) respectively to Brassica rapa. The target substance is a hydrocarbon acting via baseline toxicity, and falls within the parametric, structural and mechanistic domain of the model.

Executive summary:

The registered substance is highly volatile which complicates environmental testing. Therefore, a modeling framework is needed to account for the bioavailability of the substance to perform read-across and data gap filling. The TLM-EqP modeling has been validated as a suitable method for predicting effect values in terrestrial plants. The TLM-EqP predicted effect values for o-xylene were 104.095 and 19.942 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Avena sativa, respectively. The TLM-EqP predicted effect values for m-xylene were 67.210 and 12.875 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Brassica rapa, respectively.

Reference 4

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Detailed information covering the calculation model, compositional data used as input, validity, applicability and adequacy of the result are in the attached document (Attached justification).
The Target Lipid Model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM have been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (Koc) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The registered substance is within the scope of the TLM and EqP frameworks.
In addition, please refer to the weight of evidence justification document for the 'Toxicity to terrestrial plants' endpoint.

Qualifier:

no guideline required

Principles of method if other than guideline:

The endpoint calculated is the LL50, EL50, and NOELR -
The narcosis TLM was developed to predict the toxicity of chemicals to aquatic organisms that act via narcosis. It is based on the hypothesis that target lipid is the site of toxic action within the organism, that octanol is the appropriate surrogate, and that target lipid has the same physical–chemical properties in all organisms.
The approach describes:
• The theory and how to predict the acute toxicity to these organisms;
• Development of an Acute to Chronic ratio [ACR] for only hydrocarbons and for 29 data points.


The logkow used for calculation:
p-xylene= 3.09

GLP compliance:

no

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on preparation and application of test substrate:

N/A

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

N/A

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

N/A

Remarks:

N/A

Post exposure observation period:

N/A

Test temperature:

N/A

pH:

N/A

Moisture:

N/A

Details on test conditions:

N/A

Nominal and measured concentrations:

N/A

Key result

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

104.095 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

19.942 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Key result

Species:

Brassica rapa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

67.21 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Brassica rapa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

12.875 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Validity criteria fulfilled:

yes

Conclusions:

The TLM-EqP predicted effect values for m-xylene were 67.210 and 12.875 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively to Brassica rapa, and 104.095 and 19.942 mg/kg soil dw for short-term (14-day LL50) and long-term effect (21-day NOELR) respectively Avena sativa. The target substance is a hydrocarbon acting via baseline toxicity, and falls within the parametric, structural and mechanistic domain of the model.

Executive summary:

The registered substance is highly volatile which complicates environmental testing. Therefore, a modeling framework is needed to account for the bioavailability of the substance to perform read-across and data gap filling. The TLM-EqP modeling has been validated as a suitable method for predicting effect values in terrestrial plants. The TLM-EqP predicted effect values for m-xylene were 104.095 and 19.942 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Avena sativa, respectively. The TLM-EqP predicted effect values for m-xylene were 67.210 and 12.875 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) to Brassica rapa, respectively.

Reference 5

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

The Target Lipid Model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. The TLM have been applied to soils and sediment using equilibrium partitioning (EqP) model. This framework utilizes organic carbon partition coefficients (Koc) to convert aquatic based effect levels (CW) to bulk soil- and sediment-based effect levels. The combined TLM-EqP framework was validated previously for soil and sediment acute and chronic toxicity endpoints. The registered substance is within the scope of the TLM and EqP frameworks.

Qualifier:

no guideline required

Principles of method if other than guideline:

The endpoint calculated is the LL50, EL50, and NOELR -
The narcosis TLM was developed to predict the toxicity of chemicals to aquatic organisms that act via narcosis. It is based on the hypothesis that target lipid is the site of toxic action within the organism, that octanol is the appropriate surrogate, and that target lipid has the same physical–chemical properties in all organisms.
The approach describes:
• The theory and how to predict the acute toxicity to these organisms;
• Development of an Acute to Chronic ratio [ACR] for only hydrocarbons and for 29 data points.


The logkow used for calculation:
xylene = 3.16

GLP compliance:

no

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on preparation and application of test substrate:

N/A

Species:

Avena sativa

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

N/A

Species:

Brassica rapa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

N/A

Remarks:

N/A

Post exposure observation period:

N/A

Test temperature:

N/A

pH:

N/A

Moisture:

N/A

Details on test conditions:

N/A

Key result

Species:

Avena sativa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

191.263 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Avena sativa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

36.64 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Key result

Species:

Brassica rapa

Duration:

14 d

Dose descriptor:

other: LL50

Effect conc.:

123.49 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

seedling emergence

Key result

Species:

Brassica rapa

Duration:

21 d

Dose descriptor:

other: NOELR

Effect conc.:

23.657 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Validity criteria fulfilled:

yes

Conclusions:

The TLM-EqP predicted effect values for m-xylene were 191.263 and 36.640 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively to Avena sativa, and 123.490 and 23.657 mg/kg soil dw for short term (14-day LL50) and long-term effects (21-day NOELR) respectively to Brassica rapa. The target substance is a hydrocarbon acting via baseline toxicity, and falls within the parametric, structural and mechanistic domain of the model.

Executive summary:

The registered substance is highly volatile which complicates environmental testing. Therefore, a modeling framework is needed to account for the bioavailability of the substance to perform read-across and data gap filling. The TLM-EqP modeling has been validated as a suitable method for predicting effect values in terrestrial plants.

The TLM-EqP predicted effect values for m-xylene were 191.263 and 36.640 mg/kg soil dw for short-term (14-day LL50) and long-term effects (21-day NOELR) respectively  to Avena sativa, and 123.490 and 23.657 mg/kg soil dw for short term (14-day LL50) and long-term effects (21-day NOELR) respectively to Brassica rapa.

Reference 6

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Original study not reviewed but data taken from a reliable secondary source

Principles of method if other than guideline:

The EU RAR (ECB 2007) was prepared by the German Competent Authority and peer-reviewed by SCHER. The report is considered to be a reliable source of information.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Analytical monitoring:

not specified

Details on sampling:

No data reported

Vehicle:

not specified

Details on preparation and application of test substrate:

No data reported

Species:

other: Phaseolus multiflorus

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Runner bean

Species:

other: Pastinaca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Parsnip

Test type:

other: Leaf death

Substrate type:

not specified

Total exposure duration:

1 h

Post exposure observation period:

No data reported

Test temperature:

No data reported

pH:

No data reported

Moisture:

No data reported

Details on test conditions:

The EU RAR (ECB 2007) discusses a single study on the toxicity of ethylbenzene to terrestrial plants via the atmosphere (Ivens, 1952, see original data source for reference). The study exposed the leaves of plants to concentrations of ethylbenzene as vapour for 1 hour.

Nominal and measured concentrations:

No data reported

Reference substance (positive control):

not specified

Key result

Species:

other: Phaseolus multiflorus

Duration:

1 h

Dose descriptor:

EC50

Effect conc.:

27 other: g/m3

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Leaf death

Key result

Species:

other: Pastinaca sativa

Duration:

1 h

Dose descriptor:

EC50

Effect conc.:

48 other: g/m3

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: Leaf death

Details on results:

The EU RAR (ECB 2007) discusses a single study on the toxicity of ethylbenzene to terrestrial plants via the atmosphere (Ivens, 1952, see original data source for reference). The study exposed the leaves of plants to concentrations of ethylbenzene as vapour for 1 hour and found that the NOEC was very close to the concentration which killed leaves completely. The reported EC50 are 27 g/m3 for runner bean (Phaseolus multiflorus) and 48 g/m^3 for parsnip (Pastinaca sativa).

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

No data reported

N/A

Validity criteria fulfilled:

not specified

Conclusions:

The EU RAR (ECB 2007) discusses a single study on the toxicity of ethylbenzene to terrestrial plants via the atmosphere (Ivens, 1952), which reported EC50 are 27 g/m^3 for runner bean (Phaseolus multiflorus) and 48 g/m3 for parsnip (Pastinaca sativa).

Executive summary:

The EU RAR (ECB 2007) discusses a single study on the toxicity of ethylbenzene to terrestrial plants via the atmosphere (Ivens, 1952). The study exposed the leaves of plants to concentrations of ethylbenzene as vapour for 1 hour and found that the NOEC was very close to the concentration which killed leaves completely. The reported EC50 are 27 g/m³ for runner bean (Phaseolus multiflorus) and 48 g/m3 for parsnip (Pastinaca sativa).

The European Risk Assessment Report (ECB 2007) was prepared by the German Competent Authority and interested companies following the methods set out in Commission Regulation (EC) 1488/94 and the associated Technical Guidance Document. The document had been peer-reviewed by the Scientific Committee on Health and Environmental Risks (SCHER) and therefore the report was considered to be a reliable source of information. Only studies which addressed the volatility of ethylbenzene (using flow through or closed systems with analytical measurement) were considered for inclusion in the review of the aquatic ecotoxicity data.

Reference 7

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guideline study, published in peer reviewed literature, minor restrictions in design and/or reporting but otherwise adequate for assessment.

Justification for type of information:

The data source is used as part of a weight of evidence approach. Please refer to the 'Attached justification' section for a detailed weight of evidence document.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Analytical monitoring:

yes

Details on sampling:

Before and after test exposure period

Vehicle:

no

Details on preparation and application of test substrate:

Test compounds were dissolved in water then added to soil and thoroughly mixed. Nominal concentrations were spaced by a factor of 3.2.

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Ravel R2

Test type:

other: terrestrial plants growth test

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

14 d

Remarks:

N/A

Post exposure observation period:

None

Test temperature:

21±4°C

pH:

7.5

Moisture:

23-30% moisture content

Details on test conditions:

16L:8D at 6500 lux under fluorescent tubes. Humidity ranged from 40-80%. 1.8% organic carbon, 24% clay. Soil was collected from an orchard. Soil was 4mm sieved prior to experiment. Duplicate trays were used for the control and at least 3 test concentrations. Each 0.25 L plastic tray contained 400g soil at 25-30% moisture capacity (80% of water holding capacity). In each tray 10 seeds were sown. The trays were covered with glass plates until germination of seedlings. After removal of the glass plates evaporation of water was compensated daily by adding demineralised water. Only the first five germinating seedlings were required. After 7 and 14 days shoots were harvested by cutting them off at soil level. Fresh weight was determined immediately after harvesting

Nominal and measured concentrations:

At the start of the experiment measured concentrations were 70-150 % of nominal. At the end measured concentrations were <10 % nominal.

Reference substance (positive control):

no

Species:

Lactuca sativa

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 other: µg/kg

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Species:

Lactuca sativa

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 other: µg/kg

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Details on results:

Endpoint recorded is growth of harvested shoots. Dead plants and ungerminated seeds were not taken into account. The germination rates of the blank controls are not reported by the authors. No details are given on the condition of the seedlings or mortality rates.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Data not reported

N/A

Validity criteria fulfilled:

not specified

Remarks:

Insufficient details are given in the paper to allow us to conclude whether the validity criteria of the test were met as results from the controls are not reported.

Conclusions:

The 14 day EC50 based on reduced fresh weight of germinated seedlings is >1000 µg/kg soil. Analytical monitoring showed that concentrations of o-xylene had reduced to <10% of nominal by the end of the exposure, therefore, the effect value is estimated lower than that reported.

Executive summary:

The method used in study were equivalent to OECD 208 (1984). The main deviations from this guideline were a higher clay content than recommended, and the reporting of results at 14 days post sowing, not 14 days post germination of the controls. The exposure duration of the study is withing the ranges of the OECD 208 TG of 14 -21 days. Despite these restrictions this study does allow us to conclude that major effects on the growth of lettuce are not seen at the highest concentration tested (1000 µg/kg) although this is probably due to reduced exposure due to volatilisation or biodegradation.

Reference 8

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Original study not citeable but data taken from a reliable secondary source

Remarks:

Original studies were made available, however, they are not citeable, therefore all details used in the dossier entry are obtained from the reliable secondary source (Environmnet Canada, 2005)

Justification for type of information:

The data source is used as part of a weight of evidence approach. Please refer to the 'Attached justification' section for a detailed weight of evidence document.

Principles of method if other than guideline:

The scientific supporting document prepared by Environment Canada (2005) and has undergone external written scientific peer review/consultation. The detailed methodology has not been reported in the publication, but it has been considered robust for soil guideline derivation in Canada. The report indicates the source of the primary data as: ESG International Inc., 2002a. Toxicity Assessment of BTEX Compounds. Report prepared for Dr. Ted Nason, Canadian Council of Ministers of the Environment. Report # G1132/G1603; January 2002.

GLP compliance:

not specified

Specific details on test material used for the study:

Not specified

Analytical monitoring:

not specified

Details on sampling:

No data reported

Vehicle:

not specified

Details on preparation and application of test substrate:

Reported as coarse sandy loam soil recalculated for fine clay loam soil

Species:

other: Agropyron dasystachyum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Northern wheatgrass, Agropyron dasystachyum

Species:

other: Medicago sativa

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Alfalfa, Medicago sativa

Test type:

other: Shoot length, wet and dry mass; root length, wet and dry mass

Study type:

laboratory study

Substrate type:

not specified

Limit test:

no

Total exposure duration:

14 d

Remarks:

N/A

Post exposure observation period:

No data reported

Test temperature:

No data reported

pH:

No data reported

Moisture:

No data reported

Details on test conditions:

No data reported

Nominal and measured concentrations:

No data reported

Reference substance (positive control):

not specified

Species:

other: Northern wheatgrass, Agropyron dasystachyum

Duration:

14 d

Dose descriptor:

EC25

Remarks:

IC25

Effect conc.:

90 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: Root wet mass

Remarks on result:

other: Coarse sandy loam soil

Species:

other: Alfalfa, Medicago sativa

Duration:

14 d

Dose descriptor:

EC25

Remarks:

IC25

Effect conc.:

92 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: Shoot dry mass

Remarks on result:

other: Fine clay loam soil

Species:

other: Northern wheatgrass, Agropyron dasystachyum

Duration:

14 d

Dose descriptor:

EC25

Remarks:

IC25

Effect conc.:

241 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: Root length

Remarks on result:

other: Fine clay loam soil

Species:

other: Alfalfa, Medicago sativa

Duration:

14 d

Dose descriptor:

EC25

Remarks:

IC25

Effect conc.:

421 mg/kg soil dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

other: shoot dry mass

Remarks on result:

other: Coarse sandy loam soil

Details on results:

The results cited were based on experimental data that were recalculated to measured concentrations and volatile losses of xylenes and therefore, represent the estimated effect values. The most sensitive endpoints are detailed in the effect concentrations table, the full set of results is presented in ' Any other information on results'

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Reported as coarse sandy loam soil recalculated for fine clay loam soil

Table 4. Results extracted from Environment Canada (2005) report based on data from ESG International (2002) on mixed xylene (CAS 1330 -20 -7).

Effect, 14d	IC25mg/kg dw^1
	Northern wheatgrass, Agropyron dasystachyum		Alfalfa, Medicago sativa
	Coarse, artificial sandy loam soil	Fine, field collected clay loam soil	Coarse, artificial sandy loam soil	Fine, field collected clay loam soil
Shoot length	430	443	1200	593
Shoot wet mass	137	396	558	178
Shoot dry mass	167	367	421	92
Root length	608	241	480	101
Root wet mass	90	367	612	130
Root dry mass	196	282	442	111

¹The results cited were based on experimental data that were adjusted to measured concentrations and volatile losses of xylenes and therefore, represent the estimated effect values.

The Environment Canada (2005) report also presents data from older studies conducted by Environment Canada (1995). It was not possible to access the primary source, as the data is not published, but the results are presented from the EC (2005) report as below in Table 2.

Table 2. The effects of xylenes on terrestrial plants (extracted from Environment Canada, 2005; data from Environment Canada 1995)

Effect, duration	Species	Endpoint	Concentration of xylenes, mg/kg
			Nominal	Measured
Seedling emergence, 72 h	Radish, R. sativus	NOEC	104	1.4
		LOEC	206	33
		EC25	178	32
		EC50	291	97
	Lettuce, L. sativa	NOEC	52	0.6
		LOEC	104	19
		EC25	81	5
		EC50	132	13
Root elongation, 120 h	Radish, R. sativus	NOEC	21	0.43
		LOEC	43	0.76
		EC25	36	0.65
		EC50	180	28
	Lettuce, L. sativa	NOEC	17	0.26
		LOEC	34	0.52
		EC25	24	0.34
		EC50	66	9

Additional details reported in the EC (2005) report to complement the results in Table 1:

Soil pH: 4 - 4.5

Soil type: Artificial soil (20 % kaolinite clay, 10 % peat, 70 % silica sand)

Aalytical method: EPA Method SW846, 3810/8015 and 8020

Source: Environment Canada. 1995. Toxicity testing of National Contaminated Sites Remediation program priority substances for the development of soil quality criteria for contaminated sites. Environmental Conservation Service, Evaluation and Interpretation Branch, Guidelines Division, Ottawa. Unpub.

Validity criteria fulfilled:

not applicable

Conclusions:

The 14 day studies assessed the effects on roots and shoots, specifically their length, wet and dry mass in coarse sandy and fine clay loam soil. In coarse soils, the most sensitive endpoint for alfalfa was reduction of root dry mass with an IC25 value of 421 mg/kg for xylenes. For the northern wheatgrass, the most sensitive endpoint was an IC25 for reduction of root dry mass at 90 mg/kg for xylenes, in coarse soils (the results are based on estimated concentration accounting for volatile losses). The results for fine soils were recalculated by Komex International (2002) to account for volatile losses that occur between spiking the sample and introducing the plants 2 hours later. The most sensitive endpoint in fine soils for northern wheatgrass was reduction of root length with an IC25 of 241 mg/kg dw; and for alfalfa the most sensitive endpoint in fine soils was reduction of shoot dry mass, IC25 92 mg/kg xylenes.

Executive summary:

The Environment Canada (2005) scientific support document on the derivation of soil guideline values, presents results from ESG International (2002) studies assessing the toxicity of xylenes to Northern wheatgrass (Agropyron dasystachyum) and alfalfa (Medicago sativa). The 14 day studies assessed the effects on roots and shoots, specifically their length, wet and dry mass in coarse sandy and fine clay loam soil. In coarse soils, the most sensitive endpoint for alfalfa was reduction of root dry mass with an IC25 value of 421 mg/kg for xylenes. For the northern wheatgrass, the most sensitive endpoint was an IC25 for reduction of root dry mass at 90 mg/kg for xylenes, in coarse soils (the results are based on estimated concentration accounting for volatile losses). The results for fine soils were recalculated by Komex International (2002) to account for volatile losses that occur between spiking the sample and introducing the plants 2 hours later. The most sensitive endpoint in fine soils for northern wheatgrass was reduction of root length with an IC25 of 241 mg/kg dw; and for alfalfa the most sensitive endpoint in fine soils was reduction of shoot dry mass, IC25 92 mg/kg xylenes. The Environment Canada (2005) report includes external reviews by federal scientists, provincial government organisation, academic institutions and the private sector, therefore, the source is considered reliable and relevant.

Reference 9

Endpoint:

toxicity to terrestrial plants, other

Remarks:

Short-term exposure but measurements were taken at 24 h and following 1, 2, 4 weeks.

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1954

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Non-GLP, non guideline study, very short exposure periods at high concentration

Justification for type of information:

The data is considered unreliable to fill endpoint requirement, since the publication exposure duration is short and route of exposure is via spraying or vapour application in addition, the chemical used has not been identified with a CAS number. However, it is considered as part of a weight of evidence approach. Please refer to the 'Attached justification' section for a detailed weight of evidence document.

Principles of method if other than guideline:

No guideline followed, but detailed account of methods provided.
Tomato, barley and carrot plants were exposused to varying amounts of neat xylene via spraying and in a gas chamber.
Plants were exposed for 1/4, 1/2, 1 and 2 hours and effects were recorded after 24 hours, 1, 2 and 4 weeks.

GLP compliance:

no

Specific details on test material used for the study:

Mixture of isomers, predominantly meta-xylene.

Analytical monitoring:

no

Details on sampling:

N/A

Vehicle:

no

Details on preparation and application of test substrate:

N/A

Species:

other: Solanum lycopersicum

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

Tomato

Species:

Hordeum vulgare

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Barley

Species:

Daucus carota

Plant group:

Dicotyledonae (dicots)

Details on test organisms:

N/A

Test type:

other: leaf injury and yield

Study type:

laboratory study

Substrate type:

natural soil

Remarks:

N/A

Post exposure observation period:

N/A

Test temperature:

N/A

pH:

N/A

Moisture:

N/A

Details on test conditions:

N/A

Nominal and measured concentrations:

N/A

Species:

Daucus carota

Dose descriptor:

other:

Effect conc.:

ca. 0.46 other: x 10-4 M

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: leaf injury

Remarks on result:

other: Please refer to the section 'Any other information on results' for detailed list

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

Table 1. Results of vapor treatments on the plants tested. Per cent injury in three plant species as affected by time of treatment at 0.46 x 10-4 M concentration of xylene vapor.

Time after treatment	Xylene concentration, 0.46 x 10^-4M
	¼ h	½ h	1 h	2 h
Barley
24 h	75	85	95	98
1 week	60	60	75	90
2 weeks	25	40	70	85
4 weeks	25	25	50	75
Tomato
24 h	25	50	85	95
1 week	40	50	85	95
2 weeks	50	65	75	90
4 weeks	30	35	50	80
Carrot
24 h	0	0	2	25
1 week	0	0	0	25
2 weeks	0	0	0	10
4 weeks	0	0	0	10

Table 2. Per cent injury produced in the three plant species by spraying with xylenes for 57 days using an atomiser.

Time after treatment	Xylene concentration application amount
	2 ml	5 ml	10 ml	20 ml
Barley
24 h	60	75	98	100
1 week	50	85	98	100
2 weeks	40	85	98	100
4 weeks	75	80	98	100
Tomato
24 h	90	95	98	98
1 week	90	98	100	100
2 weeks	98	100	100	100
4 weeks	98	100	100	100
Carrot
24 h	50	95	95	98
1 week	75	98	100	100
2 weeks	85	100	100	100
4 weeks	80	100	100	100

Validity criteria fulfilled:

not specified

Conclusions:

Tomato, barley and carrot plants were esposed to vapours of xylene (0.20 x 10-4 M, 0.46 x 10-4 M and 2.4 x 10-4 M) for 1/4 -4 hours in a gas chamber and sprayed with neat xylenes (2 - 10 mL) for 57 days, the effects on plants were observed from 24 h to 4 weeks.
There were no effects in carrot plants following treatment to vapours of xylene when treated for up to 1 h, 10 - 25 % effect was observed when treated for 2 hours.
All plants were affected by spray application with > 40 % at 2 mL. Carrots were found most resistant to xylenes.

Executive summary:

Tomato, barley and carrot plants were esposed to vapours of xylene (0.20 x 10-4 M, 0.46 x 10-4 M and  2.4 x 10-4 M) for 1/4 -4 hours in a gas chamber and sprayed with neat xylenes (2 - 10 mL) for 57 days, the effects on plants were observed from 24 h to 4 weeks. No guideline was followed and the study was not done under GLP, however, it is detailed and offers indication of xylene toxicity when applied as agrochemicals. There were no effects in carrot plants following  treatment to vapours of xylene when treated for up to 1 h, 10 - 25 % effect was observed when treated for 2 hours.

All plants were affected by spray application with > 40 % at 2 mL. Carrots were found most resistant to xylenes.

Description of key information

A weight of evidence (WoE) approach was utilised as an alternative to ‘long term testing on plants’ endpoint as it is believed that the proposed study alone is unlikely to produce reliable or repeatable toxicity results due to the rapid volatilisation of xylenes from soil. QSARs supported by relevant, reliable and robust existing data from experimental studies and from literature are used to fill this endpoint.

The TLM-EqP predicted effected values for Avena sativa were 56.759 - 191.263 mg/kg soil dw for short term (14 day LL50) and 10.873 - 36.640 mg/kg soil dw for long-term effects (21 day NOELR) respectively.

The TLM-EqP predicted effected values for Brassica rapa were 36.646 - 123.490 mg/kg soil dw for short term (14 day LL50) and 7.020 - 23.657 mg/kg soil dw for long-term effects (21 day NOELR) respectively.

The Draft Screening Assessment Report (Environment Canada 2014) presents results from ESG International (2002) for the toxicity of ethylbenzene to Northern wheatgrass of 14 day LC25 of 3 mg/kg dw (coarse sandy loam). The Northern Wheatgrass value was taken by Environment Canada as the critical toxicity value for ethylbenzene toxicity to terrestrial species.

Additional information

A study to investigate the effects of o-xylene on terrestrial plants was found. This study reported a 14 day EC50 of >1 mg/kg nominal, although analytical measurements indicated that <10% nominal remained at the end of the test. The methods used in study were equivalent to OECD 208 (1984). The main deviations from this guideline were a higher clay content than recommended, and the reporting of results at 14 days post sowing, not 14 days post germination of the controls. Insufficient details are given in the paper to allow a conclusion to be made on if the validity criteria of the test were met as results from the controls are not reported. Despite these restrictions this study does allow the conclusion that major effects on the growth of lettuce are not seen at the highest concentration tested although this is probably due to reduced exposure due to volatilisation or biodegradation. The results from this study will not be used to calculate a PNEC in the risk assessment due to these limitations.

The EU RAR (ECB 2007) discusses a single study on the toxicity of ethylbenzene to terrestrial plants via the atmosphere (Ivens, 1952). The study exposed the leaves of plants to concentrations of ethylbenzene as vapour for 1 hour and found that the NOEC was very close to the concentration which killed leaves completely. The reported EC50 are 27 g/m3 for runner bean (Phaseolus multiflorus) and 48 g/m3 for parsnip (Pastinaca sativa).

The Draft Screening Assessment Report (Environment Canada 2014) presents results from ESG International (2002) for the toxicity of ethylbenzene to Northern wheatgrass of 14 day LC25 of 3 mg/kg dw (coarse sandy loam). The Northern Wheatgrass value was taken by Environment Canada as the critical toxicity value for ethylbenzene toxicity to terrestrial species.

Due to the technical challenges of testing volatile substances, a TLM-EqP modeling framework was used to support terrestrial effect values derived experimentally and are presented as supporting studies. These data were considered reliable and comparable to experimentally derived values; however, were not used in the PNEC derivation in order to comply with ECHA FDL (2014) on using experimental data to derive PNEC. The hazard to soil organisms was assessed by using the experimental data.

The TLM-EqP predicted effected values for Avena sativa were 56.759 - 191.263 mg/kg soil dw for short term (14 day LL50) and 10.873 - 36.640 mg/kg soil dw for long-term effects (21 day NOELR) respectively.

The TLM-EqP predicted effected values for Brassica rapa were 36.646 - 123.490 mg/kg soil dw for short term (14 day LL50) and 7.020 - 23.657 mg/kg soil dw for long-term effects (21 day NOELR) respectively.