Xylene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non- GLP, guideline study, published in peer reviewed literature, acceptable with restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Modified as adequate for testing volatile compounds

Principles of method if other than guideline:

For determination of 72h EC50 on Selenastrum the test vessels were modified, accordingly to Galassi and Vighi (1981) in order to maintain constant concentration and to allow sampling of the culture medium, without opening the vessel.

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:

The concentration of the toxicant was determined at the beginning and end of the exposure and after 48 hours.

Vehicle:

no

Details on test solutions:

Diluted solutions of aromatics were prepared from saturated aqueous solutions.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Data not reported

Test type:

other: Static, closed

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

None

Hardness:

Data not reported

Test temperature:

Data not reported

pH:

Data not reported

Dissolved oxygen:

Data not reported

Salinity:

Not applicable

Conductivity:

N/A

Nominal and measured concentrations:

Nominal and measured concentrations not stated. Authors state that mean measured concentrations fluctuated within 10%.

Details on test conditions:

Algal growth was evaluated by a Coulter counter apparatus.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.6 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Details on results:

Effect concentrations reported as mean measured concentrations, whose fluctuations were within 10%.

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 data to confirm validity

Conclusions:

The reported 72 hour EC50 for Pseudokirchneriella subcapitata is 4.6 mg/L.

Executive summary:

The reported 72 hour EC50 for Pseudokirchneriella subcapitata is 4.6 mg/L. This study has been conducted according to OECD standard guidelines, analytrical monitoring was performed and appropriate modifications for volatile compounds were made. Raw data were not included and therefore the validity of the test can not be confirmed.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guideline study, published in peer reviewed literature, acceptable with restrictions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Modified as adequate for testing volatile compounds

Principles of method if other than guideline:

For determination of 72 hour EC50 on Selenastrum, the test vessels were modified, accordingly to Galassi and Vighi (1981) in order to maintain constant concentration and to allow sampling of the culture medium, without opening the vessel.

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:

The concentration of the toxicant was determined at the beginning and end of the exposure and after 48 hours.

Vehicle:

no

Details on test solutions:

Diluted solutions of aromatics were prepared from saturated aqueous solutions.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Data not reported

Test type:

other: Static, closed

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

None

Hardness:

Data not reported

Test temperature:

Data not reported

pH:

Data not reported

Dissolved oxygen:

Data not reported

Salinity:

Not applicable

Conductivity:

N/A

Nominal and measured concentrations:

Nominal and measured concentrations not stated. Authors state that mean measured concentrations fluctuated within 10%.

Details on test conditions:

Algal growth was evaluated by a Coulter counter apparatus.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Details on results:

Effect concentrations reported as mean measured concentrations, whose fluctuations were within 10%.

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 data to confirm validity

Conclusions:

The reported 72 hour EC50 for Selenastrum capricornutum is 4.9 mg/L.

Executive summary:

This has been chosen as the key study on the basis that it has been conducted according to OECD standard guidelines, analytrical monitoring was performed and appropriate modifications for volatile compounds were made. Raw data was not included and therefore the validity of the test can not be confirmed.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2015

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. It is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

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

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on test solutions:

N/A

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

N/A

Hardness:

N/A

Test temperature:

N/A

pH:

N/A

Dissolved oxygen:

N/A

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

N/A

Details on test conditions:

N/A

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

4.831 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: Result from QSAR

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

0.925 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other:

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Conclusions:

The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 4.831 mg/L and the NOELR was 0.925 mg/L.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 aquatic toxicity of this substance was estimated using the Target Lipid Model based on methodologies described by McGrath et al. (2004, 2015). The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 4.831 mg/L and the NOELR was 0.925 mg/L.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, guideline study, published in peer reviewed literature, acceptable with restrictions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Modified as adequate for testing volatile compounds

Principles of method if other than guideline:

For determination of 72 hour EC50 on Selenastrum, the test vessels were modified, accordingly to Galassi and Vighi (1981), in order to maintain constant concentration and to allow sampling of the culture medium, without opening the vessel.

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:

At the beginning and end of the exposure.

Vehicle:

no

Details on test solutions:

Diluted solutions of aromatics were prepared from saturated aqueous solutions.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Data not reported

Test type:

other: Static, closed

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

None

Hardness:

Data not reported

Test temperature:

Data not reported

pH:

Data not reported

Dissolved oxygen:

Data not reported

Salinity:

Not applicable

Conductivity:

N/A

Nominal and measured concentrations:

Nominal concentrations not stated.

Details on test conditions:

Algal growth was evaluated by a Coulter counter apparatus.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.7 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The data on algal growth were not mathematically elaborated as the usual statistical procedures are considered not applicable to populations that change in number of individuals during the test. The 72 hour EC50 values were extrapolated from empical curves fitted by eye on log-probit paper, with percentage growth inhibition and log of concentration on the axes.

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 data to confirm validity

Conclusions:

The reported 72 hour EC50 for Selenastrum capricornutum is 4.7 mg/L.

Executive summary:

This has been chosen as the key study on the basis that it has been conducted according to OECD standard guidelines, analytical monitoring was performed and appropriate modifications for volatile compounds were made. Raw data was not included and therefore the validity of the test can not be confirmed.

Reference 5

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2015

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. It is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

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

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on test solutions:

N/A

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

N/A

Hardness:

N/A

Test temperature:

N/A

pH:

N/A

Dissolved oxygen:

N/A

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

N/A

Details on test conditions:

N/A

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

5.744 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: Result from QSAR

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

1.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other:

Details on results:

N/A

Results with reference substance (positive control):

N/A

N/A

Conclusions:

The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 5.744 mg/L and the NOELR was 1.100 mg/L. 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 aquatic toxicity of this substance was estimated using the Target Lipid Model based on methodologies described by McHrath et al. (2004, 2015). The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 5.744 mg/L and the NOELR was 1.100 mg/L.

Reference 6

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03/06 - 09/07/2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP, near-guideline, published in peer reviewed literature, minor restrictions in design but otherwise adequate for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

modifications for volatile substances

Principles of method if other than guideline:

Modification were made to test design as standard guidelines are not suitable for volatile substances. Modifications according to Mayer et al. were made to allow testing in closed filled test vials. A reduced initial algal cell density and increased NaHCO3 concentration (300 mg/L) were applied to avoid substantial pH changes or carbon limited growth in the closed vessels. These modifications were made to allow a substantial increase in algal biomass during the test to meet the acceptance criteria of an algal biomass increase by at least 16 times during the test of 72 hours.

GLP compliance:

yes

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:

Analytical determination of all test substance concentrations at the start and end of study, the latter determination was carried out in test media containing algae.

Vehicle:

no

Details on test solutions:

Control and 5 test concentrations. For the growth inhibition test, an amount of 13 µL p-xylene was added to 1103 g algal medium which completely filled a bottle with a magnetic strirrer bar. Then the bottle was tightly closed and stirred for approximately 18 hours. The expected p-xylene concentration was 10 mg/L, based on a density of 0.86 g/cm3, from the clear stock dilutions were prepared in medium so as to yield a nominal test substance concentration series of 0.32, 1.0, 1.8, 3.2 and 10 mg/L.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The culture was supplied by the CCAP, The Freshwater Biological Association, the Ferry House, Far Sawrey, Ambleside, Cumbria LA22 0LP. A preculture of algae in the exponential growth phase was prepared as detailed in OECD 201.

Test type:

other: Closed, static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

73 h

Post exposure observation period:

None

Hardness:

24.2 mg/L CaCO3 equivalents

Test temperature:

22.2°C, range 21.7-23.0°C.

pH:

pH at start 8.0, pH at end 8.5-9.2 except in the highest test concentration where growth was nearly completely inhibited and pH remained at 7.8-7.9.

Dissolved oxygen:

Data not reported

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0.32, 1, 1.8, 3.2 and 10 mg/L. Measured concentrations were found to be 45.2 - 80.1 % of nominal at the start of the test and 30.7 - 42.3 % at the end. The mean measured concentrations at the start of the test were N.D. (not detectable in the controls) and 0.19, 0.47, 0.81, 1.68 and 8.01 mg/L. The mean measured concentrations at the end of the test were N.D. (controls) and 0.14, 0.39, 0.56, 0.98 and 3.92 mg/L.

Details on test conditions:

Light intensity = 76-103 µmol/s/m^2. A range finding experiment was performed to determine the concentrations for the final test. In the final test the algal cultures were incubated at a temperature of 23°C and a light intensity of 76-103 µmol/s/m2. Algal cell density was determined after 0, 25.5, 49 and 73 hours. The test medium was prepared from concentrated stock solutions in ultra pure water. It was sterilised by micropore filtration and contained 300 mg/L NaHCO3. Furthermore, the medium contained Fe-citrate, because the growth of the algae can become erratic in the absence of complexed iron. A 0.4 mL volume of algal suspension was added to 40 mL of the appropriate solutions of the test substance in the test flasks. Each test vial was tightly closed after addition of algae. At each sampling time three vials per test substance concentration will be sacrified for measurements. Additional flasks with and without algae were prepared to allow chemical analysis. The test was carried out in triplicate with six controls containing algae only. All flask were incubated at 23±2°C. Algal cells were kept in suspension by rolling the flask horizontally.

Reference substance (positive control):

no

Key result

Duration:

73 h

Dose descriptor:

NOEC

Effect conc.:

0.44 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Duration:

73 h

Dose descriptor:

other: NEC

Effect conc.:

1.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks on result:

other: 1.23 - 1.36 mg/L

Duration:

73 h

Dose descriptor:

EC10

Effect conc.:

1.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

73 h

Dose descriptor:

EC50

Effect conc.:

4.36 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 4.06 - 4.67 mg/L

Duration:

73 h

Dose descriptor:

EC90

Effect conc.:

10 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

73 h

Dose descriptor:

EC10

Effect conc.:

0.72 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.44 - 0.81 mg/L

Key result

Duration:

73 h

Dose descriptor:

EC50

Effect conc.:

2.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 1.4 - 4.6 mg/L (range between tested concentrations)

Duration:

73 h

Dose descriptor:

EC90

Effect conc.:

4.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 1.4 - 4.6 mg/L (range between tested concentrations)

Details on results:

All results reported as measured. Calculated using geometric mean of the measured concentrations of p-xylene at the start and end of the test.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

See data table above

N/A

Validity criteria fulfilled:

yes

Remarks:

the validity criteria of the test guideline were met

Conclusions:

The reported 73 hour EbC50 for Selenastrum capricornutum is 2.2 mg/L.

Executive summary:

This was chosen as the key study as it follows standard OECD guidelines with appropriate modifications for volatile substances.

Reference 7

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2015

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. It is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

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

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on test solutions:

N/A

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

N/A

Hardness:

N/A

Test temperature:

N/A

pH:

N/A

Dissolved oxygen:

N/A

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

N/A

Details on test conditions:

N/A

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

6.129 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: Result from QSAR

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

1.174 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other:

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Conclusions:

The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 6.129 mg/L and the NOELR was 1.174 mg/L. 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 aquatic toxicity of this substance was estimated using the Target Lipid Model based on methodologies described by McGrath et al. (2004, 2015). The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 6.129 mg/L and the NOELR is 1.174 mg/L.

Reference 8

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2015

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. It is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

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

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on test solutions:

N/A

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

N/A

Post exposure observation period:

N/A

Hardness:

N/A

Test temperature:

N/A

pH:

N/A

Dissolved oxygen:

N/A

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

N/A

Details on test conditions:

N/A

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

5.267 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: Result from QSAR

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

1.009 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other:

Details on results:

N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

N/A

N/A

Conclusions:

The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 5.267 mg/L and the NOEC was 1.009 mg/L. 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 aquatic toxicity of this substance was estimated using the Target Lipid Model based on methodologies described by Mc~Grath et al. (2004, 2015). The estimated EL50 of Pseudokirchneriella subcapitata for this substance is 5.267 mg/L and the NOELR was 1.009 mg/L.

Description of key information

The studies by Galassi (1988) and Odersma (2004) were chosen as the key studies on the basis that they were conducted according to OECD standard guidelines, analytical monitoring was performed and appropriate modifications for volatile compounds were made. The reported 72 hours EC50 results from these studies for the different isomers and ethylbenzene for Selenastrum capricornutum had an average of 4.1 mg/L.

The lowest short-term result listed in the report from Odersma et al (2004) for algal toxicity was a 73 hour EC50 of 4.36 mg/L for p-xylene. (growth rate)

The lowest long-term result was reported by Oldersma et al (2004) for p-xylene with a 72 -hour NOEC of 0.44 mg/L.

The estimated EL50 values from TLM QSAR were 4.831 - 6.129 mg/L. The estimated NOELR values from TLM QSAR were 0.925 -1.174 mg/L.

 

The lowest values for EC50 and NOEC used in chemical safety assessment were from Oldersma 2004 (p-xylene).

Key value for chemical safety assessment

EC50 for freshwater algae:

4.36 mg/L

EC10 or NOEC for freshwater algae:

0.44 mg/L

Additional information

Data are available on the ecotoxicity of each of the xylene isomers and ethylbenzene to algae. The studies by Galassi et al (1988) and Oldersma (2004) followed OECD 201, whilst Herman et al (1990) used a non-standard method. All studies included analytical confirmation of the exposure concentrations.

The lowest short-term key result listed in the report from Odersma et al (2004) for algal toxicity was a 73 hour EC50 of 2.2 mg/L for p-xylene.

The EC50 results reported from key studies for the different isomers and ethylbenzene are very similar, with a range of 2.2 - 4.9 mg/L. The lowest long-term result was reported by Oldersma et al (2004) for p-xylene with a NOEC of 0.44 mg/L.

A TLM modeling framework was used to support values derived experimentally.

The estimated EL50 values from TLM QSAR were 4.831 - 6.129 mg/L, and the estimated NOELR values from TLM QSAR were 0.925 - 1.174 mg/L.