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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
1998
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which there is available information (Klimish =4).
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See cross-reference to justification of read-across.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.7 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
not specified
Remarks on result:
other: Based on the read-across from an analogue substance.
Validity criteria fulfilled:
not specified
Conclusions:
Based on the read-across from an analogue substance the 48 hour-EC50 is estimated to be 0.7 mg/L.
Executive summary:

Based on the read-across from an analogue substance the 48 hour-EC50 is estimated to be 0.7 mg/L.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
From November 30, 2006 to March 09, 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which a guideline study (Klimish =1) is available.
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See cross-reference to justification of read-across.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.36 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Based on the read-across from the analogue substance d-limonene.
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.074 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Based on the read-across from the analogue substance d-limonene.
Conclusions:
Based on the read-across from the analogue substance d-limonene, the 48-hours EC50 and NOEC values for l-limonene are estimated to be 0.36 and 0.074 mg/L, respectively.
Executive summary:

Based on the read-across from the analogue substance d-limonene, the 48-hours EC50 and NOEC values for l-limonene are estimated to be 0.36 and 0.074 mg/L, respectively.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which there is available information (Klimish =2).
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See cross-reference to justification of read-across.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
577 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 496-672 µg/L
Remarks:
Based on the read-across from the analogue substance d-limonene.
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
421 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Based on the read-across from the analogue substance d-limonene.
Conclusions:
Based on the read-across from the analogue substance d-limonene, the 48 hour LC50 or EC50 of l-limonene to Daphnia magna were calculated to be 577 or 421 µg/L.
Executive summary:

Based on the read-across from the analogue substance d-limonene, the 48 hour LC50 or EC50 of l-limonene to Daphnia magna were calculated to be 577 or 421 µg/L.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Read-across from an analogue substance for which there is available information (Klimish =4).
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
See cross-reference to justification of read-across.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
924 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: CL not reliable
Remarks:
Based on the read-across from the analogue substance d-limonene.
Conclusions:
Based on the read-across from the analogue substance d-limonene, the 48 hour LC50 of l-limonene to Daphnia magna was calculated to be 924 µg/L.
Executive summary:

Based on the read-across from the analogue substance d-limonene, the 48 hour LC50 of l-limonene to Daphnia magna was calculated to be 924 µg/L.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Study period:
Not applicable (calculated data)
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculation with a valid QSAR (ECOSAR), l-limonene falls within the applicability domain of the (Q)SAR model, the prediction fits for the regulatory purpose, and the information is enough documented.
Justification for type of information:
1. Relevance of the model

ECOSAR v1.00 is reported as a usable valid model by ECHA (R6: QSARs and grouping of chemicals, May 2008).
ECOSAR contains a library of class-based QSARs for predicting aquatic toxicity, overlaid with an expert decision tree for selecting the appropriate chemical class. ECOSAR Version 1.00 is programmed to identify over 120 chemical classes and allows access to over 600 QSARs for numerous endpoints and organisms.
The structure-activity relationships (SARs) presented in ECOSAR v1.00 are used to predict the aquatic toxicity of chemicals based on their similarity of structure to chemicals for which the aquatic toxicity has been previously measured. SARs are developed for chemical classes based on measured test data that have been submitted by industry to the US-Environmental Protection Agency or collected from publicly available sources. To date, over 440 SARs have been developed for more than 120 chemical classes. The supporting data sets (training sets) used to derive SARs within a chemical class range from the very large, e.g., neutral organics, to the very small, e.g., aromatic diazoniums. The class with the greatest number of SARs based on measured data is the neutral organics class, which has SARs ranging from acute and chronic toxicity to fish to a 14-day LC50 SAR for earthworms in artificial soil.
The ECOSAR Class Program is a computerized version of the ecotoxicity analysis procedures as currently practiced by the Office of Pollution Prevention and Toxics (OPPT) when data are lacking for regulatory endpoints. It has been developed within the regulatory constraints of the Toxic Substances Control Act (TSCA). It is a pragmatic approach to SAR as opposed to a theoretical approach.

2. Validation of the model

- Endpoint (OECD Principle 1)
Acute toxicity to invertebrates (lethality). For freshwater invertebrates, species frequently include Daphnia magna or Daphnia pulex. The studies collected for the training set chemicals in ECOSAR undergo an extensive data validation step to ensure appropriateness for inclusion in the model. ECOSAR study criteria articulate that the toxicity should be measured at pH 7 (replicating environmental conditions), the total organic carbon content should not exceed 2 mg/L, the water hardness should be approximately 150 mg/L CaCO3, results should be adjusted to, or measured at, 100% active ingredient, and flow-through measured is preferred over static nominal, etc. Data received or identified in the open literature which is not accompanied with full study details to confirm conditions are often not considered appropriate for model development.

- Algorithm (OECD Principle 2)
Neutral organics, DAPHNID 48-h LC50 ESTIMATED TOXICITY:
The daphnid 48-h LC50 values used to develop this SAR were measured and the octanol water partition coefficients (Kow) were calculated using the computer program, KOWWIN (Version 1.67). The SAR equation used to estimate toxicity is: Log 48-h LC50 = -0.8157 (log Kow) + 1.2695
The LC50 is in millimoles per liter (mM/L); To convert the LC50 from mM/L to mg/L, multiply by the molecular weight of the compound


-Applicability domain (OECD Principle 3)
Neutral organic chemicals are non ionizable and nonreactive and act via simple nonpolar narcosis generally thought of as a reversible, drug-induced loss of conscience (general anesthesia). This general narcosis is often referred to as baseline toxicity (Franks and Lieb 1990, Veith and Broderius 1990).
Application:
Solvents, non-reactive, non-ionizable neutral organic compounds
1. Alcohols
2. Acetals
3. Ketones
4. Ethers
5. Alkyl halides
6. Aryl halides
7. Aromatic hydrocarbons
8. Halogenated aromatic hydrocarbons
9. Halogenated aliphatic hydrocarbons
10. Sulfides and di-sulfides
Limitations:
Maximum Kow: 5.0
Maximum MW: 1000


- Uncertainty of the prediction (OECD Principle 4)
N = 115 + 37; and the Coefficient of Determination (R2) = 0.7712


4. Mechanistic interpretation: The QSAR for neutral organics is based on the assumption that all chemicals have a minimal toxicity based on the interference of the chemical with biological membranes, which can be modelled by the octanol-water partition coefficient (Kow).

5. Adequacy of result for classification & labelling an/or risk assessment
According to the main criteria used by Hulzebos and Posthumus, ECOSAR is a reliable QSAR to predict 48h-LC50 for invertebrates. The ECOSAR prediction of toxicity of l-limonene on invertebrates is adequate for the purpose of risk assessment and classification and labelling.
Qualifier:
according to
Guideline:
other: REACH Guidance document R.6 on the validation of the (Q)SAR models
Deviations:
no
Principles of method if other than guideline:
ECOSAR model for neutral organics
GLP compliance:
no
Remarks:
the data was calculated by a computer model
Analytical monitoring:
no
Details on sampling:
Not applicable (calculated data)
Vehicle:
no
Details on test solutions:
Not applicable (calculated data)
Test organisms (species):
other: For freshwater invertebrates, species frequently include Daphnia magna or Daphnia pulex
Details on test organisms:
Not applicable (calculated data)
Test type:
other: QSAR modeled data
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
Not applicable
Hardness:
ECOSAR study criteria articulate that the water hardness should be approximately 150 mg/L CaCO3
Test temperature:
Not applicable (calculated data)
pH:
ECOSAR study criteria articulate that the toxicity should be measured at pH 7 (replicating environmental conditions)
Dissolved oxygen:
Not applicable (calculated data)
Salinity:
Not applicable
Nominal and measured concentrations:
Not applicable (calculated data)
Details on test conditions:
Not applicable (calculated data)
Reference substance (positive control):
not required
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
0.678 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
1. Relevance of the model

ECOSAR v1.00 is reported as a usable valid model by ECHA (R6: QSARs and grouping of chemicals, May 2008).
ECOSAR contains a library of class-based QSARs for predicting aquatic toxicity, overlaid with an expert decision tree for selecting the appropriate chemical class. ECOSAR Version 1.00 is programmed to identify over 120 chemical classes and allows access to over 600 QSARs for numerous endpoints and organisms.
The structure-activity relationships (SARs) presented in ECOSAR v1.00 are used to predict the aquatic toxicity of chemicals based on their similarity of structure to chemicals for which the aquatic toxicity has been previously measured. SARs are developed for chemical classes based on measured test data that have been submitted by industry to the US-Environmental Protection Agency or collected from publicly available sources. To date, over 440 SARs have been developed for more than 120 chemical classes. The supporting data sets (training sets) used to derive SARs within a chemical class range from the very large, e.g., neutral organics, to the very small, e.g., aromatic diazoniums. The class with the greatest number of SARs based on measured data is the neutral organics class, which has SARs ranging from acute and chronic toxicity to fish to a 14-day LC50 SAR for earthworms in artificial soil.
The ECOSAR Class Program is a computerized version of the ecotoxicity analysis procedures as currently practiced by the Office of Pollution Prevention and Toxics (OPPT) when data are lacking for regulatory endpoints. It has been developed within the regulatory constraints of the Toxic Substances Control Act (TSCA). It is a pragmatic approach to SAR as opposed to a theoretical approach.

2. Validation of the model

- Endpoint (OECD Principle 1)
Acute toxicity to invertebrates (lethality). For freshwater invertebrates, species frequently include Daphnia magna or Daphnia pulex. The studies collected for the training set chemicals in ECOSAR undergo an extensive data validation step to ensure appropriateness for inclusion in the model. ECOSAR study criteria articulate that the toxicity should be measured at pH 7 (replicating environmental conditions), the total organic carbon content should not exceed 2 mg/L, the water hardness should be approximately 150 mg/L CaCO3, results should be adjusted to, or measured at, 100% active ingredient, and flow-through measured is preferred over static nominal, etc. Data received or identified in the open literature which is not accompanied with full study details to confirm conditions are often not considered appropriate for model development.

- Algorithm (OECD Principle 2)
Neutral organics, DAPHNID 48-h LC50 ESTIMATED TOXICITY:
The daphnid 48-h LC50 values used to develop this SAR were measured and the octanol water partition coefficients (Kow) were calculated using the computer program, KOWWIN (Version 1.67). The SAR equation used to estimate toxicity is: Log 48-h LC50 = -0.8157 (log Kow) + 1.2695
The LC50 is in millimoles per liter (mM/L); To convert the LC50 from mM/L to mg/L, multiply by the molecular weight of the compound


-Applicability domain (OECD Principle 3)
Neutral organic chemicals are non ionizable and nonreactive and act via simple nonpolar narcosis generally thought of as a reversible, drug-induced loss of conscience (general anesthesia). This general narcosis is often referred to as baseline toxicity (Franks and Lieb 1990, Veith and Broderius 1990).
Application:
Solvents, non-reactive, non-ionizable neutral organic compounds
1. Alcohols
2. Acetals
3. Ketones
4. Ethers
5. Alkyl halides
6. Aryl halides
7. Aromatic hydrocarbons
8. Halogenated aromatic hydrocarbons
9. Halogenated aliphatic hydrocarbons
10. Sulfides and di-sulfides
Limitations:
Maximum Kow: 5.0
Maximum MW: 1000


- Uncertainty of the prediction (OECD Principle 4)
N = 115 + 37; and the Coefficient of Determination (R2) = 0.7712


4. Mechanistic interpretation: The QSAR for neutral organics is based on the assumption that all chemicals have a minimal toxicity based on the interference of the chemical with biological membranes, which can be modelled by the octanol-water partition coefficient (Kow).

5. Adequacy of result for classification & labelling an/or risk assessment
According to the main criteria used by Hulzebos and Posthumus, ECOSAR is a reliable QSAR to predict 48h-LC50 for invertebrates. The ECOSAR prediction of toxicity of l-limonene on invertebrates is adequate for the purpose of risk assessment and classification and labelling.
Results with reference substance (positive control):
Not applicable (calculated data)
Reported statistics and error estimates:
Not applicable (calculated data)

No other information

Validity criteria fulfilled:
yes
Remarks:
Log Kow < 5 at 25°C; MW = 136 g/mol
Conclusions:
The result of the computer modelling to estimate the acute toxicity of l-limonene on daphnid after 48-hours exposure is 48h-LC50= 0.678 mg/L.
Executive summary:

The acute toxicity of l-limonene to aquatic invertebrates was estimated using the ECOSAR model from EPISUITE 4.1 reported as a valid model by ECHA (R6: QSAR and grouping of chemicals, May 2008). ECOSAR computes toxicity based on a linear mathematical relationship between the predicted log Kow values and the corresponding log of the measured toxicity values (mmol/L). l-limonene feld in the applicability domain of this QSAR model and the calculation was ran using its measured log Kow value of 4.38.

The result of the computer modelling to estimate the acute toxicity of l-limonene on daphnid after 48-hours exposure is 48h-LC50= 0.678 mg/L.

This ECOSAR prediction of acute toxicity of l-limonene on fish is adequate for the purpose of risk assessment and classification and labelling.

Description of key information

Weight of evidence: One reliable study was conducted with d-limonene on daphnia magna according to the relevant OECD 202 guideline under static conditions. Two other reliable studies with d-limonene similar to OECD 202 but without GLP gave similar results on daphnia magna under flow through conditions. One non assignable MITI study from a reliable source on the racemic form of limonene (dipentene) and one calculated value for l-limonene with a valid model (ECOSAR) suggested that both enantiomers have the same level of acute toxicity on daphnia. For the purpose of risk assessment and classification & labelling, the lowest toxicity value on d-limonene is considered as the most conservative value.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.36 mg/L

Additional information

Five studies investigating the acute toxicity of the substance limonene on daphnids are available and are reported as endpoint summary records.

One reliable study according to OECD 202 and complying with GLP was performed with d-limonene on daphnia magna under static conditions. A 48h-EC50 value of 0.36 mg/L was determined based on the immobilisation effect.

Two other reliable studies with d-limonene on daphnia magna support this result and were performed similarly to OECD guideline 202 but without GLP statement under flow-through conditions. The mortality was the measured effect and 48h-LC50 values were calculated to be 0.924 mg/L and 0.577 mg/L.

A similar result was found in a study from the Japan Ministry (formerly MITI) on daphnia magna with dipentene, the dl-limonene racemic form, establishing a 48h-EC50 of 0.7 mg/l. This study is not assignable because it is not well documented however, its source is reliable and the result suggests that the two enantiomers have the same level of toxicity on daphnia magna.

A valid computer modelling (ECOSAR) was used to assess the toxicity of l-limonene on daphnia and its result, a freshwater daphnia 48h-LC50 of 0.678 mg/L supports the hypothesis of similar acute toxicity of both enantiomers on daphnids.

Among these studies, the lowest value of toxicity found, an 48h-EC50 of 0.36 mg/L, obtained according to standard guideline and under GLP on d-limonene is considered as the most conservative and relevant value to be used for the purpose of risk assessment and classification and labelling.