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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study is classified as reliable with restrictions because it is an acceptable and reliable study carried out by USEPA (Q)SAR ECOSAR (v1.11). The result is calculated data as modelled by EPISUITE. Meets generally accepted scientific principles, acceptable for assessment.
Justification for type of information:
QSAR prediction
Guideline:
other: REACH guidance on QSARs R.6, May/July 2008
Principles of method if other than guideline:
The structure-activity relationships (SARs) presented in ECOSAR 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. Most SAR calculations in the ECOSAR Class Program are based upon the octanol/water partition coefficient (Kow). SARs are developed for chemical classes based on measured test data that have been submitted by industry or they are developed by other sources for chemicals with similar structures, e.g., phenols. Using the measured aquatic toxicity values and estimated Kow values, regression equations can be developed for a class of chemicals. Toxicity values for new chemicals may then be calculated by inserting the estimated Kow into the regression equation and correcting the resultant value for the molecular weight of the compound.
GLP compliance:
no
Remarks:
QSAR
Test organisms (species):
other: Daphnid
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
6.387 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Remarks on result:
other: This value is predicted for the Ester class
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
4.325 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Remarks on result:
other: This value is predicted for the baseline toxicity
Conclusions:
Based on the prediction results described, propylene glycol dibenzoate is predicted to have LC50s of 4.325 mg/L (baseline toxicity) and 6.387 mg/L (Ester class) after 48 hours exposure to Daphnid.
Executive summary:

Based on the prediction results described, propylene glycol dibenzoate is predicted to have LC50s of 4.325 mg/L (baseline toxicity) and 6.387 mg/L (Ester class) after 48 hours exposure to Daphnid.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 October 1997 - 13 October 1997.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study undertaken in GLP accredited laboratory.
Justification for type of information:
A discussion and report on the read across strategy is presented as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OTS 797.1300 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: nominal loadings - 0 (control), 1.0, 2.2, 4.6, 10, 22, 46 and 100 mg/L
- Sampling method: Duplicate pooled medium samples were taken at 0 and 48 hours; sampling methodology not specified.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The method of preparation was selected following advice given in ECETOC 1996 Monograph No 26 as the test material has poor water solubility.
Test material was added by accurate pipette to 2 L glass vessels of Elendt M4 medium and stirred for at least 18 hours. Once stirred the solutions were left to stand for one hour prior to removing the water accommodated fraction. Approximately 800 mL of the solution was removed from a mid-water position.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): In preparation of the water accommodated fraction, when it was left to stand (without stirring), globules of test material were seen at the bottom of the vessels and a film was seen on the surface of the water. In the exposure vessels, expired solutions were noted to be cloudy after 24 hours.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: Straus
- Source: Cultured in-house from a strain originating from the Institute National de Recherche Chimique Applique (IRChA), France
- Age at study initiation (mean and range, SD): Less than 24 hours old
- Method of breeding: The Daphnia used were bred under conditions which ensures that cultures reproduce by parthenogenesis


ACCLIMATION
- Acclimation period: Not applicable - the Daphnia used were all less than 24 hours old. Stock culture conditions are provided below.
- Type and amount of food: A suspension of the unicellular green alga, Chlorella vulgaris
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
19 to 21°C
pH:
7.9 to 8.1
Dissolved oxygen:
7.0 to 8.0 mgO2 / L
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal loadings(fresh) ; 0 (control), 1.0, 2.2, 4.6, 10.0, 22, 46 and 100 mg/L
Measured concentrations of dipropylene glycol dibenzoate (expressed as % of loading)
1.0 mg/L: 33.9 (Fresh prepared), 18.1 (expired / 48 hours old)
2.2 mg/L: 40.7, 27.3
4.6 mg/L: 30.8, 26.8
10 mg/L: 49.4, 26.6
22 mg/L: 40.3, 27.5
46 mg/L: 13.8, 9.2
100 mg/L: 19.3, 7.1
Measured concentrations for dipropylene glycol monobenzoate (expressed as % loading rate in terms of dipropylene glycol dibenzoate)
1.0 mg/L: 3.6 (Fresh prepared), 9.0 (expired / 48 hours old)
2.2 mg/L: 5.0, 13.7
4.6 mg/L: 5.2, 16.0
10 mg/L: 4.8, 18.2
22 mg/L: 5.8, 11.3
46 mg/L: 7.6, 8.3
100 mg/L: 13.9, 6.9
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type : closed ( loosely covered to minimise evaporative losses)
- Material, size, headspace, fill volume: 250 mL glass jars, filled with 200 mL test medium
- Renewal rate of test solution (frequency/flow rate): None (static test)
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 40 mL test solution per organism.


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium, prepared in house using analytical reagents and deionised water

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 hours light / 8 hours dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EL50
Effect conc.:
43.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
19.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limits : 13.1 - 28.5 mg/L
Key result
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
2.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 5% immobilisation was caused at 2.2 mg/L; this level of immobilisation is not considered significant.
Details on results:
- Mortality of control: Two Daphnia in the control level were immobilised after 48 hours. As this corresponded to the no-effect level of 10%, the study results were still considered valid.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Precipitation was observed, as noted previously. The analytical method used to confirm the concentration of test material in solution determined concentrations of dipropylene glycol monobenzoate DPGMB) as well as dipropylene glycol dibenzoate (DPGDB); the concentration of DPGDB was found to be lower after 48 hours than at the start of the test in all cases, whereas the concentration of DPGMB had generally increased. This observation suggests that the monobenzoate was a degradation product of the dibenzoate.
Validity criteria fulfilled:
yes
Conclusions:
The 48 hour EL50 (immobilisation value for DPGDB with Daphnia magna) was determined to be 19.3 mg/L. The "no-observed effect loading rate" (NOELR) was 2.2 mg/L.
Executive summary:

Key data is available for propylene glycol dibenzoate (PGDB). This data is supported by relevant information available from a structural analogue Dipropylene glycol dibenzoate (DPGDB). The justification for read across is presented as an attachment included in Section 13 of the IUCLID dossier.

An acute Daphnia Immobilisation study was performed to determine the actue toxicity to Daphnia of the test material dipropylene glycol dibenzoate (DPGDB). The study was conducted according to EC, OECD, and US EPA test guidelines, and in compliance with GLP.

The 48 hour EL50 (immobilisation value for DPGDB with Daphnia Magna) was determined to be 19.3 mg/L. The "no-observed effect loading rate" (NOELR) was 2.2 mg/L.

Description of key information

Key data is available for propylene glycol dibenzoate (PGDB). This data is supported by relevant information available from a structural analogue Dipropylene glycol dibenzoate (DPGDB). The justification for read across is presented as an attachment included in Section 13 of the IUCLID dossier.

Propylene glycol dibenzoate is predicted to have LC50s of 4.325 mg/L (baseline toxicity) and 6.387 mg/L (Ester class) after 48 hours exposure to Daphnid (US EPA, 2012; Klimisch score = 2).

In an acute Daphnia Immobilisation GLP study conducted according to EC, OECD, and US EPA test guidelines (Huntingdon Life Sciences, 2001a; Klimisch score = 1), the 48 hour EL50 (immobilisation value with Daphnia Magna) for dipropylene glycol dibenzoate was determined to be 19.3 mg/L. The "no-observed effect loading rate" (NOELR) was 2.2 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
4.325 mg/L

Additional information