dibenzylbenzene, ar-methyl derivative, hydrogenated

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

adopted 13 April 2004

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: hydrogenious 005
- Expiration date of the lot/batch: >3 years, unlimited shelf life
- Purity: > 95%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at ambient temperature (15 ± 10°C)
- Stability under test conditions: stable

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 mg/l, 100 mg/l (nominal WAF loading rate)
- Sampling method: Duplicate samples were taken at the start and end of the 48-hour exposure period. Samples were taken from the remaining test media after filling test vessels for 0-hours (start) and pooled replicate vessels for 48-hours (end of test). Analysis of those samples for the verification of exposure concentrations was performed using HPLC-UV
- Sample storage conditions before analysis: no storage

Vehicle:

no

Details on test solutions:

As the test substance was insoulble in water, the test solutions were prepared according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures. OECD Environmental Health and Safety Publication, Series on Testing and Assessment. No. 23. The test concentrations (loading rates) for both the range-finding and definitive tests were prepared separately following the direct addition method as described in the OECD guidance document on aquatic toxicity testing of difficult substances and mixtures no. 23. Calculated weights of test sample were weighed into aspirators to provide enough solution for testing and subsequent water quality measurements. The loading rates were stirred on magnetic stirrers for 22 hours and 15 minutes in the range-finding test and 46 hours and 30 minutes in the definitive test and left to settle for 6 hours in the range-finder test and for 4 hours and 30 minutes in the definitive test. After settling the aqueous phase was drawn off for testing leaving any sedimented/undissolved material behind. The control media and test loading rate in the definitive test were filtered using a Whatman 54 filter, the first 100-200ml were discarded prior to testing and thereby saturating the filter before removal of test dilutions.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: Daphnia magna Straus, genotype 5
- Source: from cultures maintained at Chemex Environmental International Ltd since July 2014 and originally sourced from a clone of genotype 5.
- Age of daphnia at start of test: <= 24 h
- Feeding during test: none
- Medium: Elendt M4 reconstituted Daphnia medium (as described in the guideline)

CULTURE CONDITIONS OF STOCK
- Type and amount of food: suspension of Chlorella vulgaris
- Feeding frequency: daily
- Medium: Elendt M4 as prescribed in the guideline
- Conditions: cultured under static conditions at 20 ± 2°C, >60% ASV dissolved oxygen
- Photoperiod: 16 hours light and 8 hours dark

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

20.1 - 20.4

pH:

6.74 - 6.91

Dissolved oxygen:

6.26 - 7.15

Nominal and measured concentrations:

100 mg/l, limit test
All concentrations of the test substance are reported as nominal as received, expressed as loading rates from direct addition since the test substance was insoluble in water. The substance was not detected by HPLC analysis in the exposure dilutions at 48-hours and was below LOQ at 0- hours.

Details on test conditions:

TEST SYSTEM
- Test vessel: 40 ml
- Type: closed
- Material, size, headspace, fill volume: glass vessel, 25 ml test volume
- Aeration: not mentioned
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: de-ionised water, no further details mentioned
- Intervals of water quality measurement: not mentioned
- Culture medium: Recontituted Elendt M4 medium prepared according to OECD 202

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 hours light and 8 hours dark
- Light intensity: not mentioned

EFFECT PARAMETERS MEASURED:
- Number of immobilised Daphnia, sub-lethal effects (movement, coloration, trapped in meniscus, sedimentation, debris attached to Daphnia) after 24 and 48 hours of exposure
- Water quality measurements: pH (to 0.01), dissolved oxygen mg/l (to 0.01) at 0 hours on remaining test solution, and at 48-hour endpoint on pooled replicates for each test and control solution
- Temperature: measurement (to 0.1°C) recorded at 0, 24 and 48 hours

RANGE-FINDING STUDY
- Test concentrations: 0.1, 1.0, 10 and 100mg/l
- Results used to determine the conditions for the definitive study: No effects were seen at 100 mg/l loading rate, definitive test would be a limit test at a single loading rate of 100 mg/l.

Reference substance (positive control):

yes

Remarks:

A separate GLP study was performed between 11th and 13th May 2016 with potassium dichromate (K2Cr2O7)

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: Sub-lethal effects were seen at 100mg/l loading rate; the animals showed slower movement.
- Observations on body length and weight: not performed
- Other biological observations: At 100 mg/l loading rate the daphnia became trapped in the meniscus and had debris attached to them.
- Mortality of control: none
- Other adverse effects control: None of the sub-lethal effects seen at the treated animals effects were seen among the control daphnia.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not applicable
- Effect concentrations exceeding solubility of substance in test medium: not applicable

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 24-hour EC50 >1.8mg/l, 48-hour EC50 = 1.67mg/l potassium dichromate (K2Cr2O7)
- Other: EC50 was within the acceptable range 0.6 mg/l to 2.1 mg/l as specified in Technical Corrigendum to ISO6341

see picture below

Validity criteria fulfilled:

yes

Conclusions:

Dibenzylbenzene, ar-methyl derivative, hydrogenated was not toxic to daphnia in the range of water solubility under the conditions of this study.

Executive summary:

The study was performed according to the OECD 202 2004 guideline under the conditions of GLP and met all validity criteria. The test substance was insoluble in water therefore preparation of loading rates was performed by direct addition and an extended mixing period according to OECD Guidance Document 23.

The 24-hour EL50 and 48-hour EL50 of dibenzylbenzene, ar-methyl derivative, hydrogenated to Daphnia magna were both >100mg/l and the 48-hour NOEL was 100mg/l. These were all determined through direct observation of the data, since no Daphnia were immobilised. The Daphnia were examined at 24 hours and 48 hours for abnormal behaviour during the determination of immobility. Three types of abnormality were observed in all twenty Daphnia at 48 hours at 100mg/l. This included debris attached to Daphnia, slower movement and mobile Daphnia trapped in the meniscus . None (0%) of the twenty control Daphnia maintained in dilution water were immobilised and none were trapped in the meniscus during the study. Analytical measurements of the freshly prepared exposure solutions indicated that the initial measured concentrations were not within 80-120% of nominal concentrations. In addition, analytical measurements of the 48 hour aged exposure solutions could not detect the test substance in the samples and therefore were also not within 80-120% of nominal concentrations or 80-120% of the initial measured concentrations. This was expected due to the lack of water-solubility of dibenzylbenzene, ar-methyl derivative, hydrogenated.

In conclusion, dibenzylbenzene, ar-methyl derivative, hydrogenated was not toxic to daphnia in the range of water solubility under the conditions of this study.

Description of key information

The study was performed according to the OECD 202 2004 guideline under the conditions of GLP and met all validity criteria. The test substance was insoluble in water therefore preparation of loading rates was performed by direct addition and an extended mixing period according to OECD Guidance Document 23.

The 24-hour EL50 and 48-hour EL50 of dibenzylbenzene, ar-methyl derivative, hydrogenated to Daphnia magna were both >100mg/l and the 48-hour NOEL was 100mg/l. These were all determined through direct observation of the data, since no Daphnia were immobilised. The Daphnia were examined at 24 hours and 48 hours for abnormal behaviour during the determination of immobility. Three types of abnormality were observed in all twenty Daphnia at 48 hours at 100mg/l. This included debris attached to Daphnia, slower movement and mobile Daphnia trapped in the meniscus . None (0%) of the twenty control Daphnia maintained in dilution water were immobilised and none were trapped in the meniscus during the study. Analytical measurements of the freshly prepared exposure solutions indicated that the initial measured concentrations were not within 80-120% of nominal concentrations. In addition, analytical measurements of the 48 hour aged exposure solutions could not detect the test substance in the samples and therefore were also not within 80-120% of nominal concentrations or 80-120% of the initial measured concentrations. This was expected due to the lack of water-solubility of dibenzylbenzene, ar-methyl derivative, hydrogenated.

In conclusion, dibenzylbenzene, ar-methyl derivative, hydrogenated was not toxic to daphnia in the range of water solubility under the conditions of this study.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L