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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000-08-23 until 2000-12-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline-conform study under GLP without restrictions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: Butyl methoxydibenzoylmethan (BMDBM)
- Substance type: organic mono constituent
- Physical state: White to pale yellow powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0 - 100 mg/l
- Sampling method: During the study samples were taken from the blank-control and the filtered and unfiltered solutions prepared at 100 mg/I for analysis.
Sampling:
Frequency At t= 0 h and t= 48 h.
Volume 10 ml from the approximate centre of the test vessels.
- Sample storage conditions before analysis: Samples were stored in a freezer until analysis.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Preparation started with three solutions containing a loading of 100 mg/I. These three solutions were stirred for 3 days in the dark. Two of the resulting suspensions were then filtered through a paper filter (5 µm) to remove the fraction of non-dissolved test substance particles. The other suspension was not filtered and was used as such. Hence, as a consequence of the high degree of hydrophobicity, butyl methoxydibenzoylmethane was also tested at a concentration, which had the potential to disturb the test system. Preparation was performed in the dark as much as possible.
- Differential loading: 100 mg/I and 0.1, 1.0, 10 and 100% of a filtrate prepared from 100 mg/I.
- Controls: Test medium without test substance or other additives (0 mg/I).
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Deposits and a film were observed at test item concentration 100 mg/l (unfiltered)

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water fleas
- Strain: Daphnia magna (Straus, 1820)
- Source: bred in the analysing laboratory
- Age at study initiation (mean and range, SD): Maximum age of the cultures 4 weeks
- Length at study initiation (length definition, mean, range and SD): no data
- Method of breeding: Start of each batch: With new-born animals, i.e. less than 3 days old, by placing about 250 of them into 10 litres of medium in
an all-glass culture vessel.
- Feeding during test
- Food type: fresh water algae
- Amount: no data
- Frequency: daily


ACCLIMATION
not applicable


QUARANTINE (wild caught)
not applicable

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
not reported

Test conditions

Hardness:
250 mg/I expressed as CaCO3
Test temperature:
18-22°C
pH:
At test start: 7.9 - 8.1
At test end: 7.9 - 8.0
Dissolved oxygen:
At test start: 8.6 - 9.2 mg/l
At test end: 8.1 - 8.6 mg/l
Salinity:
Not particularly stated, however detailed description of the composition of Medium M7, as prescribed by Dr. Elendt-Schneider, is given in the original study report.
Nominal and measured concentrations:
Nominal concentration: 100 mg/l

Measured:
Sampling time: hours 0
Unflitered sample measured concentration: 17 mg/l
Flitered sample measured concentration: 0.194 mg/l

Sampling time: hours 48
Unflitered sample measured concentration: 0.3 mg/l
Flitered sample measured concentration: < 0.04 mg/l (= LOD)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 100 ml, headspace 20 ml
- Aeration: No aeration of the test solution.
- No. of organisms per vessel: 10 per vessel
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates):2
- Biomass loading rate: no data


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: prepared in milli-RO water
- Total organic carbon: Not particularly stated, however detailed description of the composition of Medium M7, as prescribed by Dr. Elendt-Schneider, is given in the original study report.
- Particulate matter: no data
- Metals: Concentrations not particularly stated, however detailed description of the composition of Medium M7, as prescribed by Dr. Elendt-Schneider, is given in the original study report (Ca, Mg, Na, K, B, Fe, Mn, Li, Rb, Sr, Mo, Cu, Zn, Co, Se, V).
- Alkalinity: Not particularly stated, however detailed description of the composition of Medium M7, as prescribed by Dr. Elendt-Schneider, is given in the original study report.
- Ca/Mg ratio: 0.52
- Conductivity: Not particularly stated, however detailed description of the composition of Medium M7, as prescribed by Dr. Elendt-Schneider, is given in the original study report.
- Culture medium different from test medium: no
- Intervals of water quality measurement: at 0h and 48 h


OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: Exposure in the dark.
- Light intensity: Exposure in the dark.


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


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study
- Test concentrations: Filtered: 0.1%, 1%, 10%, and 100% of a 100 mg/l test item solution; 100 mg/l test item solution unfiltered
- Results used to determine the conditions for the definitive study: As expected, analysis of the samples taken from the unfiltered test solution showed that the concentration measured in the water phase decreased during the test period from 17.0 to 0.28 mg/I due to precipitation and deposition of the undissolved test substance particles. The concentration measured in the filtered test solution decreased from 0.19 mg/I to a value below
the limit of detection, i.e. below 0.04 mg/I during the test period. These decreases in test concentrations could not be prevented and were a consequence of the extremely low water solubility of 1789, i.e. 3 µg/I. Note that the measured concentration at the end of the test period in the unfiltered solution was still far above the water solubility. Degradation or hydrolysis was not expected to have occurred although there were no data on stability of butyl methoxydibenzoylmethane in water.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.03 mg/L
Nominal / measured:
nominal
Conc. based on:
dissolved
Basis for effect:
mobility
Remarks on result:
other: 5 µm filtered test solution prepared at a nominal loading of 100 mg/I; max. water solubility determined was 0.03 mg/l.
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.03 mg/L
Nominal / measured:
nominal
Conc. based on:
dissolved
Basis for effect:
mobility
Remarks on result:
other: 5 µm filtered test solution prepared at a nominal loading of 100 mg/I; max. water solubility determined was 0.03 mg/l.
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: WAF: 5 µm filtered test solution prepared at a nominal loading of 100 mg/L, the regulatory limit concentration.
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: WAF: 5 µm filtered test solution prepared at a nominal loading of 100 mg/L, the regulatory limit concentration.
Details on results:
- Behavioural abnormalities: none reported
- Observations on body length and weight: none reported
- Other biological observations: Three out of twenty daphnids exposed to the unfiltered solution became immobilised after 48 hours. However, this response was probably related to the presence of undissolved test substance particles causing mechanical damage by hampering the swimming capacity of the daphnids.
- Mortality of control: 0
- Other adverse effects control: none reported
- Abnormal responses: none reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Owing to the extremely low solubility of butyl methoxydibenzoylmethane in water, actual concentrations in both the filtered and unfiltered solution could not be maintained at more than 80% of the initial concentration. However, every possible effort was made to ensure that the maximum soluble fraction of butyl methoxydibenzoylmethane was tested and maintained (continuous stirring for three days of a supersaturated 100 mg/I solution followed by filtration). Further, the measured concentration in the unfiltered solution at the end of the test period was still far above the water solubility (3 µg/I).
- Effect concentrations exceeding solubility of substance in test medium: Yes. Nominal concentration 100 mg/l. Water solubility reported to be 3 µg/l only.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Mortality: no data
- EC50/LC50: The 48h-EC50 was 0.60 mg/I with 95% fiducial limits of 0.52 — 0.76 mg/I.
- Other:
Reported statistics and error estimates:
no statistics applied

Any other information on results incl. tables

Table 2: Incidence of immobility in the combined limit/range-finding test:

 Test group  Measured concentrations (mg/l)

Response at 48 h

Number 

Response at 48 h      

 Blank control n.d.   0 0       
 Blank control  n.d.  0 0       
   0.1%  filtrate  n.m.   0     0   
   1%  filtrate  n.m.   0  0      
  10%  filtrate   n.m.  0     0
 100% filtrate   0.19 - <0.04**  0     0
  100% filtrate   0.19 - <0.04    0
 100 mg/l  17 - 0.28  2 *   20

  100 mg/l

 17 - 0.28 

1 * 

 10

n.d. not detected

 n.m. not measured

* Deposits and a film were observed.

10 Daphnids exposed in each batch.

** detection limit: 0.04 mg/l

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Due to low solubility of test item, actual concentrations could not be maintained at more than 80% of the initial concentration. However, every possible effort was made to ensure that the maximum soluble fraction of the test item was tested and maintained
Conclusions:
Owing to the extremely low solubility of butyl methoxydibenzoylmethan in water (0.03 mg/I), concentration levels toxic for crustaceans could not be reached. Therefore, the 48h-EC50 for Daphnia magna exceeded the maximum solubility of butyl methoxydibenzoylmethan in water.
Executive summary:

The purpose of this study was to evaluate the acute toxicity of test item butyl methoxydibenzoylmethan to Daphnia magna. The study followed the protocol as described in OECD Guideline 202.

Butyl methoxydibenzoylmethan induced no immobility in Daphnia magna exposed to a filtered (ca. 5 µm) solution prepared at nominal 100 mg/I (NOEC). Three out of twenty daphnids exposed to the unfiltered solution became immobilised after 48 hours. However, as the measured concentration in unfiltered test medium was above the water solubility of 0.03 mg/l, this response was likely related to the presence of undissolved test substance particles causing mechanical damage by hampering the swimming capacity of the daphnids.

In conclusion: Owing to the extremely low solubility of butyl methoxydibenzoylmethan in water (0.03 mg/I), concentration levels toxic for crustaceans could not be reached. Therefore, the 48h-EC5O for Daphnia magna exceeded the maximum solubility of butyl methoxydibenzoylmethane in water.