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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Administrative data

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD guideline 219
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Lot nr 079K0115
- Purity: 99.9 wt%

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Analytical measurements were made on additional replicate systems at day 0 and day 28 for determination of test substance concentrations in overlying water.

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
other: Chironomus riparius
Details on test organisms:
Laboratory cultures used to provide 1st instar (1-day old) individuals at test initiation. Age was confirmed by measurement of head capsule widths of a representative sample.

Breeding conditions: Cultured at room temperature (21-25 degrees C) in laboratory culture water.
Handling of egg masses and larvae: Egg masses collected and isolated in freshwater, maintained at 20 degrees C.
- Feeding during test: prepared invertebrate food- a suspension of commercial fish flake food
- Amount: Daily, 2.5-3 ml of 2.0 mg/ml during 1st 10 days, 6-8 ml for remainder

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
28 d

Test conditions

Hardness:
140 to 162 mg CaCO3/L
Test temperature:
19.4 to 21.7 ° C
pH:
8.5 to 8.7
Dissolved oxygen:
5.2 to 9.3 mg/L (60 to 95% saturation)
Nominal and measured concentrations:
Nominal concentrations definitive test : 0 (control), 2.5, 5.0, 10, 20, 40 and 80 mg B/L.
Geometric Mean Measured Overlying Water Total Concentrations: 0.298, 3.06, 5.93, 11.0, 20.4, 43.3, and 89.3 mg B/L
Geometric Mean Measured Overlying Water Added Concentrations: 0, 2.76, 5.63, 10.7, 20.1, 43.0, and 89.0 mg B/L
Details on test conditions:
Test chambers were 1-L glass jars containing approximately 255 g of sediment (clean washed sand) Sediment depth was approximately 2 cm. Dilution water (600 mL) was added to each replicate chamber using a deflector to minimize disturbance of the sediment. Water depth was approx 8 cm, so the water: sediment volume ratio was approx 4:1. Polypropylene emergence traps with nylon mesh were used to monitor adult midge emergence. Chambers were left for 1 d to equilibrate before the test started.

At least 7 replicate chambers were prepared for each treatment level and control. Two were used to provide samples for chemical analysis and 3 chambers were used for biological observations. 20 midge larvae were added to each chamber for the chemical and biological observations. Seven different exposures were tested, a control and six treatments. Larvae were impartially added to cups, then the cups randomly assigned to a replicate chamber.

Overlying water was aerated during the test beginning 24 h after addition of the organisms by gentle bubbling. Midges were fed 2.5 to 3 ml of a commercial flake fish food suspension (2.0 mg/ml) for the first 10 d, then 8 ml daily for the remainder of the test. Algae were added during the first 3 days as food for the first instar larvae. Lighting was 16 h: 8 h light:dark cycle with a 30 m transition period. Light intensity was 520 lux. Temperature was maintained at 20 +/- 2 degrees C by keeping the test chambers in a flowing water bath. Water was not replaced during the test.

Emergence of adult flies was monitored from day 18. Presence of adults or exuviae in traps was monitored. Adult flies were identified by gender.

Results and discussion

Effect concentrationsopen allclose all
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
20.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element
Basis for effect:
mortality
Duration:
28 d
Dose descriptor:
LC10
Effect conc.:
52.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element
Basis for effect:
mortality
Remarks on result:
other: confidence limits: 49.8 - 54.6 mg/L
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
20.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element
Basis for effect:
other: emergence
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
43.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element
Basis for effect:
other: emergence time
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
43.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
element
Basis for effect:
other: development rate
Details on results:
The nominal concentrations were added in the effect concentrations table, following the usual practice that a nominal concentration may be used if the measured values are reasonably close to the nominal. EC10 could not be calculated for the endpoints emergence time and development rate. For the endpoint mortality both NOEC and LC10 values are reported, and preference is given to the use of LC10 value for PNEC derivation. For the endpoint emergence, an EC10 of 9.7 mg/L (7.4 E-23 - 1.3 E+24 mg/L) has been calculated but was not fruther used because of the large confidence limits.
Results with reference substance (positive control):
s
Reported statistics and error estimates:
Statistical analysis based on one-way ANOVA followed by Dunnett's test. The LC10/EC10 values have been recalculated with the log-logistic model using Toxicity Relationship Analysis Program, Version 1.21A.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Expressed as nominal added boron the NOEC values for survival and percent emergence were 20 mg B-added/L and LOECs were 40 mg B-added/L. The NOEC value for development rate was 40 mg B-added/L.

Based on survival and percent emergence, the NOEC (total) was 20.4 mg B/L and LOEC (total) was 43.3 mg B/L. The EC10 (total) for survival was 43.0 mg B/L. The EC10 (total) for percent emergence was 40.8 mg B/L (95% CI 30.5 to 51.1 mg B/L) The NOECs (total) for time to emergence for males and females (calculated separately and combined) were 43.3 mg B/L. The NOECs (total) for development rate for males and females (calculated separately and combined) were 43.3 mg B/L.

Expressed as added boron the NOEC values for survival and percent emergence were 20.1 mg B-added/L and LOECs were 43.0 mg B-added/L. The NOEC value for development rate was 43.0 mg B-added/L. The EC10 for survival would be 42.7 mg B-added/L and the EC10 for percent emergence would be 40.5 mg B-added/L.

Analyses of the overlying water at test initiation and termination documented that the boron concentrations were relatively constant in the overlying water. This suggests that the silica sand sediment did not remove any significant amount of the boric acid spiked into the water.