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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance to GLP following OECD-202, Daphnia sp., Acute Immobilization Test, Part 1.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report date:
2004

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Characterization of the test and reference material used in this study was not conducted following GLP standards; however, a record of custody providing the purity and composition of the test material was provided by the supplier.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
A transparent yellowish liquid, reported to have a measured purity of 99.65% (comprised of 96.07% trans MOD-1 and 3.58% cis MOD-1 isomers).

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The concentration of MOD-1 in the test solutions was confirmed by analyzing a sample from each replicate fresh test solution on day 0 and each replicate spent test solution on day 2. Aliquots (5 mL) were collected from the control ALDW, 2.72, 4.54 and 7.56 mg/L dose levels and transferred to 4-dram vials containing 5 mL of brine.

The samples were extracted with 1 mL of cyclohexane. For the 12.6, 21.0 and 35.0 mg/L dose levels, aliquots (2 mL) were collected and transferred to 4-dram vials containing 2 mL of brine. The samples were extracted with 2 mL of cyclohexane. All samples were extracted by shaking on a flatbed shaker set on low speed for 30 minutes, then centrifuging for 10 minutes at 2000 rpm. The organic extract was transferred to autosampler vials for analysis by GC/FID.

Test solutions

Vehicle:
no
Details on test solutions:
0 (water control), 2.72, 4.54, 7.56, 12.6, 21.0, and 35.0 mg MOD-1/L.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
The test organism was the freshwater daphnid, Daphnia magna, from in-house cultures initially obtained from New England Bioassay, Inc., Manchester, Connecticut. Daphniainstars less than 24- hours old from a laboratory-reared culture were used as the test organisms.

Rearing conditions were as follows: illumination (cool-white fluorescent) 2050 ± 350 lux; 16-hour light/8- hour dark photoperiod; temperature 20 ± 2°C. Daphnia were fed a mixed diet of Pseudokirchneriella subcapitata, a freshwater green alga (formerly known as Selenastrum capricornutum) and YCT (yeast, Cerophyll, and trout chow suspension) five times weekly. The day before instars were needed for testing, stock tanks with Daphnia, which have had at least three broods, were removed from the incubator. The instars were separated from adults by gently lifting the screened insert from the 2-L stock tank, releasing instars through the nylon mesh screen while retaining the adult Daphnia. The screened insert containing adult Daphnia was then placed in another stock tank that contained daphnid water. The original solution with instars was poured through a metal sieve into another stock tank. The instars collected on the sieve were discarded, and the original solution was poured back into the initial stock tank. The corresponding screened insert holding adult Daphnia was then put back in place. This procedure was repeated the day the study was set to collect < 24-hour old instars for use in the study.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h

Test conditions

Test temperature:
20-21°C
pH:
7.6 ± 0.1 (7.4-7.7).
Dissolved oxygen:
8.3 ± 0.2 mg/L (8.1 mg/L-8.6 mg/L).
Percent oxygen saturation averaged 93% and remained >= 91% throughout the study
Nominal and measured concentrations:
Nominal: 0, 2.72, 4.54, 7.56, 12.6, 21.0, and 35.0 mg MOD-1/L.
Measured: <0.2 mg/L (

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 30.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
26.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
19.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
All biological results are expressed in terms of mean measured concentrations of MOD-1.

Summary results of the biological observations are presented in Table 6. Daphnia were observed at 24 and 48 hours of exposure and the primary endpoint of interest in this acute study was immobility. Immobility was observed in 30% (6/20) and 75% (15/20) of the Daphnia at the 30.8 mg/L dose level following 24 and 48 hours of exposure, respectively. In addition, all Daphnia at the 30.8 mg/L dose level were observed to be at the bottom of the vessels following both 24 and 48 hours of exposure. This behavior was not observed in the remaining dose levels or the water control. No immobility was observed in the 19.1 mg/L and below dose levels or in the water control during the conduct of the study. The resulting acute toxicity values for MOD-1 with Daphnia magna were statistically evaluated, where applicable, using mean measured concentrations and are listed below:

• The 24-hour EC50 value was greater than the highest concentration tested of 30.8 mg/L.
• The 48-hour EC50 value was 26.3 mg/L; no reliable 95% confidence interval could be determined.
• The 48-hour NOEC was 19.1 mg/L and was determined based on interpretation of the biological data and the highest exposure level exhibiting no Daphnia immobility.

Applicant's summary and conclusion

Conclusions:
The 24-hour EC50 value was greater than the highest concentration tested of 30.8 mg/L.

The 48-hour EC50 value was 26.3 mg/L; no reliable 95% confidence interval could be determined.

The 48-hour NOEC was 19.1 mg/L and was determined based on interpretation of the biological data and the highest exposure level exhibiting no Daphnia immobility.