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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP test comparable to OECD guidance

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
other: EPA TSCA Guideline 40 CFR 797.1060
Principles of method if other than guideline:
OECD TG 201 (1984) was also considered in the study protocol
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Ethane,2,2-dichloro-1,1,1-trifluoro-
IUPAC Name:
Ethane,2,2-dichloro-1,1,1-trifluoro-
Constituent 2
Chemical structure
Reference substance name:
2,2-dichloro-1,1,1-trifluoroethane
EC Number:
206-190-3
EC Name:
2,2-dichloro-1,1,1-trifluoroethane
Cas Number:
306-83-2
Molecular formula:
C2HCl2F3
IUPAC Name:
2,2-dichloro-1,1,1-trifluoroethane
Details on test material:
- Name of test material (as cited in study report): HCFC-123
- Analytical purity: not reported.
- Name of test material (as cited in study report): HCFC 123
- Molecular formula (if other than submission substance): same as submission
- Molecular weight (if other than submission substance): same as submission
- Smiles notation (if other than submission substance): same as submission
- InChl (if other than submission substance): same as submission
- Structural formula attached as image file (if other than submission substance): same as submission
- Substance type: halogenated ethane
- Physical state: liquid
- Analytical purity: not reported
- Impurities (identity and concentrations): not reported
- Purity test date: not reported
- Lot/batch No.: BB305 D55A
- Expiration date of the lot/batch: not reported
- Stability under test conditions: stable
- Storage condition of test material: at room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At the start of the test, duplicate samples of 2 ml were removed from the test medium of one additional bottle at each exposure level.The procedure was repeated at 48 and 96 hours using the other additional bottle. Samples were removed through the septum in the top of each bottle and were immediately placed in sealed analytical vials

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Before the start of the test, test bottles of 300 ml capacity were filled with 50 ml EPA synthetic salts medium and sterilised by autoclaving. Each bottle was sealed with an airthight screw-cap fitted with a rubber septum. At the start of the test, 50 ml of the algae inoculum were added to each bottle to give a density of 1x 10E4 cells/ml. Aliquots of HCFC 123 were injected directly into thetest medium contained in the sealed bottles to give the final nominal concentrations of 13.3, 42.5, 133, 425 and 1327 mg/l.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Triplicate algal cultures with a cell count of 1E4/mL were exposed.
TEST ORGANISM
- Common name:
- Strain: S. capricornutum CCAP 278/4
- Source (laboratory, culture collection): Culture Centre for Algae and Protozoa (CCAP), Ambleside UK

Study design

Test type:
other: biomass and growth rate
Water media type:
not specified
Total exposure duration:
96 h
Post exposure observation period:
These subcultures were incubated for 10 days and their cell densities were determined.

Test conditions

Test temperature:
The temperature of the incubator ranged from 18.0-23.5ºC. The temperature of the contents of control and test bottles ranged, at the start of the test, from 22.2 to 22.3ºC and after 96 hours, from 19.2 to 21.9ºC.
pH:
Their pH ranged between 7.2 and 7.9 at the start of the test. After 96 hours, values varied between 8.1 and 9.9 in control bottles and test bottles at 13.3, 42.5, 133, and 425 mg/L nominal, but ranged from 7.5 to 7.7 at 1327 mg/L nominal.
Nominal and measured concentrations:
5 nominal concentrations of 13.3, 42.5, 133, 425, and 1327 mg/L
Details on test conditions:
The test was conducted in mineral salts medium at temperatures in the range 18.0 to 23.5ºC in an illuminated orbital incubator. Triplicate algal cultures with a cell count of 1E4/mL were exposed to HCFC-123 in sealed vessels containing mineral salts medium. Since the material was known to be volatile, it was injected through a rubber septum directly into the test medium. The cell density of each culture was measured, using a hemocytometer, at 24-hour intervals during the test. Growth rate (the rate of change in cell number with time) and biomass (the number of cells per mL) were both calculated. A set of control cultures was established in synthetic salts medium alone. Five bottles were established for each test and control group.
Exposure levels were monitored by a GC method of analysis. One bottle from each group, which was not incubated, was used for chemical analysis at the start of the test and then discarded. The remaining 4 bottles were incubated, of which 3 were used for cell counts during the test whilst the fourth was used for chemical analysis at 48 and 96 hours. The minimum, maximum, and ambient temperature and light intensity in the test area were determined each day. Following the removal of samples for chemical analysis at the start of the test, the temperature and pH of the contents of the fourth bottle in each group were determined. At the end of the test, after the removal of samples for analysis, the temperature and pH of the contents of each bottle were determined. On 3 occasions during the test (0, 48, and 96 hours) duplicate samples were removed from the test medium at each concentration for analysis. At the end of the test, in order to establish whether toxic levels of HCFC-123 caused inhibition of algal growth (were algistatic) or algal cell death (were algicidal), samples from cultures at the two highest nominal levels (1327 and 425 mg/L) were diluted (1:100) with fresh culture medium.

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
other: EC50 growth rate
Effect conc.:
96.6 mg/L
Basis for effect:
other: biomass and growth rate
Duration:
96 h
Dose descriptor:
other: EC50 biomass
Effect conc.:
67.8 mg/L
Basis for effect:
other: biomass and growth rate
Details on results:
On the day of preparation, control and test cultures were clear and colorless. Measured concentrations of HCFC-123 were low compared to nominal values. At 13.3 and 42.5 mg/L, measured concentrations increased over the first 48 hours. During the second 48 hours of the test, all measured concentrations showed some decline. Measured HCFC-123 levels were maintained at 50 to 93% of initial (0 hours) levels across the range between the no-effect and maximum effect concentrations (nominally 133-1327 mg/L). These low aqueous levels were not unexpected because the volatility of HCFC-123 is likely to have caused its loss, both during dosing and subsequently from the test media into the headspace of the vessels. Furthermore, although HCFC-123 was soluble at the test concentrations, it was not easy to disperse under the conditions of the test. However, since toxic concentrations were achieved and maintained, it was considered that calculation of biological effect concentrations based on measured exposure levels was valid.

Exposure at mean measured concentrations of 169 mg/L (nominally 1327 mg/L) resulted in a significant reduction in both biomass and average specific growth rate compared to control cultures. Biomass was also significantly reduced at 56.3 mg/L (nominally 425 mg/L). Thus the no-observed-effect concentration for biomass and growth rate, respectively, based on mean measured exposure concentrations, were 51.4 and 56.3 mg/L (nominal levels of 133 and 425 mg/L). Growth was reestablished in each subculture at the end of the test, indicating that at 1327 and 425 mg/L nominal, the material was algistatic.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Growth was reestablished in each subculture at the end of the test, indicating that at 1327 and 425 mg/L nominal, the material was algistatic.