(1E)-1-chloro-3,3,3-trifluoroprop-1-ene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 April 2009 to 09 April 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study conducted under GLP conditions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Aliquots of 60 mL of the appropriate test solutions were dispensed to each test and blank vessel, with the remainder of the test solutions being used for physical and chemical analyses. One extra vessel for each concentration and the control was prepared and sealed for 0 hour analysis due to the volatility of the test substance. Samples for analysis were taken at 0 hours from a specific airtight vessel (to prevent loss of volatile test substance) and at 72 hours from a single test replicate solution of each exposure (containing alga).

Vehicle:

no

Details on test solutions:

PREPARATION OF TEST SOLUTION:
The test solutions were prepared by additions of stock solution to sterile culture medium. A stock solution of the highest concentration was prepared by bubbling test substance through 3500 mL of sterile media for approximately 60 minutes to obtain a saturated solution of the gas (100 %). This was diluted to 70 % saturation with sterile oxygenated media; this stock was used for the top concentration. All other concentrations were made from this, and inverted in volumetric flasks to mix. The resulting solutions were clear and colourless. The control consisted of sterile culture medium only. In all cases the final solutions contained nutrients as required.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST SPECIES:
The test species was the unicellular green alga Pseudokirchneriella subcapitata strain ATCC 22662 from laboratory cultures maintained under axenic conditions. A 3 day old culture of the alga in the exponential growth phase was used as inoculum for the test. The culture was grown in the medium, and under the environmental conditions, described for the test.

CULTURE MEDIUM:
The culture medium used for the test was AAP-medium which had additional bicarbonate added as a carbon source for the algae as the test was run in sealed vessels with no headspace. The medium used for the maintenance of cultures was AAP-medium only. Both media are based on information published by Miller et al. (1978).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 - 25 °C

pH:

- Start: pH 7.91 - 8.26
- End: pH 8.48 - 10.14

Nominal and measured concentrations:

- Nominal concentrations: 4.38, 8.75, 17.5, 35 and 70 % of saturation.
- Measured concentrations (t=0): - Measured concentrations (t=72h): - Measured concentrations (mean):

Details on test conditions:

TEST PROCEDURE AND APPARATUS:
The test vessels were glass bottles of 50 mL nominal capacity, filled completely with approximately 60 mL of test solution, with airtight, Teflon faced disc/crimp closures. The cultures were incubated at 24 ± 2 °C (the nominal test temperature), under continuous "cool-white" illumination of approximately 8000 lux, with a nominal orbital shaking at 160 ± 10 rpm. Small glass beads were placed into each vessel to aid mixing and prevent algal clumping.
Two replicates of the control and each concentration of test substance were employed for each sampling occasion (24, 48 and 72 hours), thus there were 6 replicates for the control and each test concentration in total. One blank vessel (without algal inoculum) was incubated concurrently for the control and each test concentration to be used to determine ‘background’ particle density at each sampling occasion (24, 48 and 72 hours). Analytical samples for 0 hours were taken from excess solutions. One extra vessel for each concentration and the control were prepared and sealed for 72 hour analytical analysis. The position of each test replicate vessel in the incubator was randomised by rows daily.
The algal cell densities of the inoculum and test cultures were determined by electronic particle counting, using a Coulter counter model Z1 and counting at a lower threshold equivalent spherical diameter of approximately 2.3 μm. Each replicate test vessel was inoculated with 0.35 mL of the inoculum culture to give a nominal cell density of 0.100E+04 cells/mL. One 60 mL volume of Coulter electrolyte, inoculated in the same manner, had a cell density of 0.109E+04 cells/mL. This value was used for growth calculations.
After 24, 48 and 72 hours, appropriate vessels were removed for the blank, control and each test concentration. The appropriate blank particle count was subtracted from that of the test culture to obtain the cell density.
At the end of the test microscopic observations were made on samples taken from a single replicate of the control and each test substance concentration.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

115 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 215 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

BIOLOGICAL DATA:
Algal cell particle densities (cell particles per unit volume) were measured as a surrogate for biomass. A hormetic effect was seen in the test concentrations 13.5, 32.0 and 60.5 mg/L; as a consequence of this hormesis EyC50 was calculated via linear interpolation. A significant difference in yield was found at 32.0 mg/L and three significant differences in growth rate were found at 13.5, 32.0 and 60.5 mg/L. These effects were however considered due to the hormetic effect rather than an inhibitory effect, and were thus discounted. The EC50 for growth rate could not be calculated as < 50 % inhibition was seen.
The increase in biomass for the parent inoculum culture was monitored over its 3-day growth period and was considered to be in an exponential growth phase. As such, the overall factor increase in cell particle density (considered equivalent to biomass) was 131 times, an approximate daily factor of 5.1, which is deemed acceptable.
The microscopic observations, made at the end of the test, showed that compared to the control the algal cells sampled from the 13.5, 32.0, 60.5 mg/L test concentrations appeared normal. At 115 and 215 mg/L test concentrations algal cells sampled were enlarged, with deformed cells only noted in the top concentration (215 mg/L) where very low cells numbers were also observed.

ANALYTICAL DATA:
Due to the preparation technique of the primary stock solution (bubbling) the nominal concentrations of test substance were unknown until analytical analysis was conducted. Therefore it is not possible to make a comparison between the nominal and measured concentrations.

Reported statistics and error estimates:

Cell particle densities were examined by one-way analysis of variance and Dunnett’s procedure was used to identify significant differences (p < 0.05) from the control.

Mean growth rates over the test period

Mean measured concentration [mg/L]	Mean growth rate (0-72 hours)	Percentage of control
Control	1.51	-
13.5	1.88*	124
32.0	1.92*	127
60.5	1.80*	119
115	1.52	101
215	0.956*	63

* Significant difference (P < 0.05) from control

 

Mean yields over the test period

Mean measured concentration [mg/L]	Mean yield (0-72 hours)	Percentage of control
Control	10.1	-
13.5	30.3	299
32.0	34.4*	339
60.5	23.8	235
115	10.5	103
215	1.81	18

* Significant difference (P < 0.05) from control

Validity criteria fulfilled:

yes

Conclusions:

The 72-h ErC50 in Pseudokirchneriella subcapitata is > 215 mg/L (measured concentration).
The 72-h NOErC in Pseudokirchneriella subcapitata is 115 mg/L (measured concentration).

Executive summary:

The toxicity of the substance to algae was determined in a study in accordance with OECD TG 201 and in compliance with GLP criteria. In this study, freshwater algae (Pseudokirchneriella subcapitata) were exposed to nominal concentrations of 0, 4.38, 8.75, 17.5, 35 and 70 % of saturation for 72 hours under static conditions. Nominal concentrations were prepared by bubbling test substance through 3500 mL of sterile media for approximately 60 minutes to obtain a saturated solution of the gas (100 %). This was diluted to 70 % saturation with sterile oxygenated media; this stock was used for the top concentration. All other concentrations were made from this, and inverted in volumetric flasks to mix. Test concentrations were analytical verified. Mean measured concentrations were 13.5, 32.0, 60.5, 115, and 215 mg/L. After 72 hours exposure, a significant difference in yield was found at 32.0 mg/L and three significant differences in growth rate were found at 13.5, 32.0 and 60.5 mg/L. These effects were however considered due to the hormetic effect rather than an inhibitory effect, and were thus discounted. Only at the highest concentration tested was a significant harmful effect on growth rate observed (37 % inhibition compared to control). Based on these findings, the ErC50 (for growth rate) could not be calculated as inhibition remained below 50 %. The NOErC was determined at 115 mg/L (measured concentration).

Description of key information

The toxicity of the substance to algae was determined in a study in accordance with OECD TG 201. In this study, the NOErC was determined to be 115 mg/L (measured concentration), and the ErC50 was determined to be > 215 mg/L.  

Key value for chemical safety assessment

EC50 for freshwater algae:

215 mg/L

EC10 or NOEC for freshwater algae:

115 mg/L

Additional information

The toxicity of the substance to algae was determined in a study in accordance with OECD TG 201 and in compliance with GLP criteria (Brixham Envriomental laboratory, 2009). In this study, freshwater algae (Pseudokirchneriella subcapitata) were exposed to nominal concentrations of 0, 4.38, 8.75, 17.5, 35 and 70 % of saturation for 72 hours under static conditions. Nominal concentrations were prepared by bubbling test substance through 3500 mL of sterile media for approximately 60 minutes to obtain a saturated solution of the gas (100 %). This was diluted to 70 % saturation with sterile oxygenated media; this stock was used for the top concentration. All other concentrations were prepared from this stock, and inverted in volumetric flasks to mix. Test concentrations were analytically verified. Mean measured concentrations were 13.5, 32.0, 60.5, 115, and 215 mg/L. After 72 hours exposure, a significant difference in yield was found at 32.0 mg/L and three significant differences in growth rate were found at 13.5, 32.0 and 60.5 mg/L. These effects were however considered due to the hormetic effect rather than an inhibitory effect, and were thus discounted. Only at the highest tested concentration of 215 mg/L was a significant harmful effect on growth rate observed (37 % inhibition compared to control). Based on these findings, the NOErC was determined at 115 mg/L (measured concentration). The ErC50 (for growth rate) could not be calculated as inhibition remained below 50 %. For purpose of assessment, the ErC50 is determined at >215 mg/L and therewith at 215 mg/L.