Trifluoroiodomethane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 Apr 2019 to 18 Apr 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April, 2004.

Qualifier:

according to guideline

Guideline:

other: Guidance document on aqueous-phase aquatic toxicity testing of difficult test chemicals, OECD series on testing and assessment number 23

Version / remarks:

2018

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Double samples for possible analysis were taken from all test concentrations and the control according to the schedule below.
- Frequency: at t=0 h and t=48 h
- Volume: 0.1 and 1.0 mL from the approximate centre of the test vessels. The 0.1 mL samples were directly diluted with 0.9 mL test medium.
- Storage: samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the test facility.

At the end of the exposure period, the replicates were pooled at each concentration before sampling. Additionally, double reserve samples of 0.1 and 1.0 mL were taken for possible analysis. If not used, these samples were stored in a freezer (≤-15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Vehicle:

no

Details on test solutions:

Preparation of test solutions started with a minimum loading rate of 500 mg/L applying a 4 – 5 hour period of shaking in Tedlar® gas sampling bags to ensure maximum dissolution of the test item in medium. The obtained mixture was allowed to settle overnight (approximately 19 hours). Thereafter, the aqueous Saturated Solution (SS) was used as the highest test concentration. Lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All test solutions were clear and colorless at the end of the preparation procedure.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Straus, 1820
- Source: In-house laboratory culture with a known history.
- Reason for selection: This system has been selected as an internationally accepted invertebrate species.
- Validity of batch: Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
- Characteristics: Daphnia, less than 24 hours old, from parental daphnids of more than two weeks old. The organisms were at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.

CULTURING CONDITIONS
- Start of each batch: Approximately 250 newborn daphnids, i.e. less than 3 days old, were placed into 5 litres of medium in an allglass culture vessel.
- Maximum age of the cultures: 4 weeks
- Renewal of the cultures: After 7 days of cultivation, half of the medium twice a week.
- Temperature of medium: 18-22°C
- Feeding: Daily, a suspension of fresh water algae
- Culture medium: M7

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

CaCO3: 180 mg/L

Test temperature:

19 - 20°C

pH:

7.1 - 7.8

Dissolved oxygen:

8.2 - 9.1 mg/L

Nominal and measured concentrations:

- Nominal loading rates: Solutions containing 0 (control), 10, 18, 32, 56 and 100% of the SS, prepared at a loading rate of 500 mg/L.
- Mean measured concentrations:

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL, all-glass, airtight closed without headspace.
- Aeration: No aeration of the test solutions was applied.
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4
- Introduction of daphnids: Within 25 minutes after preparation of the test solutions.
- Feeding during study: No

TEST MEDIUM / WATER PARAMETERS
The following salts (analytical grade) were added to tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
- CaCl2.2H2O 211.5 mg/L
- MgSO4.7H2O 88.8 mg/L
- NaHCO3 46.7 mg/L
- KCl 4.2 mg/L

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: A daily photoperiod of 16 hours.

WATER QUALITY MEASUREMENTS
- pH and dissolved oxygen: At the beginning and at the end of the test, for all concentrations and the control.
- Temperature: Continuously in a temperature control vessel, beginning at the start of the test.

EFFECT PARAMETERS MEASURED: immobility
Immobility (including mortality) was observed at 24 and 48 hours exposure.

RANGE-FINDING STUDY
Ten daphnids per concentration (in duplicate, 5 per vessel) were exposed to 1.0 and 10% of the SS prepared at a loading rate of 100 mg/L in the combined range-finding test. A final test was performed based on the results of a combined limit/range-finding test.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

66 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobility was observed in the control and the two lowest test concentrations throughout the exposure period. At the end of the test, a dose-related increase of immobility was observed at 39 mg/L (32% of the SS), reaching 100% immobility at the highest test concentration. The responses recorded in this test allowed for reliable determination of an EC50 and were in agreement with what was expected based on the results of the combined limit/range-finding test. See 'Any other information on results incl. tables'.

Reported statistics and error estimates:

All results are calculated using values as per the raw data rounding procedure and may not be exactly reproduced from the individual data presented. The average exposure concentrations were calculated as geometric means of the concentrations of the test substance measured in the samples taken at the start (Ct=0) and the end of the test (Ct=48).

The confidence intervals of the EC50-values could not be determined using a regression method. Instead, the 24 and 48h-EC50-values were calculated by applying the Spearman-Karber procedure (non-linear; without trimming) on the percentages of affected daphnids and the logarithms of the corresponding average exposure concentrations. ToxRat Professional v 3.2.1 (ToxRat Solutions® GmbH, Germany) was used to perform the analysis.

Table 2. Number of Introduced Daphnids and Incidence of Immobility in the Final Test

Time (h)	Replicate	Test substance average exposure conc. (mg/L)
		Control	2.8	14	39	62	92
0	A	5	5	5	5	5	5
	B	5	5	5	5	5	5
	C	5	5	5	5	5	5
	D	5	5	5	5	5	5
	Total introduced	20	20	20	20	20	20
24	A	0	0	0	0	1	5
	B	0	0	0	1	1	5
	C	0	0	0	0	0	5
	D	0	0	0	0	1	5
	Total immobilised	0	0	0	1	3	20
	Effect %	0	0	0	5	15	100
48	A	0	0	0	0	1	5*
	B	0	0	0	2	0	5
	C	0	0	0	0	1	5
	D	0	0	0	0	1	5
	Total immobilised	0	0	0	2	3	20
	Effect %	0	0	0	10	15*	100

* It should be noted that these daphnia are mobile, but have more difficulty swimming in comparison to the control;

# Microscopic observation revealed no test item attached to the daphnids.

Validity criteria fulfilled:

yes

Conclusions:

The 48h-EC50 for Daphnia magna exposed to the test substance was 66 mg/L based on average exposure concentrations (95% confidence interval between 58 and 74 mg/L).

Executive summary:

The objective of the study was to evaluate the test substance for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC50 at 24 and 48 hours of exposure. The study procedures described in this report were based on the OECD guideline No. 202, 2004. In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23, 2018. The batch of test substance tested was a liquefied gas with a purity of >99.99% and not completely soluble in test medium at the loading rate initially prepared. A Saturated Solution (SS) was prepared at a minimum loading rate of 500 mg/L and used as the highest concentration. Lower concentrations were prepared by diluting the highest concentration in test medium. A final test was performed based on the results of a combined limit/range-finding test. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to solutions containing 10, 18, 32, 56 and 100% of the SS prepared at a minimum loading rate of 500 mg/L. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. Samples taken from all test concentrations and the control were analyzed. The measured concentrations at the start of the test were 15, 18, 48, 94 and 140 mg/L, respectively. During the exposure period, the concentrations decreased to 3.4, 62, 65, 43 and 43% of initial at the end of the test. Based on these results, the average exposure concentrations were calculated and used to express effect parameters. No immobility was observed in the control and the two lowest test concentrations throughout the exposure period. At the end of the test, a dose-related increase of immobility was observed at 39 mg/L (32% of the SS), reaching 100% immobility at the highest test concentration. The study met the acceptability criteria prescribed by the study plan and was considered valid. In conclusion, the 48h-EC50 for Daphnia magna exposed to the test substance was 66 mg/L based on average exposure concentrations (95% confidence interval between 58 and 74 mg/L).

Description of key information

The 48-h EC50 was determined to be 66 mg/L in Daphnia magna.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

66 mg/L

Additional information

The objective of the study was to evaluate the test substance for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC50 at 24 and 48 hours of exposure. The study procedures described in this report were based on the OECD guideline No. 202, 2004. In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23, 2018. The batch of test substance tested was a liquefied gas with a purity of >99.99% and not completely soluble in test medium at the loading rate initially prepared. A Saturated Solution (SS) was prepared at a minimum loading rate of 500 mg/L and used as the highest concentration. Lower concentrations were prepared by diluting the highest concentration in test medium. A final test was performed based on the results of a combined limit/range-finding test. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to solutions containing 10, 18, 32, 56 and 100% of the SS prepared at a minimum loading rate of 500 mg/L. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. Samples taken from all test concentrations and the control were analyzed. The measured concentrations at the start of the test were 15, 18, 48, 94 and 140 mg/L, respectively. During the exposure period, the concentrations decreased to 3.4, 62, 65, 43 and 43% of initial at the end of the test. Based on these results, the average exposure concentrations were calculated and used to express effect parameters. No immobility was observed in the control and the two lowest test concentrations throughout the exposure period. At the end of the test, a dose-related increase of immobility was observed at 39 mg/L (32% of the SS), reaching 100% immobility at the highest test concentration. The study met the acceptability criteria prescribed by the study plan and was considered valid. In conclusion, the 48h-EC50 for Daphnia magna exposed to the test substance was 66 mg/L based on average exposure concentrations (95% confidence interval between 58 and 74 mg/L).

Additional computational estimations were provided as supporting information. The results are in line with the experimental study.

ECOSAR v2.00 data was generated on the test substance. Estimations of the test substance were conducted based on the model for neutral organics identified by ECOSAR. The 48-h EC50 was

estimated to be 90.2 mg/L. The substance did not (completely) fall within the applicable domain of the model. However, it is expected that this does not affect the reliability of the prediction. Adequate and reliable documentation / justification of the ECOSAR prediction is provided.

Furthermore, a QSAR OECD Toolbox v4.2 prediction based on trend analysis was generated on the test substance. Based on the calculated log Kow, the acute toxicity to aquatic invertebrates was estimated on a plot consisting of a suitable set of subcategorized data points. The acute toxicity to aquatic invertebrates was predicted to be 98.3 mg/L. The substance falls within the log Kow domain of the data set. Adequate and reliable documentation / justification of the trend analysis prediction is provided.