4-(cyclohexylamino)butane-1-sulfonic acid

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:

13 May 2019 - 21 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

13 April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Correction factor for purity: not required
- Stability at higher temperatures: stable
- Solubility in water: 110 g/L

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All test concentrations and control
- Sampling method: 2.0 mL from the approximate centre of the test vessels at t=0 h and t=48 h.
- Sample storage conditions before analysis: 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.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: the test item was completely soluble in test medium at the concentrations tested. Preparation of test solutions started with the highest concentration of 100 mg/L applying a one-hour period of magnetic stirring to accelerate the dissolution of the test item in test medium. Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
- Controls: Test medium without test item or other additives.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Straus 1820
- Source: In-house laboratory culture with a known history
- Age of parental stock: > 2 weeks
- Age at test initiation: < 24 hours
- 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.

CULTIVATION
- Start of each batch: Approximately 250 newborn daphnids, i.e. less than 3 days old, were placed into 5 litres of M7 medium in an all-glass 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.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

180 mg/L

Test temperature:

20-21°C

pH:

At start (t=0 h): 7.9
At end (t=48 h): 8.2

Dissolved oxygen:

At start (t=0 h): 9.4 mg/L
At end (t=48 h): 9.5-9.6 mg/L

Nominal and measured concentrations:

Nominal: 0.1, 1.0, 10 and 100 mg/L
Measured: 100 mg/L at t=0 h: 119 mg/L t=48 h: 116 mg/L
Based on these results, the analytically confirmed nominal exposure concentrations were used to determine the effect parameters. See Table 2 in 'Any other information on results incl. tables' for details.

Details on test conditions:

The test was performed as a Combined Limit/range-finding Test.

TEST SYSTEM
- Test vessel: 60 mL, all-glass
- Volume of solution: 50 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 (100 mg/L group) and 2 (10, 1.0 and 0.10 mg/L group)
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO-medium, prepared with tap water purified by Reverse Osmosis and the following salts: CaCl2.2H2O: 211.5 mg/L, MgSO4.7H2O: 88.8 mg/L, NaHCO3: 46.7 mg/L, KCl: 4.2 mg/L
- Culture medium different from test medium: yes (M7 medium)
- Intervals of water quality measurement: pH and dissolved oxygen: at the beginning and at the end of the test, for all concentrations and the control. Temperature of medium: continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours

EFFECT PARAMETERS MEASURED:
- Immobility (including mortality) at 24 h and at 48 h.

Reference substance (positive control):

yes

Remarks:

potassium dichromate (performed April 2019)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: none observed in the test concentrations or the control group.
- Mortality of control: none
- No immobility was observed in the control and at any of the test concentrations, see Table 1.
- All water quality parameters remained within the requirements as laid down in the study plan throughout the test.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- The 24h-EC50 was 0.92 mg/L with a 95% confidence interval between 0.78 and 1.1 mg/L. The 24h-EC50 was within the expected range of 0.6 and 2.1 mg/L as specified in ISO International Standard 6341, October 2012.
- The 48h-EC50 was 0.55 mg/L with a 95% confidence interval between 0.47 and 0.64 mg/L.
- The responses in this reference test with K2Cr2O7 are within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.28 and 0.75 mg/L. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at the Test Facility.

Reported statistics and error estimates:

No EC50 could be calculated because the test item proved to be non-toxic (EC50 > maximum concentration tested).

Table 1: Immobility of daphnids

Time (h)	Control	0.10 mg/L	1.0 mg/L	10 mg/L	100 mg/L
0	0	0	0	0	0
24	0	0	0	0	0
48	0	0	0	0	0

Table 2: Analytical results

Time of sampling (h)	Nominal concentration (mg/L)	Analyzed concentration (mg/L)	Relative to nominal (%)	Relative to initial (%)
0	0	0.0024*	n.a.	-
	100	119	119	-
48	0	0.00093*	n.a.	n.a.
	100	116	116	98

n.a.: Not applicable; *: Estimated value, calculated by extrapolation of the calibration curve. Ecotoxicological samples might have been contaminated in course of sampling. The maximum contribution to the 100mg/L samples was 0.0024%, taking the dilution factor into account.

Validity criteria fulfilled:

yes

Remarks:

See 'Overall remarks' for details on validity criteria

Conclusions:

The 48h-EC50 for Daphnia magna exposed to the test substance was beyond the range of concentrations tested, i.e. exceeded an analytically confirmed nominal concentration of 100 mg/L.

Executive summary:

In an acute toxicity test conducted according to OECD guideline 202, Daphnia magna were exposed to the test substance at concentrations of 0.1, 1.0, 10 and 100 mg/L and an untreated control.

The nominal exposure concentration of 100 mg/L was analytically confirmed to be 119% and 116% of the nominal concentration throughout the test. Therefore, nominal concentrations were used to express the effect parameters. After an exposure time of 48 hours, no immobility was observed in the control and at any of the test solution concentrations. The 48h-EC₅₀ for immobility therefore exceeded the highest tested concentration, i.e. >100 mg/L based on analytically confirmed nominal concentrations. The study met all validity criteria and is considered to be reliable without restrictions.

Description of key information

The 48h-EC₅₀ value for Daphnia magna exposed to the test substance was determined in an acute toxicity test in accordance with OECD 202. Based on the results, the 48h-EC₅₀ value for immobility is > 100 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

> 100 mg/L

Additional information

In an acute toxicity test conducted according to OECD guideline 202, Daphnia magna were exposed to the test substance at concentrations of 0.1, 1.0, 10 and 100 mg/L and an untreated control.

The nominal exposure concentration of 100 mg/L was analytically confirmed to be 119% and 116% of the nominal concentration throughout the test. Therefore, nominal concentrations were used to express the effect parameters. After an exposure time of 48 hours, no immobility was observed in the control and at any of the test solution concentrations. The 48h-EC₅₀ for immobility therefore exceeded the highest tested concentration, i.e. >100 mg/L based on analytically confirmed nominal concentrations. The study met all validity criteria and is considered to be reliable without restrictions.