Cyclohexanethiol

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: The study was conducted according to the appropriate OECD test guideline, in compliance with GLP and analytical monitoring was carried out.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

cyclohexylmercaptan

IUPAC Name:

cyclohexylmercaptan

Constituent 2

Reference substance name:

Cyclohexanethiol

EC Number:

216-378-7

EC Name:

Cyclohexanethiol

Cas Number:

1569-69-3

Molecular formula:

C6H12S

IUPAC Name:

cyclohexanethiol

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Cyclohexyl Mercaptan

- Physical state: Clear colourless liquid with no particulate matter

- Analytical purity: 99.85%

- Impurities (identity and concentrations):
Cyclohexene: <0.01%
Heavies: 0.10%
Mercapton Sulpher: 27.39 %
Dissolved Gases: <0.0500%

- Purity test date: 29/06/2009

- Lot/batch No.: 2009-06-1550

- Expiration date of the lot/batch: Undetermined

- Stability under test conditions: Volatile

- Storage condition of test material: Room temperature in the dark

- Other: Negligable solubility in water

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.033, 0.056, 0.10, 0.18, 0.33, 0.56, 1.0, 1.8, 3.3 mg/l

- Sample storage conditions before analysis: Room temperature in the dark

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: 25 mg of test material were each separately dispersed in 500 ml of reconstituted water in sealed vessels, to give initial test material dispersions of 50 mg/l which were then shaken at 300 rpm at a temperature of 30°C for 24 hours. Removal of any undissolved test material was by filtration through a 0.2 µm Gelman Acrocap filter to give a saturated solution with a nominal concentration of 33 mg/l. Aliquots were dispersed in a final volume of 2 litres of reconstituted water to give the test concentrations of 0.033, 0.056, 0.10, 0.18, 0.33, 0.56, 1.0, 1.8, 3.3 mg/l. The concentration and stability of the test material in the test preparations were verified by chemical analysis at 0 and 48 hours.

- Controls: Reconstituted water

- Evidence of undissolved material (e.g. precipitate, surface film, etc): Stock solution was filtered to remove any undissolved test material.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia Magna

- Source: In-house laboratory cultures

- Age at study initiation (mean and range, SD): less than 24 hours old

- Method of breeding: Pathogenesis

- Feeding during test: No feeding



ACCLIMATION
- Acclimation period: In-house cultures

- Acclimation conditions (same as test or not): Similar

- Type and amount of food: Algae suspension (Chlorella sp.)

- Feeding frequency: Daily

- Health during acclimation (any mortality observed): Not reported

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

reconstituted water: 250 mg/l

Test temperature:

Range 20-21°C

pH:

Range: 0 hours: 7.8-7.9
48 hours: 7.7-8.0

Dissolved oxygen:

Range: 0 hours: 8.5-8.7 mg 0₂/l
48 hours: 8.7-9.0 mg 0₂/l

Nominal and measured concentrations:

Nominal: 0.033, 0.056, 0.10, 0.18, 0.33, 0.56, 1.0, 1.8, 3.3 mg/l
Measured at 0 hours: 0.0151, 0.0311, 0.0658, 0.126, 0.182, 0.294, 0.589, 1.01, 2.13 mg/l respectively
Measured at 48 hours: 0.0103, 0.0225, 0.0489, 0.0972, 0.138, 0.263, 0.512, 0.861, 1.74 mg/l respectively

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 ml glass jars
- Type (delete if not applicable): closed using ground glass stoppers
- Material, size, headspace, fill volume: Glass, 300 ml, completely filled with 300 ml of test solution.
- Aeration: None
- Type of flow-through (e.g. peristaltic or proportional diluter): None
- Renewal rate of test solution (frequency/flow rate): No renewal
- No. of organisms per vessel: 10 daphnids
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water

- Ca/mg ratio: approximately 2:1

- Conductivity: <5 µS cm ¯¹

- Culture medium different from test medium: No

- Intervals of water quality measurement: 0 and 48 hours

OTHER TEST CONDITIONS
- Adjustment of pH: None

- Photoperiod: 16 hours light, 8 hours darkness cycle with 20 minute dawn and dusk transition periods.

- Light intensity: Not recorded

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Any immobilisation or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. Daphnia were considered to be immobilised if they were unable to swim after approximately 15 seconds after gentle agitation.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8

- Range finding study
- Test concentrations: 3.3, 0.33, 0.033, 0.0033 mg/l
- Results used to determine the conditions for the definitive study: The number of immobilised Daphnia Magna was recorded after 24 and 48 hours. No immobilised Daphnia at test concentrations of 0.0033 and 0.033 mg/l, but immbilisation observed at concentrations of 0.33, 3.3 and 33 mg/l.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.71 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % CL of 0.51-1.1 mg/l

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.027 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: 0%

Results with reference substance (positive control):

- Results with reference substance valid? Yes

- EC₅₀: 0.78 mg/l

Reported statistics and error estimates:

Calculated using the maximum-likelihood probit method (Finney 1971) using the ToxCalc computer software package (ToxCalc 1999).

Any other information on results incl. tables

Table 1. Cumulative Immobilisation Data in the Definitive Test

Mean Measured Test Concentration (mg/l)	Cumulative Immobilised Daphnia (initial population: 10 per replicate)
	24 Hours				48 Hours
	R1	R2	Total	%	R1	R2	Total	%
Control	0	0	0	0	0	0	0	0
0.013	0	0	0	0	0	0	0	0
0.027	0	0	0	0	0	0	0	0
0.057	0	0	0	0	1	0	1	5
0.11	0	0	0	0	1	0	1	5
0.16	0	0	0	0	1	3	4	20
0.28	1	1	2	10	3	2	5	25
0.55	2	0	2	10	4	3	7	35
0.94	1	3	4	20	3	7	10	50
1.9	3	2	5	25	9	8	17	85

Table 2 Verification of Test Concentrations

Nominal Concentration (mg/l)	Measured Concentration (mg/l)				Mean Measured Concentration
	0 hours	Expressed as a Percenct of the Nominal Concentration (%)	48 hours	Expressed as a Percenct of the Nominal Concentration (%)
0.033	0.0151	46	0.0103	31	0.013
0.056	0.0311	56	0.0225	40	0.027
0.10	0.0658	66	0.0489	49	0.057
0.18	0.126	70	0.0972	54	0.112
0.33	0.182	55	0.138	42	0.160
0.56	0.294	53	0.263	47	0.279
1.0	0.589	59	0.512	51	0.551
1.8	1.01	56	0.861	48	0.936
3.3	2.13	65	1.74	53	1.935
33 (Saturated solution)	14.3	43	-		-

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of 0.71 mg/l and a NOEC of 0.027 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna. The results are expressed as mean measured concentration of the test substance over the test period.