2-hydroxypropyl [(1R,2S,5R)-2-isopropyl-5-methyl-cyclohexyl] carbonate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-04-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP study according to OECD 209 (1984). Only one concentration was tested, which corresponds to the highest test concentration that could be prepared due to the limited solubility of the test material in water.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

(1984)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

singed 1994-03-16

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Dispersion in water
- Differential loading: No, 62.5 mg test item/L tested in triplicate
- Controls: yes, one control in duplicate

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Method of cultivation: None, direct use on the day of collection
- Preparation of inoculum for exposure: 16 mL of synthetic sewage and 250 mL of the 125 mg/L stock solution were dispersed in a 500 mL conical flask. The volume was then made up to 300 mL and 200 mL inoculum were added.
- Pretreatment: THe pH was equal to 6.9 and the suspended solids equal to 3.7 g/L, continuous aeration

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

dilution water: 100 mg/L as CaCO3

Test temperature:

21 °C

pH:

6.9

Dissolved oxygen:

no data; continuous aeration

Nominal and measured concentrations:

Nominal concentration: control, 62.5 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL conical flask filled with 300 mL
- Aeration: continuous aeration
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates):
- Sludge concentration: 3.7 g/L
- Nutrients provided for bacteria: synthetic waste water according to OECD 209

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water was used; synthetic sewage (according to OECD 209) was added to the activated sewage

OTHER TEST CONDITIONS
- Photoperiod: normal laboratory light

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The rate of respiration for each culture was measured for a 10-minute period after 30 minutes and 3 hours contact time.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable, limit test
- Justification for using fewer concentrations than requested by guideline: limit test with the highest test concentration that could be prepared due to the limited solubility of the test material in water.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 62.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 of 8.0 mg/L (3 h)

Reported statistics and error estimates:

The percentage inhibition was plotted against the concentration and the EC50 values were derived by inspection for 30 minutes and 3 hours contact time.

Oxygen consumption rates and percentage inhibition

	Concentration (mg/L)	02consumption rates (mg 02/L/min)	% inhibition
30 minutes	Control R1 R2	0.47 0.45	- -
	Test item 62.5 R1 62.5 R2 62.5 R3	0.44 0.44 0.44	4 4 4
	3,5-dichlorophenol 3.2 10 32	0.50 0.25 0.12	<9> 46 74
3 hours	Control R1 R2	0.41 0.45	- -
	Test item 62.5 R1 62.5 R2 62.5 R3	0.37 0.38 0.43	14 12 0
	3,5-dichlorophenol 3.2 10 32	0.34 0.16 0.08	21 63 81

<increase>

R₁– R₃= Replicates 1 - 3

Validity criteria fulfilled:

yes

Conclusions:

The substance showed an inhibition of 8.67 % ± 7.57 % at a test item concentration of 62.5 mg test item/L after 3 hours, which corresponds to the highest test concentration that could be prepared due to the limited solubility of the test material in water. The 3-hour EC50 value for inhibition of respiration was therefore determined to be > 62.5 mg/L.

Executive summary:

The inhibition of respiration of activated sewage sludge by the test item was investigated in a 3-hour static test under GLP according to OECD 209 (1984). The substance showed an inhibition of 8.67 % ± 7.57 % at a test item concentration of 62.5 mg test item/L after 3 hours, which corresponds to the highest test concentration that could be prepared due to the limited solubility of the test material in water. The 3-hour EC50 value for inhibition of respiration was therefore determined to be >62.5 mg/L.

Description of key information

The 3-hour EC50 value for inhibition of activated sludge was estimated with >62.5 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

62.5 mg/L

Additional information

The inhibition of respiration of activated sewage sludge by the test item was investigated in a 3-hour static test under GLP according to OECD 209 (1984).The substance showed an inhibition of 8.67 % ± 7.57 % at a test item concentration of 62.5 mg test item/L after 3 hours, which corresponds to the highest test concentration that could be prepared due to the limited solubility of the test material in water. The 3-hour EC50 value for inhibition of respiration was therefore determined to be >62.5 mg/L.