Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl propionate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

The micro-organism toxicity of Isobornyl propionate is based on read-across from Isobornyl acetate. The documentation is presented in the Aquatic Endpoint summary. The accompanying files are also attached there.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

69.6 mg/L

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Effect value from the source chemical was recalculated based on Log Kow and molecular weight for the target chemical.

Validity criteria fulfilled:

yes

Remarks:

The information is based on read across. The read across rationale is documented according to Annex XI criteria.

Conclusions:

Isobornyl propionate has a NOEC for Isobornyl propionate of 69.6 mg/l, based on a conversion from Isobornyl acetate for which a NOEC of 100 mg/l was derived in a ready biodegradation test.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Remarks:

biodegradation study, measuring oxygen consumption

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 Dec 1996 to 17 Jan 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The information is used for read across to Isobornyl propionate.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of activated sludge: A biological wate water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre).
- Pretreatment: The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
- Preparation of dry weight of suspended solids: The dry weight of suspended solids is determined by taking two 50 mL samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110 °C for two hours and weighing the residue.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Test temperature:

22 °C

pH:

- Start all media: 7.39 - 7.44
- End control flasks: 7.46 - 7.66
- End test substance flasks: 7.35 - 7.41
- End reference substance flasks: 7.80 - 8.00

Nominal and measured concentrations:

- Nominal concentration: 0 (control) and 100 mg/L

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

TOXICITY
The test substance did not inhibit the intrinsic respiration of the inoculum at the test concentration (see 'Any other information on results incl. tables') and was therefore considered to be non-toxic to the inoculum at the test concentration. Also the results obtained with the reference substane (sodium benzoate) in combination with the test substance show no toxic effect on the micro-organisms.

Table: Biological demand of the test substance (BOD, mg O2/L, adjusted to nominal concentrations

		Days	3	7	13	14	21	28
BOD Sludge	replicate 1	B1	16.0	23.0	28.0	31.0	37.0	42.0
	replicate 2	B2	16.0	23.0	27.0	30.0	37.0	44.0
	mean	B	16.0	23.0	27.5	30.5	37.0	43.0
BOD test substance	replicate 1	C1	80.9	169.1	222.0	225.9	236.7	239.6
	replicate 2	C2	76.8	174.3	224.1	228.2	236.3	240.4
	replicate 1 corrected	C1-B	64.9	146.1	194.5	195.4	199.7	196.6
	replicate 2 corrected	C2-B	60.8	151.3	196.6	197.7	199.3	197.4
% Degradation	replicate 1	D1	25	56	75	75	77	75
	replicate 2	D2	23	58	75	76	76	76
	mean	D	24	57	75	75	76	75

Calculations:

B1, B2, C1, C2: experimental O2 uptake values

B = (B1 + B2) / 2

D1 = 100 * (C1 – B) / ThoD * [S]

D2 = 100 * (C2 – B) / ThoD * [S]

D = (D1 + D2)/2

[S]: Initial test substance concentration (mg/L)

ThOD test substance = 2.61 mg O2/mg

 

Table: Biological demand of the reference substance (BOD, mg O2/L, adjusted to nominal concentrations

		Days	5	7	10	14	21	28
BOD Sludge	replicate 1	B1	22.0	23.0	26.0	31.0	37.0	42.0
	replicate 2	B2	22.0	23.0	24.0	30.0	37.0	44.0
	mean	B	22.0	23.0	25.0	30.5	37.0	43.0
BOD reference substance	replicate 1	A1	143.0	152.9	164.9	172.9	184.9	195.9
	replicate 2	A2	136.0	145.0	154.9	163.9	171.9	178.9
	replicate 1 corrected	A1-B	121.0	129.9	139.9	142.4	147.9	152.9
	replicate 2 corrected	A2-B	114.0	122.0	129.9	133.4	134.9	135.9
% Degradation	replicate 1	D1	73	78	84	86	89	92
	replicate 2	D2	68	73	78	80	81	82
	mean	D	71	76	81	83	85	87

Calculations:

B1, B2, A1, A2: experimental O2 uptake values

B = (B1 + B2) / 2

D1 = 100 * (A1 – B) / ThoD * [S]

D2 = 100 * (A2 – B) / ThoD * [S]

D = (D1 + D2)/2

[S]: Initial reference substance concentration (mg/L)

ThOD reference substance = 1.67 mg O2/mg

Validity criteria fulfilled:

yes

Conclusions:

The NOEC-value for microorganisms in activated sludge, based on the results of a ready biodegradation study (OECD TG 301F), is 100 mg/L.

Executive summary:

The toxicity of the substance to microorganisms was determined in a ready biodegradability study according to OECD TG 301F and in compliance with GLP criteria. In this study, activated sludge from predominantly domestic sewage was exposed to 100 mg/L test substance. The test substance did not inhibit the endogenous respiration of the inoculum and was found to be readily biodegradable. Therefore, the test substance was considered to be non-toxic to the inoculum. Based on these findings, the NOEC for microorganisms is 100 mg/L.

Description of key information

Isobornyl propionate and micro-organism toxicity

The micro-organism toxicity of the Isobornyl propionate is 69 mg/l, respectively. These are converted values from Isobornyl acetate based on the difference in Log Kow and molecular weight (Log EC in mmol target= Log ECmmol x log Kow source/Log Kow target)

Isobornyl acetate and micro-organism toxicity

Isobornyl acetate's (CAS 125 -12 -2) toxicity to microorganisms was determined in a ready biodegradability study according to OECD TG 301F and in compliance with GLP criteria. In this study, activated sludge from predominantly domestic sewage was exposed to 100 mg/L test substance. The test substance did not inhibit the endogenous respiration of the inoculum and was found to be readily biodegradable. Therefore, the test substance was considered to be non-toxic to the inoculum. Based on these findings, the NOEC for microorganisms is 100 mg/L. The toxicity of the source chemical was converted towards the target substance based on the difference in Log Kow and molecular weight.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

69.6 mg/L