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

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

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 biodegradation of Isobornyl propionate is based on read-across from Isobornyl acetate. The read across rationale is presented in the Biodegradation Endpoint summary. The accompanying files are also attached there.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

Validity criteria fulfilled:

yes

Remarks:

The result is documented according to Annex XI requirements

Interpretation of results:

readily biodegradable

Conclusions:

Isobornyl propionate is readily biodegradable based on the result of Isobornyl acetate tested in an OECD TG 301F.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

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.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

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.

Duration of test (contact time):

28 d

Initial conc.:

102 mg/L

Based on:

test mat.

Remarks:

replicate 1

Initial conc.:

98.4 mg/L

Based on:

test mat.

Remarks:

replicate 2

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

as a percentage of ThOD

Details on study design:

COMPOSITION OF TEST MEDIUM
- Solution A: KH2PO4: 8.5 g; K2HPO4: 21.75 g; Na2HPO4·2H2O: 33.4 g; NH4Cl: 0.50 g, dissolved in water and made up to 1 litre.
- Solution B: CaCl2: 27.5 g, dissolved in water and made up to 1 L.
- Solution C: MgSO4·7H2O : 22.5 g, dissolved in water and made up to 1 L.
- Solution D: FeCl3·6H2O : 0.25 g; HCl Conc. one drop, dissolved in water and made up to 1 L.
- Preparation: Prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 L with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.

TEST CONDITIONS
- Test temperature: 22.0 °C
- Dry weight of suspended solids: Dry weight of suspended solids was 3.793 g/L. To obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 1.98 mL of sludge is needed (inoculum).

TEST SYSTEM
- Apparatus: The respirometer used during this study is a SAPROMAT D 12, made by J.M. Voith GmbH, D-7920 Heidenheim.
- Number of culture flasks/concentration: 2
- Preparation of the flasks: Test substance samples (25 mg, corresponding to 100 mg/L in a 250 mL flask) are weighed in small aluminium boats and added directly to the test flasks of the SAPROMAT whereas the reference substance (sodium benzoate) is added as 1.00 mL of a 25 mg/mL solution in mineral medium. All flasks are partly filled with mineral medium. Samples of test or reference substance, or both, are added. Then, a volume of suspended sludge corresponding to 7.5 mg dry weight is added and the content is adjusted to 250 mL with mineral medium. The pH of each flask is measured and, if necessary, adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide. About 2 g of soda lime is placed in an attachment of the stopper, the flasks are closed and placed in the water bath of the SAPROMAT. After temperature and pressure equilibration, the oxygen meter of the instrument are set to zero (time zero of the experiment).

SAMPLING
- Oxygen consumption: Every day the oxygen consumption of each flask is recorded.
- pH: At the beginning and at the end of the test period.
- Other: The temperature and stirring were checked daily.

Reference substance:

benzoic acid, sodium salt

Test performance:

VALIDITY
- Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified.
- The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance.
Therefore, the test is considered valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

Details on results:

The test substance undergoes 75% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 75% at the end of the 10-day window (day 3 to 13).

Results with reference substance:

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days.

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

Remarks:

See 'Test performance'

Interpretation of results:

readily biodegradable

Conclusions:

The substance is biodegraded by 75% at day 28 in the OECD TG 301F Manometric Respirometry Test and the 10-day time window criterion was met. Therefore, the substance should be classified as readily biodegradable.

Executive summary:

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria. In this study 100 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 28 days under aerobic conditions. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). After the 28-day incubation period 75% of the substance was biodegraded. The 10-day window criterion was met. Based on these findings, the test substance is classified as readily biodegradable.

Description of key information

Isobornyl propionate is readily biodegradable based on read across from Isobornyl acetate which was tested in an OECD TG 301F.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

For Isobornyl propionate the ready biodegradability information is derived from read across of Isobornyl acetate. First the ready test of Isobornyl acetate will be presented and thereafter the read across rationale.

Isobornyl acetate's ready biodegradability

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria. In this study 100 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 28 days under aerobic conditions. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). After the 28-day incubation period 75% of the substance was biodegraded. The 10-day window criterion was met. Based on these findings, the test substance is classified as readily biodegradable.

Ready biodegradability of Isobornyl propionate (CAS #2756-56-1) based on read-across from data available for Isobornyl acetate (CAS #125-12-2).

 

Introduction and hypothesis for the analogue approach

Isobornyl propionate has an exo-1,7,7-Trimethylbicyclo[2.2.1]heptane-2-ol (Isobornyl alcohol) backbone to which a propionic ester group is attached. For this substance there is no experimental biodegradation information. According to REACH Annex XI 1.5 information may be generated by other means, i.e. applying alternative methods such as QSARs, grouping and read-across. For assessing the ready biodegradability of Isobornyl propionate the analogue approach is selected because for a closely related analogue, Isobornyl acetate, ready biodegradation information is available which can be used for read-across.

Hypothesis: Isobornyl propionate has the same biodegradation potential as Isobornyl acetate

Available experimental information: Isobornyl acetate is readily biodegradable in a manometric respiratory test, according to OECD TG 301F, Rel. 1.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical(s) are shown in the data matrix, including relevant physico-chemical properties.

Purity / Impurities

Isobornyl propionate is a mono-constituent >=88%, with impurities similar to the parent substance and < 10%.

Analogue approach justification

According to Annex XI 1.5 read-across can be used to replace testing when the similarity can be based on a common backbone and a common functional group.When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue justification: For Isobornyl propionate the substance Isobornyl acetate is used as analogue because these are very similar in structure and for the acetate biodegradability information is available and e.g. not for Isobornyl butyrate.

Structural similarities and differences: Isobornyl propionate and Isobornyl acetate have the same backbone and functional ester group. The only difference between the two is the propionate and acetate group, respectively, which both are readily biodegradable.

Bioavailability: Isobornyl- propionate and the -acetate will be sufficiently bioavailable based on the similar (predicted) water solubility and log Kows.

Biodegradable fragments: Isobornyl propionate and Isobornyl acetate have the same biodegradable fragments. The propionate chain will result in minimally increased biodegradability because it is one straight C longer.

Uncertainty of the prediction: There are no other uncertainties other than those already addressed above. 

Conclusion on hazard and risk assessment

For Isobornyl propionate ready biodegradability information is not available. Isobornyl acetate is an analogue for which such information is available, which can be used for read across. When using read across the result should be applicable for classification and labelling and risk assessment as well as presented with reliable and adequate documentation. This documentation is presented in the current document. Isobornyl acetate is readily biodegradable and this information can be used for read across to Isobornyl propionate.

Final conclusion on hazard: Isobornyl propionate is readily biodegradable.

 

Data matrix supporting the Ready biodegradability of Isobornyl propionate using read across from Isobornyl acetate

Common names	Isobornyl propionate	Isobornyl acetate
Source/target	Target	Source
Chemical structures
CAS no.	2756-56-1	125-12-2
EINECS	220-410-5	204-727-6
Reach registration	2018	Registered
Empirical formula	C13H22O2	C12H20O2
Molecular weight	210.32	196.29
Phys-chem properties	Episuite calculation	EpiSuite calculation
Physical state	Liquid	Liquid
Water solubility (mg/l)	7.491	9.721 (ECHA dissemination site)
Log Kow	4.348 5 (IFF measured)	3.86 (ECHA dissemination site) 4.3 (Simonich in EpiSuite)
Environmental fate
Biodegradation	Ready biodegradable (Read across)	Readily biodegradable (OECD TG 301F)