Reaction mass of 3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-5-yl pivalate and 3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-6-yl pivalate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that the target substance and source substances have similar biodegradation properties as a result of structural similarity and a common biodegradation pathway.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
- see Test Material section of the source and target records. The chemical structures are shown in Figure 1 (see “Illustration” section of this endpoint record).

3. ANALOGUE APPROACH JUSTIFICATION
- The target substance (Pivacyclene) and source substances (Gardocyclene and Jasmacyclene) are all esters of tricyclodecenol (see Figure 1).
- All three substances are expected to exhibit similar biodegradation profiles due to the presence of the same carbon skeleton and ester functional group. The first biotransformation step is expected to be hydrolysis of the ester functional group to give the common degradation product (alcohol A, Figure 2 in the “Illustration” section of this endpoint record) and corresponding carboxylic acid.
- Valid ready biodegradation screening studies performed according to OECD301F are available for the two source substances (see cross-reference source studies and data matrix below).
- The results for both source substances indicate partial degradation. The levels of biodegradation achieved after 28 days are 14 and 22% respectively for Jasmacylene and Gardocyclene. Prolonging the test to 61 days does not lead to any significant increase in the levels of biodegradation seen indicating that stable primary biodegradation products may have been formed.
- For each source study, at the end of the test (day 61) the primary biodegradation products were identified using LC-MS and GC-MS techniques . The same three degradation products were identified confirming a common biodegradation pathway for this family of esters. The three degradation products identified were:
3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-ol / 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-ol (Degradation Product A)
3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-one/ 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-one (Degradation Product B)
8-oxatricyclo[5.3.1.02,6]undec-4-en-9-one / 8-oxatricyclo[5.3.1.02,6]undec-3-en-9-one (Degradation Product C)
The degradation products identified are consistent with the proposed pathway in Figure 2 (see “Illustration” section of this endpoint record).
- For each source study, the n-octanol/water partition coefficients of the products of the primary biodegradation were determined according to the HPLC method (OECD 117). A sample was drawn from the biodegradation test flasks at day 61. The only sample preparation was filtration of the sample. The chromatograms showed two peaks corresponding to partition coefficients of 2.3 to 2.4 (84% rpa in Jasmacylene Study; 82% rpa in Gardocyclene Study ) and 3.3 (16% rpa in Jasmacylene Study; 18 % rpa in Gardocyclene Study). No peak was found corresponding to the log Kow of the parent substance (see data matrix below) indicating complete primary biodegradation.
-The carboxylic acid degradation product (RC=OOH) formed during the first step of this biodegradation pathway is most likely completely mineralised in the case of the two source studies. This is supported by available data for acetic acid and 2-methylpropanoic acid (see data matrix) and is consistent with the biodegradation levels observed for the two source substances as determined by the oxygen consumed, which was 14-16% for Jasmacyclene and 22-23% for Gardocyclene. These biodegradation percentages would correspond, respectively, to the mineralisation of acetic acid (2 carbon atoms) and 2-methylpropanoic acid (4 carbon atoms).
- In summary, Pivacyclene is expected to have the same biodegradation profile as the two source substances as a result of structural similarity and a common biodegradation pathway. Thus it is concluded that Pivacyclene is not readily biodegradable but undergoes complete primary degradation to the corresponding carboxylic acid (pivalic acid, CAS 75-98-9) and 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5/6-ol (Degradation Product A) with the latter subsequently biotransformed to the corresponding ketone (degradation product B) and then lactone (Degradation Product C). The biodegradation products (A-C) have log Kow values that are < 4.5 and as such do not meet the bioaccumulation screening critera of the PBT/vPvB assessment. Pivalic acid is less easily degraded than the corresponding carboxylic acids for the two source substances (see data matrix) but also has a log Kow of < 4.5 (log Kow = 1.8, information available on ECHA website). Thus, based on the evidence of primary biodegradation for this family of esters, it is considered that Pivacyclene is not persistent and that any degradation products formed are not potential vPvB/PBT substances.

4. DATA MATRIX
- See "Any other information on materials and methods incl. tables".

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-02-09 to 2010-03-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted in compliance with OECD Guideline 301F without any deviation.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage in the city of Bois-de-Bay, 1242 Satigny, switzerland.
- The sludge is collected in the morning, washed 3 times in the mineral medium and kept aerobic being used in the same day
- Concentration of sludge: 4.6 g/L (dry weight of suspended solids); to obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 1.63 mL of sludge is needed (inoculum).

Duration of test (contact time):

61 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: compliant with recommendations of TG on mineral medium
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 22°C
- pH: 7.6 (initial) to a mean of 7.79 (final) from 7.53 to 8.12.
- pH adjusted: no
- Suspended solids concentration: 30 mg/l
- Continuous darkness: not stated

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: stirring
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: SAPROMAT D12
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: soda lime pellets

SAMPLING
- Sampling frequency: everyday O2 consumption is recorded and correct temperature and stirring are checked
- Sampling method: SAPROMAT automatic measurement

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

Reference substance:

benzoic acid, sodium salt

Remarks:

Purity 99.0 %

Preliminary study:

No data

Test performance:

No data

Parameter:

% degradation (O2 consumption)

Value:

16

Sampling time:

61 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

14

Sampling time:

28 d

Details on results:

- Initial test material concentration: 100 mg/L (nominal)
- Theoretical oxygen demand (ThOD) = 2.50 mg O2/mg
- % biodegradation on Day 28 = 14%, Day 61 = 16%

At the end of the test (day 61) the n-octanol/water partition coefficients of the products of the primary biodegradation of Jasmacyclene were determined.

The chromatograms show one partially resolved double-peak at an average retention time of 3.82 to 3.96 minutes (84% relative peak area), corresponding to partition coefficient (log value) of 2.3 to 2.4, and to one peak at an average retention time of 5.62 minutes (16% relative peak area), corresponding to a partition coefficient (log value) of 3.3.

In a non-GLP part of the study, by using LC-MS and GC-MS techniques, the primary biodegradation products could be identified as:
3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-ol / 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-ol, and
3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-one/ 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-one, and
8-oxatricyclo[5.3.1.02,6]undec-4-en-9-one / 8-oxatricyclo[5.3.1.02,6]undec-3-en-9-one

Results with reference substance:

Degradation of the reference substance exceeds 40% after 7 days and 65% after 14 days. The test is therefore considered as valid.

Table 1 Biological Oxygen Demand (BOD, mg O2/L, adjusted to nominal concentrations)

		Days	4	5	14	15	28	60	61
BOD sludge	1^stflask	B1	6.0	7.0	19.0	20.0	27.0	43.0	43.0
	2^ndflask	B2	12.0	13.0	19.0	21.0	30.0	47.0	47.0
	Mean	B	9.0	10.0	19.0	20.5	28.5	45.0	45.0
O2 uptake of test Subst. + sludge	1^stflask	C1	32.0	35.0	47.0	49.0	60.0	80.0	80.0
	2^ndflask	C2	34.0	38.0	52.0	54.0	67.0	90.0	90.0
O2 uptake of test substance		C1-B	23.0	25.0	28.0	28.5	31.5	35.0	35.0
		C2-B	25.0	28.0	33.0	33.5	38.5	45.0	45.0
% degr. of test substance		D1	9	10	11	11	13	14	14
		D2	10	11	13	13	15	18	18
	mean	D	10	11	12	12	14	16	16
% degrad. of test subst. in presence of reference subst. (co-metabolism)		Dco1	18	18	14	14	15	18	17
		Dco2	14	13	10	10	12	16	16
		Dco	16	15	12	12	14	17	16

B=(B1 +B2)/2

D1=100*(C1 -B) / ThOD * S

D2=100*(C2 -B) / ThOD * S

D=(D1 +D2) / 2

Dco1=100*(E-A1)/ThOD*[S]

Dco2=100*(E-A2)/ThOD*[S]

Dco=(Dco1 +Dco2)/2

[S] : initial test substance concentration (mg/l)

ThOD = 2.50 mg O2 / mg

MW = 192.26 g/mol

formula = C12H16N0O2

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under the test conditions, the substance is considered as not readily biodegradable since it achieved < 60% degradation after 28 days. However, analysis at 61 days confirmed that primary degradation of Jasmacyclene had occurred. Three degradation products were identified with Log Kow values of 2.3, 2.4 and 3.3.

Executive summary:

The biodegradation of Jasmacyclene was studied using a Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 301F. Inoculum came from fresh activated sludge from a biological waste water treatment plant in the city of Bois-de-Bay that treated predominantly domestic sewage. Sodium Benzoate was used as a reference substance. Toxicity of the test substance has been investigated and showed no inhibition. Initial concentration of the test substance was 100 mg/l. Biodegradation of the test substance is recorded by the evolution of the O2 consumption during the study. O2 consumption was recorded every day.

Jasmacyclene undergoes 14% biodegradation after 28 days. Therefore, and in accordance with The OECD Guidelines 301F, Jasmacyclene is considered as not ready biodegradable. Validity criteria are all met, the study is considered as acceptable for the endpoint.

The test was prolonged to 61 days. The level of biodegradation increased slightly to 16% . Degradation levels of 14 -16% indicate that primary degradation has occurred. At the end of the test (day 61) the n-octanol/water partition coefficients of the products of the primary biodegradation of Jasmacyclene were determined. The chromatograms show one partially resolved double-peak at an average retention time of 3.82 to 3.96 minutes (84% relative peak area), corresponding to partition coefficient (log value) of 2.3 to 2.4, and to one peak at an average retention time of 5.62 minutes (16% relative peak area), corresponding to a partition coefficient (log value) of 3.3. In a non-GLP part of the study, by using LC-MS and GC-MS techniques, the primary biodegradation products could be identified as: 3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-ol / 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-ol, and 3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-one/ 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-one, and 8 -oxatricyclo[5.3.1.02,6]undec-4 -en-9 -one / 8 -oxatricyclo[5.3.1.02,6]undec-3 -en-9 -one

Cross-reference 2

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-02-12 to 2010-03-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted in compliance with OECD Guideline 301F without any deviation.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage in the city of Bois-de-Bay, 1242 Satigny, switzerland.
- The sludge is collected in the morning, washed 3 times in the mineral medium and kept aerobic being used in the same day
- Concentration of sludge: 4.6 g/L (dry weight of suspended solids); to obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 1.63 mL of sludge is needed (inoculum).

Duration of test (contact time):

61 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: compliant with recommendations of TG on mineral medium
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 22°C
- pH: 7.6 (initial) to a mean of 7.81 (final) from 7.53 to 8.15.
- pH adjusted: no
- Suspended solids concentration: 30 mg/l
- Continuous darkness: not stated

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: stirring
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: SAPROMAT D12
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: soda lime pellets

SAMPLING
- Sampling frequency: everyday O2 consumption is recorded and correct temperature and stirring are checked
- Sampling method: SAPROMAT automatic measurement

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

Reference substance:

benzoic acid, sodium salt

Remarks:

Purity 99.0 %

Preliminary study:

No data

Test performance:

No data

Parameter:

% degradation (O2 consumption)

Value:

23

Sampling time:

61 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

22

Sampling time:

28 d

Details on results:

- Initial test material concentration: 100 mg/L (nominal)
- Theoretical oxygen demand (ThOD) = 2.61 mg O2/mg
- % biodegradation on Day 28 = 22%, Day 61 = 23%

At the end of the test (day 61) the n-octanol/water partition coefficients of the products of the primary biodegradation of Gardocyclene were determined.

The chromatograms showed two peaks at average retention times of 3.95 minutes (82% relative peak area) and 5.60 minutes (18% relative peak area), corresponding to partition coefficients (log value) of 2.4 and 3.3 respectively.

In a non-GLP part of the study, by using LC-MS, the primary biodegradation products could be identified as:
3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-ol / 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-ol, and
3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-one/ 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-one, and
8-oxatricyclo[5.3.1.02,6]undec-4-en-9-one / 8-oxatricyclo[5.3.1.02,6]undec-3-en-9-one

Results with reference substance:

Degradation of the reference substance exceeds 40% after 7 days and 65% after 14 days. The test is the considered as valid.

Table 1 Biological Oxygen Demand (BOD, mg O2/L, adjusted to nominal concentrations)

		Days	4	5	14	15	28	60	61
BOD sludge	1^stflask	B1	6.0	7.0	19.0	20.0	27.0	43.0	43.0
	2^ndflask	B2	12.0	13.0	19.0	21.0	30.0	47.0	47.0
	Mean	B	9.0	10.0	19.0	20.5	28.5	45.0	45.0
O2 uptake of test Subst. + sludge	1^stflask	C1	65.0	69.0	80.0	80.0	96.0	118.0	118.0
	2^ndflask	C2	49.0	53.0	64.0	64.0	77.0	94.0	94.0
O2 uptake of test substance		C1-B	56.0	59.0	61.0	59.5	67.5	73.0	73.0
		C2-B	40.0	43.0	45.0	43.5	48.5	49.0	49.0
% degr. of test substance		D1	21	23	23	23	26	28	28
		D2	15	16	17	17	19	19	19
	mean	D	18	20	20	20	22	23	23
% degrad. of test subst. in presence of reference subst. (co-metabolism)		Dco1	8	8	18	18	20	20	20
		Dco2	3	3	14	14	17	18	18
		Dco	5	6	16	16	18	19	19

B=(B1 +B2)/2

D1=100*(C1 -B) / ThOD * S

D2=100*(C2 -B) / ThOD * S

D=(D1 +D2) / 2

Dco1=100*(E-A1)/ThOD*[S]

Dco2=100*(E-A2)/ThOD*[S]

Dco=(Dco1 +Dco2)/2

[S] : initial test substance concentration (mg/l)

ThOD = 2.61 mg O2 / mg

MW = 220.31 g/mol

formula = C14H20N0O2

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under the test conditions, the substance is considered as not readily biodegradable since it achieved < 60% degradation after 28 days. However, analysis at 61 days confirmed that primary degradation of Gardacyclene had occurred. Three degradation products were identified with Log Kow values ranging from 2.4 to 3.3.

Executive summary:

The biodegradation of Gardocyclene was studied using a Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 301F. Inoculum came from fresh activated sludge from a biological waste water treatment plant in the city of Bois-de-Bay that treated predominantly domestic sewage. Sodium Benzoate was used as a reference substance. Toxicity of the test substance has been investigated and showed no inhibition. Initial concentration of the test substance was 100 mg/l. Biodegradation of the test substance is recorded by the evolution of the O2 consumption during the study. O2 consumption was recorded every day.

Gardocyclene undergoes 22% biodegradation after 28 days. Therefore, and in accordance with The OECD Guidelines 301F, Gardocyclene is considered as not ready biodegradable. Validity criteria are all met, the study is considered as acceptable for the endpoint.

The test was prolonged to 61 days. The level of biodegradation increased slightly to 23% . Degradation levels of 22 -23% indicate that primary degradation has occurred. At the end of the test (day 61) the n-octanol/water partition coefficients of the products of the primary biodegradation of Gardocyclene were determined. The chromatograms showed two peaks at average retention times of 3.95 minutes (82% relative peak area) and 5.60 minutes (18% relative peak area), corresponding to partition coefficients (log value) of 2.4 and 3.3 respectively. In a non-GLP part of the study, by using LC-MS and GC-MS techniques, the primary biodegradation products could be identified as: 3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-ol / 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-ol, and 3s,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-5-one/ 3a,4,5,6,7,7a-Hexahydro-4,7-methano-1H-inden-6-one, and 8 -oxatricyclo[5.3.1.02,6]undec-4 -en-9 -one / 8 -oxatricyclo[5.3.1.02,6]undec-3 -en-9 –one

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-6-yl pivalate

EC Number:

268-259-4

EC Name:

3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-6-yl pivalate

Cas Number:

68039-44-1

Molecular formula:

C15H22O2

IUPAC Name:

3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoinden-6-yl pivalate

Constituent 2

Reference substance name:

3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-5-yl pivalate

EC Number:

268-261-5

EC Name:

3a,4,5,6,7,7a-hexahydro-4,7-methano-1H-inden-5-yl pivalate

Cas Number:

68039-45-2

Molecular formula:

C15H22O2

IUPAC Name:

3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoinden-5-yl pivalate

impurity 1

Reference substance name:

rel-(1R,2S,3aR,4S,5R,6aS,7R)-octahydro-1,5:2,4-dimethanopentalen-7-yl pivalate

Molecular formula:

C15H22)2

IUPAC Name:

rel-(1R,2S,3aR,4S,5R,6aS,7R)-octahydro-1,5:2,4-dimethanopentalen-7-yl pivalate

Test material form:

other: liquid, may crystalize to white solid

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

14

Sampling time:

28 d

Remarks on result:

other: read-across from Jasmacyclene

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

16

Sampling time:

61 d

Remarks on result:

other: read-across from Jasmacyclene

% Degradation 3

Parameter:

% degradation (O2 consumption)

Value:

22

Sampling time:

28 d

Remarks on result:

other: read-across from Gardocyclene

% Degradation 4

Parameter:

% degradation (O2 consumption)

Value:

23

Sampling time:

61 d

Remarks on result:

other: read-across from Gardocyclene

Details on results:

The results for both source substances indicate partial degradation. The levels of biodegradation achieved after 28 days are 14 and 22% respectively for Jasmacylene and Gardocyclene. Since the level of degadation achieved is less than the 60% pass criterion, both Jasmacyclene and Gardocyclene are regarded as not readily biodegradable.

Pivacyclene is expected to have the same biodegradation profile as the two source substances as a result of structural similarity and a common biodegradation pathway (see ANALOGUE APPROACH JUSTIFICATION ABOVE for details). In summary, there is evidence that the biodegradation pathway for this family of esters involves, as the first step, hydrolysis to the corresponding alcohol (a common degradation product) and carboxylic acid. The level of biodegradation observed for Jasmacyclene (14-16%) and Gardocyclene (22-23%) is likely attributed to complete mineralisation of carboxylic degradation product (acetic acid and 2-methylpropanooic acid, respectively). The carboxylic acid degradation product for Pivacyclene, is less easily degraded (see DATA MATRIX above), therefore the predicted % biodegradation for Pivacyclene after 28 days is < 22%. Thus Pivacyclene is regarded as not readily biodegradable.

The two source studies were prolonged to 61 days. At the end of the test, the n-octanol/water partition coefficients of the products of the primary biodegradation were determined according to the HPLC method (OECD 117). A sample was drawn from the biodegradation test flasks at day 61. The only sample preparation was filtration of the sample. The chromatograms showed two peaks corresponding to partition coefficients of 2.3 to 2.4 (84% rpa in Jasmacylene Study; 82% rpa in Gardocyclene Study ) and 3.3 (16% rpa in Jasmacylene Study; 18 % rpa in Gardocyclene Study). No peak was found corresponding to the log Kow of the parent substance (see DATA MATRIX above) indicating complete primary biodegradation. The same three biodegradation products were identified in both source studies confirming a common biodegradation pathway for this family of esters (See Figure 2). Thus Pivacyclene is also expected to undergo complete primary biodegradation and as such is regarded as not persistent. The primary degradation products are not PBT/vPvB substances since they have log Kow values which are less than the B/vB screening citerion of log Kow > 4.5.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In a guideline study, conducted according to GLP, the closely-related substances Jasmacyclene and Gardocylene were found to undergo 14% and 22 % biodegradation respectively after 28 days - see source study summary for details. Pivacyclene is expected to have the same biodegradation profile as the two source substances as a result of structural similarity and a common biodegradation pathway. Therefore, Pivacylene is also expected to be not readily biodegradable.

The two source studies were prolonged to 61 days. At the end of the test, the n-octanol/water partition coefficients of the products of the primary biodegradation were determined according to the HPLC method (OECD 117). The chromatograms showed two peaks corresponding to partition coefficients of 2.3 to 2.4 (84% rpa in Jasmacylene Study; 82% rpa in Gardocyclene Study ) and 3.3 (16% rpa in Jasmacylene Study; 18 % rpa in Gardocyclene Study). No peak was found corresponding to the log Kow of the parent substance (see DATA MATRIX above) indicating complete primary biodegradation for both source substances. Given the evidence that this family of esters are degraded by a common biodegradation pathway (see ANALOGUE APPROACH JUSTIFICATION), Pivacyclene is also expected to undergo complete primary degradation and as such is regarded as not persistent. The primary degradation products are not PBT/vPvB substances since they have log Kow values which are less than the B/vB screening criterion of log Kow > 4.5.