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PBT assessment

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PBT assessment: overall result

Reference
Name:
Reaction product of 2,4-Dinitrotoluene and 2,6-Dinitrotoluene and hydrogen
Type of composition:
boundary composition of the substance
State / form:
liquid
Reference substance:
Composition 1
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB
Justification:

PBT / vPvB - Assessment for the parent compound MCDA (EC 939 -489 -9):

Based on a modified MITI (I) test according to OECD 301C, the substance is not readily biodegradable with a degradation of -1% after 28 days (based on BOD/ThOD; BASF SE, 2011; Project No. 09G0117/10G061).

Therefore it is assessed to be potentially P/vP, from a precautionary point of view. Nevertheless, the substance is not B/vB based on an experimentally derived log Kow 0.12 (at 23 °C, pH 12; BASF SE, 2011, report no.: 11L00071, see IUCLID Ch. 4.7) and supported by calculated data from several QSAR models (calculated BCF values for the representative constituents of MCDA, CAS 13897 -55 -7 and CAS 13897 -56 -8 range between 1.03 and 11.5 L/kg, BASF SE, 2017, 2020). In addition, the substance is also not T since the lowest available chronic value is > 0.01 mg/L (daphnids, 21 -d EC10 = 4.7 mg/L, BASF SE 2013; report no. 51E0117/10E132) and it holds no relevant classification.

In conclusion, the substance is considered to be not PBT / vPvB.

PBT / vPvB - Assessment for modelled metabolites of MCDA (EC 939 -489 -9):

ECHA Guidance on information requirements and chemical safety assessment (v3.0, June 2017), Chapter R.11.4.1 specifies that “Constituents, impurities and additives should normally be considered relevant for the PBT/vPvB assessment when they are present in concentration of ≥ 0.1% (w/w)” […] “Similar arguments apply to relevant transformation/degradation products”.

In order to identify the relevant degradation products of MCDA (EC 939-489-9) a standard information requirement according to Column 1, Section 9.2.3. of Annex IX to REACH and for purposes of an assessment of potential PBT/vPvB properties, the metabolites were modelled using CATALOGIC 301C v11.15 – July 2018 (OASIS CATALOGIC v5.13.1.156).

Overall, the model CATALOGIC 301C v11.15 calculated 86 metabolites of 4-methylcyclohexane-1,3-diamine (CAS 13897-55-7) and 47 metabolites of 2-methylcyclohexane-1,3-diamine (CAS 13897-56-8; see corresponding study entries; IUCLID Ch. 5.2.1) identifying 9 metabolites of CAS 13897-55-7 and 10 metabolites of CAS 13897-56-8 as relevant degradation products in terms of PBT/vPvB assessment (see Table), with an estimated quantity of ≥0.1% (equivalent to quantity setting in OASIS CATALOGIC: 0.001-2 [mol/mol parent]).

Table: QSAR prediction for CAS 13897-55-7 and CAS 13897-56-8 using CATALOGIC 301C v11.15 – July 2018 (OASIS CATALOGIC v5.13.1.156;metabolites with a quantity > 0.001 mol/mol parent (approx. 0.1%) after 28 d are highlighted by grey background and bold type; metabolite no: according to (Q)SAR model Catalogic v11.15 – July 2018 (OASIS CATALOGIC v5.13.156))

#

Metabolite
No

Smiles

Substance name (CAS)

Quantity
(mol/mol parent)

LogKow

BOD prediction
(% after 28 d)

PBT-Assessment
(ECHA (disseminated substances)

parent

1

CC1CCC(N)CC1N

4-methylcyclohexane-1,3-diamine (CAS 13897-55-7)

0.132

0.12

55

 

1

2

CC1CCC(N)CC1=O

3-amino-6-methylcyclohexanone

0.155

-0.001

63

No results were found.

2

15

CC1CCC(=O)CC1N

3-amino-4-methylcyclohexanon (CAS 2138125-40-1)

0.155

-0.001

62

No results were found.

7

63

CC1CCC(N)C(=O)OC1N

3,7-diamino-6-methyl-oxepan-2-one

0.0011

-0.2457

63

No results were found.

8

75

CC1CCC(N)OC(=O)C1N

3,7-diamino-4-methyl-oxepan-2-one

0.0011

-0.2457

58

No results were found.

20

18

NC1CCC(C(O)=O)C(N)C1

2,4-diaminocyclohexancarboxylic acid

0.0034

-3.933

55

No results were found.

29

19

NC1CCC(C(O)=O)C(=O)C1

4-amino-2-oxocyclohexane-1-carboxylic acid

0.0014

-4.438

72

No results were found.

30

27

NC1CC(=O)CCC1C(O)=O

6-amino-4-oxocyclohexane-1-carboxylic acid

0.0039

-4.438

56

No results were found.

71

24

NC(CC(O)=O)CC(O)=O

3-aminopentanedioic acid (CAS 1948-48-7)

0.003418

-5.008

62

No results were found.

80

73

CCC(O)=O

propionic acid (CAS 79-09-4)

0.001625

0.578

100

Not PBT/vPvB

parent

1

CC1C(N)CCCC1N

2-methylcyclohexane-1,3-diamine (CAS 13897-56-8)

0.13

0.12

50

 

1

2

CC1C(N)CCCC1=O

5-amino-6-methylcyclohexanone

0.31

0.00

57

No results were found.

13

16

NC1CCCC(N)C1C(O)=O

2,6-diaminociclohexane-1-carboxylic acid

0.0035

-3.93

36

No results were found.

20

17

NC1CCCC(=O)C1C(O)=O

6-amino-2-oxocyclohexane-1-carboxylic acid

0.0079

-4.44

39

No results were found.

27

50

C=C

Ethylene (CAS 74-85-1)

0.0010

1.27

10

Not PBT/vPvB

29

18

OC(=O)C1C(=O)CCCC1=O

2,6-dioxocyclohexane-1-carboxylic acid

0.0042

-0.39

60

No results were found.

37

29

CC(C=O)C(N)CC(O)=O

3-amino-4-formyl-pentanoic acid

0.0016

-4.26

47

No results were found.

40

8

CCC(=O)OCCC(O)=O

3-(propionyloxy)propane acid (CAS 1085694-20-7)

0.058

0.61

92

No results were found.

43

40

CCC(N)=CC

pent-1-en-3-amine (CAS 70267-50-4)

0.0014

1.17

17

No results were found.

46

21

OCC(=O)CCCC(O)=O

6-hydroxy-5-oxohexanoic acid (CAS 497844-76-5)

0.0040

-0.55

100

No results were found.

47

23

OCCCC(=O)CC(O)=O

3-oxo-6-hydroxyhexanoic acid

0.0040

-1.46

94

No results were found.

 

Persistence (“P/vP”):

In order to assess the biodegradation potential of the relevant degradation products, the (Q)SAR model CATALOGIC 301C v11.15 – July 2018 (OASIS CATALOGIC v5.13.1.156) was applied.    

Concerning the applicability domain (OECD Principle 3) the representative constituents of MCDA, 4-methylcyclohexane-1,3-diamine (CAS 13897-55-7) and 2-methylcyclohexane-1,3-diamine (CAS 13897-56-8) are in the parametric, the structural and the metabolic domain (100%).

- The model was used to predict potential metabolites.

- CAS 13897-55-7: 3 of the 9 metabolites identified as relevant degradation products were calculated to be not readily biodegradable (threshold value: <60% BOD). Individual biodegradation of these metabolites was estimated to be in a range of 55% to 58% after 28 days (based on BOD). The remaining six relevant metabolites were estimated to be readily biodegradable (threshold value: ≥60%), with individually calculated biodegradation values between 62% and 100% after 28 days (based on BOD).

- CAS 13897-56-8: 6 of the 10 metabolites identified as relevant degradation products were calculated to be not readily biodegradable (threshold value: <60% BOD). Individual biodegradation of these metabolites was estimated to be in a range of 10% to 57% after 28 days (based on BOD). The remaining 4 relevant metabolites were estimated to be readily biodegradable (threshold value: ≥60%), with individually calculated biodegradation values between 60% and 100% after 28 days (based on BOD).

In conclusion, 47% of the predicted metabolites present in concentration of ≥0.1% (equivalent to quantity setting in OASIS CATALOGIC: 0.001-2 [mol/mol parent]) are estimated to be not readily biodegradable while 53% of the relevant metabolites are predicted to be readily biodegradable.

The 9 degradation products of the representative constituents of MCDA which are predicted as not readily biodegradable metabolites should be considered as potentially P/vP from a precautionary point of view.

Bioaccumulation (“B/vB”):

In a test according to OECD 107 a log Kow of 0.12 at 23 °C and pH 12 was measured for the parent compound MCDA (BASF SE, 2011, report no.: 11L00071, see IUCLID Ch. 4.7). This value indicates low potential for bioaccumulation.

Without exception, all of the 86 metabolites of 4-methylcyclohexane-1,3-diamine (CAS 13897-55-7) and 47 metabolites of 2-methylcyclohexane-1,3-diamine (CAS 13897-56-8) were estimated to exhibit log Kow values of clearly < 4.5 (see Table, and IUCLID Ch. 5.2.1), thereby not fulfilling the screening criteria for bioaccumulation (B/vB) as laid down in Section 3.1 of REACH Annex XIII.

Based on the estimation data available for the modelled metabolites, all relevant metabolites of the two representative constituents of MCDA are concluded to be “not B” and “not vB”.

 

Toxicity (“T”):

Considering potential “T” properties, limited data are available for the relevant metabolites of the representative constituents of MCDA. Only few of the relevant metabolites of the CATALOGIC model are registered under REACH. None of these substances were assessed to fulfill the criteria for “T”. Based on the available data on the persistence and bioaccumulation potential of all of the relevant metabolites, it can be concluded that all relevant degradation products do neither fulfill the PBT criteria (not PBT) nor the vPvB criteria (not vPvB).

 

Overall conclusion:

1.  Sufficient test data are available to assess the PBT/vPvB properties of MCDA (EC 939-489-9), and its representative constituents 4-methylcyclohexane-1,3-diamine (CAS 13897-55-7) and 2-methylcyclohexane-1,3-diamine (CAS 13897-56-8).

2.  Potentially relevant degradation products were modeled using (Q)SARmodel CATALOGIC 301C v11.15 – July 2018:

2a. Based on modeled data relevant degradation products present in concentration of ≥ 0.1% (equivalent to quantity setting in OASIS CATALOGIC: 0.001-2 [mol/mol parent]) do neither fulfill the PBT criteria (not PBT) nor the vPvB criteria (not vPvB).

2b. However, 9 predicted relevant metabolites present in concentration of ≥0.1% (equivalent to quantity setting in OASIS CATALOGIC: 0.001-2 [mol/mol parent]; CATALOGIC 301C v11.15) should be considered as potentially P/vP from a precautionary point of view.