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Environmental fate & pathways

Hydrolysis

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Endpoint:
hydrolysis
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 Aug - 23 Aug 2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
- Sampling intervals for the parent: 0, 1, 24, 96 and 120 h (5 days).
Buffers:
- pH: 4
- Type and final molarity of buffer: citric acid/potassium hydroxide/sodium chloride buffer; ready-to-use solution

- pH: 7
- Type and final molarity of buffer: potassium dihydrogen phosphate/di-sodium hydrogen phosphaten buffer; ready-to-use solution

- pH: 9
- Type and final molarity of buffer: borax/hydrochloric acid; ready-to-use solution
Details on test conditions:
TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 100 mL volumetric flask for the stock solution preparation; 250 mL erlenmeyer flasks for the test solution preparation. Agitation of the solutions in a closed dark shaking heat regulator
- Sterilisation method: The used buffer solutions were considered as sterilised at the applied temperature for the time of the test.

TEST MEDIUM
- Preparation of test medium: A p-chloro-m-cresol stock solution was prepared by dissolving 1370 mg into a 100 mL volumetric flask, which was filled to the mark with acetonitrile. For each pH value, a 250 mL Erlenmeyer flask was flushed with argon to remove the oxygen than filled with 1 mL of the stock solution, 100 mL buffer solution was added, argon was passed through he solution for 5 min to remove the oxygen.
- Identity and concentration of co-solvent: Acetonitrile
Duration:
120 h
pH:
4
Temp.:
50 °C
Initial conc. measured:
136 mg/L
Duration:
120 h
pH:
7
Temp.:
50 °C
Initial conc. measured:
136 mg/L
Duration:
120 h
pH:
9
Temp.:
50 °C
Initial conc. measured:
136 mg/L
Number of replicates:
no replicates
Positive controls:
no
Negative controls:
not specified
Preliminary study:
The test item was considered to be stable in the preliminary test at 50 °C. Thus, no further main test was performed.
Transformation products:
not measured
pH:
4
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
pH:
7
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
pH:
9
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test

Table 1: Hydrolysis of p-chloro-m-cresol at pH 4, 7 and 9, respectively after different incubation times (50 °C)

Incubation time (h)

Ct/C0 %

[% from initial concentration]

 

pH 4

pH 7

pH 9

0

100.0%

100.0%

100.0%

15

99.7%

100.0%

99.7%

24

100.6%

100.6%

100.6%

96

101.1%

100.9%

100.9%

120

99.9%

100.2%

100.2%

Statistical evaluation

 

k (s-1)

1.00702 x 10-8

1.09222 x 10-8

1.31740 x 10-8

DT50(s)

-68831451.645

-63462367.885

-52614804.419

r

0.34589

0.54869

0.54874

Ct= concentration at time point t; C0= initial concentration

Validity criteria fulfilled:
not applicable
Conclusions:
Considering the hydrolytic stability of p-chloro-m-cresol determined under environmental pH conditions, it should not be expected that hydrolytic processes will contribute to its degradation in the environment.
Executive summary:

The hydrolysis of p-chloro-m-cresol was studied in aqueous buffered solutions at pH 4 (citric acid/potassium hydroxide/sodium chloride buffer), pH 7 (potassium dihydrogen phosphate/di-sodium hydrogen phosphate buffer) and pH 9 (borax/hydrochloric acid buffer) according to EC Guideline 92/69/EC, C.7 (Erstling and Feldhues, 2001). Buffer solutions spiked with the test substance were kept at 50°C for 5 d. The measurement of p-chloro-m-cresol was conducted via HPLC-UV.

P-chloro-m-cresol was stable under acidic (pH 4), neutral (pH 7) and alkaline (pH 9) conditions at 50°C. The test substance still accounted for about 100% in the solutions at termination of the experiments compared to initially applied amounts. The formation of hydrolysis products was not followed in the course of the study. However, due to the hydrolytic stability of the test substance this aspect is of no relevance.

Endpoint:
hydrolysis
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to analogue justification document provided in IUCLID section 13.
Reason / purpose:
read-across source
Transformation products:
not measured
pH:
4
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Remarks:
source, CAS 59-50-7, key rel 1, Erstling & Feldhues 2001
pH:
7
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Remarks:
source, CAS 59-50-7, key rel 1, Erstling & Feldhues 2001
pH:
9
Temp.:
50 °C
Remarks on result:
hydrolytically stable based on preliminary test
Remarks:
source, CAS 59-50-7, key rel 1, Erstling & Feldhues 2001

Description of key information

Hydrolytically stable under environmental conditions based on preliminary test (EU Method C.7), read-across.

Key value for chemical safety assessment

Additional information

No study investigating the potential for hydrolytic degradation of sodium p-chloro-m-cresolate (CAS 15733-22-9) is available. Therefore, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to the source substance (p-chloro-m-cresol, CAS 59-50-7) which is the main transformation product of the target substance sodium p-chloro-m-cresolate (CAS 15733-22-9) is applied.

The source substance p-chloro-m-cresol is the common compound in this analogue approach and is solely responsible for the environmental fate behaviour. Thus, the source substance is considered a suitable representative for the evaluation of the hydrolytic degradation. The read-across approach is justified in detail within the analogue justification in IUCLID section 13.

The hydrolysis of p-chloro-m-cresol (CAS 59-50-7) was studied in aqueous buffered solutions at pH 4 (citric acid/potassium hydroxide/sodium chloride buffer), pH 7 (potassium dihydrogen phosphate/di-sodium hydrogen phosphate buffer) and pH 9 (borax/hydrochloric acid buffer) according to EC Guideline 92/69/EC, C.7 (Erstling and Feldhues, 2001). Buffer solutions spiked with the test substance were kept at 50 °C for 5 days. The measurement of p-chloro-m-cresol was conducted via HPLC-UV. P-chloro-m-cresol was stable under acidic (pH 4), neutral (pH 7) and alkaline (pH 9) conditions at 50 °C. The test substance still accounted for about 100% in the solutions at termination of the experiments compared to initially applied amounts. The formation of hydrolysis products was not followed in the course of the study. However, due to the hydrolytic stability of the test substance this aspect is of no relevance. Considering the hydrolytic stability of p-chloro-m-cresol determined under environmental pH conditions, it should not be expected that hydrolytic processes will contribute to its degradation in the environment.

Based on the available results from a structurally similar source substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is the main transformation product of the target substance and is characterized by a similar environmental fate behavior and comparable structure, it can be concluded that sodium p-chloro-m-cresolate is hydrolytically stable. Moreover the substance does not contain chemical groups for hydrolysis.