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Environmental fate & pathways

Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Non-GLP non-guideline experimental study, published in peer reviewed literature, notable limitations in design and/or reporting, but adequate for assessment
Principles of method if other than guideline:
Aliquots of 15 ml 1.00 ppm solution were placed in Pyrex tubes, which were placed in a light-proof conatiner and kept in the laboratory at 25 C.
Tubes were removed periodically for analysis by a hollow fiber-mass spectroscopic method.
GLP compliance:
not specified
Remarks:
study conducted before implementation of GLP
Radiolabelling:
not specified
Analytical monitoring:
yes
Estimation method (if used):
Not specified in report
Details on test conditions:
15 ml of the test solution was placed in 18-mm i.d. x 150-mm Pyrex tubes. The icecooled tubes, previously constricted at the neck, were sealed.
The tubes were placed in a light-proof container and kept in the laboratory at 25 C. The tubes were shaken every week or two.
Duration:
1 yr
Temp.:
25 °C
Initial conc. measured:
1 mg/L
Transformation products:
not specified
% Recovery:
> 44 - < 48
Temp.:
25 °C
Duration:
1 yr
Key result
pH:
7
Temp.:
25 °C
DT50:
10.7 mo
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: dark
Conclusions:
The abiotic degradation half-life for trichloroethylene was measured to be 10.7 months using a closed system (Pyrex tubes) in the dark at room temperature of 25°C.
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Published in peer reviewed literature, notable limitations in design and/or reporting, but adequate for assessment
Principles of method if other than guideline:
Hydrolysis of a series of chlorinated hydrocarbon test chemicals was measured in dilute aqueous solutions at varying temperatures(0 to 180 oC) and varying pH (3 to 14) in zero dead-volume stainless steel tubes or flame sealed glass bulbs.
GLP compliance:
not specified
Remarks:
study conducted before implementation of GLP
Transformation products:
not specified
Key result
pH:
7
Temp.:
25 °C
DT50:
1 300 000 yr

A half-life for abiotic degradation of trichloroethylene of 1.3 million years at pH 7 and 25 °C was calculated

Conclusions:
A half-life for abiotic degradation of trichloroethylene of 1.3 million years at pH 7 and 25 °C was calculated.
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Remarks:
(only secondary source), but adequate for assessment
Principles of method if other than guideline:
The half-life for hydrolysis of trichloroethylene has been measured at 25°C and various pHs
GLP compliance:
not specified
Transformation products:
not specified
Key result
pH:
3
Temp.:
25 °C
DT50:
2 809 h
Key result
pH:
7
Temp.:
25 °C
Remarks on result:
other: no hydrolysis observed
Key result
pH:
9
Temp.:
25 °C
DT50:
3 489 h

The half life for hydrolysis of trichloroethylene has been measured at 25°C and various pHs. At pH 3 the half life was 2,809 hours (117 days), at pH 7 no hydrolysis was observed and at pH 9 the half life was 3,489 hours (145 days).

Conclusions:
The half life for hydrolysis of trichloroethylene has been measured at 25°C and various pHs.
At pH 3 the half life was 2,809 hours (117 days), at pH 7 no hydrolysis was observed and at pH 9 the half life was 3,489 hours (145 days).

Description of key information

Hydrolysis is not a significant removal process for trichloroethylene.

Key value for chemical safety assessment

Half-life for hydrolysis:
1 300 000 yr
at the temperature of:
298 K

Additional information

Within a weight of evidence, the endpoint hydrolysis of trichloroethylene was evaluated.

Reliable information from literature is available with consistent evidence to conclude that hydrolysis is not an important removal process for trichloroethylene.

Half-lives in the range from 10.7 months to 1.3 million years have been reported.

The abiotic degradation half-life for trichloroethylene was measured to be 10.7 months using a closed system (Pyrex tubes) in the dark at room temperature of 25°C. (Dilling et al., 1975)

A half-life for abiotic degradation of 1.3 million years at pH 7 and 25 °C was calculated by Jeffers et al., 1989.

Korte reported measured half-life for hydrolysis of trichloroethylene at 25°C and various pHs. At pH 3 the half-life was 2,809 hours (117 days), at pH 7 no hydrolysis was observed and at pH 9 the half-life was 3,489 hours (145 days). (Korte et al., 1981)

The information is in agreement with assessments from European Union and US EPA.