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Environmental fate & pathways

Hydrolysis

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Administrative data

Endpoint:
hydrolysis
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Peer-reviewed publication, but very poorly documented (complete lack of documentation of experimental conditions like pH, buffer systems, sterility, etc.), therefore considered as invalid. Abiotic fate processes take place in a non-chiral or 'racemic' environment, and thus will not discriminate between enantiomers. Therefore, albeit the study was conducted on LL-lactide, the results are equivalently applicable also to DD-lactide.

Data source

Reference
Reference Type:
publication
Title:
Safety assessment of polylactide (PLA) for use as a food-contact polymer
Author:
Conn RE, Kolstad JJ, Borzelleca JF, Dixler DS, Filer LJ Jr, LaDu BN Jr, Pariza MW
Year:
1995
Bibliographic source:
Food Chem Toxicol. 33(4): 273-283

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Hydrolysis of L-lactide. A 100 or 1000 ppm solution of L-lactide was prepared by diluting a 1 % solution of lactide in acetonitrile with distilled water or 8 % ethanol at the appropriate temperature. Samples were aged at the respective temperatures, removed at various times and analysed directly by gas chromatography (GC).
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
not specified
Details on test material:
- Name of test material (as cited in study report): L-lactide
- Substance type: Organic
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Directly analysed by GC.
Duration of testopen allclose all
Duration:
30 min
Temp.:
80 °C
Initial conc. measured:
ca. 100 other: ppm
Duration:
90 min
Temp.:
60 °C
Initial conc. measured:
ca. 100 other: ppm
Duration:
180 min
Temp.:
21 °C
Initial conc. measured:
ca. 100 other: ppm

Results and discussion

Transformation products:
not measured
Dissipation DT50 of parent compound
Temp.:
21 °C
Hydrolysis rate constant:
ca. 0.23 h-1
DT50:
ca. 3 h
Type:
(pseudo-)first order (= half-life)

Applicant's summary and conclusion

Validity criteria fulfilled:
no
Conclusions:
At 21 °C a hydrolysis half-life of 3 h (k = 0.23 h^-1) was determinded for L-lactide. The expermiments are, however, very poorly documented, not allowing an assessment of reliability. The study is considered to be invalid.
Executive summary:

Hydrolyis experiments with L-lactide are reported in a published paper, but methods and results are very poorly documented. Analytical methods, employed pH, buffers (if relevant), sterility of equipment, initial and measured concentrations, or any other crucial conditions, were not reported. The study is thus considered to be unreliable.

The half-life of L-lactide in water at 21 °C was determined to be 3 h, corresponding to a rate constant of 0.23 h–1.