Registration Dossier

Administrative data

Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: A scientifically sound publication. Basic data available.

Data source

Reference
Reference Type:
publication
Title:
Degradation of trifluoroacetate in oxic and anoxic sediments
Author:
Visscher P.T. et al.
Year:
1994
Bibliographic source:
Letters to Nature, Vol. 369, 30 June 1994, p. 729 - 731

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Guideline not indicated.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test substrate

Vehicle:
no
Details on sediment and application:
PREPARATION OF SEDIMENT
Sediments were homogenised anaerobically with either artificial bay water (for saltmarsh sediments) or with lake water (for fresh water) to yield final rations of 1:3 sediment: water. Slurries were contained in 57-mL serum bottles sealed under O2-free N2 with black butyl-crimp-stoppers

Test organisms

Test organisms (species):
other: microbial soil flora (not specified)

Study design

Limit test:
no

Test conditions

Nominal and measured concentrations:
0, 0.185, 0.463, 0.925 µM
Details on test conditions:
TEST SYSTEM
- Test container: 57 mL serum bottle (anoxic test) and 160-mL serum bottle (oxic test)
- Sediment volume: 20 mL sediment slurry
The oxic samples were pre-incubated by shaking with exposure to the atmosphere for 20h.

EXPOSURE REGIME
- No. of replicates per treatment group: 3
- No. of replicates per control: 3

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site:
Anoxic sediments: from San Francisco Bay saltmarsh and from a freshwater lake



Results and discussion

Effect concentrations
Duration:
27 d
Dose descriptor:
other: degradation
Effect conc.:
< 0.925 other: µM
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
other: degradation
Details on results:
The degradation of TFA was investigated in anoxic and oxic sediments between 8 and 27 days. The results obtained show that TFA can be degraded microbially by reductive defluorination under anoxic conditions and by decarboxylation under oxic conditions at concentrations below 0.925 µM. This is confirmed by the very low or absent degradation of TFA in autoclaved sediments resp. sediments inhibited by 2-bromoethanesulphonic acid and further reinforces the conclusion, that this degradation is due to microbial rather than to chemical reactions.

Applicant's summary and conclusion