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EC number: 207-236-5
CAS number: 455-14-1
p-TFMA ahs to be considered as not readily biodegradable.
(Hoechst, 1996) on a biodegradation test concludes about readily
biodegradation potential for pTFMA.
was discussed with the study director who provided additional
information about nitrification potential and the calculation of the
theoretical oxygen demand.
The summary of the disregarded study is the
In a study (Hoechst, 1996), the
biodegradability of p-TFMA was evaluated according to OECD 301F
guideline under GLP.
The biodegradation of the test item was
followed during 28 days, at a concentration of 71.5 mg/L, using 30 mg/L
of inoculum from Municipal sewage treatment plant.
After 28 days, the test item was found
readily biodegradable (reaching the 10-day window).
However this test is not fully valid,
because there are some deficiencies in regards the recommendations in
the OECD 301 guideline:no
pH measurements (it should be adjusted to 7.4 +/- 0.2), no abiotic
sterile control, no toxicity control, no details on analytical method.
In addition a replicate in the control had to be disregarded but this is
not discussed in the report. Finally the calculation of the
theoretical demand in oxygen is not in line with the OECD recommendation
and significant differences in the final result may come from this
In the end the nitrification of the test
item was not taken into account in this study. Based on calculation
IV.2 of OECD 301 guideline, the percentage of biodegradation expected in
this study, would have been47.5 to 57.3% after 28 days.
In these conditions p-TFMA would have been
considered as not readily biodegradable.
For all the above deficiencies /
uncertainties in the study and despite the additional information provided
by the study director, the data had to be unvalidated
for the following reasons:
- the test
is not fully valid in regards to OECD 301 recommendations,
- the report
does not contain any details on the preparation of the inoculum,
effects" that conducted to invalidate a replicate in the control is not
theoretical oxygen demand is not calculated as recommended in the OECD
guideline (and the calculation according to the OECD301Fguideline
would have lead to higher values, then the substance may have had a
lower potential for biodegradation)
- there is
no evidence in the literature to show that a nitrification process is
not expected for these compounds
similar compounds have been tested and found "non readily
biodegradable": o-TFMA, 2,6 dichloro-pTFMA, 4 fluoroaniline,
similar compounds are found "non readily biodegradable" with structure
activity models: pTFMA, 2,4 difluoroaniline, 2 Fluoroaniline, 4-
Fluoroaniline, 3,5 difhuoroaniline.
the actual deficiencies in the study and the result of the literature
search on the biodegradation potential for similar fluorinated compounds
it is proposed to keep the "R53" classification and consider the
substance as "non readily biodegradable”.
of QSAR, considering as key study concludes about "non readily
biodegradable" substance with all relevant prediction models (BIOWIN
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