Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 473-390-7
CAS number: -
It is not expected that FC-770 will have a significant presence in the
aquatic compartment, and testing conducted under artificial conditions
that force FC-770 to remain in solution would not provide a realistic
assessment of bioaccumulation potential. A pilot BCF study demonstrated
that testing under artificial conditions of closed test vessels with a
high rate of flow-through was not adequate to maintain consistent test
concentrations that were close to the nominal concentration, yet at the
same time these test conditions caused extensive mortality and morbidity
in fish. The test methodology was developed in response to Substance
Evaluation decision SEV-D-2114434716-46-01/F, which mandated a BCF test
under flow-through conditions that would maintain stable test
concentrations of FC-770 in water. For both the uptake and the
depuration data there were large variabilities noted in the fish
concentrations from the same test chamber (i.e., the same time point),
as well as swings in the tissue concentrations (e.g, day 21 to day 27 or
day 27 to day 28). Both of these aspects of the fish concentration data
contributed to the large confidence interval associated with the
calculated provisional kinetic BCF. In addition, numerous issues were
identified with this pilot study that, when combined, could lead to a
substantially lower BCF. The issues are documented as follows:
a. The sampling method was open to the atmosphere. In this
preliminary test, no attempt was made to establish recovery from
samples. Volatilization losses of FC-770 during sampling cannot be
excluded. Such losses might explain the low observed test substance
concentrations relative to the nominal (see below) in closed-bottle
trials. We anticipate that the actual concentrations in the tank could
have been much closer to nominal than the measured values, and therefore
the true BCF could be much lower than the provisional kinetic BCF.
b. The measured concentrations in this pilot study as well as the
previous diluter trials was significantly lower than the nominal
concentration by a factor of 7. FC-770 loss could have occurred via
leaks in the test chambers, during daily feeding and cleaning operations
while the test chambers were temporarily open, or through volatilization
loss during sampling. Despite increased nominal concentrations in the
pilot study relative to the preliminary trial (100 µg/L vs 60 µg/L), the
measured concentration was actually lower in the pilot study relative to
the preliminary trial (mean 9.3 µg/L in the pre-test equilibration
period vs 19.9 µg/L in the preliminary trial). This difference
demonstrates the difficulty of establishing exposure concentration for a
substance that is both poorly soluble as well as volatile. It is worth
noting also that the observed variability in concentration would have
likely presented an issue if the test material had been radio labeled.
c. Measured exposure concentration was quite variable in some
cases even within the same test chamber (e.g., %SD between top middle
and bottom samples ranged from 4.94% on day 1 to 70.7% on day 28), and
across all the bottles (%SD of 58.94% across all measurements taken).
Concentrations appeared to decrease over time with the exception of day
21. The reason for the apparent buildup and the observed variability are
not known. It is possible that differences in organic carbon
accumulation in each test system could have contributed to variability
in measured concentration across the test chambers. Unfortunately,
DOC/TOC values were not measured in the chamber during the duration of
this pilot study, but only in the influent.
d. Abnormalities (e.g., popeye) and fish mortality were present in
both the solvent control and the test chambers. Mortality was 33% and
83% in the control chambers and ranged from 0 to 67 % in the test
chambers. The earliest mortality was observed at day 3. Mortality did
not associate with exposure concentrations or observed morphological
stress. In addition, mortality was not observed by the contract lab in a
standard BCF study of an unrelated test material that was run with the
same batch of fish at the same time as the pilot study. The underlying
mechanism for the observed mortality in both the solvent control and
treatment replicates cannot be definitively identified based on the
measurements and observations collected during the study but possible
reasons include: (A) fish crowding during feeding-contact and
competition for food stress at the small opening of the aspirator bottle
test chambers (as a result, feeding procedure was changed on day 18 –
the water level was lowered to increase the feeding area for the fish),
(B) accumulation of fish waste and excess food in systems resulting in
reduced water quality, (C) changes in daily water volumes during feeding
after day 18, (D) changes in water quality concentrations and/or (E)
high flow rates.
e. High microbial growth in test chambers was noted in the test
chambers. This prompted the laboratory to perform daily cleaning of the
test chambers. Flow was stopped and medium drawn down via the stopcock.
Sides and bottom of the bottle were scraped and siphoned to dislodge
biomass and remove uneaten food and debris, after which the flow was
restarted, and medium level restored. The process required ca. 30
minutes each day during which the test chambers were open to the
atmosphere. The reason for the high microbial growth could not be
precisely identified but possible explanations include 1) the use of
solvent which could have acted as a carbon source for microbial activity
2) the glass equipment used could have been more conducive to microbial
growth and more difficult to clean compared to other Teflon-lined
equipment used regularly in the lab.
f. The lack of a premixing chamber was a limitation of this study.
The large variability in concentrations between the test chambers
suggest that the fish may have been exposed as separate microcosms as
opposed to one consistent exposure group. The use of a premixing chamber
was avoided as a potential source of volatilization losses.
g. High uncertainty in the measured BCF. The uncertainty in the
water concentration measurements, the observed variability in water
concentration, as well as the noted signs of fish stress all affect the
reliability of the derived BCF value.
In the Substance Evaluation decision, a bioaccumulation feeding study
was mandated if it were concluded that the flow-through exposure study
was determined to be not feasible. For similar reasons to the
flow-through test, however, a feeding study is not likely to be
feasible. The pilot BCF result is used as such in the PBT Analysis.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
Damit Sie die Website optimal nutzen können, verwenden wir Cookies.
Welcome to the ECHA website. This site is not fully supported in Internet Explorer 7 (and earlier versions). Please upgrade your Internet Explorer to a newer version.
Do not show this message again