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EC number: 206-996-5
CAS number: 420-46-2
Since the substance is a gas with a boiling point of -47.4 deg C, the
only relevant route of exposure is by inhalation. The DNELacute only
needs to be derived in the case where the substance is labelled for
acute toxicty hazard and when peak exposures substantially higher than
the DNELlong-term are possible. As it is not classified as an acute
toxiciy hazard, it does not require a DNELacute. As 1,1,1
-trifluoroethane is not irritating, carcinogenic, mutagenic or toxic to
reproduction or development, these endpoint do not need to be considered
in deriving a DNEL. Therefore only a DNELlong-term for general toxic
effects in the worker population is required.
The Workplace Environmental Exoposure Level Committee of the American
Industrial Hygiene Association (WEEL) has reviewed the toxicology data
on this substance and determined that the appropriate occupational
exposure level for this substance is 1000 ppm as an 8-hr
Time-Weighted-Average. This is based on the studies that have shown that
the LC50 > 540,000 ppm in rats. In dogs, a cardiac sensitization
response to adrenalin was observed only at 300,000 ppm. In repeat
inhalation toxicity and developmental toxicity studies the NOEL was
40,000 ppm, the highest level tested.
to the REACH “Guidance on information requirements and chemical safety
assessment”, a leading DN(M)EL needs to be derived for every relevant
human population and every relevant route, duration and frequency of
exposure, if feasible.
1,1,1 -trifluoroethane is a gas, oral and dermal routes of exposure
are considered to be irrelevant, therefore no DNELs were derived for
the substance is not classified for acute toxicity, according to the
REACH “Guidance on information requirements and chemical safety
assessment” (R.188.8.131.52), no acute / short-term exposure DNELs need to
long-term exposure, data from a 90 day repeated dose toxicity study is
available. In this study, no adverse effects were observed in rats at
the high concentration tested (NOAEC of 214000 mg/m3, corresponding to
a target limit concentration of 40000 ppm). This value will be used to
derive a DNEL for long-term exposure. The substance is not genotoxic,
not carcinogenic, and is not a reproductive or developmental toxicant.
Therefore, no DNELs will be derived for these endpoints,i.e.,
the long-term DNEL is also considered sufficient to protect against
DNEL for long-term exposure - local/systemic effects for workers is
derived as follows:
Step 1) Relevant dose-descriptor
The highest concentration in the subacute toxicity study with rats; no adverse effects were observed.
Step 2) Modification of starting point
6.7 m3/10 m3
Correction of exposure duration in study (6 hrs/day, 5 days/week) to default worker exposure (8 hrs/day, 5 days/week);
Correction for activity driven differences of respiratory volumes in workers compared to workers in rest (6.7 m3/10 m3).
Step 3) Assessment factors
No additional interspecies factor is applied as:
- regarding toxicokinetics: no metabolic differences between rats and humans are expected for HFC-143a based on the substance chemical inertness and rapid excretion in unmetabolised form;
- regarding toxicodynamics: no effects were observed up to the relatively very high concentration of 214000 mg/m3. In addition, no differences are expected based on the chemical inertness of HFC-143a.
HFC-143a can be considered as chemically and biologically inert, without expected toxicological properties. An assessment factor of 3 is considered sufficient to account for the intraspecies differences in the worker population
No assessment factor for duration extrapolation (subacute to chronic) is applied as no adverse effects were observed in the subacute study at the very high tested concentration. Furthermore, the available toxicokinetic data shows that the substance is rapidly excreted and does not accumulate. Therefore it is not expected that adverse effects will occur at lower concentrations after chronic exposure and the use of an assessment factor is considered to be unnecessary.
Quality of database
214000 x 6/8 x 6.7/10 / (1 x 3 x 1 x 1 x 1) = 38800 mg/m3(10400 ppm)
DNEL of 38800 mg/m3corresponds to the concentration of
10400 ppm. This value is more than a factor 10 higher than the TLV for
inert gases (1000 ppm) established by the ACGIH, indicating that the
substance presents an extremely low toxicological concern.
Exposures for 6-hr/day, 5 days/wk for 13 weeks at levels up to 40,000
ppm did not result in any systemic effects.
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.
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