Toxicological profile HFC-236fa

HFC-236fa has very low acute inhalation toxicity with a 4-hour inhalation LC50 in male and female rats greater than 457,000 ppm.  Like other halocarbons, HFC-236fa was associated with cardiac sensitization in a sensitive laboratory animal species.  The threshold concentration for cardiac sensitization was 150,000 ppm.

HFC-236fa was not mutagenic in the Ames test, the mouse micronucleus, or an in vitro cytogenetic assay in human lymphocytes.
 
HFC-236fa has very low repeated inhalation toxicity. In a 90-day inhalation study, groups of rats were exposed 6 hours a day, 5 days a week, to 5000, 20,000, or 50,000 ppm of HFC-236fa.  A diminished alerting response was observed in the 50,000 ppm exposure group. There were no significant body weight or organ weight changes, clinical pathology effects, or histopathologic changes.  The NOAEL was 20,000 ppm. 
 
HFC-236fa did not produce developmental toxicity when tested in multiple laboratory animal species.  Exposure concentrations were as high as 50,000 ppm.

Basis for AEL
 
    HFC-236fa has a low potential for systemic absorption and metabolism, and has low 
inhalation toxicity.  HFC-236fa primarily affected the CNS with narcosis seen in rats exposed to 
20,000 ppm or more.  HFC-236fa did produce cardiac sensitization, but the threshold for this 
effect was quite high, 150,000 ppm.  There was no evidence for developmental or genetic 
toxicity.  Analogy to other similar fluorocarbons, HFC-134a, HFC-143a, and HFC-152a, all with AELs of 1000 ppm, and HFC-338pcc, with an AEL of 500 ppm was also considered.  
 
   Based on NOAELs of 5000 ppm determined in the 2-week and developmental 
inhalation toxicity studies and a NOAEL of 20,000 ppm determined in the 90-day inhalation 
study, an AEL of 1000 ppm (8- and 12-hour TWA) was recommended.
 
References
 
DuPont Co., Haskell Laboratory Data:
 
  1992a.  Memo D. A. Keller to J. J. Daly et al., dated March 27, 1992 (C-6330).
  1992b.  Letter H. J. Trochimowicz to S. H. Swearingen, dated April 1, 1992 (C-6330).
  1993.    MR-9203-1, HL-761-93
  1994a.  MR-9930-1, HL-596-94
  1994b.  MR-9930-1, HL-602-94
  1994c.  MR-9930-1, HL-604-94
  1994d.  MR-9930-1, HL-647-94
  1995a.  MR-9930-1, HL-66-95
  1995b. MR-9930-1, HL-211-95
  1996a. MR-9930-1, HL-417-96
  1996b. MR-10651-1, HL-74-96.
 
Huntingdon Research Centre, Ltd. 91994).  Report DPT 293/931308 (J-10,126). 
 
Richard C. Graham - October 3, 1995

Updated by:
K. A. Mikles - March 16, 2001
R. C. Graham – June 16, 2006
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Source: Safety Data Sheet of DuPont

Updated: July 2010