2,2-dichloro-1,1,1-trifluoroethane

Endpoint summary

Additional information

Hoet et al (1997) reported the occurrence of liver disease in workers exposed to HCFC-123 and HCFC-124 (1-chloro-1,2,2,2-tetrafluoroethane). Workers were exposed when the refrigerant permeated the tubing and leaked into the cab of an overhead crane. Six workers were affected to various degrees. Liver biopsy in 1 employee showed hepatocellular necrosis that was prominent in pre-venular zone 3 and extended focally from portal tracts and centrilobular areas. Trifluoroacetyl-adducted proteins were detected in surviving hepatocytes. Auto-antibodies previously associated with halothane-induced hepatitis were detected in the serum of 5 of the workers. The workers recovered when exposure was discontinued. No estimate of exposure levels was provided.

Takebayashi et al (1998) also reported liver dysfunction among workers exposed to HCFC-123 for 2 months. Four out of 14 workers developed severe liver damage as determined by liver function tests. Other symptoms included poor appetite and abdominal pain. Five workers were reported to have slight increases in serum aspartate transaminase (AST) and serum alanine transferase (ALT) with normal bilirubin levels. Viral and other causes of hepatitis were ruled out. All workers recovered quickly when removed from exposure. No estimate of exposure levels was provided.

A case of acute and recurrent hepatitis was reported in a 49-year old female dry-cleaning worker. The dry-cleaning solvent used was a mixture of HCFC-123 (23.7% w/w) and HCFC-141b (29.7%) in n-heptane (46.4%). Subsequently, simulated exposure concentrations were measured to be as high as 1,370 and 1,590 ppm HCFC-123 (8,560 and 9,940 mg/m3) (2 personal samples) for 10 minutes. The corresponding mean area concentrations were 1,360 and 1,990 ppm HCFC- 123 (8,500 and 12,440 mg/m3) (2 points at the work place). Upon the actual exposure, the patient showed acute hepatitis as demonstrated by high hepatic function parameters, including serum AST, ALT, alkali phosphatase (ALP), γ-glutamyl transpeptidase (GGT), LDH and total bilirubin, without viral infection. Serum parameters returned to normal within a few weeks without specific treatment. Upon return to her dry-cleaning job, after 1 day, the patient relapsed into the same symptoms and clinical signs and was diagnosed with chronic hepatitis. As before, serum parameters of liver dysfunction returned to normal within about 1 month. The authors concluded that the hepatitis was induced by HCFC-123, although urinary metabolites were not determined (Omae et al, 2000).

Boucher et al (2003) indicated that when HCFC-123 was introduced as a precision cleaning agent in a controlled operation, marked elevations in ALT and AST were seen in exposed workers. Industrial hygiene sampling collected at that location during the start-up period indicated personal samples ranging from 24 to 480 ppm (150 - 3,000 mg/m3) for 375 and 21 minutes, respectively. Personal and area samples collected at the site after the liver abnormalities had been observed were 5 to 12 ppm (31 - 75 mg/m3), but exposure data were not available during the time when abnormalities were suspected to have developed. The authors describe two models developed to estimate exposure during the monitored period. One model treated the plant as one homogeneous box whereas the other divided the plant into smaller work zones. The one homogeneous box model estimated 8-h TWA exposures ranging from 10 to 35 ppm (63 - 219 mg/m3). Modelling using estimates of work area and air exchange rates indicate that individuals working with the degreaser could have been exposed to peak levels from 280 to 2,100 ppm (8-h TWA 252 - 1,630 ppm) (1,750 - 13,100; 1,580 - 10,200 mg/m3). Modelling of the work environment estimated to be one-third of the volume of the entire open building indicated that employees in the area could have been exposed to peak levels from 28 to 210 ppm (8-h TWA 25 - 163 ppm) (175 - 1,310; 156 - 1,020 mg/m3). The investigators’ estimates using 12 air changes per day suggest that peak levels around the degreaser could have been from 635 to 2,100 ppm (8-h TWA 499 - 1,630 ppm) (3,970 - 13,100; 3,120 - 10,200 mg/m3) and in the work area 63 - 207 ppm (8-h TWAs 50 - 163 ppm) (394 - 1,290; 313 - 1,020 mg/m3). All liver function parameters returned to normal upon termination of the use of HCFC-123.