Substance-Specific Issues

Isopropanol; classification with respect to sensitization

Substance:

isopropanol (2-propanol); CAS No. 67-63-0

Issue:

Does isopropanol fall within the [WHMIS] Controlled Products Regulations (CPR) criteria for skin sensitization?

Background:

While working at a chemical pathology laboratory a 55-year-old female technician developed several incidences of diffuse acute contact dermatitis after working for years with ethanol. She was initially patch tested and found to be hypersensitive to commercial grade isopropanol [48-case III]. She was tested again at a later date to confirm her hypersensitivity, this time using gas-chromatographically pure (100%) isopropanol [1]. The material was applied for 48 hours to the back. Twenty-four hours post exposure a strong eczematous reaction was observed. Tests on 20 volunteers were negative.

A 45-year old female worker at a cosmetic manufacturing company who had been previously occupationally exposed to commercial isopropanol volunteered to be patch tested with triple distilled (100%) isopropanol (analyzed by GC and MS). Aqueous solutions from 99% to 2.5% isopropanol were applied for 24 hours to the back and readings were made at 24, 48 and 72 hours after removal. Concentrations of 2.5% and higher yielded positive results at all three time readings, indicating hypersensitivity [2].

Considerations:

As stated in the Health Canada Reference Manual interpretation / discussion of section 56 of the CPR, when determining whether or not a chemical falls within the CPR criteria for sensitization, the number of cases reported in relation to the size of the population that has been exposed and the extent of the exposure should be taken into consideration [3]. For example, a high-production-volume chemical, used in large quantities in many workplaces would not warrant classification if only a few cases of sensitization had been reported over a period of several years.

Conclusion:

As only very few cases have been reported in the literature with this widely used chemical, isopropanol would not fall within the CPR criteria for skin sensitization.

Note: should the number of cases increase or should new cases be reported in the literature, the potential of isopropanol to induce skin sensitization may be reevaluated.

References:

1. Fregert, S., et al (1971) Hypersensitivity to Secondary alcohols. Acta Dertmatovener (Stockholm):51:271-72.
   
   
2. Ludwig, E & Hausen, B. (1977) Sensitivity to isopropyl alcohol. Contact Dermatitis:3:240-44.
   
   
3. Health Canada; "Reference Manual for the WHMIS Requirements of the Hazardous Product Act and Controlled Products Regulations"