Correspondence

Contact Dermatitis from an Immersion Oil for Microscopy

N Engl J Med 1998; 339:406-407August 6, 1998

Article

To the Editor:

Since November 1997, we have observed contact dermatitis in three technicians working in a genetics laboratory in Leuven, Belgium, and in two working in the University Laboratory of Bacteriology in Strasbourg, France. The patients, all of whom were women, ranged in age from 32 to 51 years, had no history of allergy, and had worked in the laboratories for several years. The dermatitis, mainly located on the hands and face, relapsed after each occupational exposure to an immersion oil used for microscopy (Leica, Wetzlar, Germany).

Patch testing showed positive reactions to epoxy resins, 1 percent in white petrolatum, from the European standard series (in all four patients tested) and to the Leica immersion oil (undiluted in two patients and 1 percent in white petrolatum in two others). The fifth patient, who was pregnant, was tested with the epoxy resins and the undiluted Leica oil, with a positive reaction to the epoxy resins. In two patients, tests performed with the ingredients of the immersion oil (provided by Leica to the French center only) confirmed sensitization to the epoxy-resin components.

According to Leica, modified epoxy resins were contained in the new oil, at a concentration of more than 80 percent, in order to achieve specific optical properties. A safety-data sheet indicated that the formula was revised in August 1997, when chlorinated paraffins, considered dangerous to human health and the environment, were replaced with liquid epoxy resins. There are no warnings about skin sensitization and no recommendations about protective gloves and eye protection for persons using the new formulation.

Epoxy resins are a well-known source of occupational contact dermatitis,1 and components of epoxy resins have been reported to be sensitizers in fluids such as neat cutting oil2 and grinding oil.3 Until now, contact allergy has not been a problem with the immersion oils used in microscopy. Epoxy-resin compounds are collective allergens at high concentrations and provoke sensitization after a single contact in about 50 percent of people. After one technician became allergic, a colleague replaced her and was rapidly sensitized. Despite the use of gloves, there were relapses of dermatitis until the oil was completely eliminated from the microscope eyepieces and rollers.

Because this immersion oil is widely used and is considered to be innocuous and safe by technicians, additional cases of contact sensitization can be expected.

Christophe Le Coz, M.D.
University Hospital, F-67091 Strasbourg, France

An Goossens, R.Ph., Ph.D.
University Hospital, B-3000 Leuven, Belgium

3 References

1. 1

   Jolanki R, Kanerva L, Estlander T, Tarvainen K, Keskinen H, Henriks-Eckerman ML. Occupational dermatoses from epoxy resin compounds. Contact Dermatitis 1990;23:172-183
   CrossRef | Web of Science | Medline

2. 2

   Scerri L, Dalziel KL. Occupational contact sensitization to the stabilized chlorinated paraffin fraction in neat cutting oil. Am J Contact Dermat 1996;1:35-37
   CrossRef

3. 3

   Rycroft RJ. Allergic contact sensitization to Epoxide 7 in grinding oil. Contact Dermatitis 1980;6:316-320
   CrossRef | Web of Science | Medline

Author/Editor Response

Spokespersons for Leica Microsystems reply:

To the Editor: For immersion oils, most manufacturers originally used natural oils, such as oil from cedar wood, but these were later replaced with synthetic oils based on polychlorinated biphenyls. Because of the hazard of polychlorinated biphenyls, most manufacturers switched to chlorinated paraffins more than 20 years ago.

To be suitable, an immersion oil has to fulfill several conditions. The optical data, refractive index, Abbe value (for dispersion), and transmission have to meet all the established specifications. Also viscosity, nonvolatility, nontoxicity, durability, and temperature dependence have to be guaranteed under typical laboratory conditions. The oil has to be easily removable and must not harm the optics, coatings, and lens mounts.

When experiments showed that chlorinated paraffins are not harmless, we decided to remove these ingredients. We replaced them with epoxy resins, as well as other components that meet all the technical specifications noted above.

The first cases in which contact dermatitis may possibly have been related to the use of this modified immersion oil came to our attention only recently. Further investigations have shown that such allergic reactions occur with a low probability, on the basis of the experience with mixed adhesives, grinding oils, and so forth, which are based on epoxy resins.

We immediately informed our selling offices worldwide in order to increase awareness of the problem of contact dermatitis and inform those who work with immersion oil. In addition, all bottles containing the oil will carry a more detailed warning. We are working closely with our supplier to find substitutes that will allow us to continue to guarantee the highest performance. For users with allergies to epoxy resins, there is another Leica immersion oil available, but with slightly inferior technical specifications.

Horst Kirstein, C.E.
Anita Röhm, Ph.D.
Leica Microsystems, D-35578 Wetzlar, Germany

Citing Articles (3)

Citing Articles

1. 1

   Lasse Kanerva, Riitta Jolanki, Tuula Estlander. (2001) Active sensitization by epoxy in LeicaR immersion oil. Contact Dermatitis 44:3, 194-196
   CrossRef

2. 2

   Yu-Chuan Lee, David Llewellyn Gordon, Lynette Anne Gordon. (1999) Epoxy resin allergy from microscopy immersion oil. Australasian Journal of Dermatology 40:4, 228-229
   CrossRef

3. 3

   Christophe-J. Coz, Dagmar Coninx, Annik Rengen, Suzane Aboubi, Georges Ducombs, Marie-Hélène Benz, Sylvie Boursier, Martine Avenel-Audran, Jean-Luc Verret, Ulrika Erikstam, Magnus Bruze, An Goossens. (1999) An epidemic of occupational contact dermatitis from an immersion oil for microscopy in laboratory personnel. Contact Dermatitis 40:2, 77-83
   CrossRef