Environmental Health Perspectives 105, Supplement 5, September 1997: Article by Greim and Ziegler-Skylakakis

Environmental Health Perspectives 105, Supplement 5, September 1997

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Strategies for Setting Occupational Exposure Limits for Particles

Helmut A. Greim and Kyriakoula Ziegler-Skylakakis

GSF-National Research Center for Environment and Health, Institute of Toxicology, Neuherberg, Germany

Abstract
To set occupational exposure limits (OELs) for aerosol particles, dusts, or chemicals, one has to evaluate whether mechanistic considerations permit identification of a no observed effect level (NOEL). In the case of carcinogenic effects, this can be assumed if no genotoxicity is involved, and exposure is considered safe if it does not exceed the NOEL. If tumor induction is associated with genotoxicity, any exposure is considered to be of risk, although a NOEL may be identified in the animal or human exposure studies. This must also be assumed when no information on the carcinogenic mechanism, including genotoxicity, is available. Aerosol particles, especially fibrous dusts, which include man-made mineral fiber(s) (MMMF), present a challenge for toxicological evaluation. Many MMMF that have been investigated have induced tumors in animals and genotoxicity in vitro . Since these effects have been associated with long-thin fiber geometry and high durability in vivo , all fibers meeting such criteria are considered carcinogenic unless the opposite has been demonstrated. This approach is practicable. Investigations on fiber tumorigenicity/genotoxicity should include information on dose response, pathobiochemistry, particle clearance, and persistence of the material in the target organ. Such information will introduce quantitative aspects into the qualitative approach that has so far been used to classify fibrous dusts as carcinogens. The rationales for classifying the potential carcinogenicity of MMMF and for setting OELs used by the different European committees and regulatory agencies are described. -- Environ Health Perspect 105(Suppl 5):1357-1361 (1997)

Key words : occupational exposure limits, classification of carcinogens, man-made mineral fibers, fibrous dust particles, regulations of man-made mineral fibers

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1997; accepted 13 May 1997.

Address correspondence to Dr. H. Greim, GSF-National Research Center for Environment and Health, Institute of Toxicology, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany. Telephone: 49 89 3187 24 46. Fax: 49 89 3187 34 49.

Abbreviations used: AGS, Ausschuß für Gefahrstoffe (Commission for Dangerous Chemicals, German Federal Ministry of Labor); DECOS, Dutch Expert Committee on Occupational Standards; EU, European Union; IARC, International Agency for Research on Cancer; MAK, maximale Arbeits-platz-Konzentration (maximum workplace concentration); MMMF, man-made mineral fiber(s); MMVF, man-made vitreous fiber(s); NOEL, no observed effect level; OEL, occupational exposure limit; TLV, threshold limit value; TRK, technische Richtkonzentration (technical guidance value).

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Last Update: November 26, 1997