Revision of French Occupational Exposure Limits of Asbestos and Recommendation of Measurement Method: Can the Dimensional Characteristics of the Asbestos Fibers (Long, Thin, Short) Be Taken Into Account?

Abstract

In France, the present regulations on occupational exposure to asbestos fibers take into account fibers (FRp: fibers measured for industrial hygiene) with the following dimensions: L > 5 μm, D < 3 μm, and L/D > 3 where L is the length and D the diameter of the fiber. The limit value is set at 0.1 f/cm³ for 1 hr. By definition short asbestos fibers (SAFs) are the fibers with 0.5 μm < L< 5 μm, D < 3 μm, and L/D ≥ 3; thin asbestos fibers (TAFs) are the fibers with L ≥ 5 μm, D < 0.2 μm, and L/D ≥ 3. The aim assigned to the French Agency for Environmental and Occupational Health Safety (AFSSET) Occupational Exposure Limit (OEL) Committee, was essentially to evaluate the following elements: the relevance of the present French OEL, knowing that this limit excludes the counting of SAFs and TAFs; the consistency of the OEL in light of the different varieties of asbestos by studying possible differential toxicity according to the type of asbestos (chrysotile vs. amphiboles); and the assessment of different measuring methods and their adaptation for taking into account the dimensional characteristics of the asbestos fibers (long, thin, short). In conclusion of this appraisal, AFSSET is calling for the OEL for asbestos to be lowered. Presently set at 0.1 f/cm³ (100 f/L), this leads to an excess risk for a worker that cannot be regarded as acceptable. Initially and without delay, AFSSET is suggesting lowering it to 10 f/L, as an average over 8 hr, In addition, AFSSET recommends that over a period of 15 minutes a concentration equal to 5 times the 8-hr value (8-hr OEL) should not be exceeded, in order to protect workers from the effects of potential peaks in exposure. Moreover, AFSSET recommends changing from optical to electronic microscopy to count asbestos fibers, within the framework of workplace regulations. This will allow thin asbestos fibers to be included.

KEY WORDS:

• exposure levels
• health effects
• limit values
• measurement methods
• mesothelioma
• occupational environment
• OEL
• PCM
• reference value
• SEM
• short asbestos fibers
• thin asbestos fibers
• TEM

ACKNOWLEDGMENTS

Members of AFSSET Scientific Expert Committee on Occupational Exposure Limits include M. Bisson, B. Diers, M. Donnadieu-Claraz, M. Falcy, F. Falson, A. Fastier, S. Grimbuhler, J. M. Haguenoer, Y. Iwatsubo, S. Kerdine-Roemer, C. Lecarpentier, T. Mace, M. Matrat, C. Nisse, F. Pilliere, M. O. Rambourg, J. P. Sandino, M. Sloïm, M. Stoklov, M. Telle-Lamberton, C. Viau, and R. Vincent. Members of AFSSET Working Group on Thin/Short Fibers of Asbestos include C. Allard, M. A. Billon Galland, C. Dion, M. C. Jaurand, A. Leroyer, A. Sobaszek, J. Ameille, P. Bartsch, O. Blanchard, P. Dumortier, M. Guillemin, E. Kauffer, and J. C. Pairon.

Notes

1. Analogous data reassessed by Cullen et al. (2000).

2. Original data in Bernstein (2003) completed for this publication.

3. Analogous data reassessed by Musselman et al. (1994).

4. The French National Institute for Health and Medical Research report noted the heterogeneous nature of the slopes depending on, among others, the asbestos variety. However, Kp = 1 was chosen to simplify the calculations.

5. For more information, refer to the collective appraisal report on establishing Occupational Exposure Limits for chemicals in the workplace, dated December 2008, detailing the recommendations on Occupational Exposure Limits with a view to limiting the effects and the number of exposure peaks during the working day.