COMPARISON OF PHASE CONTRAST AND ELECTRON MICROSCOPIC COUNTING FOR EVALUATION OF OCCUPATIONAL ASBESTOS EXPOSURES

C. Eypert-Blaison*, M.C. Starck, F. Clerc, A. Roméro-Hariot

*INRS - Centre de Lorraine, Rue du Morvan - 54500 VANDOEUVRE LES NANCY –

FRANCE CONTEXT

METHODOLOGY

MAIN RESULTS

CONCLUSIONS

2009: the French agency for environmental and occupational health protection (ANSES) published a report on the toxicity of short and fine asbestos fibers, which are systematically present in workplace areas.

Comparison of PCOM evaluation and ATEM analyses on 205 sampling filters, representative of 25 worksites types (ACM/removal technique combinations).൳ Sampling of 2 hours at 3 L.min-1 on opened cassettes with an ester cellulose membrane of 37 mm

diameter൳ Direct preparation of filters for PCOM evaluations (according to standard AFNOR XP X 43-269)൳ Indirect Preparation of filters for ATEM evaluations (according to standard AFNOR NF X 43-050)

൳ A complete and consistent study in the air of workplaces on various worksites representative of “material – removal/technical process” combinations. A comparison of methods conducted on the same sample filters.

൳ Undeniable limitations of PCOM and indisputable technical advantages of the ATEM for the assessment of exposure of workers to asbestos fibers. ൳ Risk of insufficiently protecting operators in the case of assessments based on PCOM. ൳ Confirmation of the necessity of adopting, as France has done since July 1st 2012, ATEM to evaluate the exposure of the workers to asbestos fibers,

as already done for ambient air.൳ Need for further studies, especially:൳ On the toxicity of SAFs, ൳ In order to establish protection factors of respiratory protection devices in work situations based on ATEM analyses൳ In order to acquire knowledge about dust level by ATEM (maintenance operations)…

2010: The French Directorate-General for Labor (DGT) launched an asbestos exposure measurement investigation using ATEM:൳ to establish a method and validate the feasibility of sampling airborne asbestos fibers in the

occupational environment with an ATEM analysis൳ to ascertain the dust level generated by the various “Asbestos containing material (ACMs) – Technical

process” combinations when measured by ATEM, in order to implement technical rules minimizing the release of dust into the air and determine protective measures adapted to these levels

൳ to established the particle size distribution of the different classes of fibers on the sampling filters

ANSES recommended, especially, using ATEM in replacement of PCOM for the evaluation of the asbestos level concentration in workplace areas.

ATEM filter preparation: Depending on the level of dust, for one sampling: ൳ Both filters were treated together (very low dust), ൳ The ½ of each filter were treated together (low dust) ൳ The ¼ of each filter were treated together (strong dust)൳ The 1/8 of each filter was treated together (very strong dust)

൳ No distinction of asbestos fibers from other fibers

൳ No observation of the finest fiber always present in the air of workplaces

൳ Disadvantage of direct preparation method in the case of overload of dust

൳ Specific analysis method that allows to observe the finest fibers and analyzing unambiguously on the basis of morphology, chemistry and crystallography

൳ Advantage of indirect preparation method in the case of overload of dust

WHOL>5µm

0,2µm<d<3µmSAFs

L<5µmd<3µm

TAFs

L>5µmd<0,2µm

Schematic representation of the particle size distribution of asbestos fibers in workplace area

Fibers: L/d >3

©INRS

PCOM Limitations: ATEM Benefits:

F1(1 hour)

C1 by ATEM C’1 by PCOM (Average C ½ F1 – C ½ F2)

F2(1 hour)

Natureofasbestosfibers

WHO WHO+TAFs

Mean Std Dev Mean Std Dev

Serpentines 4.31 9.42 14.92 37.14

Amphiboles 0.39 0.67 0.58 0.78

Nature of ACM

WHO WHO+TAFs

Plaster asbestos 18.6 94.5

Paints & coatings 15.1 41.1

Asphalt asbestos 0.5 2.2

Nature of removal/technical process

WHO WHO+TAFs

Grinding - sanding 13.3 41.8

Very or Ultra High Pressure 11.1 124.3

Cutting - Sawing - Chainsaw 0.2 0.9

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