Occupational exposure to carbon fibers impregnated with epoxy resins and evaluation of their respirability

ABSTRACT Objectives: The study aims to investigate occupational exposure to carbon fibers impregnated with epoxy resins (carbon fiber reinforced [CFR]) in workers at an airplane fuselage section construction plant, by environmental and biological monitoring. Materials and methods: Determination of airborne CFR was done by environmental sampling with active samplers, 11 of which were stationary and 19 personal samplings. The subsequent analyses were performed in the scanning electron microscope fitted with an X-ray microanalysis system (SEMEDXA). Biological monitoring was carried out by determining CFR in exhaled breath condensate (EBC) collected from 19 male workers who wore personal environmental samplers (exposed workers) and from 10 male workers at the same factory who had no occupational exposure to CFR (internal controls). CFR analysis was done by SEM, applying the method used for determining asbestos fibers in aqueous samples. Results: The airborne CFR concentrations were found to be significantly higher (p¼0.03) at personal samplings (median value 7.01 ff/L, range 1.24–11.16 ff/L) than stationary samplings (median value 1.93 ff/L, range 0.55–10.09 ff/L). The aerodynamic diameters calculated starting from the length and geometric diameter of the sampled CFRs were always higher than 20 mm. CFR was not found in any of the EBC samples collected from the exposed workers and controls. Conclusions: Despite the evidence of occupational exposure to low concentrations of CFR, the absence of such fibers in the EBC in the exposed workers confirms their non-respirability, as expected based on their aerodynamic diameter. Abbreviations: ACGIH: American Conference of Governmental Hygienist; CFR: Carbon Fiber Reinforced; EBC: Exhaled Breath Condensate; SCOEL: Scientific Committee on Occupational Limits; SEM: Scanning Electron Microscopy; WHO: World Health Organization