Carbon composites

By definition, a composite material is formed from several components including a reinforcement (carbon fibres, in this case) and a matrix (typically a thermoplastic or thermosetting resin). The use of composite materials varies widely (sporting goods, manufacture of craft for recreational boating, aerospace, etc.) due to their unique mechanical characteristics and the weight saving achieved when they are used.

As an illustration, the share of composite materials in aerospace during 2010 amounted to over 50% of the structural weight of aircraft made by Boeing and Airbus.

The Agency was asked by the General Confederation of Labour (CGT) to conduct an assessment of the health risks associated with the manufacture and machining of carbon composites. The CGT thus wished to anticipate and manage potential risks to workers’ health as a result of the finding that there is widespread use of these materials in the aerospace industry.

The Agency considered the CGT’s request to be appropriate, both in administrative and scientific terms. However, in light of the questions raised, the Agency considered it necessary to broaden the investigative scope to include other industries employing these materials (shipbuilding, wind turbine energy, public works and civil engineering, sporting goods manufacturing, etc.). This work led to the publication of an Opinion and a Report in the spring of 2010.

Results and Recommendations

Based on the conclusions of the collective expert appraisal conducted by the Agency, the risks associated with the manufacture and machining of these materials mainly concern the potential toxicity of carbon fibres through dermal or respiratory exposure. Inhalation exposure occurs due to the potential of the fibre to split into finer microfibrils that can penetrate deep into the bronchial tree during some machining operations. Since the long-term toxic potential of inhaled carbon fibres had been insufficiently investigated as of 2010, the Agency considered it necessary to develop studies to improve the characterisation of worker exposure to carbon fibres, by developing suitable metrological tools. Dermal exposure, for its part, results from contact with the constituents of composite materials, particularly epoxy resins. It is associated with irritant and allergenic dermatitis, conditions frequently described by the French National Network for Monitoring and Prevention of Occupational Diseases (RNV3P) for industrial sectors in which workers are exposed to constituents of carbon composites.

The expert appraisal conducted by the Agency identified several possible ways of advancing the prevention of occupational risks. On the basis of this report, the Agency recommended implementation of a structured approach to prevention for workers in industry by establishing an appropriate metrology for measuring identified pollutants; developing recommendations for medical follow-up, in conjunction with the relevant stakeholders; promoting study and research on the hazards and risks, particularly through toxicity studies on representative samples of occupational exposure; and monitoring emerging risks potentially associated with these uses, especially when using nanomaterials in formulations (carbon nanotubes, for example).