ABSTRACT 

This case study presents an intervention in a pharmaceutical firm which is specialized in the making of glass syringes. The main objective of this firm was to have his machine-tool being in conformity with the european legal requirements NO. 89/139/CE from June 12th, and in conformity with the french decree No. 93-40 from January 11th 1993, prescribing firms to evaluate and limitate hazards due to the functioning of the production machine-tool. A previous operation has been carried out by safety experts from a big safety office in France. This intervention has given rise to the design of safety devices. But these devices did not seem to meet the agreement of the workers. We then proceeded by an investigation of the naive causal analysis of accidents and risks by the machine-operators by means of individual interviews and direct observation at the workplace. We also constituted a workshop with different operators aiming to design safety devices bearing on this naive causal analysis. The results showed the relevance of naive causal analysis for the diagnosis of security. Particularly, the machine-operators pointed out to risks which have not been identified by experts and didn't necessarily propose the same safety devices as the experts did. By taking into account the naive causal analysis in the diagnosis of security, we were then able to conceive of complementary and more efficient safety devices for the machine-tool and to conceive of new organizational adjustments.

KEYWORDS: conformity with legal requirements, safety diagnosis, naive causal explanation, expertise, ergonomic adjustments.