[Systemic sclerosis: epidemiology and environmental factors].

The pathophysiology of systemic sclerosis (SSc), probably multifactorial, is not yet well elucidated. Among the many endogenous and exogenous factors probably involved, environmental and occupational elements may play an essential role. SSc is a rare disease. Prevalence is estimated between 3 and 24 per 100,000 population. Reports of sporadic clusters of higher prevalence suggest environmental factors, which have not yet been defined. Silica, first suggested in 1917, plays a role in SSc development, as officially recognized in France for purposes of workers' compensation. Solvents have been associated with SSc by several rigorous case-control studies that suggest a causal role. Current data about other toxic agents (epoxy resins, vibrations, welding fumes) do not justify conclusions about their role in SSc. The severity of SSc (determined by the extent of diffuse cutaneous lesions, pulmonary involvement, and immunological profile) is probably associated with occupational exposure.