Environmental risk factors of systemic sclerosis.

Systemic sclerosis (SSc) has a complex pathogenesis. Although, there is a growing evidence that environmental factors have an impact on alterations and modulation of epigenetic determinants, resulting in SSc onset and progression. A marked correlation has thus been found between SSc onset and occupational exposure to crystalline silica and the following organic solvents: white spirit, aromatic solvents, chlorinated solvents, trichloroethylene, and ketones; the risk associated with high cumulative exposure to silica and organic solvents further appears to be strongly increased in SSc. Altogether, occupational exposure should be systematically checked in all SSc patients at diagnosis, as (1) exposed patients seem to develop more severe forms of SSc and (2) the identification of the occupational agents will allow its interruption, which may lead to potential improvement of SSc outcome. By contrast, based on current published data, there is insufficient evidence that exposure to other chemical agents (including notably pesticides as well as personal care such as silicone and hair dye), physical agents (ionizing radiation, ultraviolet radiation, electric and magnetic fields), and biological agents (infections and diet, foods, and dietary contaminants) is a causative factor of SSc. Further investigations are still warranted to identify other environmental factors that may be associated with SSc onset and progression.