Exposure to silicon carbide and cancer risk: a systematic review.

Purpose: To conduct a systematic review of epidemiologic studies on risk of cancer from exposure to silicon carbide (SiC).
Methods: We followed established guidelines to search electronic databases for studies on populations exposed to SiC. We conducted meta-analyses when the data justified it.
Results: We identified two studies of SiC production workers and several studies of users. The studies of production workers indicated an increased risk of lung cancer. The increased risk was restricted to workers with elevated dust exposure and, in the most informative study from Norway, was linked to estimated cristobalite exposure, a form of crystalline silica. Increased risk was not linked to SiC particles, once cristobalite exposure was controlled for. Studies of SiC users in various industries did not reveal an increased risk of lung cancer.
Conclusions: The increased risk of lung cancer detected in the SiC production industry appears to be associated with high exposure levels to total dust, including crystalline silica and cristobalite which occurred in this industry in the past decades. It may not persist under current exposure circumstances, characterized by lower levels and use of personal protection equipment. Commercial users of SiC-based products were not affected.