Epidemiologic studies of chrome and cancer mortality: a series of meta-analyses

We used 49 epidemiologic studies based on 84 papers published since 1950 to develop an array of meta-analyses relating exposure to chrome-six compounds with 10 causes of death. Most exposures occurred in occupational settings. Studies were assessed for quality, and for control of smoking or economic status if they related to lung or stomach cancer. There was no excess mortality from all causes combined among chrome-exposed persons. A minimal excess of cancer (SMR=112), overall, was due primarily to an excess of lung cancer (SMR=141) but the SMR was 112 among the better-quality, smoking-controlled studies. The overall SMR for stomach cancer was 113 but it was 82 among the studies that were controlled for economic status. Findings were unremarkable for the six other cancers evaluated: prostate, kidney, and central nervous system cancer and leukemia, Hodgkin's disease and other lymphatohematopoietic cancer. This series of meta-analyses indicates that chrome-six is a weak cause of lung cancer and is not a cause of any of the other seven forms of cancer evaluated.