General mortality from 1944 through 1994 for a silicon-based chemical company.

The objective of this study is to reevaluate the statistically significant elevated risk of lung cancer among men with >or=20 years of employment at Dow Corning Corporation, a manufacturer of silicon-based materials. The cohort included 712 deaths among 8266 employees who were hired from 1943 to 1992 with follow-up through 1994. Standardized mortality ratios (SMRs) were calculated for 63 causes of death. Analysis confirmed a statistically significant increased mortality from cancer of the bronchus, trachea, and lung among men, prior to 1985, who jointly classified with >or=30 years of work duration and >or=30 years since first employed. SMRs for lung cancer after 1985, however, were not statistically significant and were inconsistent across work duration and years since first employed intervals. The study provides no evidence for elevated mortality among Dow Corning workers since the 1991 cohort mortality study. This study describes the updated mortality experience of a large employee cohort from a major silicon-based manufacturer. It illustrates that a well-designed mortality study can be a key component of employee health surveillance efforts in an industrial setting with potential hazardous workplace exposures.

Silicone gel breast implant rupture rates: research issues.

Documenting the rate of rupture of silicone breast implants appears to be deceptively easy. Largely because of the phenomenon of "silent rupture," it isn't. The authors explore the various technical biases (selection, misclassification, and confounding) and methodological problems that have plagued much of the research conducted to date. By means of a series of illustrations, they argue that explantation has limited utility. Noninvasive techniques have to be used to gather the proper type of data on the timing and frequency of these events. Only with the proper incidence data will researchers be able to identify better the different mechanisms underlying implant rupture and the relative importance of each. The authors recommend that better and standardized definitions of implant rupture be developed, that greater recognition be given to the technical biases and a greater effort be made to eliminate them from investigations of implant rupture, and that more research be conducted by multidisciplinary teams. Because of the growing awareness of the complexity of this issue, the authors also recommend that properly constituted advisory teams be used to provide comprehensive oversight of future research projects from beginning to end.