Cancer mortality in women with probable exposure to silica: a death certificate study in 24 states of the U.S.

BACKGROUND

Silica exposure is known to cause an increased risk of pneumoconiosis and some types of cancers. Exposure to silica is becoming an increasingly common occupational hazard for women. Studies contradict each other on whether or not women suffer more occupational pneumoconiosis than men, but no studies have evaluated cancer risks among women exposed to silica.

METHODS

Death certificate data on occupation and industry from 24 states in the U.S. between 1984 and 1993 were used to calculate proportional mortality ratios (PMRs) for workers exposed to silica.

RESULTS

Over 20,000 deaths (4% of all deaths in persons with possible work-related silica-exposure) occurred among women. The PMR for pneumoconiosis among women working in occupations or industries with possible silica exposure was 13.6 (95% CI: 7.2-23.2), for men 3.8 (CI: 3.7-4.0). Both men and women had higher than expected PMRs for respiratory diseases, lung and esophageal cancers, and external causes of death. In the group with probable silica exposure (both occupation and industry associated with silica), women had elevated PMRs for thyroid cancer (PMR = 5.5), multiple myeloma (PMR = 1.3), digestive organ cancers (PMR = 1.2), whereas men had no increased PMRs for these cancers. Both genders had significantly decreased PMRs for breast cancer, cerebrovascular diseases, nervous system diseases, and brain and other central nervous system cancers.

CONCLUSIONS

An in depth look at the types of silica exposures (specific work duties) and adjustment for confounders is warranted to determine the importance of these gender-specific excess mortalities associated with possible silica exposure.