Background: Breast cancer is the most common tumor among women, and the causes remain almost unknown apart from changes in the reproductive pattern. Based on experimental evidence, some organic solvents may have carcinogenic properties to the female breast.
Methods: We used a comprehensive national data linkage to examine the adjusted breast cancer risk among relatively young (20-55 years) Danish women employed in industries with extensive use of organic solvents (i.e., the metal product, wood and furniture, printing, chemical, and textile and clothing industries). Relative risks (OR) were estimated from a matched case-control study on 7,802 women with breast cancer (1970-1989). Potential exposure to organic solvents was accessed from the duration of employment within the selected industries and reconstructed from the files of a nationwide compulsory pension fund. Socioeconomic status and the individual reproductive pattern were obtained from the central person registry.
Results: The adjusted OR for breast cancer after 15 years latency was increased in each of the selected industrial groups (from 1.4 to 2.4). For the entire group with over 10 years of employment, the OR was significantly elevated (twofold).
Conclusions: This study supports the observation that long-term occupational exposure to organic solvents may play a role in breast cancer risk. However, some residual confounding may exist, and further studies are required to identify specific carcinogenic organic solvents.