Risk of bile duct cancer among printing workers exposed to 1,2-dichloropropane and/or dichloromethane.
OBJECTIVE
We conducted a retrospective cohort study to examine the risk of bile duct cancer among current and former workers in the offset color proof printing department at a printing company in Osaka, Japan.


METHODS
Standardized incidence ratios (SIRs) between January 1, 1985, and December 31, 2012, were estimated for the cumulative years of exposure to two chemicals, dichloromethane (DCM) and 1,2-dichloropropane (1,2-DCP), using the national incidence level as a reference. In addition, we examined risk patterns by the calendar year in which observation started.


RESULTS
Among 106 workers with a total of 1,452.4 person-years of exposure, 17 bile duct cancer cases were observed, resulting in an estimated overall SIR of 1,132.5 (95% confidence interval (CI): 659.7-1,813.2). The SIR was 1,319.9 (95% CI: 658.9-2,361.7) for those who were exposed to both DCM and 1,2-DCP, and it was 1,002.8 (95% CI: 368.0-2,182.8) for those exposed to 1,2-DCP only. SIRs tended to increase according to years of exposure to 1,2-DCP but not DCM when a 5-year lag time was assumed. The SIRs were higher for the cohorts in which observation started in 1993-2000, particularly in cohorts in which it started in 1996-1999, compared with those in which it started before or after 1993-2000.


CONCLUSIONS
We observed an extraordinarily high risk of bile duct cancer among the offset color proof printing workers. Elevated risk may be related to cumulative exposure to 1,2-DCP, but there remains some possibility that a portion of the risk is due to other unidentified substances.
Department of Environmental Medicine and Population Sciences, Graduate School of Medicine, Osaka University.
Tomotaka
T
Sobue
Mai
M
Utada
Takeshi
T
Makiuchi
Yuko
Y
Ohno
Shinichiro
S
Uehara
Tomoshige
T
Hayashi
Kyoko Kogawa
KK
Sato
Ginji
G
Endo
D000328:Adult; D017668:Age of Onset; D001650:Bile Duct Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007281:Ink; D007564:Japan / Q000453:epidemiology; D008297:Male; D008752:Methylene Chloride / Q000633:toxicity*; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology; D016273:Occupational Exposure / Q000009:adverse effects*; D011327:Printing; D011407:Propane / Q000031:analogs & derivatives* / Q000633:toxicity; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
D008752:Methylene Chloride; C004765:propylene dichloride; D011407:Propane