University of Connecticut Health Center, Farmington, CT 06030, USA.
Occup Environ Med. 2011 Feb;68(2):154-62. doi: 10.1136/oem.2009.053512. Epub 2010 Oct 20.
Based on the idea that electric light at night might account for a portion of the high and rising risk of breast cancer worldwide, it was predicted long ago that women working a non-day shift would be at higher risk compared with day-working women. This hypothesis has been extended more recently to prostate cancer. On the basis of limited human evidence and sufficient evidence in experimental animals, in 2007 the International Agency for Research on Cancer (IARC) classified 'shift work that involves circadian disruption' as a probable human carcinogen, group 2A. A limitation of the epidemiological studies carried out to date is in the definition of 'shift work.' IARC convened a workshop in April 2009 to consider how 'shift work' should be assessed and what domains of occupational history need to be quantified for more valid studies of shift work and cancer in the future. The working group identified several major domains of non-day shifts and shift schedules that should be captured in future studies: (1) shift system (start time of shift, number of hours per day, rotating or permanent, speed and direction of a rotating system, regular or irregular); (2) years on a particular non-day shift schedule (and cumulative exposure to the shift system over the subject's working life); and (3) shift intensity (time off between successive work days on the shift schedule). The group also recognised that for further domains to be identified, more research needs to be conducted on the impact of various shift schedules and routines on physiological and circadian rhythms of workers in real-world environments.
基于夜间电灯可能是导致全球乳腺癌发病率升高的一个因素的观点，很久以前就有人预测，上倒班的女性比上日班的女性患乳腺癌的风险更高。这一假说最近又扩展到了前列腺癌。基于有限的人类证据和充足的实验动物证据，国际癌症研究机构（IARC）在 2007 年将“涉及昼夜节律打乱的轮班工作”归类为可能的人类致癌物质，2A 组。迄今为止进行的流行病学研究的一个局限性在于“轮班工作”的定义。IARC 在 2009 年 4 月召开了一次研讨会，讨论如何评估“轮班工作”以及在未来的轮班工作和癌症研究中需要量化哪些职业史领域，以便更有效地进行研究。工作组确定了未来研究中应纳入的几个非白班和轮班时间表的主要领域：（1）轮班系统（轮班开始时间、每天工作小时数、轮班或固定、轮班系统的速度和方向、规则或不规则）；（2）特定非白班轮班时间表上的年限（以及在研究对象的工作生涯中累积接触轮班系统的情况）；（3）轮班强度（轮班时间表上连续工作日之间的休息时间）。该小组还认识到，为了确定进一步的领域，需要对各种轮班时间表和常规对现实环境中工人的生理和昼夜节律的影响进行更多的研究。
