Home | << 1 2 3 >> |
![]() |
Dickerman, B., & Liu, J. (2012). Does current scientific evidence support a link between light at night and breast cancer among female night-shift nurses? Review of evidence and implications for occupational and environmental health nurses. Workplace Health Saf, 60(6), 273–81; quiz 282.
Abstract: Breast cancer is increasingly prevalent in industrialized regions of the world, and exposure to light at night (LAN) has been proposed as a potential risk factor. Epidemiological observations have documented an increased breast cancer risk among female night-shift workers, and strong experimental evidence for this relationship has also been found in rodent models. Indirect support for the LAN hypothesis comes from studies involving blind women, sleep duration, bedroom light levels, and community nighttime light levels. This article reviews the literature, discusses possible mechanisms of action, and provides recommendations for occupational health nursing research, practice, and education. Research is needed to further explore the relationship between exposure to LAN and breast cancer risk and elucidate the mechanisms underlying this relationship before interventions can be designed for prevention and mitigation of breast cancer.
Keywords: Human Health; Breast Neoplasms/*epidemiology/nursing; Chronobiology Disorders/*epidemiology/nursing; Education, Nursing, Continuing; Environmental Health; Evidence-Based Nursing; Female; Humans; Light; Night Care/*statistics & numerical data; *Occupational Health Nursing; Risk Factors; *Work Schedule Tolerance
|
Dumont, M., Lanctot, V., Cadieux-Viau, R., & Paquet, J. (2012). Melatonin production and light exposure of rotating night workers. Chronobiol Int, 29(2), 203–210.
Abstract: Decreased melatonin production, due to acute suppression of pineal melatonin secretion by light exposure during night work, has been suggested to underlie higher cancer risks associated with prolonged experience of night work. However, the association between light exposure and melatonin production has never been measured in the field. In this study, 24-h melatonin production and ambulatory light exposure were assessed during both night-shift and day/evening-shift periods in 13 full-time rotating shiftworkers. Melatonin production was estimated with the excretion of urinary 6-sulfatoxymelatonin (aMT6s), and light exposure was measured with an ambulatory photometer. There was no difference in total 24-h aMT6s excretion between the two work periods. The night-shift period was characterized by a desynchrony between melatonin and sleep-wake rhythms, as shown by higher melatonin production during work and lower melatonin production during sleep when working night shifts than when working day/evening shifts. Light exposure during night work showed no correlation with aMT6s excreted during the night of work (p > .5), or with the difference in 24-h aMT6s excretion between the two work periods (p > .1). However, light exposure during night work was negatively correlated with total 24-h aMT6s excretion over the entire night-shift period (p < .01). In conclusion, there was no evidence of direct melatonin suppression during night work in this population. However, higher levels of light exposure during night work may have decreased total melatonin production, possibly by initiating re-entrainment and causing internal desynchrony. This interpretation is consistent with the proposition that circadian disruption, of which decreased melatonin production is only one of the adverse consequences, could be the mediator between night shiftwork and cancer risks.
|
Fritschi, L., Erren, T. C., Glass, D. C., Girschik, J., Thomson, A. K., Saunders, C., et al. (2013). The association between different night shiftwork factors and breast cancer: a case-control study. Br J Cancer, 109(9), 2472–2480.
Abstract: BACKGROUND: Research on the possible association between shiftwork and breast cancer is complicated because there are many different shiftwork factors, which might be involved including: light at night, phase shift, sleep disruption and changes in lifestyle factors while on shiftwork (diet, physical activity, alcohol intake and low sun exposure). METHODS: We conducted a population-based case-control study in Western Australia from 2009 to 2011 with 1205 incident breast cancer cases and 1789 frequency age-matched controls. A self-administered questionnaire was used to collect demographic, reproductive, and lifestyle factors and lifetime occupational history and a telephone interview was used to obtain further details about the shiftwork factors listed above. RESULTS: A small increase in risk was suggested for those ever doing the graveyard shift (work between midnight and 0500 hours) and breast cancer (odds ratio (OR)=1.16, 95% confidence interval (CI)=0.97-1.39). For phase shift, we found a 22% increase in breast cancer risk (OR=1.22, 95% CI=1.01-1.47) with a statistically significant dose-response relationship (P=0.04). For the other shiftwork factors, risks were marginally elevated and not statistically significant. CONCLUSION: We found some evidence that some of the factors involved in shiftwork may be associated with breast cancer but the ORs were low and there were inconsistencies in duration and dose-response relationships.
|
Hansen, J., & Lassen, C. F. (2012). Nested case-control study of night shift work and breast cancer risk among women in the Danish military. Occup Environ Med, 69(8), 551–556.
Abstract: OBJECTIVES: Growing but limited evidence suggests that night shift work is associated with breast cancer. The authors conducted a nationwide case-control study nested within a cohort of 18,551 female military employees born in 1929-1968 to investigate the risk for breast cancer after night shift work and to explore the role of leisure time sun exposure and diurnal preference. METHODS: The authors documented 218 cases of breast cancer (1990-2003) and selected 899 age-matched controls from the cohort by incidence density sampling. Information on shift work, sun exposure habits, diurnal preference and other potential confounders was obtained from a structured questionnaire. ORs were estimated by multivariate conditional logistic regression. RESULTS: Overall, the authors observed an adjusted OR of 1.4 (95% CI 0.9 to 2.1) among women with ever compared with never night shifts. The RR for breast cancer tended to increase with increasing number of years of night shift work (p=0.03) and with cumulative number of shifts (p=0.02),with a neutral risk for fewer than three night shifts per week. The OR for the group with the highest tertile of cumulative exposure was 2.3 (95% CI 1.2 to 4.6). The most pronounced effect of night shift work on breast cancer risk was observed in women with morning chronotype preference and intense night shifts (OR=3.9, 95% CI 1.6 to 9.5). Night shift workers tended to sunbathe more frequently than day workers. CONCLUSIONS: The results indicate that frequent night shift work increases the risk for breast cancer and suggest a higher risk with longer duration of intense night shifts. Women with morning preference who worked on night shifts tended to have a higher risk than those with evening preference.
|
Haus, E., & Smolensky, M. (2006). Biological clocks and shift work: circadian dysregulation and potential long-term effects. Cancer Causes Control, 17(4), 489–500.
Abstract: Long-term epidemiologic studies on large numbers of night and rotating shift workers have suggested an increase in the incidence of breast and colon cancer in these populations. These studies suffer from poor definition and quantification of the work schedules of the exposed subjects. Against this background, the pathophysiology of phase shift and phase adaptation is reviewed. A phase shift as experienced in night and rotating shift work involves desynchronization at the molecular level in the circadian oscillators in the central nervous tissue and in most peripheral tissues of the body. There is a change in the coordination between oscillators with transient loss of control by the master-oscillator (the Suprachiasmatic Nucleus, SCN) in the hypothalamus. The implications of the pathophysiology of phase shift are discussed for long-term health effects and for the design of ergonomic work schedules minimizing the adverse health effects upon the worker.
Keywords: Human Health; Adaptation, Physiological; Animals; Biological Clocks; Cardiovascular Abnormalities/etiology; Chronobiology Disorders/*complications/physiopathology; Chronobiology Phenomena; Humans; Neoplasms/etiology; Occupational Diseases/*etiology; Risk Factors; Suprachiasmatic Nucleus/physiopathology; *Work Schedule Tolerance
|