234 Urinary 8-hydroxydeoxyguanosine levels of emergency medical shift workers are higher than those of factory workers

Introduction Shiftwork is known as a risk factor of breast cancer and prostate cancer. In fact, the International Agency for Research on Cancer (IARC) classified shiftwork as Class 2A. One mechanism is that shiftwork increases cellular oxidative stress and results in DNA damage. Urinary 8-hydroxydeoxyguanosine (8-OHdG) is frequently analysed as an oxidative stress marker. However, there have been few studies investigating the association of shiftwork with urinary 8-OHdG levels. In this study, we investigated the association between shiftwork with oxidative stress and urinary 8-OHdG levels. Methods Urine samples from eight medical shift workers were collected before and after the night shift. The 8-OHdG levels were measured with a high-performance liquid chromatography (HPLC) system equipped with an electrochemical detector. Results The mean level of urinary 8-OHdG (µg/ng creatinine) in this study was 5.40±1.70, and was higher than that of factory workers in a past study. There were no significant differences in the urinary 8-OHdG levels before and after the night shift work. Conclusion These results suggest that shiftwork, strain, and chronic fatigue lead to oxidative stress and DNA damage. The urinary 8-OHdG level may be a useful biomarker, as an evaluating factor for chronic fatigue in regard to shiftwork.