Humans are exposed to the environmental pollutants 2, 4-dichlorophenol (2, 4-DCP) and 2, 5-dichlorophenol (2, 5-DCP) through air, use of water and consuming products. In this study, we evaluated the urinary concentrations of these compounds in Korean people from the age of 18 to 69 years by making use of the data from the Korean National Human Biomonitoring Survey that was completed in 2009. Of 1,865 representative Koreans, 63.4% and 97.9% were found to have concentrations of 2, 4-DCP and 2, 5-DCP > 0.05 μg/L (limit of detection) in their urine. The geometric mean urinary concentrations were 0.14 μg/L (confidence interval of 95% = 0.13–0.16) and 0.44 μg/L (confidence interval = 0.41–0.48), respectively. It was fond that the adjusted proportional changes in 2, 4-DCP concentrations were significantly associated with body mass index, whereas those of 2, 5-DCP concentrations were influenced by place of residence. From these findings, it is evident that most adults in Korea have levels of 2, 4-DCP and 2, 5-DCP that are detectable in their urine and burden of these compounds on their bodies varies depending on numerous demographic factors.

Although many attempts have been made to improve the efficacy of radiotherapy to treat cancer, radiation resistance is still an obstacle in lung cancer treatment. Oridonin is a natural compound with promising antitumor efficacy that can trigger cancer cell death; however, its direct cellular targets, efficacy as a radiosensitizer, and underlying mechanisms of activity remain unclear. Herein, we report that oridonin exhibits additive cytotoxic and antitumor activity with radiation using H460 non-small cell lung cancer cell lines. We assessed the radiosensitizing effect of oridonin by MTT, clonogenic, reactive oxygen species (ROS) production, DNA damage, and apoptosis assays. In vitro, oridonin enhanced the radiation-induced inhibition of cell growth and clonogenic survival. Oridonin also facilitated radiation-induced ROS production and DNA damage and enhanced apoptotic cell death. In vivo, the combination of oridonin and radiation effectively inhibited H460 xenograft tumor growth, with higher caspase-3 activation and H2A histone family member X (H2AX) phosphorylation compared with that of radiation alone. Our findings suggest that oridonin possesses a novel mechanism to enhance radiation therapeutic responses by increasing DNA damage and apoptosis. In conclusion, oridonin may be a novel small molecule to improve radiotherapy in non-small cell lung cancer.