Relationship between high incidence of lung cancer among non-smoking women and silica in C1 bituminous coal in Xuanwei, Yunnan Province, China / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To measure the content of silica in C1 bituminous coal and its combustion products in the high-incidence area of lung cancer in Xuanwei, Yunnan Province, China and to investigate the relationship between high incidence of lung cancer among non-smoking women and silica produced naturally in C1 bituminous coal in Xuan Wei.</p><p><b>METHODS</b>The C1 bituminous coal widely used in the high-incidence area of lung cancer in Xuanwei was selected as experiment group, while the C2+1, K7, and M30 bituminous coal that was mined and used in the low-incidence area of lung cancer in Xuanwei for more than 10 years were selected as control group. Fourteen paraffin-embedded cancer tissue samples from the non-smoking women with non-small cell lung cancer who were born in Xuanwei and were at least the 3rd generation of the family living there were collected from the department of pathology, the third affiliated hospital of kunming medical university (tumor hospital of yunnan province). Titrimetric potassium silicofluoride method was used to measure the content of silica in raw coal and its bottom ashes in 20 samples from the experimental group and control group. Scanning electron microscopy (SEM) was used to observe the morphology of silica particles in C1 bituminous coal and its bottom ashes, and scanning electron microscopy coupled with energy dispersive X-ray analyzer (SEM-EDX) was used to analyze the microscopic composition. Transmission electron microscope (TEM) was used to observe the morphology of silica particles in the bottom ashes and coal soot of C1 bituminous coal as well as the lung cancer tissue from the non-smoking women in Xuanwei, and transmission electron microscope coupled with energy dispersive X-ray analyzer (TEM-EDX) was used to analyze the microscopic composition. The silica particles were separated from the coal soot and bottom ashes and characterized by physical method.</p><p><b>RESULTS</b>The silica content in C1 bituminous coal and its bottom ashes was significantly higher than that in C2+1, K7, and M30 bituminous coal (P < 0.05). The bottom ashes of C1 bituminous coal contained a large quantity of silica particles, mostly with microscale sizes. Silica particles were found in the soot of C1 bituminous coal and the lung cancer tissue from non-smoking women in Xuanwei. The silica particles in the bottom ashes were mostly 120 ∼ 500 nm in diameter, had various shapes, and contained such elements as iron, aluminium, calcium, and potassium; the silica particles in the coal soot were mostly nanoscale, ranging from 37 nm to 80 nm in diameter, had various shapes, with some in fibrous form, had non smooth surfaces, and contained such elements as iron, potassium, calcium, aluminium, and sulfur.</p><p><b>CONCLUSION</b>In Xuanwei, the incidence of lung cancer among non-smoking women is high in the area where silica-rich C1 bituminous coal is produced. There are silica particles enriched in both the combustion products (coal soot and bottom ashes) of C1 bituminous coal and the cancer tissue from the non-smoking women with non-small cell lung cancer, with similar morphology and microscopic composition. We hypothesize that the silica particles from combusted C1 bituminous coal in Xuanwei are mixed with indoor air and inhaled along with other suspended particles.</p>

The impact of temperature on cardiovascular disease deaths in 4 cities, China: a time-series study / 中华流行病学杂志

Objective To estimate the effects of temperature on cardiovascular disease (CVD) deaths in 4 cities-Kunming,Changsha,Guangzhou and Zhuhai,from southern part of China.Methods Daily CVD deaths,meteorological and air pollution data were used to explore the association between temperature and mortality.Distributed lag non-linear model was fitted for each city to access the delayed and cumulative effects of low,median and high temperature on CVD deaths.Cold and hot effects of temperature on CVD deaths were then accessed,based on the linear threshold model.Results The city-specific exposure-response functions appeared to be non-linear.Temperatures that associated with the lowest mortality for Changsha,Kunming,Guangzhou and Zhuhai were 22.0 ℃,20.0 ℃,26.0 ℃,and 25.5 ℃.The greatest cumulative RRs (95％CI) for CVD deaths of low temperature during the delayed period of the study in the 4 cities were 1.858 (1.089-3.170),1.537 (1.306-1.809),2.121 (1.771-2.540) and 1.934 (1.469-2.548),while 1.100 (0.816-1.483),1.061 (0.956-1.177),1.134 (1.047-1.230) and 1.259 (1.104-1.436) for high temperatures in Changsha,Kunming,Guangzhou and Zhuhai respectively.The hot effect was greater than the cold effect on the current days.The hot effect was restricted to the first week,whereas the cold effect increased over the lag days,and then last for 3-4 weeks.Conclusion The city-specific exposure-response functions appeared to be non-linear.Both high and cold temperatures were associated with increased CVD deaths,but the impact of low temperature was more notable.Cold effect was delayed by several days but last for a longer period than the hot effect did.