乌鲁木齐大气PM2.5对质粒DNA的损伤研究

2012年1月~2012年12月采集乌鲁木齐大气PM2.5样品,使用质粒DNA评价法研究了不同季节PM2.5的氧化能力,并进行氧化性毒性与相应气象因素和质量浓度之间的相关性研究.结果表明,乌鲁木齐大气PM2.5的质量浓度具有冬季最高,春季和秋季次之,夏季最低的季节性变化特征;PM2.5全样和水溶部分氧化能力的季节差异较大,对质粒DNA的氧化性损伤具有冬季最大,春季和夏季之次,秋季最低.冬、春、夏、秋季大气PM2.5全样的TD30(PM2.5对质粒DNA造成破坏达到30%所需要的颗粒物的剂量)平均值分别为440,491,503,515μg/mL,水溶部分分别为474,721,666,600μg/mL.绝大部分PM2.5样品全样的TD30值均小于水溶部分样,表明全样的毒性大于相应的水溶部分样.全样TD30值与平均温度显著(P<0.05)正相关,表明寒冷的天气/季节可能造成PM2.5的高毒性.水溶样TD30值与风速显著(P<0.01)正相关,与相对湿度显著负相关.这表明,高的风速和低的相对湿度可能跟较低和较高的PM2.5的毒性有关.PM2.5氧化性损伤能力的大小与其质量浓度之间的相关性不明显,表明仅以颗粒物的质量浓度来评价大气颗粒物氧化性损伤能力大小的方法并不能真实地反映其对人体健康的危害程度,起决定作用的还是颗粒物的化学组成及其表面吸附的有害成分.

A toxicological assessment of PM2.5 in Urumqi based on plasmid DNA assay

An in vitro plasmid DNA assay was employed to study the oxidative capacity of PM2.5 collected in Urumqi during January 2012 to December 2012, and the correlation between the toxicity represented by oxidative capacity and the corresponding environmental factors and mass concentrations were investigated. The result showed that, the mass concentrations of atmospheric PM2.5 in Urumqi with the values of oxidative damage to DNA had seasonal variation, characterized by a highest in winter, moderately high in spring and autumn, the lowest in summer. The oxidative capacity of whole and water soluble fraction of PM2.5 in different seasons varied greatly, with the values of oxidative damage to DNA being highest in winter, followed by summer, spring, and autumn in descending order. The average TD30 values (toxic dosages of PM2.5 causing 30% of plasmid DNA damage) of whole solution of PM2.5 in winter, spring, summer and autumn were 440, 491, 503and515μg/mL, respectively, and the average TD30 values of corresponding water-soluble fraction were 474, 721, 666 and 600μg/mL, respectively. The TD30 values of the whole solution were mostly less than the water-soluble fraction,indicating that the toxicity of whole particles were higher than their corresponding water-soluble fractions. The TD30 value of whole fraction showed a notable (P<0.05) positive correlation with average temperature, implying that the cold weather/season may facilitate a higher toxicity of PM2.5. the TD30value of water-soluble fraction showed a notable (P<0.01) positive correlation with wind speed, and a notable (P<0.01) negative correlation with the relative humidity. This demonstrated that the higher wind speed and lower relative humidity may be associated with a lower higher toxicity of PM2.5. Further analysis showed no obvious correlation between the TD30 value and mass concentrations of PM2.5, showing that the method of evaluating the health impact of atmospheric particulate matter only by the mass concentration did not truly reflect its degree of harm to human health, and the chemical composition of particulate matter and its harmful components of surface adsorption should be considered.