This study focuses on exposures of metal constituents of particulate matter (PM) in the ambient air sample collected at Indian Institute of Technology Delhi (IIT Delhi), India, which might lead to occurrence of non-cancerous events and cancer events. A step-wise construction of risk assessment framework for estimating risks due to exposures of PM_2.5 presented. Samples from winter and pre-monsoon seasons of Delhi region (28.5450°N, 77.1926°E) (duration 1: December 2013–February 2014; duration 2: March 2014–May 14) were collected. More than 12 samples were collected using PM_2.5 sampler on an 8-h basis and analysed gravimetrically for determining mass content and chemically for determining metal content of PM_2.5. Twenty-eight metals in samples were detected using Energy Dispersive X-Ray Fluorescence (ED-XRF). Using these values, health risks of hypotheticals exposures of PM_2.5 in ambient air samples were estimated either in terms of hazard quotient (i.e. ratio of daily inhaled dose to daily acceptable dose) for exposures of non-carcinogenic metals or lifetime excess risk of cancer for exposures of carcinogenic metals. Dose–response information of different metals was taken from the U.S. EPA IRIS database. Among metals, S content was highest followed by Cl, Si, K, Ca and Fe, Zn and Pb. High S can be attributed to vehicular emission or particles generated from abrasion of tyres of vehicles. High contents of Si, Ca, Fe in PM samples may be contributed from resuspension road dust, while source of K may be local biomass burning for space heating in winter. Zn comes from vehicle and coal burning probably used by local residents for space heating. Chlorine used in lubricants and diesel fuel could be a source of high Cl content in samples collected in the present work. Small traces of Pb in samples might be coming from brake and tyre wear or resuspension of road dust contaminated with lead used earlier in diesel and/or petrol to improve combustion. Estimates of potential risk due to hypothetical exposure of adults and children to four carcinogenic metals of PM_2.5 were found to be more than 1/10,000,000, indicating chance of cancer risks. Among metals, exposures to PM-associated Cd resulted in consistent cancerous risk in both seasons, whereas exposures to PM-associated Cr resulted in HQ value > 1 indicating chance of non-carcinogenic risks.

中文翻译：

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德里冬季和季风前季节PM 2.5微量元素的非致癌和致癌风险评估：一个案例研究

这项研究的重点是印度德里印度理工学院（IIT Delhi）收集的周围空气样本中颗粒物质（PM）的金属成分的暴露，这可能导致非癌性事件和癌症事件的发生。提出了逐步评估的风险评估框架，以评估由于暴露于PM _2.5而造成的风险。收集了德里地区冬季和季风前季节（28.5450°N，77.1926°E）（持续时间1：2013年12月至2014年2月；持续时间2：2014年3月至5月14日）的样本。使用PM _2.5采样器在8小时内收集了12个以上的样品，并进行了重量分析，以确定质量含量，化学分析了PM _2.5中的金属含量。使用能量色散X射线荧光（ED-XRF）检测了样品中的28种金属。使用这些值，假设的PM _2.5暴露会给健康带来风险根据非致癌金属暴露的危险商（即每日吸入剂量与每日可接受剂量之比）或暴露于致癌金属的终生癌症风险，估算环境空气中的样品。不同金属的剂量反应信息来自美国EPA IRIS数据库。在金属中，S含量最高，其次是Cl，Si，K，Ca和Fe，Zn和Pb。高S可归因于车辆排放或由于车辆轮胎的磨损产生的颗粒。悬浮道路粉尘可能导致PM样品中高含量的Si，Ca，Fe，而K的来源可能是局部生物质燃烧，以供冬季空间加热。锌来自车辆和燃煤，当地居民可能将其用于空间供暖。润滑剂和柴油中使用的氯可能是本工作中收集的样品中高Cl含量的来源。样品中的痕量Pb可能来自刹车和轮胎磨损，或者是道路路面灰尘的再悬浮，该道路灰尘早先被柴油和/或汽油中使用以改善燃烧效果。假定成人和儿童暴露于四种PM致癌金属的潜在风险估计_2.5被发现超过1 / 10,000,000，表明有患癌风险的机会。在金属中，在两个季节中，与PM相关的Cd接触均导致一致的癌变风险，而与PM相关的Cr接触则导致HQ值> 1，表明存在非致癌风险。