Atmospheric and Environmental Chemistry Laboratory, Chemistry Division, Atomic Energy Centre, P.O. Box 164, Dhaka 1000, Bangladesh.
Department of Chemistry, University of Dhaka, Bangladesh; Department of Microbiology, Stamford University Bangladesh, Dhaka, Bangladesh.
Sci Total Environ. 2019 Apr 10;660:1610-1622. doi: 10.1016/j.scitotenv.2018.12.425. Epub 2019 Jan 2.
Contaminants in road dusts can directly pose significant human health risks through oral ingestion, particle inhalation, and dermal contact. Therefore, this study has been designed to analyze heavy metal contaminations in 88 street dusts collected from the 22 high traffic sites and industrial areas of the Southeast Asian Megacity: Dhaka (capital of Bangladesh) using energy dispersive X-ray fluorescence (EDXRF) spectroscopy. This study revealed that the maximum Pb, Cd, Zn, Cr, Ni, As, Mn and Cu contents in the street dust samples were 18.9, 11.6, 239.2, 144.3, 37.1, 8.1, 261.5 and 49.6 mg/ kg respectively in which Ni and Pb concentration were 2 times, and Cd concentration was 200 times higher than the background level in soil; and As concentration was slightly higher than soil background level. The spatial distribution of heavy metal concentrations in street dust samples in Dhaka City was revealed that the hot spot areas of Pb, Ni, Cd and As were mainly associated with heavy traffic and industrial activities. The risk assessment strategies were used for this study for identifying the routes of exposure through oral ingestion, inhalation, and dermal contact by the fine particles (~75 μm) of street dust, especially for children based on the US EPA health risk models. Both non-carcinogenic and carcinogenic risks of heavy metals were characterized in street dust samples. Results based on the hazard index (HI), in the case of non-cancer effect, the ingestion of dust particles of children and adults in Dhaka City appeared to be the route of exposure to street dust that results in a higher risk for heavy metals, followed by dermal contact. This study revealed that the inhalation of re-suspended particles through mouth and nose were almost negligible. It was also noticed that children were experiencing the potential health risk due to HI for Cr (1.04), which was slightly higher than the safe level 1, and Cd (0.69) was close to the safe level 1. Reversely, cancer risk for Cr (i.e. 4.27 × 10) was fallen within the range of threshold values (10 to 10) and As (i.e. 9.59 × 10) was close to the upper limit of threshold values (10 to 10).
道路尘埃中的污染物可通过口服摄入、吸入颗粒物和皮肤接触直接对人体健康造成重大风险。因此，本研究设计从孟加拉国首都达卡的 22 个交通繁忙地点和工业区采集 88 个街道灰尘样本，使用能量色散 X 射线荧光（EDXRF）光谱法分析重金属污染。研究表明，街道灰尘样本中 Pb、Cd、Zn、Cr、Ni、As、Mn 和 Cu 的最大含量分别为 18.9、11.6、239.2、144.3、37.1、8.1、261.5 和 49.6mg/kg，其中 Ni 和 Pb 的浓度分别是土壤背景值的两倍，而 Cd 的浓度则是土壤背景值的 200 倍；As 的浓度略高于土壤背景值。研究揭示了达卡市街道灰尘中重金属浓度的空间分布，表明 Pb、Ni、Cd 和 As 的热点区域主要与交通和工业活动有关。本研究采用风险评估策略，通过街道灰尘的细颗粒（~75μm），特别是儿童通过口服摄入、吸入和皮肤接触的暴露途径，根据美国环保署健康风险模型，识别风险。研究对街道灰尘样本进行了非致癌和致癌风险评估。基于危害指数（HI）的结果，在非致癌效应的情况下，摄入达卡市儿童和成人的灰尘颗粒似乎是暴露于街道灰尘的途径，这导致重金属的风险更高，其次是皮肤接触。研究表明，通过口腔和鼻腔吸入再悬浮颗粒的可能性几乎可以忽略不计。还注意到，由于 HI 值，儿童 Cr（1.04）面临潜在健康风险，略高于安全水平 1，而 Cd（0.69）接近安全水平 1。相反，Cr 的癌症风险（即 4.27×10）在阈值范围（10 到 10）内，As（即 9.59×10）接近阈值上限（10 到 10）。
