Abstract
Particulate matter may comprise toxic trace elements with carcinogenic effects. Of these trace elements, Cadmium (Cd), Chromium (Cr), Arsenic (As), Beryllium (Be) and Nickel (Ni) are classified as probable human carcinogens. During the annual Hajj pilgrimage, 2.3 million pilgrims stay in Makkah, Saudi Arabia; the increased vehicle traffic contributes to elevated concentrations of particulate matter. We aimed to determine the excess cancer risk (ECR) associated with inhalation exposure in the Makkah population. This study was conducted in the Arafat area, which is a highly-crowded area during Hajj. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for trace element analysis. ECR resulting from inhalation exposure to each metal was calculated in accordance with the unit risk suggested by the Integrated Risk Information System. In summer, including Hajj, mean Cd, Cr, As, Be, and Ni atmospheric concentrations were 0.098, 0.008, 0.26, 0.03, and 0.012 μg/m3, respectively; in autumn, values were 0.06, 0.006, 0.16, 0.002, and 0.01 μg/m3, respectively. ECRs were 1.08 × 10𕒸, 7.21 × 10𕒸, 4.0 × 10𕒺, 4.6 × 10𕒺, and 2.4 × 10𕒺, respectively, exceeding the acceptable inhalation risk level (1.0 × 10𕒺) set by the US Environmental Protection Agency for each element. Higher atmospheric trace element concentrations in summer were due to high temperatures that increased atmospheric turbulence, leading to a greater amount of re-suspended dust from roads and blowing sand particles. These findings can be used by relevant authorities while developing regulations and strategies for developing air quality management to improve the health of pilgrims; however, larger prospective studies are required to estimate ECR in different seasons.
Highlights
Since the metals can exist in a particle form, they can contribute to particulate matter (PM) levels or react with gases in the atmosphere to form pollutant compounds [1]
During the annual Hajj pilgrimage, 2.3 million pilgrims stay in Makkah, Saudi Arabia; the increased vehicle traffic contributes to elevated concentrations of particulate matter
PM10 concentrations in the Arafat area increased during the pilgrimage period in summer owing to the high increase in pollution problems due to transportation, resulting in an unspecified amount of trace elements causing air pollution
Summary
Since the metals can exist in a particle form, they can contribute to particulate matter (PM) levels or react with gases in the atmosphere to form pollutant compounds [1]. USEPA estimated that, if a person were to continuously breathe air containing Cd at a concentration of 0.0006 μg/m3 (6 × 10−7 mg/m3) throughout his or her lifetime, he or she would theoretically have less than one in a million risk of cancer development due to Cd inhalation. Those continuously breathing air containing 0.06 μg/m3 (6 × 10−5 mg/m3) Cd would have an approximately one in 10,000 risk of cancer development due to Cd inhalation [8]
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