Lung Cancer and Pleural Mesothelioma Risk Assessment for the General Population Exposed to Asbestos in Different Regions of Tehran, Iran

Our plain-English summary of Lung Cancer and Pleural Mesothelioma Risk Assessment for the General Population Exposed to Asbestos in Different Regions of Tehran, Iran, by N. Nasirzadeh, Z. Soltanpour, Y. Mohammadian, et al (Journal of Research in Health Sciences, 2022).

The study

• Authors: N. Nasirzadeh, Z. Soltanpour, Y. Mohammadian, B. Pourhasan
• Journal: Journal of Research in Health Sciences
• Published: 2022;22(4):e00563
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Asbestos is a natural fiber leading to health risks like chronic lung diseases. The current study aimed to estimate pleural mesothelioma and lung cancer risk for population exposure to asbestos in Tehran, Iran.

Study Design: A cross-sectional study.

Methods: According to the annual report of Air Quality Control Company (AQCC), from 2011-2020, carcinogenic risk and mesothelioma were assessed based on the Environmental Protection Agency (EPA) method using the Monte Carlo simulation (MCS). The relative risk (RR) of mortality cancer was calculated based on Camus and colleagues' model. Moreover, mesothelioma risk was estimated by Bourgault and colleagues' model.

Results: The mean concentration and health risk of asbestos in ambient air generally reduced from 2011 to 2020. The highest mortality risk for lung cancer was 8.4 per 100000 persons in 2011 and reduced to 1.8 in 2017. For mesothelioma, the corresponding values were 8.96 per 100000 persons in 2011 and reduced to 1.92 in 2017.

Conclusion: The findings of this study could be helpful to health policymakers in the management of asbestos risk.

© 2022 The Author(s); Published by Hamadan University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In plain English

This study did not count actual cases of disease. It used air-monitoring results to estimate cancer risk for the general population of Tehran, Iran. The authors took yearly average outdoor asbestos fiber concentrations for 2011 to 2020 from the Tehran Air Quality Control Company. They applied an EPA method with Monte Carlo simulation and published potency factors: Bourgault and colleagues' for lung cancer and, for mesothelioma, an amphibole factor based on Berman and Crump's data. Chrysotile, tremolite and actinolite were reported as the main fibers in Tehran air. Mean concentrations were higher than a WHO-recommended level and generally fell over the period, with an unexpected increase in 2016. The best-estimate lifetime lung cancer mortality risk was 8.4 per 100 000 persons in 2011 and 1.8 in 2017. For mesothelioma the figures were 8.96 and 1.92 per 100 000. The authors concluded that these risks exceeded the health threshold, although they had fallen in recent years. They noted that the data relied on phase contrast microscopy, and that genetics, food and smoking also affect cancer.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Quantitative health risk assessment using existing yearly air-monitoring data and published risk models. These were an EPA method with Monte Carlo simulation, lung cancer potency factors from Bourgault and colleagues, and a mesothelioma potency factor for amphibole fibers based on Berman and Crump's data. The authors describe it as a cross-sectional study. No people were examined or followed.
• Who was studied: The general population of Tehran, Iran, modeled from outdoor air-monitoring results for different regions of the city, 2011 to 2020
• Exposure: Asbestos fibers in outdoor (ambient) air of Tehran, sampled by the Air Quality Control Company and analysed by NIOSH 7400. Chrysotile, tremolite and actinolite were reported as the main fibers. For mesothelioma the authors used a potency factor for amphibole fibers based on Berman and Crump's data. The exposure assumptions were 24 hours a day, 180 days a year and 24 years for adults, with cumulative exposure calculated over 50 years.
• Main results:
  • The mean concentration of asbestos in Tehran ambient air was higher than the WHO-recommended standard of 5 × 10−5 PCM f/mL
  • In general, mean asbestos concentration fell from 2011 to 2020, with an unexpected increase in 2016. Table 1 shows 0.0065 f/mL in 2011 and 0.0014 f/mL in 2017.
  • The text states that the mean carcinogenic risk was between 1.26E-4 and 9.55E-5, and that cancer risk was at a considerable level in 2011 and 2012. Table 1 lists 2.41E-4 for 2011 and 5.08E-5 for 2017.
  • Predicted lifetime lung cancer mortality risk (best estimate) was highest at 8.4 per 100 000 persons in 2011 and fell to 1.8 per 100 000 in 2017. Table 1 gives upper-bound values of 30.8 and 6.6.
  • Predicted lifetime mesothelioma mortality risk (best estimate) was 8.96 per 100 000 persons in 2011 and fell to 1.92 per 100 000 in 2017. Table 2 gives upper-bound values of 27.70 and 5.90.
• The authors' conclusion: The authors concluded that mean asbestos concentration was higher than the WHO standard and that carcinogenic risk was at a considerable level in 2011 and 2012. They found that the lifetime mortality risk for lung cancer and mesothelioma exceeded the health threshold, although risk decreased in recent years as concentrations fell. They said the findings could help health policymakers manage asbestos risk.
• Limitations the authors state:
  • The risk assessment relied only on the data available from the Air Quality Control Company
  • The company's phase contrast microscopy (PCM) analysis cannot exactly show what effect the asbestos ban had on urban concentrations
  • Cancers such as mesothelioma depend on other factors besides asbestos concentration, such as genetics, food and smoking
  • Mesothelioma risk estimates depend on the chosen potency factor and may differ between studies. The authors could not compare their mesothelioma results with similar studies.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Pleural Mesothelioma, Carcinogenic, Mesothelioma, Relative Risk.

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