Environmental asbestos exposure in rural Turkey and risk of lung cancer

Our plain-English summary of Environmental asbestos exposure in rural Turkey and risk of lung cancer, by S. Metintas, M. Metintas, G. Ak, et al (International Journal of Environmental Health Research, 2012).

The study

• Authors: S. Metintas, M. Metintas, G. Ak, C. Kalyoncu
• Journal: International Journal of Environmental Health Research
• Published: 2012;22(5):468-79
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of this study was to determine the risk of lung cancer in a cohort of villagers with environmental asbestos exposure. The study was carried out as a field-based epidemiological study. Information from 3143 individuals in 15 asbestos exposed villages and 2175 individuals in 12 control villages was obtained. Asbestos fiber type to which villagers were exposed mainly was tremolite or tremolite, actinolite, chrysotile mixtures. The cumulative fiber count of the villagers during their lifespan ranged from 0.19 to 4.61 fiber-years/ml. The annual average incidence ratio of lung cancer was 135.21/100,000 persons/year in men and 47.28 in women in the asbestos exposed villages. For the control villages, this ratio was 60.15/100,000 person/year in men and 15.06 in women. Being a male, advanced age, smoking and asbestos exposure were established to increase the risk of lung cancer. Environmental asbestos exposure in rural area is a risk factor for lung cancer independent of smoking.

In plain English

This field-based epidemiological study looked at lung cancer among farming villagers in rural Eskisehir, Turkey, where the white soil villagers used contained asbestos. The authors compared 3143 people in 15 asbestos-exposed villages with 2175 people in 12 control villages, counting cases from 1994 to 2004. The asbestos was mainly tremolite or mixtures of tremolite, actinolite and chrysotile. There were 24 lung cancer cases in men and 8 in women in the asbestos villages, against 9 and 2 in the control villages. Standardized average yearly lung cancer rates per 100,000 were 135.21 (95% confidence interval 116.78 to 153.64) for men and 47.28 (36.38 to 58.18) for women in the asbestos villages, and 60.15 (47.86 to 72.44) and 15.06 (8.91 to 21.21) in control villages. In a model also including smoking, age and sex, asbestos exposure had a hazard ratio of 2.305 (95% confidence interval 1.125 to 4.722). The authors concluded that environmental asbestos exposure in rural areas is a risk factor for lung cancer independent of smoking. They did not study second-hand smoke, which they said may affect the relationship.

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: Field-based epidemiological cohort study comparing asbestos-exposed and control villages, with person-years counted for 1994 to 2004 and a Cox proportional hazards model
• Who was studied: 3143 individuals from 1011 households in 15 asbestos-exposed villages and 2175 individuals from 700 households in 12 control villages in the Eskisehir region of Turkey. All villagers were farmers. Follow-up covered 1994 to 2004.
• Exposure: Environmental exposure to asbestos in the white soil used by villagers, for example white-washed house walls. The fibers were mainly tremolite or tremolite, actinolite and chrysotile mixtures, with a lower rate of anthophyllite and chrysotile mixtures. The authors found no occupational asbestos exposure in the study population.
• Main results:
  • Measured air fiber concentrations in the asbestos villages: indoor 0.009 to 0.28 fibers/ml (mean 0.089 f/ml); outdoor 0.009 to 0.04 fibers/ml (mean 0.012 fibers/ml).
  • Mean calculated cumulative exposure in the asbestos villages: 4.0 fiber-years/ml for women (median exposure duration 52 years) and 2.7 fiber-years/ml for men (median exposure duration 55 years).
  • Lung cancer cases: 24 men and 8 women in the asbestos villages; 9 men and 2 women in the control villages.
  • Standardized average annual lung cancer incidence rates per 100,000. Asbestos villages: men 135.21 (95% CI 116.78 to 153.64), women 47.28 (95% CI 36.38 to 58.18). Control villages: men 60.15 (95% CI 47.86 to 72.44), women 15.06 (95% CI 8.91 to 21.21).
  • Lung cancer standardized incidence ratios for residents of the asbestos villages: men, 24 observed against 13.18 expected, SIR 1.82 (95% CI 1.42 to 2.22); women, 8 observed against 2.80 expected, SIR 2.86, with a printed 95% CI of 1.43 to 2.00.
  • Lung cancer standardized incidence ratios (based on Izmir Cancer Registry data) for asbestos-exposed non-smoking men: 9 observed against 1.31 expected, SIR 6.87 (95% CI 3.58 to 13.20).
  • Lung cancer standardized incidence ratios for asbestos-exposed non-smoking women: 8 observed against 0.2 expected, SIR 40.0 (95% CI 20.08 to 79.75). There were no smokers among the women.
  • Smoking rate: 30% in the asbestos villages and 33% in the control villages.
  • In the Cox regression model, asbestos exposure had a hazard ratio for lung cancer of 2.305 (95% CI 1.125 to 4.722, p = 0.022). Being male, advanced age and smoking history were also found to increase risk.
• The authors' conclusion: The authors concluded that environmental asbestos exposure in rural areas is a risk factor for lung cancer independent of smoking.
• Limitations the authors state:
  • The authors did not investigate second-hand smoke. They noted that passive smoking may affect the relationship between asbestos exposure and lung cancer in this cohort, because many men smoke at home around non-smoking family members.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Lung Cancer, Tremolite, Actinolite, Chrysotile, Fiber Year.

Related studies

• Malignant mesothelioma due to environmental exposure to asbestos: follow-up of a Turkish cohort living in a rural area — S. Metintas, M. Metintas, et al. (2002)
• Nonmalignant pleural lesions due to environmental exposure to asbestos: a field-based, cross-sectional study — M. Metintas, S. Metintas, et al. (2005)
• Turkey National Mesothelioma Surveillance and Environmental Asbestos Exposure Control Program — S. Metintaş, H.F. Batırel, et al. (2017)
• Determination of environmental exposure to asbestos (tremolite) and mesothelioma risks in the southeastern region of Turkey — A. Senyigit, A. Dalgic, et al. (2004)
• Malignant pleural mesothelioma caused by environmental exposure to asbestos or erionite in rural Turkey: CT findings in 84 patients — A.A. Sahin, L. Cöplü, et al. (1993)
• Is risk of pleural mesothelioma an environmental risk outside Turkey? A study on immigrants to Sweden — S.M. Mousavi, J. Sundquist, et al. (2010)

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