Occupational and environmental cancer incidence and mortality in China

Our plain-English summary of Occupational and environmental cancer incidence and mortality in China, by P. Li, S.S. Deng, J.B. Wang, et al (Occupational Medicine, 2012).

The study

• Authors: P. Li, S.S. Deng, J.B. Wang, A. Iwata, Y.L. Qiao, X.B. Dai, P. Boffetta
• Journal: Occupational Medicine
• Published: 2012;62(4):281-7
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Most cancers are due to environmental, occupational or other non-genetic factors and are potentially preventable.

Aims: To provide an evidence-based assessment of the burden of occupational and environmental-related cancers in China in 2005.

Methods: The population attributable fraction (PAF) was calculated based on the assumption of no occupational agent exposure. Relative risk estimates for specific cancers of interest and prevalence of exposure were mainly derived from large-scale studies. Data on cancer incidence and mortality was obtained from the Third National Death Cause Survey and cancer registries in China.

Results: We estimated that a total of 48,511 deaths of cancer were attributable to occupational agents in China in 2005, with 34,975 among men (3.1% of all cancer deaths) and 13,536 among women (2.1%). A total of 59,410 incident cases of cancer were attributable to occupational agents in China in 2005, with 42,724 among men (2.8% of all cancer incident cases) and 16,686 among women (1.6%). The highest PAF was observed for mesothelioma with asbestos, followed by leukaemia, bladder and lung cancers. Indoor radon was responsible for 0.2% of lung cancer-related deaths among men and women.

Conclusions: Occupational agents represent an important cause of cancer, but indoor radon plays a relatively limited role in cancer causes in China. Our report provides strong evidence of the need for policy makers to develop strategies to reduce the risk of occupational cancers.

In plain English

This study estimated how much cancer in China in 2005 could be attributed to workplace agents and to indoor radon. The authors did not study any workers directly. They combined relative risks from published studies with estimates of how many people were exposed, mainly from a 1985 national industrial census. They applied these figures to national cancer death data from the Third National Death Cause Survey, and estimated new cases from the death data. Asbestos exposure was estimated from asbestos mines and factories, using a relative risk of 182.30 for mesothelioma and 5.60 for lung cancer. The authors estimated that occupational agents accounted for 34 975 cancer deaths among men (3.1% of all cancer deaths) and 13 536 among women (2.1%). Asbestos accounted for an estimated 18.6% of mesothelioma among men and 18.8% among women, the highest fraction for any cancer. It accounted for 0.6% of lung cancer in each sex. Indoor radon accounted for 0.2% of lung cancer deaths. The authors noted that asbestos exposure might be underestimated. They concluded that strategies to reduce occupational cancer risk are needed.

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: Population attributable fraction (burden) estimate. Published relative risks were combined with exposure prevalence using Levin's formula; no new data were collected on individuals.
• Who was studied: The population of China in 2005. Cancer deaths came from the Third National Death Cause Survey (160 randomly selected counties and 53 cancer high-risk areas, 2004 to 2005; 193 841 cancer deaths). Incidence was estimated with a mortality-to-incidence ratio from 32 cancer registries.
• Exposure: Occupational agents: asbestos (lung cancer and mesothelioma), benzidine, benzene, arsenic, chromate, silica, coke oven emissions, wood and leather dust, and the rubber industry. The environmental exposure was indoor radon over 100 Bq/m3. Asbestos exposure was estimated from asbestos mines and factories, with prevalence taken as 0.1% for men and women. The relative risk used was 182.30 for mesothelioma. For lung cancer it was 5.60, the factory figure; mines had a relative risk of 13.96, which was not used nationally.
• Main results:
  • Occupational agents were estimated to account for 34 975 cancer deaths among men (3.1% of all cancer deaths) and 13 536 among women (2.1%), a total of 48 511.
  • Occupational agents were estimated to account for 42 724 new cancer cases among men (2.8% of all cancer cases) and 16 686 among women (1.6%), a total of 59 410.
  • Asbestos was estimated to account for 18.6% of mesothelioma among men (133 new cases, 126 deaths) and 18.8% among women (126 new cases, 94 deaths). This was the highest attributable fraction observed.
  • Asbestos was estimated to account for 0.6% of lung cancer in both men (1867 new cases, 1629 deaths) and women (901 new cases, 780 deaths).
  • Asbestos, arsenic, chromate, silica and coke oven emissions together were estimated to account for 10.6% of male and 7.0% of female lung cancer deaths.
  • Indoor radon was estimated to account for 0.2% of lung cancer deaths among men and among women.
• The authors' conclusion: The authors concluded that occupational agents are an important cause of cancer in China and indoor radon a relatively limited one. They said their report shows a need for policy makers to develop strategies to reduce the risk of occupational cancers.
• Limitations the authors state:
  • The prevalence of exposure to some agents, including asbestos, might be underestimated.
  • Some occupational and para-occupational sources of asbestos exposure were not included, because national data were not available.
  • No information was available on duration and intensity of work, local control measures, or personal protective equipment.
  • Relative risks from men or both sexes were applied to women.
  • Some risk estimates may not have been adjusted for confounders such as age and smoking.
  • Other occupational agents were excluded, which may make the overall burden estimate conservative.

Topics

Medical terms in this study, explained in our Lexicon: Population Attributable Fraction (PAF), Relative Risk, Mesothelioma, Lung Cancer.

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