Outdoor Air Pollution and Lung cancer

Outdoor air pollution and lung cancer

 

 

 

• According to the International Agency for Research on Cancer (IARC), certain substances are classified as carcinogenic to humans (Group 1).
• Particulate matter found in the air, including PM10 (particles with a diameter of 10 micrometers or less) and PM2.5 (particles with a diameter of 2.5 micrometers or less), is categorized as fine dust.
• Air pollutants, whether human-made or naturally occurring, can travel long distances and cross international borders, forming secondarily in the atmosphere rather than being directly emitted.
• Major sources of air pollution include emissions from power plants, industrial activities, agriculture, residential heating and cooking, and vehicles and transportation methods; these pollutants can lead to lung cancer.

■  Lung cancer

 

1.   Harvard 6 Cities study

A study was conducted on 8,111 white individuals aged 25 to 74 years from six cities in the eastern United States with varying levels of air pollution exposure. The purpose of the study was to assess the health effects of outdoor air pollution. The study commenced in each city between 1975 and 1977 and continued until 1991. Follow-up was maintained through postal codes, and data on deaths were collected until 2009. The results indicated epidemiological evidence linking exposure to sulfate and PM2.5 air pollution with lung cancer (1, 2). In the entire cohort studied up to 2009, it was confirmed that 4,495 individuals (7.8%) died from lung cancer. Additionally, it was found that with a 1-3 year moving average increase of 10 μg/㎥ in PM2.5, the comparative risk of developing lung cancer increased to 1.37 (95% CI: 1.07-1.75) (3).

 

2.   American Cancer Society study

The American Cancer Society (ACS) found a link between air pollution and lung cancer mortality. Studies spanning from 1982 involved 1.2 million adults, analyzing birth and health data before 1989 and death data post-1989. They discovered that for every 10μg/m³ increase in PM2.5, lung cancer risk increased by 8-11%. However, there was no observed link between other pollutants like ozone, SO2, NO2, and CO with lung cancer. Further research, including a 26-year study on non-smokers, confirmed the relationship between PM2.5 exposure and increased lung cancer mortality. Additional studies in California also supported these findings, incorporating satellite data for more accurate pollutant measurement (4).

 

3.   Trips; Trucking Industry Particle Study

The study aimed to examine the connection between occupational exposure to truck exhaust and lung cancer among workers in the trucking industry in the United States. It was a retrospective occupational cohort study involving men. The findings revealed that annual outdoor exposure to PM10, SO2, and NO2 was linked to increased mortality from lung cancer. The researches, conducted by Hart et al. in 2009 and 2011, demonstrated that in 2000, for every increase of 4μg/㎥ in PM2.5, there was a 1.02 times higher risk of lung cancer in the entire cohort, with a confidence interval of 95% (0.95-1.10). Excluding long-distance drivers, the risk increased to 1.07 times (95%CI, 0.97-1.17). Notable strengths of the study included the ability to control for occupational exposure and predict residential pollutant levels over time (5, 6).

 

4.   European cohort study

Beelen et al. carried out a prospective cohort study in the Netherlands involving over 120,000 participants. They explored the relationship between air pollution and lung cancer occurrence and mortality. Using various data sources, including GIS and actual measurement data for pollutants like PM2.5, NO2, and SO2, they estimated individual exposure levels. The study revealed a statistically significant association between PM2.5 concentration and lung cancer risk (8, 9).

Raaschou-Nielsen et al. conducted studies in Denmark, investigating the impact of NOx concentration on lung cancer risk. They found that higher NOx concentrations were associated with increased relative risks of lung cancer, with the risk rising as NOx concentration increased (10, 11).

The ESCAPE study (Raaschou-Nielsen et al., 2013) involved 17 European cohorts and examined the association between air pollution and lung cancer. They found that increased PM10 and PM2.5 concentrations were linked to higher relative risks of lung cancer, particularly in adenocarcinoma cases. However, no significant association was observed between lung cancer risk and exposure to NO2, NOx, or traffic indicators (12).

Cesaroni et al. investigated air pollution and lung cancer among residents of Rome, Italy. They observed that higher PM2.5 and NO2 concentrations were associated with increased relative risks of death from lung cancer. Analysis also revealed a significant trend of increasing risk with higher exposure levels (13).

 

■   References

(1)     Dockery, D. W., Pope, C. A., Xu, X., Spengler, J. D., Ware, J. H., Fay, M. E., . . .Speizer, F. E. (1993). An association between air pollution and mortality in six US cities. N Engl J Med, 329 (24), 1753-1759.

(2)     Laden, F., Schwartz, J., Speizer, F. E., & Dockery, D. W. (2006). Reduction in fine particulate air pollution and mortality: extended follow-up of the Harvard Six Cities study. Am J Respir Crit Care Med, 173 (6), 667-672.

(3)     Lepeule, J., Laden, F., Dockery, D., & Schwartz, J. (2012). Chronic exposure to fine particles and mortality: an extended follow-up of the Harvard Six Cities study from 1974 to 2009. Environ Health Perspect, 120(7), 965-970.

(4)     Krewski, D., Jerrett, M., Burnett, R. T., Ma, R., Hughes, E., Shi, Y., . . . Calle, E. E. (2009). Extended follow-up and spatial analysis of the American Cancer Society study linking particulate air pollution and mortality : Health Effects Institute Boston, MA.

(5)     Hart, J. E., Garshick, E., Dockery, D. W., Smith, T. J., Ryan, L., & Laden, F. (2011). Long-term ambient multipollutant exposures and mortality. Am J Respir Crit Care Med, 183 (1), 73-78.

(6)     Hart, J. E., Yanosky, J. D., Puett, R. C., Ryan, L., Dockery, D. W., Smith, T. J., . . . Laden, F. (2009). Spatial modeling of PM10 and NO2 in the continental United States, 1985–2000. Environ Health Perspect, 117 (11), 1690-1696.

(7)     Beelen, R., Hoek, G., van den Brandt, P. A., Goldbohm, R. A., Fischer, P., Schouten, L. J., . . . Brunekreef, B. (2008). Long-term exposure to traffic related air pollution and lung cancer risk. Epidemiology, 702-710.

(8)     Beelen, R., Hoek, G., van Den Brandt, P. A., Goldbohm, R. A., Fischer, P., Schouten, L. J., . . . Brunekreef, B. (2008). Long-term effects of traffic related air pollution on mortality in a Dutch cohort (NLCS-AIR study). Environ Health Perspect, 116(2), 196-202.

(9)     Raaschou-Nielsen, O., Andersen, Z. J., Hvidberg, M., Jensen, S. S., Ketzel, M., Sørensen, M., . . . Tjønneland, A. (2011). Lung cancer incidence and long-term exposure to air pollution from traffic. Environ Health Perspect, 119 (6), 860-865.

(10)  Raaschou-Nielsen, O., Bak, H., Sørensen, M., Jensen, S. S., Ketzel, M., Hvidberg, M., . . . Loft, S. (2010). Air pollution from traffic and risk for lung cancer in three Danish cohorts. Cancer Epidemiol Biomarkers Prev, 19 (5), 1284-1291.

(11)  Raaschou-Nielsen, O., Andersen, Z. J., Beelen, R., Samoli, E., Stafoggia, M., Weinmayr, G., . . . Brunekreef, B. (2013). Air pollution and lung cancer incidence in 17 European cohorts: prospective analyses from the European Study of Cohorts for Air Pollution Effects (ESCAPE). The lancet oncology,

(12)  Cesaroni, G., Badaloni, C., Gariazzo, C., Stafoggia, M., Sozzi, R., Davoli, M., & Forastiere, F. (2013). Long-term exposure to urban air pollution and mortality in a cohort of more than a million adults in Rome. Environ Health Perspect, 121(3), 324-331.

(13)  Pedersen, D. U., Durant, J. L., Penman, B. W., Crespi, C. L., Hemond, H. F., Lafleur, A. L., & Cass, G. R. (2004). Human-cell mutagens in respirable airborne particles in the northeastern United States. 1. Mutagenicity of fractionated samples. Environ Sci Technol, 38 (3), 682-689.