Increased air pollution has been related to an increase in incidences of lung adenocarcinoma (LADC) worldwide, according to an international team of experts led by Nanyang Technological University, Singapore (NTU Singapore). The same study found that a reduction in global cigarette consumption is statistically connected to a reduction in lung squamous cell carcinoma people (LSCC).
Lung adenocarcinoma is a cancer type in which research strongly implies that hereditary, environmental, and lifestyle factors play a role, whereas lung squamous cell carcinoma is frequently connected to a smoking history.
A 0.1 micrograms per cubic meter (g/m3) rise in black carbon, popularly known as soot, in the Earth’s atmosphere is connected with a 12% increase in LADC incidence globally, according to a study conducted by NTU and the Chinese University of Hong Kong.
Black carbon is a pollutant that is classed as less than PM2.5, and the research team discovered that it has increased by 3.6 g/m3 annually worldwide from 1990 to 2012.
Meanwhile, a 1% reduction in smoking prevalence was linked to a 9% reduction in LSCC incidence over the world. Between 1990 and 2012, the number of smokers globally declined by 0.26 percent every year, totaling approximately 6%.
According to CA: A Cancer Journal for Clinicians, lung cancer will continue to be the leading cause of cancer death in 2020, with an anticipated 1.8 million deaths. Lung cancer trends have been highlighted by global data, but knowing what causes them has been a mystery until the NTU-led study, which linked the tumors’ occurrence to tobacco use and air pollution.
The study’s lead author, Professor Joseph Sung, NTU’s Senior Vice President (Health and Life Sciences) and Dean, Lee Kong Chian School of Medicine (LKCMedicine), said: “In our research, we discovered that the global rise in lung adenocarcinoma is most likely linked to air pollution. It’s always been a mystery why, in recent decades, more women and nonsmokers have developed lung cancer around the world. Our findings suggest that environmental factors have a role in the development of various forms of lung cancer. “
Our study provided us with an indication as to the reason behind the rising trend of lung adenocarcinoma, despite the decreasing trend of smoking prevalence. Our findings pinpoint the necessity and urgency to reduce air pollutant emissions especially black carbon.”
Steve Yim, Associate Professor, NTU’s Asian School of the Environment and first author of the study
The study looked at data on lung cancers from the World Health Organization from 1990 to 2012, while the dataset for age-standardized smoking prevalence rates from 1980 to 2012 came from the University of Washington’s Institute for Health Metrics and Evaluation, an independent global health research center. The National Aeronautics and Space Administration provided the pollution figures (NASA). Black carbon, sulfate, and PM2.5 were the pollutants studied.
In November, the study’s findings were published in the peer-reviewed academic journal Atmospheric Environment.
Gender and geography both play a role.
Lung cancer and black carbon are linked with different cancers in different genders and on different countries. For example, females had a greater connection between the pollutant and the incidence of both LADC and LSCC than males.
A 0.1 g/m3 annual increase in black carbon was connected to a 14% increase in LADC in women, compared to 9% in men, globally. In the case of LSCC, the same rise in the pollutant was connected to a 14% increase in females, compared to 8% for the males.
The study discovered that the relationship between air pollution and LADC differed by continent. A 0.1 g/m3 rise in black carbon was associated with a 10% increase in LADC cases in North America, compared to 7% in Europe.
According to the researchers, global data shows that the decline in LSCC is more significant among males, and that the falling trend coincides with the decline in cigarette smoking.
Despite the overall decline in tobacco use, a positive relationship between smoking and LSCC was shown for females in Asia, North America, and Oceania, where a 1% increase in the number of female smokers was related with a 12% rise in the cancer rate in those regions.
Impact of population growth and rising air pollution
According to the researchers, despite a reduced overall percentage of smokers around the world, there were more smokers due to huge population expansion between 1980 and 2012, with the number of female smokers increasing by 7%.
According to the experts, the increased prevalence of LADC is particularly noticeable in Asia, where black carbon and sulfate emissions are on the rise.
The biggest annual increase in LADC among Asian boys was 24%, owing mostly to significant increases in Japan (38%) and South Korea (24%) in recent years (37 per cent yearly). LADC grew by 25% year for Asian females, with both Japan (43% yearly) and South Korea (36% yearly) indicating a notable upward trend.
The researchers point to a noticeable trend of air pollution in Asia, with black carbon (11.9 g/m3/year) and sulfate (35.4 g/m3/year) showing the highest increases globally, with South Korea having the highest increase for both pollutants.
In most metropolitan contexts, the combustion of fossil fuels for power generation or transportation has long been recognized as a cause of particle air pollution. It also exacerbates climate change by increasing CO2 emissions, which contribute to global warming.
Prof. Sung continued, “Results of this study should give us fair warning that air pollution should be better controlled to protect health and avoid premature deaths from lung cancer or related illnesses, particularly in populations that live near urban areas, which are known to experience high levels of pollutant emissions. Air pollution, together with climate change, is one of the greatest environmental threats to human health. Our findings underscore the urgent need for further research into how pollutants such as black carbon and sulfate lead to the development of lung adenocarcinoma,
Assoc Prof Yim went on to say: “While national environmental regulatory bodies commonly measure and report on the levels of fine particulate matter, our results pinpoint the importance to measure individual types of particulates, especially, black carbon. The information would be useful for formulating effective emission control policies, supporting policies for sustainable development.”
The researchers intend to conduct more research into the roles of black carbon and sulfate in the development of LADC, which could lead to new studies to prevent the cancer’s rise. The cancers also want to look at other chemicals that could be linked to lung cancer. The sooty black material released by gas and diesel engines, coal-fired power plants, and other fossil-fuel-burning sources is known as black carbon. Particulate matter (PM) in the atmosphere with a diameter of less than 2.5 micrometers, or three-hundredths of the diameter of a human hair. CA: A Clinician’s Guide to Cancer. GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries, Global Cancer Statistics 2020 (2020). Sulfates are formed by the burning of sulfur-containing petroleum-derived products. Inhaling them can lead to a reduction in lung function, an exacerbation of asthmatic symptoms, and an increased risk of emergency room visits, hospitalizations, and death in people with chronic heart or lung problems.