The concentrations of metal and 210Po traces in human lung tissue from São Paulo city residents indicated that there is a close association between exposures to air pollution. Urbanization process has promoted a better quality of life, however, it has also caused a series of environmental impacts that directly or indirectly affect human health, such as air pollution. In Sao Paulo city, weak national and local environmental legislation, unplanned urbanization, industrial structure, unsustainable pattern of energy consumption and generation and road based transportation are major drivers of our deteriorated air quality.
The effects of air pollution on human health vary from moderate to severe effects and depend on the concentration to which individuals are exposed, its composition, age and presence of preexisting diseases.
The presence of heavy metals associated with fine particulate matter is one of the determinants of health risks posed by air pollution. Different studies that evaluated the elemental composition of particulate air pollution from Sao Paulo city have shown positive results for the following metals: SO4(2-), NO3-, NH4+, Zn, Fe, Al, Ba, Cu, Pb, Mn and Ni 23
Particulate matter is generated essentially by the incomplete burning of fossil fuels and biomass. Other particles can be generated from sources unrelated to the combustion process, such as brake, tire, clutch and road surface release 24. In general, it consists of a central elementary carbon core and on its surface other compounds are bounded, such as metals 25,26. In addition, PM are capable of carrying radioactive particles 27.
In this study we demonstrated that the presence of Po210 in lungs of Sao Paulo city residents is associated with vehicular emission/air pollution. Other metals detected in lung tissues are also related to exposure air pollution and time of residence in the city and time spent commuting are also determinant.
After inhalation, Radon and its progenies can deposit somewhere along the respiratory tract, increasing the risk of cancer2 and non-cancer diseases 28 Radon is the second leading cause of lung cancer resulting in approximately 21,000 lung cancer deaths each year in the US (EPA). In Europe, it is estimated that approximately 3,000 deaths are caused by exposure to radon annually. The World Health Organization (WHO) estimates that radon is the leading cause of lung cancer, accounting for up to 14% of cases worldwide 13
Some metals are required for different cellular functions and homeostasis, however, depending on the dose and exposure duration they can be toxic affecting different physiological processes. Most of the evidence on the negative effects of inhaling heavy metals inhalation come from occupational exposures29. For example, occupational exposure to cobalt metal or cobalt-containing hard metal is associated with respiratory effects such as asthma, interstitial lung disease, wheezing, and dyspnea (https://www.atsdr.cdc.gov/toxprofiles/tp33.pdf). Studies on the effects of environmental exposure to low levels of heavy metals in humans, as chromium are scarce, however prolonged occupational exposure are related to negative effects on the respiratory system, kidney and liver and cancer 30
Zinc is found as ZnO in particulate air pollution 31 and depending on the inhaled concentration it can induce respiratory distress in response to metal deposition 32
A meta-analysis conducted by Catalini et al. 33 evaluate the concentrations of metals in lung tissue as factors involved into the development of lung cancer. Results have shown that Zn and Cu were the metals more represented, and there is no clear relationship between concentrations and age. Just one study included in the meta-analysis found a positive correlation between Ni and Cr concentrations and age 34. Among smoker, concentrations of Al, Cd, Cr, Ni, Pb and Mn were higher, but results could be biased by past occupational exposure to metals Tsuchiyama et al 35Cr and Pb showed the highest concentrations.
Although it is descriptive study using a small sample, it has many strengths. The detailed interview with a family member about the individual's daily activities, potential occupational exposure, tobacco use, time spent in traffic, and the assessment of lifetime exposure using the pulmonary anthracosis index made it possible to control factors that could bias the results of the analysis.
The analysis and characterization of the presence of these metals in the lungs of residents of the city of Sao Paulo allows us to more plausibly infer and suggest the contribution of the exposure to air pollution to different diseases associated with exposure to heavy metals and radioactive elements, such as lung cancer, hematological and neurodegenerative diseases. Besides, knowing which metals are Hence, knowing
In addition, knowledge about the presence of metals in human tissues may allow us to identify new sources of exposure and create measures to reduce or protect human health
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