Introduction Environment-related carcinogenic factors include both natural and man-made factors, such as air, water, soil, and food. Although the risk of cancer caused by these environmental exposures is relatively milder than that caused by individual lifestyles, cancer caused by environmental pollution is still of public concern. Outdoor air pollution Polluted air particles are considered to be toxic to health, especially when humans inhale specific substances (PM). In Europe, the median PM10 concentration in 2000 was 24 μg/m3 . According to statistics, the risk rate of lung cancer (RRS) for people living in severe air pollution environments is at least 1.3-1.5 times higher than those living in low-pollution environments. In Europe, lung cancer caused by air pollution accounts for 5-7% of all lung cancers. The polluted air contains: nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons (PAHs), formaldehyde, 1,3-butadiene, benzene, etc. Some of these substances have been classified as Class I carcinogens in the working environment by the International Agency for Research on Cancer. In addition, there is a basis to show that in human body, these airborne pollutants have heritable toxicity, because the information is limited at present, this research is still continuing. Exposure to radon gas decay products Radon gas has been proven to cause lung cancer in humans. Radon gas is commonly found in soil and air and causes the development of lung cancer by producing radioactive uranium-238. Although the concentration of radon gas in the air in human living environment is much lower than that in a specific working environment, the concentration of radon gas will accumulate indoors because of continuous human exposure in the living environment and poor indoor ventilation. A study found that the risk rate of lung cancer will increase at least 8%-11% when living in a radon exposed environment (radon gas concentration of 100Bq/m3). In Europe, the average concentration of radon gas in human living environment is 59 Bq/m3 (7 Bq/m3 in Cyprus and 140 Bq/m3 in Czech Republic). According to statistics, lung cancer produced by radon gas accounts for 9% of all lung cancers in Europe. Hazards of second-hand smoke Second-hand smoke contains a large amount of carcinogenic substances. Aggregate analysis shows that exposure to spouse’s smoking environment increases the incidence of lung cancer by 10-20%, and passive smoking of secondhand smoke in the work environment increases the incidence of lung cancer as well. There are indications that parental smoking can cause children to develop a variety of cancers in childhood, such as leukemia and brain tumors, and these causes are currently under intensive study. Other factors of indoor air pollution Other factors of indoor air pollution include by-products of heating or cooking, such as smoke from burning coal and cooking fumes. For Chinese women, the use of solid fuels in daily life is an important risk factor for the development of lung cancer. The difference may be due to the different fuels, cooking oils, types of stoves, heating systems or indoor ventilation systems used by Chinese and Europeans. One study in Eastern Europe reported that the use of solid fuels increased the incidence of lung cancer by 24%. Electromagnetic fields Electromagnetic fields (EMFs) are classified as very low frequency (1 Hz-1 kHz), radio frequency (1 MHz-1G Hz), and microwave (1-300G Hz). These radiations originate from power lines, factories, medical industries, household appliances, radios, televisions, cell phones, etc. Electromagnetic radiation has now been classified as a potential human carcinogen by the International Agency for Research on Cancer (IARC), and can cause leukemia if exposed to electromagnetic radiation above 0.3-0.4 μT during childhood in humans. The results of the pooled analysis show that the amount of electromagnetic radiation required to cause childhood leukemia is higher than 0.4 μT, with a confidence interval of 1.1 μT-3.4 μT. Only 1% of children in Europe are exposed to electromagnetic radiation in the carcinogenic range, with an average of 0.01-0.2 μT. Recently, there have been numerous experiments examining The correlation between cell phone use and the occurrence of brain tumors in humans, but there is no evidence yet to confirm this association. Asbestos Exposure to asbestos in residential settings, such as living in close proximity to mines, or other sources, etc. Exposure may also arise from the installation, movement, repair, and decomposition of asbestos products. Human exposure to asbestos in the residential environment is much less severe than exposure in specific occupational settings. A correlation between asbestos and the development of lung cancer and mesothelioma has been established. A study of asbestos-dwelling environments showed that the relative risk (RR) for mesothelioma was 8.1 (95% confidence interval CI: 5.3-12) and for lung cancer was 1.1 (95% confidence interval CI: 0.9-1.5) for high exposure to asbestos. Continuous exposure to organochlorines Organochlorines are made up of polychlorinated biphenyls (PCBS), pesticides (DDT), chlorinated dif-ings, and furans. These substances are unique in that they can persist in the environment, can accumulate in the food chain, and there are indications that they have endocrine disrupting properties. Nevertheless, there is no strong evidence to confirm the association of these toxic organochlorines with cancer development in humans. Currently tetrachloro-p-dif-ing has been classified by the International Agency for Research on Cancer (IARC) as a carcinogen in animal studies, which mainly affects tumor growth, and as a human carcinogen. Nevertheless, no definite relationship between tetrachloro-p -dif-ing and certain tumors has been confirmed. Exposure to high concentrations of tetrachloro-p -dif-ing in animal studies increased mortality in lung cancer, non-Hodgkin’s lymphoma, multiple myeloma, and digestive system tumors, but not in a dose-dependent manner. This suggests that tetrachloro-p -dif-ing is not significant for increasing cancer incidence, especially at very low concentrations of tetrachloro-p -dif-ing. Other pesticides Through animal studies, the International Agency for Research on Cancer (IARC) has classified some pesticides as carcinogens. Nevertheless, with the exception of arsenic (arsenic), thousands of pesticides have not been classified as human carcinogens. Epidemiologically, the potential association between a specific pesticide and cancer is difficult to assess because firstly, detailed records are rarely available, and secondly, most commercial pesticides consist of many ingredients together and farmers often use a wide range of pesticides. Inorganic arsenic in drinking water In many areas of Europe, inorganic arsenic contamination of groundwater has exceeded the WHO maximum of 10 μg/L. In these areas, inorganic arsenic concentrations in groundwater generally range from 10-200 μg/L, but in eastern Hungary inorganic arsenic concentrations in groundwater can exceed 500 μg/L. Inorganic arsenic in drinking water has been shown to cause skin cancer, lung cancer, and bladder cancer. The inorganic arsenic in drinking water has been shown to cause skin cancer, lung cancer, and bladder cancer, and may have a synergistic effect with tobacco. Some experimental studies have found that the concentration of inorganic arsenic in drinking water >10μg/L bladder cancer risk will increase. Disinfectants in drinking water Chloroform is the most commonly used water disinfectant in the world, in the water will react to produce many products, such as trihalomethanes. The concentration of products in disinfectants depends on the season, the temperature of the water, the geographical location and the amount of organic material in the water. Pooled analysis showed that the relative risk (RR) of bladder cancer was 1.18 (95% confidence interval CI: 1.06-1.32) for concentrations of disinfectant products in drinking water above 1 μg/L. Susceptibility to environmental pollution Tumor susceptibility is associated with genetic variation, abnormal metabolism of genes, DNA repair, and diminished action of oncogenes. In particular, polymorphisms of genes encoding metabolic activities in the body or detoxifying external substances are closely related to cancer risk. For example, glutathione S-transferase genes are involved in the metabolism of many chemicals (e.g., pesticides, solvents, etc.) in the body. A study confirmed that deletion of GSTT1 is potentially protective in patients exposed to asbestos. Further studies on the role of gene polymorphisms in chemical biotransformation may provide interventions for cancer risk factors. In conclusion Current epidemiological studies have confirmed that in some specific environments, such as radon pollution, indoor or outdoor air pollution particles increase the relative risk rate of human lung cancer development. Some other potential pollutants, such as organic pesticides, are currently difficult to quantify in a quantitative manner to measure the relative risk rate of carcinogenesis. Although it seems reasonable that some pollutants increase cancer risk, however, outside of industrially polluted areas, their exposure is scattered and at low concentrations, making it more difficult to quantify their risk. However, given the widespread nature of some types of pollutants, even a slight carcinogenic risk can produce a significant disease burden.