Environmental impact on the risk of cancer

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Environmental impact on the risk of cancer

Chapter 1: fundamental principles and definitions

Cancer, in essence, is a group of more than 100 diseases characterized by uncontrolled growth and the spread of abnormal cells. This complex process, called carcinogenesis, is multi -stage and includes both genetic and epigenetic changes, leading to the transformation of normal cells into malignant ones. Although the genetic predisposition plays a significant role in determining the individual risk of cancer, evidence indicates that most cancer cases (according to estimates, from 70% to 90%) are associated with environmental factors and lifestyle. In this chapter, we will determine what is meant by the “environment” in the context of cancer risk, and also consider the fundamental principles of carcinogenesis and the interaction of genes and the environment.

1.1. Determination of the “environment” in the context of the risk of cancer

In the context of the risk of cancer development, the “environment” covers all external factors that can affect the human body and its cells. This includes:

Physical factors: Ionizing and non-ionizing radiation (ultraviolet radiation, x-rays, gamma rays, radio waves), Azbest, Radon, solid particles in the air (PM2.5, PM10).
Chemical factors: Air pollutants (benzene, formaldehyde, dioxins), water pollutants (arsenic, nitrates), pesticides, heavy metals (lead, cadmium, chromium), industrial chemicals (polychlorified diphenyls – PHD, polycyclic aromatic hydrocarbons – PAU), components of tobacco smoke.
Biological factors: Viruses (human papillomavirus – HPV, hepatitis B and C virus, Epstein -Barr virus), bacteria (Helicobacter pylori), parasites (Schistosoma haematobium).
Life lifestyle factors: Diet (high consumption of treated meat, insufficient consumption of fruits and vegetables), physical activity, drinking alcohol, smoking, reproductive history, breastfeeding.
Socio-economic factors: The income level, education, access to healthcare, working conditions, housing conditions, geographical location.

It is important to note that these factors often interact with each other, increasing or weakening the risk of cancer. For example, smoking and exposure to asbestos have a synergistic effect regarding the risk of lung cancer.

1.2. Fundamentals of carcinogenesis: multi -stage process

Carcinogenesis is a complex, multi -stage process that usually takes years or even decades. It includes a sequence of genetic and epigenetic changes, which ultimately lead to uncontrolled growth and cell spread. The main stages of carcinogenesis include:

Initiation: The initial stage at which the normal cell is exposed to carcinogens causing DNA damage. If this damage is not restored, it can lead to mutation. It is important to note that one mutation is usually not enough to turn the cell into cancer.
Promotion: At this stage, cells with damaged DNA are stimulated to growth and division. Promotors are not carcinogens on their own, but they enhance the effect of initiators. Examples of promoters are hormones and growth factors. Inflammation can also play the role of promoter.
Progression: At this stage, the cells become more and more anormal and acquire the ability to invade surrounding tissues and metastasize into distant areas of the body. At this stage, additional genetic and epigenetic changes occur, which give the cells competitive advantages.
Metastasis: The final stage at which cancer cells break off the primary tumor and spread to other parts of the body through the blood or lymph system. Metastases are the main cause of death from cancer.

1.3. Interaction of genes and the environment

The risk of cancer is the result of a complex interaction between a genetic predisposition and the influence of environmental factors. Some people can be genetically more susceptible to certain carcinogens, while others can be more stable. Genes involved in the metabolism of carcinogens, DNA restoration, immune response and regulation of the cell cycle can affect the individual risk of cancer.

Metabolism genes of carcinogens: These genes encode enzymes that activate or deactivate carcinogens. Polymorphisms in these genes can affect the rate of metabolism of carcinogens, thereby affecting the risk of cancer. Examples of such genes are CYP1A1, CYP2E1, GSTM1, GSTT1.
DNA recovery genes: These genes encode proteins that restore damaged DNA. Mutations in these genes can reduce the ability of the cell to restore DNA damage, increasing the risk of cancer. Examples of such genes are BRCA1, BRCA2, TP53.
Genes of the immune response: These genes encode proteins that participate in the immune response to cancer cells. Polymorphisms in these genes can affect the ability of the immune system to recognize and destroy cancer cells, increasing the risk of cancer.
Epigenetic changes: Epigenetics refers to changes in genes expression, which are not associated with changes in the DNA sequence. Epigenetic changes can be caused by environmental factors and can affect the risk of cancer. Examples of epigenetic changes are DNA methylation and histone modification.

Understanding the interaction of genes and the environment is crucial for the development of effective cancer prevention strategies. The identification of people with a genetic predisposition to certain types of cancer can allow targeted preventive measures, such as screening and modification of lifestyle.

Chapter 2: Air pollution and cancer risk

Air pollution is a complex mixture of solid particles, liquid drops and gases located in atmospheric air. The main sources of air pollution are transport, industry, agriculture, the burning of fossil fuel and natural sources, such as dusty storms and forest fires. Air pollution has a significant negative effect on human health, including increased risk of respiratory diseases, cardiovascular diseases and cancer.

2.1. The main air pollutants associated with the risk of cancer

Some of the main air pollutants, which were associated with an increased risk of cancer, include:

Solid particles (PM): PM belong to tiny particles located in the air that can be inhaled and settled in the lungs. PM are divided into two main categories: PM10 (particles in size less than 10 micrometers) and PM2.5 (particles in size less than 2.5 micrometers). PM2.5 is a special problem, since they can penetrate deep into the lungs and even in the bloodstream. PM sources include transport, industry, burning fossil fuel, agriculture and dust storms. PM are associated with an increased risk of lung cancer, bladder cancer and other types of cancer.
Polycyclic aromatic hydrocarbons (PAU): PAU is a group of chemicals that form with incomplete combustion of organic substances, such as coal, oil, gas, wood and garbage. PAUs are widespread in the environment and are found in contaminated air, tobacco smoke, grilled foods and creosotes. Some PAUs are well -known carcinogens for humans and are associated with an increased risk of lung cancer, skin cancer, bladder cancer and stomach cancer. Benzo[a]Pyrene is the most studied and possibly the most carcinogenic PAU.
Benzol: Benzole is a colorless, flammable liquid with a sweet smell. It is used as a solvent in the production of other chemicals. Benzole is a famous carcinogen for humans and is associated with an increased risk of leukemia, lymphoma and other types of blood cancer. The main sources of benzene in the environment are emissions from vehicles, industrial emissions and tobacco smoke.
Formaldehyde: Formaldehyde is a colorless gas with a pungent smell. It is used in the production of resins, fabrics, adhesives and preservatives. Formaldehyde is a probable carcinogen for humans and is associated with an increased risk of cancer of the nasopharynx, leukemia and other types of cancer. Formaldehyde sources include emissions from industrial enterprises, vehicles and building materials. It can also be allocated from furniture and carpets.
Dioxins and furats: Dioxins and furanes are a group of persistent organic pollutants (SAS) formed as a result of industrial processes, combustion of waste and other types of burning. Dioxins and fuels are very toxic and can accumulate in the environment and in the food chain. They are known carcinogens for humans and are associated with an increased risk of various types of cancer, including lung cancer, liver cancer and soft tissue cancer.
Asbestos: Although it is usually considered as a professional risk factor, the Azbest can also be present in the air due to erosion of natural deposits or the destruction of asbestos-containing building materials. Inhaling the fibers of asbestos is associated with the risk of lung cancer, mesotheliomes (cancer of the lung, abdomen or heart) and laryngeal cancer and ovaries.

2.2. The mechanisms with which air pollution contributes to the development of cancer

Air pollution can contribute to the development of cancer through various mechanisms, including:

DNA damage: Some air pollutants, such as PAU and benzene, can directly damage DNA, causing mutations that can lead to carcinogenesis. PAU can form DNA-adules that disrupt the normal structure and function of DNA. Benzole can be metabolized into toxic metabolites that damage DNA.
Inflammation: Air pollution can cause chronic inflammation in the lungs and other organs. Chronic inflammation can damage DNA, suppress the immune system and stimulate the growth and spread of cancer cells. PM2.5 can cause inflammatory reactions in the lungs, leading to the release of cytokines and other inflammatory mediators.
Oxidizing stress: Air pollution can cause oxidative stress, which is an imbalance between the production of free radicals and the ability of the body to neutralize them. Free radicals can damage DNA, proteins and lipids, which can lead to carcinogenesis. PM2.5 can generate free radicals that cause oxidative stress in the lungs and other organs.
Epigenetic changes: Air pollution can cause epigenetic changes, such as DNA methylation and histone modification, which can affect the expression of genes participating in carcinogenesis. PAU can cause DNA methylation, which can suppress the expression of genes that overwhelm the tumors.
Suppression of the immune system: Some air pollutants can suppress the immune system, reducing its ability to recognize and destroy cancer cells. Dioxins and furats can suppress the function of immune cells, such as T cells and NK cells.

2.3. Evidence that connects air pollution with certain types of cancer

Epidemiological studies consistently associate air pollution with an increased risk of various types of cancer, including:

Lung cancer: The most studied connection is the connection between air pollution and lung cancer. Numerous studies have shown that people living in areas with a high level of air pollution undergo increased risk of lung cancer. This connection is especially strong for PM2.5 and PAU. The World Health Organization (WHO) classified atmospheric air pollution as a carcinogen for humans.
Bladder cancer: Some studies have shown that air pollution is associated with an increased risk of bladder cancer. PAU found in polluted air can be excreted in the urine and damage the cells of the bladder.
Blood cancer (leukemia, lymphoma): The effect of benzene, a common air pollutant, is firmly associated with an increased risk of leukemia, especially acute myeloidal leukemia (OML). Some studies also showed the connection between air pollution and other types of blood cancer, such as lymphoma.
Breast cancer: Evidence that binding air pollution with breast cancer is less convincing than for other types of cancer. However, some studies have shown the relationship between the effects of air pollution and the increased risk of breast cancer, especially in postmenopausa women. It is assumed that PAU and other air pollutants can violate the endocrine system and influence the risk of breast cancer.
Children’s cancer: The effect of air pollution during pregnancy and in early childhood can increase the risk of children’s cancer, such as leukemia and brain tumors. Air pollutants can pass through the placenta and influence the development of the fetus, increasing the risk of carcinogenesis at a later age.

2.4. Strategies for reducing risk of cancer associated with air pollution

Reducing the risk of cancer associated with air pollution requires comprehensive strategies that include:

Reducing emissions of pollutants: The implementation of the more stringent emissions for vehicles, industrial enterprises and power plants. The transition to cleaner energy sources, such as renewable energy sources (solar, wind, hydropower). Improving public transport and stimulating the use of bicycles and hiking.
Improving the quality of air in the premises: Using HEPA air filters in houses and offices. Providing proper ventilation of the premises. Reducing the use of products releasing pollutants, such as chemical cleaning agents and air fresheners. The ban on smoking in the premises.
Individual precautions: Avoiding areas with a high level of air pollution, when possible. The use of masks to protect against air pollution, especially during periods of severe pollution. The consumption of a diet rich in antioxidants, which can help protect against damage caused by air pollution. Regular physical exercises (but avoid them during periods of strong pollution).
Improving public awareness: Information of the public about health risks associated with air pollution, and measures that can be taken to reduce the impact. Support for politicians and programs aimed at improving air quality.

Chapter 3: Water pollution and cancer risk

Water pollution is a serious threat to human health, since many water pollutants can have a carcinogenic effect. Water pollution comes from various sources, including industry, agriculture, household waste and leaks from underground storage facilities.

3.1. The main water pollutants associated with the risk of cancer

Some of the main water pollutants, which were associated with an increased risk of cancer, include:

Arsenic: Arsenic is a natural element that can fall into water from rocks and soil. It can also fall into the water as a result of industrial processes, such as mineral extraction and pesticides. Arsenic is a famous carcinogen for humans and is associated with an increased risk of skin cancer, bladder cancer, lung cancer, liver cancer and kidney cancer. The chronic effect of even low mouse levels in drinking water can increase the risk of cancer.
Nitrate: Nitrates are chemical compounds that are widely used as fertilizers in agriculture. They can fall into water from flow of fertilizers, wastewater and septic tanks. A high level of nitrates in drinking water can be especially dangerous for babies, since it can cause methemoglobinemia (a “blue child” syndrome). Nitrates can also turn into nitrosamines in the body, which are known carcinogens for humans and are associated with an increased risk of stomach cancer, colon cancer and ovarian cancer.
Trigalometan (Tgm): TGM is the by -food disinfection formed during chlorination of drinking water. Chlorine reacts with organic substances present in the water, forming TGM, such as chloroform, bromodichlormethane, dibrochlormethane and bromorm. Some TGMs are likely carcinogens for humans and are associated with an increased risk of bladder cancer, colon cancer and rectum cancer.
Per- and polyfettorcene substances (PFAS): PFAS is a group of synthetic chemicals that were widely used in various industrial and consumer goods, such as anti -stick dishes, fire -resistant foam and water -repellent clothing. PFAS is very resistant to decomposition and can be preserved in the environment and in the human body for a long time. Some PFAS are associated with an increased risk of kidney cancer, egg cancer, thyroid cancer and other diseases.
Radon: Radon is a radioactive gas formed as a result of the collapse of uranium in the soil and rocks. Radon can fall into drinking water from underground sources. Inhalation of radon is the main factor in the risk of lung cancer, but the use of water containing radon can also increase the risk of stomach cancer.
Pesticides: Many pesticides used in agriculture can fall into the water through the drain and pollute drinking water sources. Some pesticides are probable or possible carcinogens for humans and are associated with an increased risk of blood cancer (leukemia, lymphoma), breast cancer, prostate cancer and other types of cancer.
Heavy metals (lead, cadmium, chrome): Heavy metals can fall into water from industrial waste, mining and corrosion of water pipes. Some heavy metals are carcinogens for humans and are associated with an increased risk of lung cancer, kidney cancer, bladder cancer and stomach cancer.

3.2. The mechanisms by which water pollution contributes to the development of cancer

Water pollution can contribute to the development of cancer through various mechanisms similar to mechanisms associated with air pollution, including:

DNA damage: Some water pollutants, such as arsenic, can directly damage DNA, causing mutations that can lead to carcinogenesis. Arsenic can inhibit DNA restoration enzymes, increasing the risk of mutations.
Inflammation: Water pollution can cause chronic inflammation in various organs. Chronic inflammation can damage DNA, suppress the immune system and stimulate the growth and spread of cancer cells.
Oxidizing stress: Water pollution can cause oxidative stress, which is an imbalance between the production of free radicals and the ability of the body to neutralize them. Free radicals can damage DNA, proteins and lipids, which can lead to carcinogenesis.
Epigenetic changes: Water pollution can cause epigenetic changes, such as DNA methylation and histone modification, which can affect the expression of genes participating in carcinogenesis.
Violation of the endocrine system: Some water pollutants, such as pesticides and PFAS, can violate the endocrine system, affecting the level of hormones and increasing the risk of hormones, such as breast cancer, prostate cancer and thyroid cancer.

3.3. Evidence connecting water pollution with certain types of cancer

Epidemiological studies consistently associate water pollution with an increased risk of various types of cancer, including:

Bladder cancer: The effect of arsenic and TGM in drinking water is firmly associated with an increased risk of bladder cancer. Some studies have shown that the risk of bladder cancer increases with an increase in the concentration of arsenic and TGM in drinking water.
Skin cancer: The chronic effect of arsenic in drinking water is the main factor in the risk of skin cancer, especially basal cell and flat cell cancer. This connection is especially strong in regions with a high level of arsenic in groundwater.
Lung cancer: Inhalation of radon from drinking water (released into the air when using water) is the main factor in the risk of lung cancer. The use of water containing radon can also increase the risk of stomach cancer.
Kidneys and testicles cancer: Some studies have shown the relationship between the effects of PFAS in drinking water and the increased risk of kidney and egg cancer.
Cancer of the stomach and colon: A high level of nitrates in drinking water can turn into nitrosamines in the body, which are known carcinogens for humans and are associated with an increased risk of stomach and colon cancer.
Cancer Baked: A long -term exposure to arsenic in drinking water is associated with an increased risk of liver cancer.

3.4. Strategies for reducing risk of cancer associated with water pollution

Reducing the risk of cancer associated with water pollution requires complex strategies that include:

Protection of drinking water sources: The implementation of strict rules to prevent pollution of water bodies with industrial waste, agricultural runoff and household waste. Protection of water-bell grounds and other natural territories that help filter and purify water.
Cleaning drinking water: Using effective water purification technologies to remove pollutants from drinking water. This may include filtering, chlorination, ozoning, ultraviolet irradiation and reverse osmosis. Reducing the formation of TGM by optimizing disinfection processes.
Water quality monitoring: Regular monitoring of the quality of drinking water to identify and control pollutants. Providing the public with information about the quality of drinking water.
Individual precautions: Using water filters at home to remove pollutants from drinking water. Checking the level of radon in water and taking measures to reduce it, if the level is increased. Avoiding the use of polluted water sources for drinking, cooking and bathing. Using alternative water sources if drinking water is contaminated.
Improving public awareness: Information of the public about health risks associated with water pollution, and about measures that can be taken to reduce exposure. Support for politicians and programs aimed at protecting drinking water sources and improving the quality of drinking water.

Chapter 4: Cancer Risk and Risk

Radiation is energy that spreads in the form of waves or particles. There are two main types of radiation: ionizing and non -ionizing. Ionizing radiation has sufficient energy to knock out electrons from atoms and molecules, damaging DNA and increasing the risk of cancer. Nononization radiation has less energy and is usually not considered carcinogenic, although some types of non -ionizing radiation can have other harmful effects on health.

4.1. Ionizing radiation and risk of cancer

Ionizing radiation includes:

X-rays and gamma rays: These types of radiation are used in medicine for the diagnosis and treatment of diseases, as well as in industry for various purposes. X-rays and gamma rays can penetrate deep into the body and damage DNA.
Radioactive substances: Radioactive substances distinguish ionizing radiation in the process of radioactive decay. Radioactive substances can fall into the environment as a result of nuclear accidents, tests of nuclear weapons and industrial processes.
Radon: Radon is a radioactive gas formed as a result of the collapse of uranium in the soil and rocks. Radon is the main source of natural ionizing radiation.

The effect of ionizing radiation is associated with an increased risk of various types of cancer, including:

Leukemia: The most studied relationship is the connection between the effects of ionizing radiation and leukemia, especially the acute myeloid leukemia (oml). People who survived the atomic bombing of Hiroshima and Nagasaki were subjected to significantly increased risk of leukemia. Employees of the nuclear industry and persons undergoing medical irradiation are also subjected to increased risk of leukemia.
Thyroid cancer: The effect of ionizing radiation, especially in childhood, is associated with an increased risk of thyroid cancer. Children living near the Chernobyl nuclear power plant during the 1986 accident were significantly increased in the thyroid cancer.
Breast cancer: Some studies have shown the relationship between the effects of ionizing radiation and the increased risk of breast cancer. Women who have undergone a multiple x -ray examination of the breast or radiation therapy are at increased risk of breast cancer.
Lung cancer: Inhalation of Radon is the main factor in the risk of lung cancer, especially among smokers. Radon breaks up in the lungs, secreting alpha particles that damage the cells of the lungs.
Bones cancer: The effect of ionizing radiation is associated with an increased risk of bone cancer, especially osteosarcoma.
Multiple myeloma: Some studies have shown the relationship between the effects of ionizing radiation and the increased risk of multiple myeloma.

4.2. Non -ionizing radiation and risk of cancer

Nononizing radiation includes:

Ultraviolet (UV) radiation: UV radiation comes from the sun, solariums and some types of lamps. UV radiation is the main risk factor for skin cancer.
Radio frequency (RF) radiation: RF radiation comes from mobile phones, Wi-Fi routers, radio transmitters and other wireless devices. RF radiation is classified by the International Cancer Learning Agency (Mair) as “possible carcinogenic for humans” (group 2B) based on limited evidence of the connection with the glioma (brain tumor) and acoustic neurinoma (auditory nerve tumor).
Electric and magnetic fields (EMP): EMPs are created by electric currents and magnetic fields. EMP comes from the lines of power transmission, household electrical appliances and other sources. Mair classifies EMP as “possibly carcinogenic for a person” (group 2B) based on limited evidence of communication with child leukemia.

4.3. Ultraviolet (UV) radiation and skin cancer

UV radiation is the main risk factor for skin cancer, including:

Basal -cell cancer: The most common type of skin cancer, which usually does not metastasize. Basal cell cancer is associated with a long effect of UV radiation.
Squamous cell cancer: The second most prevalence type of skin cancer, which can be metastasized if it is not treated. Plant-cell cancer is also associated with prolonged exposure to UV radiation.
Melanoma: The most dangerous type of skin cancer, which can quickly metastasize. Melanoma is associated with intense, interspersed exposure to UV radiation, such as sunburn.

The risk of skin cancer increases with an increase in the effects of UV radiation. People with pale skin, blond hair and blue eyes are at greater risk of skin cancer. Other skin cancer risk factors include a family history of skin cancer, multiple moles and sunburn history.

4.4. Strategies for reducing the risk of cancer associated with radiation

Reducing the risk of radiation cancer requires complex strategies that include:

Minimization of the effects of ionizing radiation: Avoiding unnecessary medical radiation, especially in childhood. Compliance with safety rules when working with sources of ionizing radiation. Checking the level of radon in houses and taking measures to reduce it, if the level is increased.
UV protection protection: The use of a high SUN with a high SPF. Wearing protective clothes, such as hats and shirts with long sleeves. Avoiding stay in the sun in a peak time. Avoiding the use of solariums.
Limiting the effects of RF radiation and EMP: Limiting the time of conversation on a mobile phone. Using a speakerphone or headset when talking on a mobile phone. Holding a mobile phone at a distance from the body. Maintaining the distance from power lines and electrical appliances.
Improving public awareness: Information of the public about health risks associated with radiation, and about measures that can be taken to reduce influence.

Chapter 5: professional risk factors for cancer

The impact of certain chemicals and other factors at the workplace can significantly increase the risk of cancer. Professional cancer is a significant part of all cases of cancer, and it can be prevented by implementing proper control and safety measures.

5.1. The main professional carcinogens and types of cancer, associated with them

Some of the main professional carcinogens and types of cancer with which they are connected include:

Asbestos: The effect of asbestos is associated with an increased risk of lung cancer, mesotheliomes (cancer of the lung, abdomen or heart), laryngeal cancer and ovarian cancer. Asbest was widely used in construction and shipbuilding before its carcinogenic properties became known. Workers who have exposed to asbestos include builders, shipbuilders, insulation workers and mechanics.
Benzol: The effect of benzene is associated with an increased risk of leukemia, especially acute myeloidal leukemia (OML). Benzole is used as a solvent and in the production of other chemicals. Workers who have exposed to benzene include working petrochemical industry, printing workers and shoe factories workers.
Silica: The effect of crystalline silica is associated with an increased risk of lung cancer, silicosis (

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