Cancer is caused by a change in the normal functioning of cells due to changes in the DNA. These changes may have a genetic origin, due to mutations that we may inherit from our parents, or an epigenetic origin, when they occur due to environmental factors.
Environmental factors that can lead to cancer are identified as risk factors for cancer. Depending on their nature, we can divide them into physical, chemical or biological factors.
Physical factors
Within this group are certain types of radiation that may induce changes in the genetic make-up of cells:
- Exposure to electromagnetic fields appears to increase the incidence of childhood leukemia, as well as for breast cancer in women exposed to high doses. The World Health Organization (WHO) considers a magnetic field greater than 50/60 Hz as a risk factor for cancer.
- Ionizing radiation is a known carcinogen that spontaneously produces tumors in different body organs. Their danger was discovered in the mid-twentieth century, with the children who survived the atomic bombs of Hiroshima and Nagasaki. Currently, the greatest radiation source to which we are exposed is usually that produced by xrays used in diagnostic tests, as well as radiation therapy.
- Ultraviolet (UV) radiation is the most common environmental factor affecting our skin. It has been shown that too much exposure to UV radiation significantly increases the risk of skin cancer. In addition, repeated and prolonged use of UVA light lamps for tanning has shown an increased risk of melanoma or squamous cell carcinoma.
Chemical factors
Chemical factors are the chemical substances identified as carcinogenic agents, the most important of which are:
- Cigarettes and smoking cause around 6 million deaths worldwide each year. According to the International Agency for Research on Cancer (IARC), 70 components of cigarettes have been identified as carcinogens in laboratory studies, and of them, 16 are recognized as carcinogens for humans. In addition to causing cancer in the oral and respiratory cavities, there is evidence that smoking can cause breast cancer and leukemia in children.
- Alcohol consumption has shown an increased risk of cancers of the mouth, throat, larynx, esophagus, liver and breast. The extent of risk varies depending on the amount of alcohol consumed and the type of alcohol. However, regular consumption of even small amounts shows a significant increase of risk.
- Nitrosamines are compounds with potent carcinogenic activity, present in various food products, particularly in processed meat and fish, but also in beer or soy sauce and which are associated with gastric cancer. This group includes substances such as aromatic heterocyclic amines formed at 300ºC in protein products. We can find them on the surface of meat or fish when cooking them over fire. Other compounds such as acrylamide are produced during high-temperature cooking of starch-rich foods such as potato chips, coffee or bread.
- Other chemicals produced by car emissions, industrial pollutants and toxic industrial waste are associated with an increase in cases of childhood cancer. High exposure to incense smoke, pesticides, hair dyes or agricultural products may also increase the risk of cancer in adults.
Biological factors
- Diet is a very important part of people’s health, and an unhealthy diet is one of the leading causes of malignancy. The World Cancer Research Fund estimates that 35% of global cancer cases can be attributed to poor nutrition along with a lack of physical activity. The types of tumors most affected by this factor are colorectal, breast, esophageal, stomach and pancreatic tumors. Dietary factors most predisposing to its occurrence include high calorie intake and obesity, high fat intake, inadequate fiber intake, low calcium and vitamin intake, and high sodium intake.
- Lack of physical activity influences many body processes that can lead to excess weight, which results in increased levels of circulating estrogens, androgens, insulin and growth factors. These factors are related to the growth of cells and tumors.
- Mutagenic and carcinogenic compounds are present in several foods. They can be naturally occurring substances or substances formed as a result of food storage and processing. One of the most dangerous are mycotoxins, highly toxic carcinogens produced by mold. Some of them are involved in the induction of breast, liver, esophageal and prostate cancer.
- Increasing attention is being paid to infectious agents as a possible causative factor for cancer. Infections with bacteria such as Helicobacter pylori have been shown to be associated with gastric cancer, C. pneumoniae with lung cancer and Chlamydia trachomatis with cervical cancer. With regard to viruses, some human viruses such as Epstein-Barr (EBV) are related to the occurrence of various types of cancer such as nasopharyngeal carcinoma, Burkitt’s lymphoma, gastric cancer, Hodgkin’s lymphoma or tongue cancer. Human papillomavirus (HPV) is the leading cause of cervical cancer and has recently been found to also cause tongue and tonsil cancer.
Environmental factors are currently known to be the main threat of neoplastic changes. It’s important to pay attention to these factors and try to minimize our exposure to them while living a healthy lifestyle.
Sources:
Lewandowska AM, Rudzki M, Rudzki S, Lewandowski T, Laskowska B. Environmental risk factors for cancer – review paper. Ann Agric Environ
Med. 2019; 26(1): 1–7. doi: 10.26444/aaem/94299
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