Monday, October 2, 2023

Causes of Cancer

Environmental exposures

Pollutions of the living environment. Air pollution, mostly emissions from manufacturing and traffic, greatly raises the risk of Lung Cancer. Air pollution is a risk factor which is marginal compared with Tobacco. However, studies are currently underway, among other items, on how wood-heated houses and small particle emissions are related to cancer.

Drinking water processing by surface water chlorination produces mutation-causing compounds which can slightly increase the risk of genitourinary cancer, for example. The arsenic tends to have a similar impact in drilled well water.

Over recent years, measurement results describing the state of the environment have been increasingly obtained, and they can be used to better assess the causes of cancer risk. An example of this is an environmental health analysis of people who once lived in houses that were built and then demolished on top of a former Myllypuro landfill in Helsinki. According to the first study, some more cancer and asthma were identified in the residents of these houses compared to comparison residents, but the latest studies show that those living in the area of Myllypuro were not diagnosed with cancer more frequently than those living in any other region of Helsinki in the 2000s.

Ionising radiation

Ionising radiation exists everywhere, as radiation can be contained e.g. in the natural radioactive compounds of the earth’s surface, which are carried by nutrition through the human body. Radon inhalation causes a dose of radiation primarily only in the lungs. The only clearly defined impact on radon is the increased risk of Lung Cancer. In smokers, the risk of radon-caused Lung Cancer is higher than in non-smokers. It is estimated that radon in indoor air causes roughly in conjunction with smoking.

X-ray radiation is used in radiology, and radiation treatments use various forms. Therefore, in health care, it should always be carefully assessed if the benefit obtained with the use of radiation is greater than the risk it creates. Cancer patients seeking radiation treatment undergo extremely high dosages of radiation, and other tissues may also be exposed to radiation in addition to the tumor. Patients treated with radiation therapy have an increased risk of developing leukaemia and certain other cancers, but treatment benefits are much greater than the drawbacks.

It has been estimated that ionizing radiation causes 1-3 per cent of all cancers. Radiation increases the risk of leukaemia and of thyroid, breast, lung and bladder cancer particularly strongly.

Non-ionising radiation

Non-Ionising radiation involves ultraviolet radiation, as well as the magnetic and electric fields. Ultraviolet radiation is obtained primarily from sunlight and sunbeds, and it causes skin cancers. Repeated burning of the skin is the main cause of cutaneous melanoma due to excessive UV radiation, particularly in infancy and youth.

Power cords and electrical devices generate very low frequency magnetic fields around them (50-60 Hz). Their effect on cancer risk and, above all, the risk of childhood leukaemia was tested several times, but the findings were inconsistent. The risk of cancer in children or adults in the vicinity of power lines is not increased according to studies.

The strength of magnetic fields with radio frequencies is million hertz. They are generated by radar, radio transmitters, cell phones and base stations among others. Radio-frequency radiation does not induce mutation, and animal studies have not raised cancers. Mobile phone usage was not shown to increase the risk of cancer in humans in epidemiological studies either (Interphone Study Group 2010), but the issue with the studies was the relatively short follow-up duration of ten years and the unreliability of questionnaire-based knowledge use. New large-scale, ongoing follow-up studies are hoped to provide more information in different countries.