Information on this webpage is drawn from our 2005 report: Breast cancer - an environmental disease: the case for primary prevention, available free as a pdf, see Downloads. For current statistics and data, see our homepage.Physical carcinogens The best known example is high-energy radiation, including nuclear radiation and X-rays.
RadiationBecause ionising radiation is of sufficiently high energy to disrupt electrons from atoms it is the most dangerous type of radiation for all living organisms.
'The harmful effects of atomic or ionizing radiation have been known since the early discoveries of Roentgen, Becquerel and Madame Curie, but the present impacts and mechanisms of nuclear pollution are still not fully understood. Radiation penetrates biological matter and acts on the cells and their constituent parts by causing chemical, molecular or physical damage often resulting in cell death or genetic mutation. Unlike most toxic chemicals, with radiation there appears to be no level of dose below which damage cannot be caused.'Examples of some sources of ionizing radiation that we live with:
- 'natural sources – the sun (UV rays), uranium and radon, and building materials containing these elements
- industrial sources – fallout from man-made nuclear explosions and power station accidents
- medical sources – X-rays
- domestic sources – cathode ray tubes (computers and TVs), some smoke alarms and fluorescent dials
- our bodies – radioactive elements e.g. potassium (natural) and strontium-90 (man-made nuclear fission product [stored in our bones]).'
Electromagnetic field non-ionising radiationElectromagnetic Fields (EMFs) are long-wave forms of non-ionising radiation. EMF emissions in the environment come from natural sources e.g. the sun, the earth's magnetic field and from manufactured sources e.g. highvoltage power lines, power transmission stations and electrical appliances such as computers, electric blankets, hairdryers, TV sets and microwave ovens.
'Risks posed by EMFs depend on the distance from source and duration of exposure. For instance, transmission lines located only 200 to 300 feet away expose people to fewer EMFs than many common domestic appliances … substantial evidence … strongly suggests the carcinogenicity of EMFs … at least eighteen occupational studies link EMF exposure to leukemia, five to brain cancer and thirteen to other cancers, including breast cancer.'
(Epstein Steinman LeVert 1997)
EMFs and melatoninEMFs interfere with the normal production of melatonin, a hormone of particular significance when studying the causes of breast cancer. Melatonin is: 'a hormone made by the pineal gland deep within the brain … [it] is only secreted at night and is an important regulator of the body's 24 hour clock. It also regulates various hormones, including oestrogen. Laboratory tests have shown that melatonin also suppresses the growth of human breast cancer cells.'
Working or sleeping in a situation of near-constant and bright, artificial 'light at night' (LAN) may interfere with the normal production and work of melatonin. Many scientists consider regular exposure to LAN an added risk for breast cancer since it can affect regulatory control of oestrogen (the hormone most strongly associated with breast cancer) as a result of LAN impact on the pineal gland.
'Sleep interruption, especially in women working the graveyard shift, is associated with an increased risk of breast cancer.'
(O'Neill Risks 24)
There can be no doubt that a major cause of cancer today is our involuntary exposure to carcinogens from an ever increasing number of sources in our environment, from higher-than-normal levels of background radiation in our homes to hazardous chemicals in products. Although our knowledge of cancer is incomplete, we do have sufficient understanding of the processes involved to know that cancer incidence can be reduced.
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Reg. address: Breast Cancer UK Ltd, Solva, Southwick Road, Denmead, Waterlooville, Hants. PO7 6LA UK | last updated: 05/10/2006