Wednesday July 29 2009
Tanning beds are now classed in the highest cancer risk category
“Sunbeds are as likely to cause cancer as smoking and have been classified in the highest level of risk alongside cigarettes and asbestos,” The Times reported. It said that the International Agency for Research on Cancer (IARC) has moved sunbeds to the highest cancer risk category of ‘carcinogenic to humans’, from its previous category of ‘probably carcinogenic’. The change is based on studies which found that people who use tanning devices before 30 years of age increase their risk of skin melanoma by 75%.
This work was carried out by the IARC, part of the World Health Organisation (WHO), and its conclusions are based on solid evidence assessed by leading experts. The changes follow a reassessment of the evidence of the risk of cancer from several forms of radiation, one of which was solar radiation and UV-emitting tanning beds. This revision highlights the real danger from such devices, placing it in the highest risk group along with arsenic, hepatitis, smoking and ethanol. The WHO recommends avoiding sunlamps and tanning parlours, and to protect yourself from overexposure to the sun.
Where did the story come from?
This was a special policy report presenting the conclusions of a scientific meeting at the International Agency for Research on Cancer (IARC) and published in the Lancet Oncology journal.
At the meeting, scientists from nine countries reassessed the carcinogenicity of different types of radiation, and identified pathways of cancer development. They examined observational studies that assessed the effects of different types of radiation on various populations, including medical patients, survivors of nuclear accidents, and specific occupation groups, such as miners, radium-dial painters and plutonium-production workers.
What were the results of the study?
The group discussed the evidence for the risk of various cancers from several forms of radiation, including:
- X-rays and gamma radiation
- solar radiation and UV-emitting tanning devices
Radionuclides are highly charged atoms with an unstable nucleus that emits alpha or beta particles, which can penetrate tissues. Alpha particles are ionising radiation with a low capacity to penetrate living tissue. Beta particles are less ionising, but they are more capable of penetrating several millimetres into living tissue.
Radionuclides that emit these particles include radon-222, thorium-232, radium-224 and -226, and their decay products, and plutonium, phosphorus-32, fission products such as strontium-90 and radioiodines such as iodine-131. There is evidence of a link between lung cancer and radon-222 and bone cancer and radium-226. The report also highlights the Chernobyl incident where children exposed to iodine-131 had an increased risk of thyroid cancer.
X-rays or gamma-rays, such as those emitted by atomic bombs, penetrate living tissue with fast-moving electrons and cause tissue damage. Follow-up of atomic bomb survivors found an increased risk of cancer at various body sites. In particular, it has been noted that exposure of a pregnant woman to X-rays increases the risk of cancer in the developing baby.
Solar radiation causes the three types of skin cancer: malignant melanoma, basal cell and squamous cell carcinoma. Solar radiation is the main source of ultraviolet light, which is 95% UVA and 5% UVB. UVA has been associated with a specific structural change in DNA. The use of UV-tanning beds is now widespread in many countries. The group used a systematic review of studies investigating the risk of malignant melanoma from tanning devices.
The review found that when use of tanning devices starts before age 30, the risk of melanoma increases by 75%. Furthermore, there is evidence from several case–control studies of a link between UV-emitting tanning devices and melanoma of the eye.
The researchers discuss how radiation causes tissue damage in the body, and say that the high level energy of ionising radiation causes molecular change and complex DNA damage. This DNA damage can lead to mutations and a change in cell function - effects that can contribute to cancer development.
What interpretations did the committee draw from these results?
Overall, the IARC reaffirmed the cancer-causing properties of radionuclides that emit alpha or beta particles, all ionising radiation, X-rays and gamma-rays, neutron radiation, as well as solar radiation.
They also raised the risk of UV tanning beds from ‘probably carcinogenic’ to ‘carcinogenic to humans’.
What does the NHS Knowledge Service make of this study?
This brief report includes the conclusions of a meeting at the International Agency for Research on Cancer. At the meeting, scientists reassessed the evidence from various observational studies of populations that were exposed to radionuclides and their decay products, other forms of ionising radiation, gamma rays and X-rays, and solar radiation and UV light.
The report highlights that these all increase the risk of cancers at various sites of the body. In particular, UV light, which is emitted from tanning beds, has clearly been associated with an increased risk of malignant melanoma. The conclusions that ionising and solar radiation and tanning beds are associated with an increased risk of cancer match those of the COMARE report in June.
The conclusions of this expert committee emphasise the need for public awareness of the dangers of exposure to the sun and tanning devices.
Sun safety advice remains the same:
- Avoid exposure to bright sunlight wherever possible, e.g. avoidance of sunbathing, keeping out of the sun between 11am and 3pm on hot days.
- Wear cool, loose clothing to cover up.
- High-factor sun cream that is regularly reapplied.
- Sunglasses with 100% UV protection.
- Ensure that the delicate skin of young children is protected from sunlight as much as possible.