Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: Atomic-S on 11/06/2012 23:05:58

Title: How is the risk of skin cancer affected by dose distribution in time?
Post by: Atomic-S on 11/06/2012 23:05:58

Is there any difference in the probability of developing skin cancer in a person exposed to the direct overhead sun for 10 minutes per day over a 1 year period, compared to a person exposed 1 minute a day over a 10 year period?

Title: Re: How is the risk of skin cancer affected by dose distribution in time?
Post by: cheryl j on 12/06/2012 01:14:41

Well they say the risk increases with actual  sunburns so I would imagine that getting a lot of exposure in a short period of time is worse than small exposure over a long period of time. Maybe if the skin is damaged in a sunburn, you have a rapid repair process, which means a lot of cell divisions, in addition to whatever changes the radiation might cause in the dna inside skin cells.

Title: Re: How is the risk of skin cancer affected by dose distribution in time?
Post by: Atomic-S on 22/06/2012 05:47:37

Interesting. I wonder if that holds true also for other types of ionizing radiation, such as gamma rays, that reach deeper into the body and have higher quantum energy.

Title: Re: How is the risk of skin cancer affected by dose distribution in time?
Post by: Atomic-S on 22/06/2012 05:53:06

Another issue is, although you say that when actual sunburn sets in, the risk of cancer increases significantly, would that mean that if the intensity is spread out sufficiently, the risk goes to zero? That is, per joule of radiation. If a joule of radiation be spread over a long enough time and wide enough skin area, the probability (per the joule) goes to zero, or is there some irreduceable minimum risk no matter how dilute the dose? But if there is, is it significant?  (I.e., a risk of one case per 10,000 years does not mean much in a species that rarely lives beyond 100).