I remember reading a study of cadavers that found everyone has microscopic cancers throughout their bodies, throughout their lives. It seems there's a dance between evironments that drive the proliferation of micro-cancers and our body's ability to repair this damage.
This panel by the Mars Society actually had a very interesting discussion of this area of human health that deserves much more study. https://youtu.be/sFHQlobJbwY
http://en.wikipedia.org/wiki/Hormesis http://en.wikipedia.org/wiki/Radiation_hormesis
I imagine that vitamin D production and DNA damage are separate events. Presumably, both can occur at the same time.
So would someone who took vitamin D supplements but didn't get sun exposure be slightly less likely to develop cancer than someone who got just enough sunlight for their body to produce enough vitamin D?
If that's the case, it's not really a general rule that small exposures to carcinogens prevent cancer.
Is a farm worker more likely to contract cancer from the 8 hours/day exposure to sunshine, or to glyphosate?
I personally have no idea, but I think it would be an interesting measure.
http://monographs.iarc.fr/ENG/Classification/Classifications...
Carbon monoxide is toxic. If I breath it while walking a previously fired forest, I feel bad today. If I breath too much I die. But if I get out alive tomorrow my body will be fine.
Carcinogen work in totally different ways. If I contact or breath it I will feel fine today but I will have created damage to some of my cells DNA. This damage will create other damages when 5 years from no my cells transcribe some genes in a chain reaction, or will accumulate errors over time.
Five years from now one of the damaged cells will start replicating itself without control, and I will get cancer.
We get cancer by indirect ways, and delayed in time, on people that are not isolated so it is hard to get the cause effect relationship.
I worked in a Hospital for some time. On oncology got people that smoke 3-4 cigarettes packages a day that got pulmonary cancer, but they were seriously convinced that smoking had nothing to do with it.
It took decades to establish a relationship between smoking and cancer, and that was with half of the population smoking. With smaller populations it becomes harder and harder.