WHO | UV Index

Good morning all,

As we head into warmer weather, thoughts inevitably turn to outdoor activities.  With them comes, of course, exposure to sunlight and its radiation.  Natural light offers us warmth, pleasurable sensations, and stimulates vitamin D production.  As we have been discussing in lab, sunlight also contains dangerous levels of UV radiation.

One of the safety concepts we hear reported related to outdoor activities is the "UV index".  This is a scale meant to represent the relative degree of exposure risk posed by harmful UV radiation.  The World Health Organization, in partnership with other health agencies, promotes the use of this index as a way to keep the public quickly and easily informed of their exposure risk.  The index is fairly easy to interpret: low index numbers, relatively low risk; higher numbers, more risk.

https://www.who.int/uv/intersunprogramme/activities/uv_index/en/

Behind the index is a fair amount of science, in which measured amounts of UV exposure were assessed for their ability to cause cell and tissue damage.  Many of the initial studies were done without direct knowledge of what was changing in cells, or what was driving tissue damage.  Now, health scientists are able to marry environmental exposure studies to genetic studies, leading to genetic profiles for many of our genes.  For example, we now know that the gene responsible for directing production of the melanocortin 1 receptor (gene MC1R) is often mutated by UV radiation; its mutation is one of the leading agents of skin cancer.  The normal role of the MC1R gene product is to regulate the production of melanin (eumelanin) in our skin cells, the same melanin which gives us a 'tan' after UV exposure.  We all have different levels of melanin production; those of us with lighter skin produce relatively less of it and are at higher risk of UV damage.

https://ghr.nlm.nih.gov/gene/MC1R#conditions

Our lab exercise of the past two weeks demonstrated how even short durations of UV exposure can mutate DNA, and also showed how critical DNA monitoring/repair is to continued health.  The plate coverings that we used all provided some degree of protection from radiation.  While it may be impractical to cover ourselves with tin foil when we venture outside, sunscreen or even thin cloth provided very useful protection.  Remember those plates which were empty of yeast the next time you think about spending long hours in the sun - be sure to use sunscreen!

Have a great weekend -
Dr. Nealen