Natural radiation may affect DNA

In a recent study scientists have reported that exposure to high levels of naturally occurring radiation can cause mutations in the genetic material DNA. Previously, concerns about the harmful effects of radiation tend to focus on man-made sources, such as nuclear power plants and weapons. Everyone is exposed to radiation in the environment, but the amount varies from place to place. Along the coast of India, a small area in the state of Kerala has the highest level of natural radiation in a densely populated place. Because of a 10 kilometre by 1 kilometre strip of the radioactive mineral monazite, the radiation level in this area is about 10 times higher than the worldwide average.Researchers at the University of Cambridge studied 988 Kerala residents from 248 families, including some that lived in the high-radiation area and others that lived in a low-radiation part of the state. They screened the participants for changes in mitochondrial DNA, a type of DNA that is passed on by the mother. They detected 22 mutations in the DNA sequences of high-radiation families but just a single mutation in the low-radiation families. The mutations tended to be located in DNA regions that are known as 'evolutionary hot spots' because they undergo mutations more often than other areas. However, none of the mutations became fixed in later descendants. Based on previous studies, there is no conclusive evidence that residents of this part of India are at increased risk of birth defects or another abnormalities because of radiation exposure. The findings do not mean that people living in places with naturally high radiation levels need to start packing. But the findings highlight the need to take a second look at current radiation standards and suggests that it may be a good idea to reconsider limits for workers exposed to radiation. However, more research is needed to obtain quantitative conclusions.