Read the following article and select the best answer. Article: The worldwide increase in the use of cellphones has caused concerns regarding possible harmful effects caused by cellphone radiation. People are particularly concerned that the radiation will put cellphone users at a higher risk of suffering from cancer. However, studies of the association between cellphone use and the risk of brain cancer have reached different conclusions(some, but not all, studies showed increased risk). Researchers conducted a study to examine if cellphone radiation affected regional activity in the human brain. The study, conducted between January 1 and December 31, 2009,included 47 participants. Cellphones were placed on the left and right ears, and brain imaging was performed to measure brain glucose metabolism twice: one with the right cellphone activated for 50 minutes("on" condition) and once with both cellphones deactivated("off" condition). An analysis was conducted to check the association of metabolism and cellphone radiation. The scans were compared to assess the effect of cellphone use on brain glucose metabolism. The researchers found that whole-brain metabolism did not differ between the on and off conditions. However there were regional effects. Metabolism in some brain region was higher (about 7 percent) for cellphone on than for cellphone off conditions. This indicates that the regions expected to absorb more cellphone radiation were the ones that showed the larger increases in glucose metabolism. These results provide evidence that the human brain is sensitive to the effects of acute cellphone radiation. However, how cellphone radiation could affect brain glucose metabolism is unclear. Concerns have been raised by the possibility that cellphone radiation may _ brain cancer. Results of this study provide evidence that acute cellphone radiation affects brain metabolic activity. However, these results provide no information as to their connection regarding possible carcinogenic effects (or lack of such effects) of chronic cellphone use. Further studies are needed to... Question: What does the passage mainly talk about? - The current situation of cellphone use. - To phone or not to phone. - The link between cellphone use and brain cancer. - Long-term harmful effects of cellphones.
The link between cellphone use and brain cancer.