The question of whether cell phones cause cancer, especially brain cancer, has sparked a lively debate in the scientific community this year. And a large Danish study released on October 21 provides new evidence for the view that cell phones do not cause brain cancer. The new round of discussion was sparked by the International Agency for Research on Cancer. In May, the research center released a report saying that long-term, high-intensity use of cell phones and other wireless communication devices may increase the chances of developing cancer. But the conclusion was then questioned by some wireless communication industry organizations. In July, the Cancer Research UK issued a report on this issue, saying that the available evidence does not prove that the use of cell phones causes cancer. Researchers from the Danish Institute of Cancer Epidemiology and other institutions reported in the latest issue of the British Medical Journal that they investigated the data of all Danish people born after 1925 and aged 30 or above, and they were divided into two groups of cell phone subscribers and non-mobile phone subscribers according to the contract information of cell phone operators, among which there were more than 350,000 cell phone subscribers. At the same time, the researchers investigated the number of brain cancer patients in Denmark between 1990 and 2007, the period when cell phones became widely used. The results showed that there were more than 10,000 cases of brain cancer, but there was no significant difference in the rate of brain cancer for the two groups of cell phone subscribers and non-cell phone subscribers. The researchers said the study is strong because it covers the entire Danish population, the sample size is large enough and the results are more credible. But it also has shortcomings, namely that the criteria used to divide the two groups was cell phone sign-up, which does not fully reflect how they use their phones, and some users use their phones much more frequently than others, and the study did not distinguish between this group of heavy users. Overall, the results of this study support the view that cell phones do not cause brain cancer. Whether there is a causal relationship between cell phone use and cancer, especially brain cancer, needs to be further studied by the scientific community. Currently, the scientific community and national regulatory agencies are emphasizing the point that adolescents should use cell phones with caution. The ears and skull of teenagers are smaller and thinner than those of adults, and the radiation absorbed by their brains when using cell phones is said to be 50% higher than that of adults.