An AT&T official on Thursday called the health risk of cellphones a serious issue meriting more research but downplayed new studies warning of a link to a type of brain cancer. Two days after World Health Organization cancer experts warned that electromagnetic fields generated by cellphones are \"possibly carcinogenic to humans,\" the US telecoms giant\'s Ralph de la Vega said the data was not especially new. \"This is a serious issue,\" said De la Vega, chief executive of AT&T Mobility and Consumer Markets. But \"the WHO didn\'t do any new study,\" he added, saying their study was one year old. \"The industry should not have too much to worry about; nevertheless, we should continue to study\" the issue, he said at the All Things Digital D9 conference in California. Experts of the WHO\'s International Agency for Research on Cancer presented their evidence at a conference in Lyon, France on Tuesday that suggested mobile phone users may be at increased risk of glioma, a malignant type of brain cancer. Although they cautioned that the scientific evidence showed only a possible link, not a proven one, they recommended the most intense phone users make use of texting and hands-free devices to reduce exposure to the dangerous fields. \"There is some evidence of increased risk of glioma\" and another form of non-malignant tumor called acoustic neuroma, said IARC scientist Kurt Straif. The global wireless industry group CTIA-The Wireless Association disputed the significance of the report, citing possible \"bias\" and \"data flaws\" in the studies.