A week after the US released serious warnings about health issues associated with cellular phone use, the Health Ministry on Sunday published advice on cellular phone usage. According to the Health Ministry, as not enough research has been carried out on the topic, maximum care must be taken. The report recommended limiting children's exposure to cellular telephones, using a speaker or earphone which is not wireless, and keeping phones away from the body whilst not in use. A recommendation to avoid talking in shielded areas, such as in elevators or trains was also published. The Health Ministry added that the high level of radiation emitted from the antenna of a cellular device was likely to cause health problems by warming the body ('the thermal effect'), the implications of which would be researched in a further line of studies.