For manufacturers it is the issue that refuses to go away and a source of litigation that could bankrupt an entire industry. For millions of users taking part in arguably the world's largest science experiment, it is little more than a passing thought before making the next call.
But for brain cancer victims the question is whether science will ever prove their suffering is caused by the world's most successful portable device - the mobile phone.
The debate is more than a decade old, but with an estimated 1.7 billion cellphone users worldwide and 650 million units expected to ship this year, the stakes get higher for manufacturers and users the longer it takes for science to come up with the answers.
While the world's largest mobile phone manufacturers - including Nokia and Motorola - are sued by six brain cancer victims in the United States who claim the defendants failed to warn consumers about adverse health risks associated with their products, a growing number of smaller companies are cashing in on public uncertainty with a new breed of 'safe' phone.
G-Hanz EMF Telecom, a joint venture between G-Hanz and biotechnology company EMX Corp, claims radiation emitted from its handsets is rendered harmless by superimposing a random noise field that is neutral to human tissue, 'thus mitigating the possible harmful effects to human cells'.
'The biologic effects of mobile-phone use are proven but subsequent health effects are not,' G-Hanz EMF Telecom chief executive Uday Ghosh said. 'We cut out the biologic effect so there is no question of health issues.'