Yet another body is warning of links between cellphone use and deadly brain cancer.

The WHO/International Agency for Research on Cancer (IARC) today announced it would classify radio frequency electromagnetic fields as possibly carcinogenic to humans, based on an increased risk for glioma, a malignant type of brain cancer associated with wireless phone use. Glioma made up 2/3ds of the new cases of brain cancer identified worldwide in 2008, the WHO/IARC said.

With some 5 billion cellphone subscriptions in use worldwide however, the question is, will the decision change anyone’s behavior?

On one hand, it could lead to an increase in use of hands-free devices that keep the RF antenna away from the user, as recommended by IARC. That would mean a corresponding increase in business for electronics manufacturers.

On the other hand, most users are likely to consider this warning with the same mock seriousness they give to sunscreen. It is highly unlikely that the emerging markets, few of which have built out landline infrastructure, will reverse course and spend the billions (or more) needed to offer an alternative to cellphones.