Pong Research makes cases that it says reduce radiation levels for iPhones and BlackBerrys.

Editors' note: Updated June 1, 2011.

We do a lot of top products lists here at CNET, and manufacturers are usually pretty excited to see their products on those lists. But this is one "top" list that manufacturers probably aren't too thrilled to find their products on.

As we note in our intro to the list, for a phone to pass FCC certification and be sold in the United States, its maximum SAR level must be less than 1.6 watts per kilogram. In Europe, the level is capped at 2 watts per kilogram, whereas Canada allows a maximum of 1.6 watts per kilogram, just like we do. The SAR level listed in our charts represents the highest SAR level measured with the phone next to the ear as tested by the FCC. It's possible for the SAR level to vary among different transmission bands (the same phone can use multiple bands during a call), and different testing bodies can obtain different results.

I should also add our usual disclaimer when discussing cell phone radiation levels. As editor Nicole Lee says, we are in no way implying that cell phone use is harmful to your health by publishing this list. Research abounds, but much of the literature is contradictory.

Though some researchers, including the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, have recently stated that cell phones could possibly cause cancer, others disagree and say there still is not conclusive or demonstrated evidence that cell phones cause or don't cause adverse health effects in humans. In short, the jury is still out. Research into the matter will continue, and we will continue to monitor its results. (For a more complete list of SAR ratings for various phones, check out our full Quick Guide to cell phone radiation levels.)