UPDATE:
A few months after I posted this, PUR finally contacted me with an intelligent response.
They apologized (again) and explained that their RF-9999 DOES in fact contain ion-exchange resin.
I don't know whether or not I should be surprised that it took them this long to come up with a response. Perhaps they assume that most people will have no idea what ion-exchange resin is and will therefore not ask about it or look for indication of it on the packaging.
Also, other people have responded to my review with useful comments. Check them out. For instance, one commenter explains this product's certifications.
My original review:
I own a PUR faucet attachment that takes the RF-9999 filter replacement cartridge. Out of concern for my baby girl's health, I wanted to make sure that the water we mix in her formula is free of lead and other heavy metals. The copper pipes that carry water in your house have enough lead content (to make them flexible) that water sitting in the lines for a few hours can build up unhealthy levels of lead that can cause all manner of developmental problems in children. For your health and that of your children, it's best to be sure to flush your water lines before consuming tap water. Take a shower in the morning and run your faucets a little before you make coffee and mix formula. (Save the flush water in old milk jugs for watering your plants.) As added protection, it's also a good idea to use a water filter with ion-exchange resin that will filter out residual heavy metals.
I noticed that the product description of the RF-9999 on Amazon.com mentioned that it includes ion-exchange resin. But when I looked at the filter's packaging and the PUR web site, there was no mention of it, although the product does claim certain certifications regarding reduction of various heavy metals, including lead. According to PUR, the RF-9999 filter contains something to trap sediment, activated carbon that they claim also reduces lead, and some minerals. I spoke with a hydrologist from the U.S. Geological Survey about this, and he explained that activated carbon is largely ineffective at trapping heavy metals and that none of the other components of the filter would have any effect either; only a filter with ion-exchange resin would be able to significantly reduce the lead content.
Thus, I contacted PUR to inquire as to whether or not the RF-9999 contained ion-exchange resin, and if not, I wanted to know how it filtered lead and to inform them that Amazon.com's description might be inaccurate. First, I got an automated response that seemed to have nothing to do with my question, so in accordance with their instructions, I replied, explaining that my question had not been answered. The reply to this was that they were sorry I was having trouble with their product (I had not reported any problems), and that they'd be happy to answer any questions I had. So, apparently, they lost my question. So I replied to that, repeating my question. The next respond quoted my previous email (with the question in it), and again apologized for the trouble I was having with their product, and told me that they'd be happy to answer any questions I had. I responded again, heading my email with another copy of my question. This time, I finally got something resembling an answer, but it was a brief and vague statement that the information on their web site was accurate. They said nothing to reassure me that there was anything in their product that could account for their claim of being able to reduce lead in the water.
Perhaps the people at PUR I was corresponding with were just incompetent. I can't expect the customer service contact to know anything about chemistry or hydrology, but it irks me when they don't take my question seriously enough to inquire internally to get me a proper answer, especially when I'm trying to take steps to safeguard my family's health. Besides Amazon.com making inaccurate statements about this product (probably told to them by someone at PUR), PUR's web site and packaging make claims that do not appear to stand up to basic scientific scrutiny. As far as I can determine, there's absolutely nothing in the RF-9999 that would be able to reduce lead content in water by any appreciable margin.
If you are buying water filter products, then you're probably doing it not just to improve the taste of the water, but because you have a clue that there are things in your city or well tap water that you might not want to drink. Be fully informed about these things, and never trust your health to product claims that you haven't verified.