I don't believe that there's any lead present in either flexible or rigid copper tubing. However, I think you might have heard one or both of the following:
1) Brass and bronze are copper alloys, and most (maybe all) types contains at least some lead for machinability. If brass is to be used in a brewing application--which is typically acidic--you can and should "pickle" brass to remove surface lead. I, for instance, use brass ball valves on my mash/lauter tun and on all my brew kettles. I am still alive... I think.
2) Lead solder was the norm for making connections in copper (and other) plumbing for years, but has now been replaced by other, reputedly less toxic forms of solder. Some say that even this isn't safe, particularly in an acidic brewing environment, but I'm willing to take my chances. I think you're more likely to consume more lead and other toxins straight from groundwater than will be leached from your plumbing.
I'm not a metallurgist or anything similar, so I'd encourage you to do more research from sites that are more likely to have real information on this subject. That said, it's highly doubtful that a copper coil in your brew kettle serving as a wort chiller is going to have any adverse effects. After all, copper was and still is used as the material for brew kettles in major breweries around the world.
