Mapping Lead

Somebody should develop a website that maps lead content in soil. Is there such a thing? Users could have their soil test and then post the results.

I've been doing some gardening. My guess is that our house (in Philadelphia) has lead. The neighbors three houses down have lead. I could test the soil, or if there was a website and most of the houses in my area that were tested had lead I could just assume we had it.

As it is, I'm digging out 4 inches of the original soil and buying top soil (giving me 4-10 inches of bought soil on my garden thus diluting my lead levels). One blogger who tested garden soil found it to have 0-10 ppm lead - which is low. My guess is that my soil has 100-500 ppm lead.

Or someone should systematically test for lead levels block by block...