Those test swabs work quite well. They are designed to test ceramics, clay etc. You can find them in pottery supply stores. If trying on food,I would soak or b

Those test swabs work quite well. They are designed to test ceramics, clay etc. You can find them in pottery supply stores. If trying on food,I would soak or boil that food to reduce water and thereby increase concentration if there is any. You could add lemon to the water, as acids (vinegar for example) help extract metals. The problem is you don't get an actual number, just over a certain limit. I think it might be 50 ppm. But it's been twenty years, so please check that number. Alternative is to send to a lab, ask for a 32 element icp. Should cost between 50-150$, especially if you state you don't need chain of custody proof. You will get 32 elements. Which is fun. (Can even look for gold, but that's extra $ testing.) Lead naturally occurs in the environment, depending where, in the world you are, from 2 to 20 even UpTo 50 ppm. Industrial/commercial sites are common to have up to 150ppm. Contaminated toxic sites way over that, over a thousand. We could go on. But the swabs work as a starting point.