Whenever I see articles like this I wonder the same. In theory it is possible to trace back where anything one buys came from, in practice not so much because almost inevitably you'll hit a company along the production/shipping chain refusing to disclose information. But yeah even if it were, a home test would still be a better source of truth. Assuming the test is correct. Lead tests are fairly common though (because of historic lead painting and water piping) and in some countries sort of regulated so that shouldn't be an issue. As for any other pollution: it might be saner in the end to not worry about it too much, there's just so many things which can go wrong.