I suspect nothing - Lead is unique in that the cognitive effects of exposure can cause societal collapse if widespread enough. We have other environmental cont

I suspect nothing - Lead is unique in that the cognitive effects of exposure can cause societal collapse if widespread enough. We have other environmental contaminants that are bad but broadly, they don't have the cognitive effects of Lead - biologically you can survive lead exposure - meaning you wont die - but the cognitive exposure of Lead in my opinion puts it in a category of its own.