Those are fascinating observations, Indra. You remind me of something which frustrates me. Christian scholars rarely deign to explain the reasoning behind the Levitican prohibitions, such as those pertaining to things defined as unclean. As a result, lay people are apt to assume those prohibitions are based on antiquated ideas and silly superstitions. As you point out, they were actually intended to deal with practical matters. I wish scholars would at least occasionally address such topics, instead of focussing on high-minded theology and philosophical conundrums.