I looked at one online and it was $189!!! That's A LOT of money to spend on something that may or may not do what it claims to do. Have any outside sources (not the people who created or manufacture zappers) tested whether or not these things actually do kill bacteria, viruses, parasites, etc? Also, has an outside source tested whether or not it is truly safe to use? I'm looking for concrete proof of the zapper's safety and effectiveness... not personal experiences where people found what they believe to be parasites in their poop.