If the story of the rat poison is true then your friend was dealing with a bad AK. I've taken stuff to an AK in a sandwich bag and it has worked fine. If you are allergic to plastic I am sure it would test bad. Most people aren't allergic to plastic. You are confusing acute toxicity and chronic toxicity. Most people won't see bad health results from short term exposure to plastic. Most people don't see negative health results from smoking one cigarette either. Smoke for thirty years and it may be a different story. Alcohol is the same. Regardless of what some of the studies have said, alcohol is bad for the human body. It completely dehydrates the cells. Look at all of the health problems that are related to it. Yet unless you are allergic to it then it probably won't test bad. Metal containers can't be used to test with but plastic is fine. Glass is probably the best, and most of an AK's test vials are made of glass.