My laboratory works on the health effects of contaminants from plastics and other environmental sources. With respect to what you note above, I would make some additions and corrections:
PETE does not leach bisphenol A, it is an entirely different type of plastic. There ARE some clear hard plastics labeled as BPA free that, in fact, contain bisphenol S and bisphenol F, both of which are comparable in their effects to BPA. But these are not PETE. However, there are reports of plastic beverage containers leaching chemicals that interfere with estrogen and testosterone receptor action and some of these must be PETE...
PVC has both phthalates (small amount) and organotins (quite high amounts), neither of which are particularly good for you. Both leach at relatively slow rates, but the leaching of organotins is detectable and certainly not beneficial. Some of the phthalate replacements (such as tributylcitrate) are also turning out to be problematic. The main problem is that there are few requirements for materials testing before use beyond relatively simple gross toxicity tests that protect you from acute poisoning. Testing for long-term effects is almost non-existent and nearly all safety testing is performed by the manufacturers of the materials themselves.
Group 7 is a "catch-all" for various types of plastics. It includes some types that you would rather not be exposed to such as polycarbonate (which leaches bisphenol A, particularly when you heat the plastic) as well as modern, biodegradable plastics that are much better for the environment.
Personally, I would prefer polypropylene and HDPE plastics whenever possible for aquarium water storage as they leach the least amount of miscellaneous stuff. LDPE plastics leach a fair amount of stuff into liquids - for example the "plastic-y taste" which is phthalates for the most part. Having said all this, I use HDPE barrels for my RO-DI water and pump this into an old 45G hexagon aquarium for salt water mixing and storage. The best way to avoid leaching of things you don't want into your water and food is not to store food and water in plastic for extended periods of time.
Bruce
