I knew without a doubt I would get "in trouble" for #2
FWIW I'm not condemning anyone for using "cubes", they're awesome. This is a fantastic method, and I am all about dispelling myths, assumptions, and generally uninformed opinions in the brewing community (and society in general). I just think corny's should be given a closer look, we already have them, and they are indestructable, affordable, multitaskers that can ferment, age, carbonate, and serve. Plus I don't want any more carcinogens getting in the way of my alcohol
Here's what I base my opinion from:
1) Above all, common sense. Plastics and many other substances in general may be food grade at low temp, but once heated, their molecular bonds begin to weaken and substrate chemicals are given off, if even in small amounts. The plastic vessel may maintain its general shape, and may also return to its original shape once cooled. This is what plastics and polymers do, and that is why we like them. But it's not a good idea to ingest food items that have been in contact with them when they have been in a highly "plastic" state. The FDA does not recommend that you heat foods in plastic vessels for this very reason.
2) The jury is still out on #2 HDPE, the FDA is currently doing a 5 year study that has not concluded. It will be a while before we get any major authority to release their findings because of the red tape and $$$ involved, but HPDE is currently considered safe for food AT LOW TEMP. It is not advised to heat foods in it. Here's an old, but still relevant article. See what it says about what goes into making HDPE:
http://www.mindfully.org/Plastic/Dont-Buy-Plastics.htm Again, I am not an environmental nut, but I do care about mitigating risks whenever possible (after a few pints, all bets are off
)
3) I have extensive medical and scientific education, which I will not go into for liability reasons. Again, this is in part what I have used to form MY opinion...it does not mean that you should do what I do because I have such training and education. This is my opinion based on available information.
I encourage everyone to seek their own answers from available evidence based research that is out there. I personally choose to "limit but not eliminate" the amount of heated plastic I use in my brewing, such as using silicon tubing versus braided vinyl.
All this is just one example of a potential risk I can control in my brewing process, others are using better bottles vs. glass, or using fermcap to prevent scalding myself. If you can prevent injury or illness in yourself & friends, why wouldn't you?
FWIW. IMHO.