Thanks for sharing the interesting observation, Eveheart.
Re: phytoestrogens, research was coincidentally just reported as finding that BPA is "present in far too small amounts in most people's bodies to cause suspected health effects" (Read more here: PNNL analyses: Is risk from plastic water bottles inflated?
http://www.tri-cityherald.com/2013/03/31/2336664/pnnl-research-tests-bpa-risks.html#storylink=cpy), but that finding doesn't persuade me in the slightest to start using plastic more because I think that the factors of increased spoilage, inferior taste and smell, promotion of bad bacteria and inhibiting of good bacteria, and the fact that fat is difficult to clean off of plastic containers (it apparently has to do with similar molecular structure--http://www.thekitchn.com/tip-store-bacon-fat-in-glass-n-138153) are more than enough reason to minimize use of plastic with food. While rare, increased risk of death via botulism, which has become a significant problem with Eskimos who store raw meats long term in plastic, certainly gets my attention.
I find the problems to be significantly less in the freezer than the fridge, so I do leave frozen foods in the plastic they come in and use plastic storage bags quite a lot in the freezer. Whereas with the fridge, I try not to leave food in sealed plastic for more than a day or two. If it's going to be there longer, I transfer it to a glass, metal or paper container (note: some foods don't do well in metal), or leave it exposed.
At any rate, for me, the default position is to not use food containers that haven't been used extensively for centuries or more in their current basic form/substance. The jury is out on inventions with potential significant downsides until thoroughly proven. I try to mainly use the more tried and true things and let others be the guinea pigs.
When it comes to tried-and-true things that I haven't tried myself and may have gone out of fashion for no good reason, I become much more the adventurous mad scientist.