Yup.
To expand on James' post:
Most food product containers are PET or PETE, Polyethylene terepthalate, also known as polyester. It's probably one of the safest plastics generally, but with a few possible exceptions all plastics degrade and all degradation results in the formation of different chemicals.
For PET the basic concerns are BPA, Acetaldehyde, Antinomy derivatives and pthalates. These things can form as a result of high temps, hydrolysis and bacterial/biological breakdown.
BPA is the well known, endocrine disrupting carcinogen we all love to hate.
Here is a pretty thorough overview of the literature on BPA, including the interactions between government and the scientific community. In a nutshell, early studies showed that yes it is toxic, but has a short half life and the body can handle it. More recent studies showed lasting impact at dosages "orders of magnitude" below the current max safe dosage. Primarily it's an endocrine disruptor.
Pthalates are also something many people are familiar with; the body of research on these guys is pretty clear that it leaches easily, is an endocrine disruptor, does a number on the liver and especially affects pregnant mothers and children.
Acetaldehyde, produced mainly from heat exposure, is a methyl organic compound that is a known carcinogen. It's found in higher doses in your average cup of
coffee or fruit juice than in plastic contaminated water, and actually forms naturally in your body as part of the liver's day to day activities, but consistent exposure of sufficient doses can be harmful long term.
Antinomy is an element (Sb) that is used in PET plastic manuafacture. In addition to being bound up in the plastic often a layer of it forms on the surface. In and of itself, Antinomy isn't toxic and your body does a pretty good job of handling it. At sufficient temps, however, it can form stibine (SbH3) an extremely toxic compound with a lethal dose in
mice of 50 ppm. At anything over 5ppm the CDC
recommends a full breathing apparatus. The most definitive study to date found that Antinomy and its derivatives are found in all PET containers, just at a dose they find acceptable, but that over 60 degrees celsius (140 F), it exceeded their own standards for safety by a very large degree. That study can be found
here, and is the reason I chew people out here in Texas when I find out they've had a case of water bottles in their trunk for two years "in case of emergency".
So yes, the containers are bad. It's really just a question of how bad, and what the alternatives are.