There is a basic assumption most consumers have – if it is on the shelf it must be safe. It must be safety tested. But this is just not true.
There is actually no safety testing going on regarding most products because industry is now running government. Actually, there is less safety testing going on now, than there was 20 years ago.
Plastic leaches, it is full of chemicals which are extremely toxic to the organic body, and the planet as nothing is recycled we are learning. All plastic breaks down, leaching into all food and water, especially if the food or water is sitting for any length of time in the plastic and/or it has been exposed to any heat source.
The resources below explain the dangers in plastics well with the chemicals listed and the dire health implications as a result. One of the best things you can do for your pet?
Meeker, J. D., Sathyanarayana, S., & Swan, S. H. (2009). Phthalates and other additives in plastics: human exposure and associated health outcomes. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 364(1526), 2097–2113. https://doi.org/10.1098/rstb.2008.0268