I'm starting some seeds (herbs that I plan to eat) indoors and was thinking about using water bottles as planters. I'm curious if any toxins from the plastic such as BPA will harm my plants and not make them edible. Your thoughts?
...Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed...
Whether your plastic water bottles would leach out BPA depends on the plastic. You need to check the recycle marks:
There is a lot of evidence that the BPA is quite toxic and there is evidence that plants can uptake it through their root systems, e.g.:
When [14C]BPA [ie. radioactively tagged BPA, tagged for them to follow where it goes] was administrated to tobacco seedlings from their roots, radioactivity was incorporated in BPAG and three unidentified metabolites. These metabolites were accumulated in the leaves after 4 h exposure, indicating that tobacco seedlings absorbed BPA through their root systems, metabolized to its β-glucoside and translocated the metabolites to their leaves. http://pcp.oxfordjournals.org/content/43/9/1036.full
they are thinking about using some plants to help remove BPAs from waste water, because they do uptake it:
Dracaena sanderiana and Dracaena fragrans plants, as representatives of native, tropical, evergreen plants with fibrous root systems, were evaluated for bisphenol A (BPA) tolerance and uptake capability...n the sterile hydroponic system with an initial BPA concentration of 20 microM, the plant could uptake approximately 50% of the BPA. The plant's ability to translocate BPA was confirmed by the detection of BPA that accumulated at the roots and stems, http://www.ncbi.nlm.nih.gov/pubmed/20304555
So you are right to be concerned, but should be OK if you can find bottles with recycle marks 2, 4, or 5.
What about using cottage cheese cartons, sour cream cartons, etc? The BPA's are hardeners, put in plastic to give it that nice hard glassiness. If you avoid hardened plastic, you will be better off.