Good Morning to all, I too feel uneasy about growing food in large 5-galllon plastic buckets because I don't know what is leaking from the container into the plants that produce the food I eat. I've done it, but no longer.
Here is what I do, I start seeds in the shallow black plastic you get when buying ground beef. I think if it is safe enough for raw meat, it will be safe enough to use to start seeds. Then, I transfer the seedlings into large clear plastic drinking glasses I purchased from Walmart about 6 years ago. Use them, empty them, wash them and store them in the garage until next season. From those containers I transfer the seedlings into the large cottage cheese or yogurt containers, then into the ground. Again, if it safe enough for ground meat, cottage cheese and yogurt, it's safe enough to grow seedlings.
I especially like the clear plastic drinking glasses (which one of my brothers told me is an oxymoron) for rooting rosemary stems. In early September I cut the stems about 6" down from the top, dip them in a rooting compound, and into the containers filled with a mixture of potting soil and perlite. I like these containers because I can monitor the root growth and can see when it is time to put them into larger containers.
In past years I have used the 5-gallon buckets for growing hot peppers because in my area the rabbits eat the hot pepper plants, along with beet greens, Brussels spouts plants, green beans and I forget what else.
This year, we are going to grow potatoes in cardboard boxes. As another contributor said, they are safe, and free. What's not to like?
This morning I was on You Tube and watched a video on "Plant Abundance" channel. One of the comments was from a women who used a hanging shoe container, the type that hangs on the back of a door, to grow herbs. The containers are made of canvas which drains. Sounds like a good idea to me. I also like the suggestion about sewing growing containers out of burlap, canvas, or white cotton fabric, the cotton container will probably not last more than one growing season but might be safer than the 5-gallon containers.