My cells had grown well in 40 mM arsenate in glass tubes, using two different frozen stocks and fresh and stored medium. But they didn't grow at all in the disposable polypropylene tubes (pp tubes). So I did a quick test of how the pp tubes inhibit growth. Here's the experimental plan I drew on the whiteboard outside my office:
I took cells from the glass-tube cultures and put them into (1, group on the left) glass tubes with arsenate medium from the pp tube cultures, (2, group in the middle) glass tubes with fresh arsenate medium, and (3, pp tubes with fresh arsenate medium).
And here's the results:
Thick growth in the glass tubes, even in the medium containing the corpses of cells that died when this medium was in plastic tubes. No growth in pp tubes.
So the pp tubes don't cause some stable toxic change to the medium.