Plastic water containers may not be a good idea for storing water.

[Ron99]

Did they wash the containers well before use? All plastics usually come from the factory with contaminants, mold release agents etc. You can get contamination from new powerheads or other plastic aquarium equipment if you don't wash it first. Just rinsing with RO water would not likely remove all the oily residues.

I would not think enough toxic chemicals would leach out of plastic in a short time such to cause the effects they saw unless it was from surface contaminants. Their reaction is alarmist and not based on any systematic determination of the cause of the problem. They should design a proper experiment to determine the source of any problem chemicals before making a generalized conclusion.