Water detection: in a bucket of water into a plastic bag, the plastic bag into the water when the non-toxic, can emerge; and poisonous plastic bags are not to be floating.
Hand-touch detection method: touch plastic, lubrication sense by toxic; otherwise toxic.
Jitter detection method: Hold the plastic one, hard slap, issued by the crisp sound of it toxic; otherwise toxic.
Fire detection: You can cut one side of the bag, with fire, toxic combustion is not easy; it is non-toxic, easy to burn a fire.
