The commonly used food plastic bags are mostly made of polyethylene film, which is non-toxic and can be used to hold food. There is also a type of film made of polyvinyl chloride, which itself is non-toxic, but the additives added to the film are often harmful to the human body and have a certain degree of toxicity. So these types of films and plastic bags made from them are not suitable for holding food. To distinguish between polyvinyl chloride plastic bags and polyethylene plastic bags, the following simple method can be used for identification.

Polyethylene film (non-toxic)

The film is milky white in color, semi transparent (especially noticeable when stacked several times), and feels relatively smooth to the touch. It seems to have a wax layer on the surface. When shaken vigorously, the sound is crisp, and it is flammable when exposed to fire. The flame is yellow, with sticky droplets and the smell of burning candles.

Polyvinyl chloride film (generally toxic)

If no pigment is added, it is transparent and feels a bit sticky on the surface. It shakes hard and has a low voice. It is not easy to burn when exposed to fire and extinguishes when away from the flame. The flame appears green.