How to distinguish between non-toxic and toxic plastic films? Common identification methods include sensory inspection, combustion testing, and water immersion testing.

Sensory Inspection: Polyethylene (PE) and polypropylene (PP) films have better transparency than polyvinyl chloride (PVC) film. They have a waxy luster on the surface and feel smooth to the touch. In contrast, PVC film appears milky white, has poorer transparency, feels sticky to the touch, looks dull in color, and has an overall poor appearance.

Combustion Identification Method: Polyethylene is easy to ignite. Its flame has two colors: yellow at the top and blue at the bottom. It gives off a waxy smell, produces no smoke, and continues to burn after the ignition source is removed. Polypropylene is similar to polyethylene, except that it produces a small amount of black smoke and has a petroleum-like smell. Toxic PVC, on the other hand, is difficult to ignite. Its flame also has two colors: yellow at the top and green at the bottom. The flame appears spluttering, produces white smoke, and gives off a pungent, acrid odor. It extinguishes as soon as the ignition source is removed. Because PVC film is toxic, it should not be burned in the kitchen to avoid air pollution.

Water Immersion Identification Method: This method is both simple and practical. Submerge the plastic bag in water and press it down with your hand. After releasing it, if the bag sinks and stays submerged, it is generally toxic. If it floats to the surface, it is generally non-toxic.