With wrap film packaging food should be pay attention to?

When you go shopping, the store's habitual grabbed a plastic bag to dress up you, also don't care if you buy the food, this picture can be seen everywhere in life. But I don't know if as a consumer, what are the membrane bag can be used for packing food? We are without additives commonly used packaging materials, such as polyethylene, polypropylene, use these data manufacturing feed bags, cans, such as snack box is non-toxic, how to identify plastic products can be harmful, you use the following several ways for your reference: cut a sample of the article, using tweezers, on extinguish alcohol lamp goes out, Such as soft light can substitute extinguish candles) And then check it out easily, away from the situation, fire and after fire smoked, dies scene and take breath, etc. , implement comprehensive discriminant will know what kind of plastic. Polyvinyl chloride (PVC) plastic, non-flammable, namely from the fire, fire and smoke to the bottom of the green, apex of yellow, fire destroyed after hydrochloric acid gas of comfort. Polyethylene plastic: combustible, from subsequent burning fire, flame and smoke color bottom top huang, burning, as have the melt drip, recover the paraffin wax. Polypropylene plastic: combustible, from subsequent burning fire, flame and smoke color is orange, when burning constantly have to dissolve the dropping, with oil.