1. eye observation: nontoxic plastic bag white, transparent or slightly transparent, homogeneous; poisonous plastic bag is color or white, but transparency, cloudy, plastic surface tension is not uniform, with small particles.

2. listening with ears: when using the hand shake in plastic bag, makes a ringing sound that is nontoxic plastic bags; and sound small and stuffy poisonous plastic bag.

3. touch: hand touching the surface of the plastic packaging bag, very smooth and is not toxic; sticky, astringent, waxy feeling toxic.

4. smell: not poisonous plastic bag is odorless; stimulating smell or taste unusual is toxic.

5. heavy water test: put the plastic bag into the water by hand to press it into the bottom, wait a minute, surfaced for nontoxic plastic packaging bags, submerged in the water that is poisonous plastic bag.