That danger is PVC.
PVC or polyvinyl chloride is dangerous to human health (associated to cancer, hormone disruption and severe health problems) and a danger to the environment as well.
I came across these tips from http://www.mtp2.org/healthy_schools_files/PVCFree.pdf and the following should be avoided because they most likely contain harmful components like polyvinyl chloride, polycarbonate and polystyrene plastics collectively considered toxic plastics:
- Notebooks containing metal spirals encased in colored plastic. (Oh no! I used this before when I was a kid till high school)
- Backpacks with shiny plastic design.
- PVC rainwear (will tell you later what identifying marks will point to something as made of PVC)
- Colored paper clips
- Shiny and colorful plastic umbrellas
- Lunchbox made of PVC which are said to be many
- Some plastic drinking containers
- Notebooks with uncovered metal spirals
- Stick to plain metal paper clips
- Use nylon umbrellas
- Use cardboard, fabric-covered or polypropylene binders
- Use cloth or metal lunch boxes
- If cannot avoid plastic, use plastics of the polystyrene or polycarbonate type