The following red highlight is quoted from a website " 5. PP: polypropylene. PP is used to make yogurt containers, deli food containers and winter clothing insulation. PP actually has a high heat tolerance and as such, does not seem to leach many of the chemicals other plastics do." However, as far as I understand, the melting point of PP is usually only around 100-120 degree celcius. And PP made container is not suitable for microwave oven, in that case, why it is considered to be "high heat tolerance"