Yes, foam is water resistant, but not water repellent. Over time, water vapors will penetrate and degrade the foam.

You should always paint or cover foam that will be exposed to sunlight. UV rays will cause the foam to discolor and degrade.

Never use spray polyurethane foam around fire or flame. The chemical composition of foam means that any one-component foam has the potential to combust.

When food is stored in plastic containers, a certain amount of plastic can eventually get into the food. It is very small, but it increases if the food is hot or if the food has an acidic or fatty content. Another one of the plastic chemicals that has drawn attention to its adverse effects is called BPA, which is why many plastic products are now made "BPA-free."

It is safer to avoid storing food in plastic containers and using glass, ceramic or stainless steel containers. But if you're using it, use high quality , food grade, BPA free plastic. Do not use it in the microwave to heat food or serve hot food. Discard scratched or distressed plastic containers.

No you don’t have to worry about it. The plastic boxes used for microwaves are made of the material which won’t harm us. It is safe to use the plastic boxes as they take care of the purpose they are making it for before manufacturing.

Before the number, just know that the triangle too conveys a message, about recyclability of Plastic material. The number insider triangle indicates the type/ category of Plastics which should be kept together before subjecting it to melting and recycling. Not all Plastics are the same and one type of Plastic when mixed with another type, might either spoil the whole mix or mostly it would remain incompatible. So in simple words, any plastic should be checked for its recyclability number and should be kept together before melting together for recycling.