What does the red recycling symbol with the number "1" in the middle on bottles indicate? Are these dangerous?

Answer 1

These are not dangerous. That tells you the type of plastic that the container is made of. When plastics are recycled, they must be sorted based on the plastic type. Since it is not always evident which plastic is which, the type is labeled with a sorting number.

Answer 2

someone told me it means how many times the plastic has been recycled. Nevertheless, use the ones with the number 4 or more to store your water.