Plastic is a part of our lives and will not be leaving anytime soon. Professor Fredrick S. vom Saal, a professor of biology at the University of Missouri, recommends using plastic items made with number 2 (high-density polyethylene) or 5 (polypropylene). When using the other plastics, follow these guidelines:

Recycle, do not reuse: Use the product only for what it was intended for. Do not reuse bottles or microwave trays if they were not made to be reused.

Keep the heat away from BPA: Do not warm bottles made with BPA in the stove or microwave, don\'t put boiling water in them, and do not place them in the dishwasher.

The key to using plastic safely is to use it as it is recommended

Source : Medicine Net