Plastic containers should NOT be used for freezing or microwaving foods.
The internet has been flooded with warnings to avoid freezing water bottles or using plastics in the microwave. This is mainly from concerns that carcinogenic dioxins can leach out from the plastics and into the food.
Plastics do NOT contain dioxins. Dioxins are environmental pollutants that come mostly from the incineration of waste and then are taken up by animals. Exposure to dioxins can cause reproductive and developmental problems. They have also been associated with liver damage and cancer. High levels of dioxins are known to cause chloracne, a severe form of skin disease.
People are exposed to dioxins mostly from eating meat and fish rich in fat. Tell concerned people they can lower their exposure to dioxins by limiting intake of fatty foods, which are known to contain dioxins.