There are no dioxins in the plastic containers used to store food and water. Freezing water bottles or other plastic containers does not cause chemicals to be released. Other chemicals used in manufacturing plastics – phthalates and bisphenol A (BPA) – may be released when plastic containers that are not specially manufactured for microwave use are heated in a microwave oven. Some studies have confirmed that substances used to make plastics can leach into food, however phthalates do not bioaccumulate (the body does not retain them; they are lost faster than they are absorbed) and the level of exposure to both substances is so low it is unlikely to be harmful. There is limited evidence that BPA causes cancer in animals, however at present there is no evidence that BPA or phthalates cause cancer in humans. Follow manufacturers directions about use of plastic containers, wraps, bags and utensils when cooking or storing food. Only use cookware in a microwave that is manufactured for microwave use.