This is the attention-getting title of an article in Mother Jones magazine (March/April 2014). In contrast to materials like glass, porcelain, pottery, steel and aluminum, it’s easy to be suspicious of plastics. But are they really unsafe?
Glass, porcelain, pottery and metal are inherently safe containers for food and liquids because even if they contained a small amount of a toxic substance, e.g., lead, it could not escape because of the impermeability of these materials. Plastics on the other hand may contain traces of toxic chemicals used in their manufacture and such chemicals could, in some circumstances, diffuse out and contaminate food or water in contact with the plastic.
Formerly the gorilla of the group of bad plastics was polycarbonate, because Bisphenol-A, or BPA, would leach out and it is a strong endocrine disruptor, i.e., mimicking and interfering with the body’s natural hormones. Fortunately, polycarbonate containers have essentially disappeared from the market, to be replaced by a copolyester, Tritan© (made by Eastman Chemical) that does not use BPA in its manufacture. A smaller gorilla is polyvinylchloride, or PVC, because an endocrine disruptor, DEHP, can diffuse out of it.
The Mother Jones article is based on a single piece of research that reported that small amounts of endocrine disruptors escape from virtually all plastics.* The researchers subjected a wide variety of common plastics to severe stresses that could facilitate the release of possibly toxic additives, then tested water and alcohol extracts for the presence of estrogenic activity (i.e., hormone disruption). They found that “Almost all commercially available plastic products leached chemicals having reliably detectable estrogenic activity (EA).” The most likely additives that have this property are antioxidants and UV stabilizers, which protect the plastics from degradation by light and heat. However, the EA-type chemicals were released only after the plastics were subjected to extreme wet-heat, ultraviolet light, or dry-heat in a microwave oven. It is highly unlikely that the tested plastics – polyethylene, polypropylene, polyethylene terephthalate, polystyrene, and ABS – would release hormone-disruptive chemicals during ordinary conditions of use.
Nevertheless, if we follow the Precautionary Principle, we will be careful to not cook or microwave foods in use these plastics, nor allow plastic water bottles to stand around in direct sunlight (UV). Below is a summary of common plastics.
- No.1. PET/PETG, Polyethylene terephthalate, is a clear tough plastic used in plastic bottles for water, soft drinks, juice, salad dressings, cooking oils, etc. Although the name contains the word “phthalate,” the plastic does not contain any phthalate. Nontoxic.
- No. 2. HDPE, High Density Polyethylene, is a stiff translucent plastic used as containers for milk, shampoo, laundry detergents, and cereal box liners. Nontoxic.
- No. 3. PVC, Polyvinyl Chloride, a clear flexible plastic when plasticized with phthalates (such as DEHP). Although PVC may have been used for cosmetic products, it appears to no longer be the case. I examined major brands of shampoo, hair conditioners, and skin lotions and found only one shampoo in a No. 3 container; the vast majority of such products were in No. 1 or No. 2 type containers.
- No. 4. LDPE, Low Density Polyethylene, a soft translucent plastic used in stretch film, coatings for milk cartons and hot and cold beverage cups and in some squeeze bottles (e.g., honey). Nontoxic.
- No. 5. PP, Polypropylene, a stiff clear plastic that will withstand boiling water. It is used in re-use with lids food containers. Nontoxic.
- No. 6, Polystyrene, a clear, hard and brittle plastic, but usually foamed and called “Styrofoam.” Nontoxic.
- No. 7, “Other,” usually Polycarbonate, a clear very stiff plastic used where high strength is required, for example, in 5 gallon reusable water bottles. Generally not safe because of residual BPA. Some of these large water bottles are made of Eastman Chemical’s Tritan plastic, but confusingly, they also carry the No. 7 mark. If in doubt, look for the “BPA-free mark.
In conclusion, it is the author’s opinion, the majority of plastics used for storage of food, water and beverages are safe – providing that food is not microwaved in them and bottles are not left for days in direct sunlight. Note that the author has considerable experience as a plastics and polymer technical consultant.
* Environmental Health Perspectives, vol. 119, no. 7, July 2011