We often hear that some types of plastics are safer or less toxic than others, but what does that really mean? There are many guides available that categorize plastics according to their toxicity. These guides can be misleading because most plastic consumer products have additives to enhance their functionality. A single plastic product can contain dozens of chemical additives. Most manufacturers don’t disclose those chemicals which makes it very difficult to assess the toxicity of a particular item.
Chemical Additives Can Be More Harmful Than the Plastics Themselves
One study tested over 400 plastic food packaging products including baby bottles, plastic bags, deli-containers, and water bottles. Most of the products leached chemicals that have estrogenic activity, meaning they mimic human estrogen, which has been linked to adverse health effects. Products that were stressed to replicate normal usage leached even more. Also, some BPA-free products leached at greater levels than BPA-containing products.
A surprising result of the study was that some of the products that leached these harmful chemicals were made of plastics thought to be safe including:
- polypropylene (yogurt cups, ketchup bottles),
- low-density polyethylene or LDPE (grocery bags, food storage bags),
- high-density polyethylene or HDPE (milk jugs, butter tubs, juice bottles).
The study went on show that in these particular materials, it was the additives and not the plastics themselves that were the source of the leached chemicals. When they tested pure polyethylene and polypropylene resins with no chemical additives there was no detectable levels of chemicals with estrogenic activity. Additives are more likely to leach because, in most cases, they aren’t chemically bound to the plastic (1).
This highlights why it’s so important for manufacturers to disclose all of the materials used in their products. Safer plastics are possible. But without full transparency, it is very difficult to determine the toxicity of any individual item.
Treatments Added to Finished Plastics May Also Be Toxic
I’m often asked if plastic fabrics such as Nylon or polyester are non-toxic. In their pure forms, they are relatively inert. However, treatments can be applied to add features such as waterproofing to nylon or wrinkle-resistance to polyester. For example, most nylon raincoats will have some type of Durable Water Repellent (DWR). Most DWRs are made with perfluorinated compounds (PFCs) which are linked to numerous health concerns and are persistent in the environment. Some manufacturers are working to find PFC-free waterproofing treatments but they are not yet as effective. See a statement from Patagonia, the outdoor retailer, on their progress with finder safer alternatives.
When you can’t determine all of the additives or treatments, here are some general tips to follow:
- Always avoid plastics known to be harmful to humans and the environment. Avoid PVC, Polystyrene, and Polycarbonate.
- Avoid all plastic products that come in contact with food or drink. If you must use plastic, avoid heating and dishwashing. When the plastic becomes scratched or damaged, throw it out.
- Look for manufacturers that fully disclose the additives and treatments used in and on their products.
- Consider how and when the product will be used to determine the exposure to you and your family. For example, a plastic storage bag used to hold paper clips is much less of a concern than one used to hold orange slices for a child’s lunchbox.