High density polyethylene, or HDPE, is a type of plastic that’s often used to make bottles, including milk bottles, food containers, and shampoo bottles. It offers high levels of chemical resistance, and is more resistant to mineral oils, acetone, and hydrogen peroxide than PET bottles, which is why this type of plastic is frequently chosen to hold acid-based cosmetics, and even cleaning products. But is HDPE biodegradable?
The simple answer is no. And despite increasing research being undertaken into the use of additives (1) to break down non-biodegradable plastics quicker, studies have found that these additives do not work well, and the breakdown process of HDPE can take hundreds of years. Why, then, do environmentally friendly manufacturers, such as ourselves, continue to use HDPE in cosmetics packaging? For this reason: although HDPE is not biodegradable, it is one of the very best plastics in the world for recycling.
The reason that we continue to use HDPE in our cosmetics bottles is because, in doing do, we are supporting the development of the circular economy. Research shows that HDPE can be recycled 10 times (2) before the properties of the material begin to alter, with experts estimating that HDPE can remain in operation for up to 200 years before finally becoming compromised and needing to be disposed of. Recycling HDPE is also a very simple process, especially as its vastly different density to other plastic such as PET allows it to be sorted efficiently through the sink-float separation technique at the facility.
HDPE is widely accepted by most curbside recycling schemes and at most recycling centers across the United States. The Environmental Protection Agency states that more than 30 percent of all HDPE bottles are recycled in the US (3) thanks to the ease of doing so. So while HDPE is not biodegradable, it is a very eco friendly for cosmetics packaging due to its ability to be recycled over and over, keeping it in circulation for many years.