When designing the Subpod, many factors were taken into consideration. The design team found that the best material to use now for the Subpod is polypropylene which is naturally BPA free. Polypropylene is one of the safest plastics available from a health perspective with no endocrine disruptor chemicals and undetectable leaching. Because the Subpod is designed for durability and long life use, as a priority, initially started making Subpods from virgin polypropylene. There is ongoing field testing of blends of up to 50% recycled polypropylene to verify these blends have sufficient strength and longevity to permit the use of a percentage of recycled polypropylene in Subpod manufacturing.Polypropylene is water and food safe and has been used in the food industry for many years, it is able to withstand high temperatures of about 110 degrees Celsius/ 230 Fahrenheit. Using polypropylene, Subpods are expected to have a minimum usable lifespan of 10-15 years in the soil without any leaching or degradation which is important since the Subpod will contain and be surrounded by a microbe-dense soil in a wide range of conditions, including dampness and high humidity. Doubling as bench seating requires that the materials chosen support body weight. Polypropylene based Subpods can bear up to approximately 200 kilograms/ 440 pounds. Finally, the Subpod can be recycled when it reaches the end of its life in your garden, completing its life cycle. There are exciting plastic substitutes being developed which are continually up for consideration, but most of these are designed to be composted after use and currently the need is for the Subpod to hold up strong for many years while it is efficiently composting all of your kitchen waste. It’s number for recycling is 5.