The Toxic Side of Plastic #3 September 11, 2015 Email In the United States, blister packs are most commonly made of plastics #3 and #6. Plastic #3, also known as polyvinyl chloride (PVC), is not only the least recyclable plastic, but also one of the most toxic plastics used to make consumer goods. Exposure to its chemicals, which include dioxins and phthalates, can result in hormone and gene disruption, birth defects, and cancer.