Is polypropylene toxic when heated ?

Posted by: PECOAT | on July 30, 2023

Polypropylene, also known as PP, is a thermoplastic resin and a high molecular polymer with good molding properties, high flexibility, and high temperature resistance. It is widely used in food packaging, milk bottles, PP plastic cups and other daily necessities as food-grade plastic, as well as in household appliances, automotive parts and other heavy industrial products. However, it is not toxic when heated.

Heating above 100℃: Pure polypropylene is non-toxic

At room temperature and normal pressure, polypropylene is an odorless, colorless, non-toxic, semi-transparent granular material. Unprocessed pure PP plastic particles are often used as linings for plush toys, and children’s entertainment factories also choose semi-transparent PP plastic particles to simulate sand castles for children to play with. After pure PP particles undergo processes such as melting, extrusion, blow molding, and injection molding, they form pure PP products that remain non-toxic at room temperature. Even when subjected to high-temperature heating, reaching temperatures above 100℃ or even in a molten state, pure PP products still exhibit non-toxicity.

However, pure PP products are relatively expensive and have poorer performance, such as poor light resistance and oxidation resistance. The maximum lifespan of pure PP products is up to six months. Therefore, most PP products available in the market are mixed polypropylene products.

Heating above 100℃: Polypropylene plastic products are toxic

As mentioned above, pure polypropylene has poor performance. Therefore, when processing polypropylene plastic products, manufacturers will add lubricants, plasticizers, light stabilizers, and other substances to improve their performance and enhance their lifespan. The maximum temperature for using these modified polypropylene plastic products is 100℃. Therefore, in a heating environment of 100℃, the modified polypropylene products will remain non-toxic. However, if the heating temperature exceeds 100℃, the polypropylene products may release plasticizers and lubricants. If these products are used for making cups, bowls, or containers, these additives may enter the food or water and then be ingested by humans. In such cases, polypropylene can become toxic.

Whether polypropylene is toxic or not depends mainly on its application scope and the conditions it is exposed to. In summary, pure polypropylene is generally non-toxic. However, if it is not pure polypropylene, once the usage temperature exceeds 100℃, it can become toxic.