Production

High-density polyethylene (HDPE) is a long-chain polymer synthesized at low temperatures and pressures, using Ziegler-Natta and metallocene catalysts or activated chromium oxide (known as a Phillips catalyst) (1). 

Properties and uses

Its structure allows the polymer chains to pack closely together due to the lack of branches, resulting in a dense, highly crystalline material of high strength and moderate inflexibility. Due to its melting point more than 20 °C it can be sterilized. HDPE is used for blow-molded bottles for milk and household cleaners, blow-extruded grocery bags, construction film, agricultural mulch, injection-molded pails, caps, appliance housings, and toys (1).

Toxicity

It possess many risks if it leaks into food products or the environment, it can cause dermatitis, asthma, irritation, and hormonal disruption in human beings (2). 

1) https://www.britannica.com/science/high-density-polyethylene /
2) https://doi.org/10.1016/j.scitotenv.2022.160108/