Polypropylene and polypropylene glycol are versatile polymers. They can be found in numerous manufactured products, both domestic and commercial, but there are some concerns about their safety.

Discovered in 1954 by Giulio Natta, polypropylene plastic is a plastic polymer with a chemical designation of C3H6. Its properties include the facts that it has a high melting point, is lightweight, can be dyed easily and does not absorb water.

Because of these and other properties, polypropylene is useful for a variety of applications, including food safe containers,  carpeting, ropes, thermal underwear, car parts and banknotes.

Polypropylene can be processed by either extrusion or molding and can be made to resist dust or to be more elastic so that it gives rather than breaks when under stress. It can also be formulated to be sturdy when rolled into very thin sheets, which makes it a versatile material for many applications.

Its resistance to damage by high temperatures make it ideal for such domestic uses as pan handles and dishwasher safe containers. Polypropylene is also excellent for laboratory and medical uses because it can be sterilized in an autoclave without being damaged.

Easily dyed, it can be used to create decorative containers, carpeting and colorful furniture, or spun into a filament which is then spun with other fibers and used to weave clothing.

In contrast, polypropylene glycol is a clear liquid at room temperature which absorbs and holds water. It's probably best known for its use in polyurethane coating for floors, but it's used in cosmetics and food manufacturing to hold in moisture, also as a solvent for waxes, resins and hydraulic fluids and is an ingredient in paintballs, ink, antifreeze and brake fluid.

There are safety concerns with both polypropylene and polypropylene glycol. Some chemicals were found to leak from polypropylene laboratory products, causing problems with lab results. These same chemicals are in containers used for food and drink.

While it's claimed that the small amount of polypropylene glycol in personal care products is not harmful, fumes from other uses such as floor sealants can irritate mucous membranes as well as infiltrate the blood system through the lungs if used without proper ventilation.