The history of PP polymer is very interesting. In 1951 two researchers from Phillips Petroleum Company, J. Paul Hogan, and Robert L. Banks while working to convert propylene to gaseous form discovered this polymer. Later it was polymerized by two German scientists Giulio Natta and Karl Rehn. Natta used Ziegler-Natta catalyst during the polymerization process.

With ideal properties for molding, this plastic is now days used from household hoods to make the medical device.

What's polypropylene, and what's it used for? 

Polypropylene (PP) also termed as "polypropene" is thermoplastics in nature. It is a linear hydrocarbon polymer expressed as (CnH2n). PP polymer is one of the most versatile polymers and is used as both plastic and as fiber.

The PP polymer can be processed by extrusion blow molding, injection molding, and general purpose extrusion. Expanded PP (EPP) may be molded in a specialist process. Properties of polymer make them applicable to a variety of end-use segments of the plastic market. Some of the prominent segments making use of PP plastics are:

Flexible packaging.Rigid packaging. Polypropylene sheet and tubing. Automotive. Consumer products. Industrial. Clothing. Fiber. Fabrics. Medical

Is it safe?

The pp plastics is generally considered safer than most their other counterparts plastic material. They do not leach harmful chemical when used as food containers. The PP plastics are flexible, tough, heat resistant and provide a barrier to moisture. These properties along with microwave-safe make them an obvious choice as food containers.

They are used as a plastic cup, baby bottles, food containers and other kitchenware items. As material identification to the consumer, the products are marked as “PP”

Is it BPA free?

Bisphenol A (BPA) is a chemical used in the manufacturing of polycarbonate plastics. It's also used in epoxy resins that coat the insides of canned goods and water supply pipes.

BPA leaches into food and water supplies easily. More than 93 percent of the urine samples examined in a CDC study contained BPA concentrations.

Although the FDA has said that small amounts of BPA are safe for humans, some environmental and health experts are concerned that exposure to BPA could lead to problems with brain development, immune function, learning abilities, reproductive disorders, and other health issues.

The growing concern around BPA has led to the production of several types of BPA-free plastics. Polypropylene is one type of plastic that's free of BPA.

What are the other types of plastic? 

To make it easier for consumers to recycle and for recycling facilities to process plastics, containers are labeled with a resin ID code.

This code is identified as a number between 1 and 7 stamped on the bottom of a package and framed by arrows forming a triangle.

Polypropylene's number is 5. Here's an at-a-glance guide to resin recycling codes:

Tips for safe plastic use

Because plastic is everywhere, eliminating it entirely is a tall order. Here are some tips for reducing plastic use, as well as using it more safely:

Doctors don't recommend heating food in plastic containers because heat increases the chances that chemicals will seep out of the container and into your food. Choose to heat food in glass or metal containers instead.

Choose products marked “BPA-free” if you can. Try to avoid plastics that are marked with recycle codes 3 or 7, unless there's a leaf beside the number (which indicates the plastic is BPA-free). There's typically a higher risk that these plastics contain BPA and other potentially harmful chemicals.

Discard any plastic containers you've had since before 2012. That's the year the FDATrusted Source banned the use of BPA in sippy cups, baby bottles, and baby formula containers.

Avoid using plastic or coated roasting and steaming bags. Heat may cause chemicals to be released into your food from these products.

Don't refill plastic water bottles labeled with a resin recycling code 1. They are intended as single-use containers.

Avoid handling cash register receipts coated with a shiny film. According to advocacy group Breastcancer.org, that shiny coating contains BPA.

You may want to consider replacing your plastic serve-ware and storage containers with glass or metal alternatives over time. Although polypropylene remains a safer alternative to some other types of plastic, the manufacturing process for plastic products may not be good for the environment.

The bottom line

Polypropylene is a plastic that's used to make everything from rugs to sour cream containers. It's generally considered to be one of the safer plastics. The FDA has approved its use as a food container material, and there are no known cancer-causing effects associated with polypropylene.

You can tell you're using a polypropylene container if the number 5 surrounded by a triangle is on the bottom of the container.

If you're concerned about the possibility of chemicals leaching out of a polypropylene package, you can take some steps to minimize your exposure. Transfer food into a glass or metal container before you heat it, and don't reuse containers that are intended as single-use packaging.