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MATERIAL SELECTION (Plastics # 1-7 plus terms and materials to know)

You ever look at those triangles on your takeout containers?

And wonder what do those numbers on plastic 1-7 really mean?

Let's keep on reading to find out what these numbers stand for, and learn more about their benefits and drawbacks. Scroll past this section if you're interested other materials, certifications and terms you should know.

Conventional Plastics (Numbered 1 - 7)

1. Polyethylene Terephthalate (PET or PETE):

Also known as polyester, PET is the most commonly used plastic resin worldwide. It’s widely used in the convenience industry, and mandated by the FDA as safe for single-use food and beverage contact.

However, PET is susceptible to oxidation and not an ideal material for multiple or repeated uses, long-term food storage or for high-temperature contents

2. High-Density Polyethylene (HDPE):

This plastic has a decently high strength-to-density ratio, maximizing durability for withstanding freezing and heating. HDPE can be recycled efficiently up to 10 times, and often used in industrial and food service industry applications, children’s toys, floor tiles, and artificial lawn.

On the downside, HDPE is susceptible to oxidation and stress cracking, not to mention flammable!

3. Polyvinyl Chloride (PVC):

When it comes to both food contact applications and recycling, PVC is one the least favourable plastic resins. The #3 represents strength and elasticity due to softening chemicals in the plastic, e.g., phthalates. These are toxic additives that are often disruptive to the human hormonal system. Ingestion of phthalates can affect juvenile development, immune and endocrine system function, and even cause cancer. This type of plastic is typically found in industrial applications like piping, some cleaner bottles, shower curtains, and other household items.

4. Low-Density Polyethylene (LDPE):

LDPE is known as a thermoplastic, which means it can change states when heated or cooled down. For this reason, it is most commonly used in bread wrapping, shopping bags, and packaging foam. Unfortunately, most LDPE out there doesn’t end up getting recycled, as it requires a separate process that many municipal recycling facilities don’t have the infrastructure for. LDPE products are a big time contributor to terrestrial and marine plastic waste streams.

5. Polypropylene (PP):

This is the plastic resin that ShareWares’ products are manufactured from!

It’s the second most widely produced plastic next to PET, and is light, heat resistant and very durable. PP is the choice resin for many food contact materials such as cups, containers, and utensils. This is mainly due to the non-volatile properties of the resin, and that it doesn’t react when in contact with hot foods, fatty foods, or acidic foods. It has the highest recyclability and reforming potential of all conventional plastics, and is considered the safest choice of all plastics according to the FDA. In terms of designing out waste and pollution, polypropylene is an integral material in fortifying the New Plastics Economy.

6. Polystyrene (PS):

PS is commonly known as styrofoam, and is definitely a lesser preferred plastic due to its challenges in being recycled. The material is super cheap to produce, lightweight, and easily formed. However, it is often found in notoriously frowned-upon disposable cups and containers, as well as building insulation. The main issue with PS is its fragility: it breaks up easily, and tiny pieces of this plastic can be found almost everywhere on the planet, especially on beaches and in marine creatures. The carcinogenic styrene this plastic contains can leach out when PS is heated, which is another issue of concern.

7. Miscellaneous Plastic Category:

This category encompasses all other plastic materials that don’t fall into one of the six categories above. These plastics can contain mixes of multiple different resins, plasticizers, additives, and phthalates, and aren’t typically accepted at conventional recycling centers. The #7 recycling logo also stands for polycarbonate, which is material that contains the dangerous compound Bisphenol A, widely known as BPA. Baby bottles, car parts, medical and dental equipment have all commonly been made from #7 plastic over the last few decades. If at all possible, avoid this category altogether.


Other materials

Stainless Steel - Like glass, stainless steel has quickly risen to the top of the food chain when it comes to reusables! Cups, containers, and bottles of this material are corrosion resistant, have no chemical leaching risks, and are very durable!

The issues with stainless steel lie in its production phase and its end-of-use, or recycling phase.

On our LCA page, we’ve shared some information on the emissions associated with manufacturing stainless steel, and the challenges that present with conventional recycling practices for the material. Compared to alternatives, stainless steel also is on the pricier side.

Glass - This material is quickly becoming one of the most popular for reusables around the world! There aren’t any risks of chemical leaching or migration into foods, it’s microwave and oven safe, not to mention easy to clean. However, the downfall of glass as the choice reusable to work in a system like ours is the sheer weight and fragility of the material.

Glass reusables are less likely to last as long as plastic or stainless steel options, and overall recycling rates are low in most municipal recycling facilities. Glass reusables are on the pricier side of those on the market, in comparison to plastics or silicone options, however not in comparison to stainless steel.

Silicone - Silicone is technically a synthetic rubber derived from silicon, oxygen, and other elements like carbon! It requires the use of non-renewable silica (found in sand), and petroleum hydrocarbons to form the backbone of the polymer.

When heated, silicone reusables run the risk of leaching unwanted, harmful siloxane compounds into food or beverages. Silicone products are also challenging to recycle.

Most municipal recycling facilities that receive silicone products divert them to the landfill where they remain for hundreds of years, eventually breaking down into microscopic pieces.

Ceramics - Ceramic reusables are at first glance an appealing alternative to single-use products! The kilned and fired earthen material has far less negative connotations around it than conventional plastics.

However, ceramics chip, crack, and break easily.

Several studies have produced evidence that newly purchased ceramic reusables intended for food contact contain traces of heavy metals and melamine, a compound that can induce internal organ damage and fetal growth disruption in humans upon ingestion. The risk of melamine leaching is heightened when ceramics are heated up, or used to store food for extended periods of time.


Plastic made of plants? The ‘sustainability’ of bioplastics is marketed on every platform imaginable, and there is much innovation going on in the space. Some of the most commonly known examples of bioplastics include polylactic acid (PLA) found in products like water bottles or as lining in paper packaging. However, the greenwashing around the ‘compostable’ nature of bioplastics is tremendous.

Almost all bioplastics won’t ‘compost’ unless disposed of in an industrial composter to biodegrade properly, such as if they end up in a landfill. When bioplastics in a landfill eventually do start breaking down, they release methane, a toxic gas even more damaging to our atmosphere than carbon dioxide. Bioplastic waste also contributes to the marine waste stream just as significantly as any other material, given that the materials cannot biodegrade in water.

Material Certifications

There are a couple different health and safety certifications for food contact materials, A.K.A, anything you use to eat off of or with that’s considered food-safe and/or food grade. Here are a few of the most common…

Food and Drug Administration (FDA) Approval

If a product is listed as FDA Approved, that means that it is made out of the correct type and quality of material that makes it safe for human health exposure and food contact, in our case! Typically, materials have an intended use purpose for within the recommended safe temperature range, and for certain types of food, e.g. fatty substances, acidic substances, various moisture contents, and so on.

FDA approval requires all food contact materials to hold up to the environment the product will be used in, including the cleaning and sanitizing process. Compliance with FDA approval for food contact materials follows Section 21 of the Code of Federal Regulations, or 21 CFR.

Terms to know

Some definitions and explanations…

Bisphenol A (BPA): chemical used in manufacturing of polycarbonate plastics.

leaches into food/water supplies fast, exposure causes brain dev issues, impaired human function, reproductive disorders, etc.

Migration: This word is used to describe the known phenomenon defined as the partitioning of chemical compounds or contaminants from packaging into its food contents. The rate of migration is dependent on several factors, such as plastic material type, heat exposure, time of exposure, and more. For our resins, we have conducted extensive, scientific migration testing in accredited labs to ensure that our products are safe for all kinds of food contact.

Endocrine Disruption: There are many chemicals, both natural and man-made, that have the potential to mimic or interfere with the human body’s natural hormonal processes if exposed to or ingested. These chemicals are linked to negative developmental, reproductive, brain, and immune functions. Some of the more commonly known endocrine disruptors are Bisphenol A (BPA), Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS), and Phthalates. Even low dose exposure to endocrine-disrupting chemicals is considered unsafe.

Phthalates: These are a group of chemicals used to make plastics more durable, oftentimes referred to as plasticizers. Hundreds of commercially available products have phthalates in them, especially those manufactured from polyvinyl chloride (#3 PVC). Studies have shown that phthalates affect the reproductive system in animals, however more research is needed to assess the full scope of the human health effects of exposure to phthalates.

Per and Polyfluoroalkyl Substances (PFAS): These are a large group of commonly used but little-understood chemicals, used in water-resistant clothing and plastic products, non-stick cookware, and many other commercially available items. PFAS don’t break down easily, and for this reason are of concern regarding their accumulation in the environment as well as human bodies. There are probable links between long-term exposure to PFAS’ and certain medical conditions such as kidney cancer and thyroid disease.