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.
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.