1, 2, 3, 4, 5, 6, and 7? Which One is Safe?

Posted by Kelly Wu

It is plastic that we are talking about here. The controversial health concern on how safe is plastic is not something new, especially with plastic water bottle. Plastic is made with all sorts of chemical, but one ingredient that raises the most concern is bisphenol-a (BPA). If the plastic is used as a food container, BPA can leach out of the plastic and the food is consumed by human can caused a side effect to our body’s hormones function. [Source: HowStuffWorks] So what is 1, 2, 3, 4, 5, 6, and 7? How does it related to BPA?

In 1988, the Society of the Plastics Industry (SPI) developed the SPI Resin Identification Coding System. The original goal of this coding system is for recycling purpose by categorizing plastic into 7 different categories based on the polymer used. [Source: SPI] Below is the table of the 7 different types of plastic, theirs polymer name, and their common food product applications.

SPI Resin Identification Coding System [Source: American Chemistry Council]
Polymer name
Food Product Applications
1Polyethylene terephthalate
  • Plastic bottles for soft drinks, water, juice, sports drinks, beer, mouthwash, catsup and salad dressing.
  • Food jars for peanut butter, jelly, jam and pickles.
  • Ovenable film and microwavable food trays.
2High density polyethylene
  • Bottles for milk, water, juice, cosmetics, shampoo, dish and laundry detergents, and household cleaners.
  • Bags for groceries and retail purchases.
  • Cereal box liners.
3Polyvinyl chloride
  • Flexible packaging uses include bags for bedding and medical, shrink wrap, deli and meet wrap and tamper resistance.
4Low density polyethylene
  • Bags for bread, frozen foods, fresh produce, and household garbage.
  • Shrink wrap and stretch film.
  • Coatings for paper milk cartons and hot and cold beverage cups.
  • Container lids.
  • Squeezable bottles (e.g., honey and mustard).
  • Containers for yogurt, margarine, takeout meals, and deli foods.
  • Medicine bottles.
  • Bottle caps and closures.
  • Bottles for catsup and syrup.
  • Food service items, such as cups, plates, bowls, cutlery, hinged takeout containers (clamshells), meat and poultry trays, and rigid food containers (e.g., yogurt).
  • Protective foam packaging for delicate items.
7Other plastics, including acrylic, acrylonitrile butadiene styrene, fiberglass, nylon, polycarbonate, and polylactic acid
  • Three- and five-gallon reusable water bottles, some citrus juice and catsup bottles.
  • Oven-baking bags, barrier layers, and custom packaging.

Majority of the products make with plastic should have the SPI Resin Identification Code symbol on them to inform recyclers on what can be recycled, but consumers can also use this symbol to understand what the plastic container is made of to prevent potential health hazard. For example, plastic with BPA is considered as #7 plastic. While BPA is known to cause side effect to our body’s hormones functions, what about other types of plastic? Which one is safe for our health?

The answer is none or we don’t know yet. “I used to say: ‘4, 5, 1, and 2. All the rest are bad for you.’ Now, I’m not saying that anymore. We don’t know about 4, 5, 1, or 2. This raises questions about all plastic bottles,” said Martin Wagner, an ecotoxicologist at Goethe University in Frankfurt, who finds that PET plastic also has similar side effect as BPA when it was tested on snails. [Source: Discovery News] His experiment is to test plastic bottle water against tap water and does find that estrogenic compounds are found in plastic bottle water. “It’s too soon to say whether drinking out of PET plastic bottles is harmful to human health, but it now appears possible that some as-yet unidentified chemicals in these plastics have the potential to interfere with [our health].”

So what are our options and alternatives to plastic? The only way to avoid health concerns with plastic is to minimize its use, but even some of the non-plastic container does have traces of plastic in it. Canned foods, cartons milk, or aluminum bottles are lined with some kind of plastic materials, and “plastics manufacturers do not deny that BPA is found widely in canned foods and beverages and is routinely ingested.” [Source: The Green Guide] Glass container seems like is the only container that is safe in term of not having unknown chemical leaching into the food, but no matter what we do, this is very difficult to avoid as plastic exists in so much aspect of our lives. From candy wrappers to toys, or cell phone and computer mouse, we are always in close contact with some kind of plastics. These may not have a threat to our health at this moment, but this is always an unknown until some scientists decide to look into it more, so the best we can do is to increase our awareness and pay attention to any plastic thing we use.