There are essentially two groups of grocery carry bags – conventional plastic bags (a.k.a. disposable bags) and reusable bags. Both bags serve important functions protecting the environment and our health, but it is complex. Each bag has its strengths and weaknesses.
Multi-Purpose vs Single Purpose Bags
There are often called single-use bags and there are those who think that plastic shopping bags are only used once for 20 minutes and then discarded as waste. But the reality is very different. Plastic shopping bags have in fact multi-purpose, multi-use bags that are reused for a variety of purposes – carrying groceries, picking up after pets, for storage, as book bags, to manage household waste, to recycle organics, etc.
Reusable bags are single-purpose bags used only as carry bags — to transport groceries, as a gym bag, shoe bag, a book bag, a general tote bag, or even for outings with your baby, etc. They are rarely used for any other purpose other than as a carry bag. But because they are built to last for 125 reuses, they are what is called a multi-use bag.
In North America, plastic shopping bags are made from natural gas; using HDPE (high density polyethylene plastic). Most reusables are made from plastic. Woven and Non-Woven Polypropylene is the usual material, although some reusables are made using recycled PET water bottles or nylon. There are natural fibre exceptions like cotton and hemp. For more on the types of reusable bags go to All About Reusable Bags.
Reusable bags perform better on reuse than the conventional thin plastic shopping bag and are built to last for at least 125 reuses. However, research and in-market experience show that reusables are rarely reused 125 times. The Berland study of reusables found that the average reusable bag is only reused 15 times. The concern here is the waste of resources used to make this sturdier bag.
Contrary to popular belief, plastic shopping bags enjoy very high levels of reuse but are not constructed to be reused multiple times. They are built to be recyclable using a minimum of resources in their manufacture, but are very durable and strong allowing them to be reused if consumers want to do so. The thin 8 -12-gram plastic bag is very strong – built to carry 2,000 times its weight in groceries.
There has been very little research done on how many times each plastic shopping bag is reused. However, there is considerable scientific research and surveys that show that plastic shopping bags have extremely reuse rates across Canada. The incidence of reuse is very high with an overwhelming majority of the bags being reused 2 or more times.
Plastic shopping bags are erroneously labelled “single-use” bags. The science shows that 77% of all bags distributed in Quebec are reused; in Ontario, 60% are reused; and the highest level of reuse is recorded at 91% in the Province of Manitoba,
Plastic shopping bags are 100% recyclable and are recycled in recycling facilities across Canada. Most contain at least 20-25% recycled content.
Reusable bags, although made from plastic, are not recycled in Canada, because of the cost. Reusable bags are made using multiple materials which must be separated in the recycling process which is very costly. The result is that most reusables end up in landfill at the end of their life as a carry bag.
A New and Improved Reusable Bag
The industry has developed a new and improved reusable bag made from polyethylene that is 100% recyclable and can be recycled using existing recycling infrastructure across Canada for plastic bags and other films. This new bag is a thicker bag that can be reused 100+ times and has the potential to contain as much as 40% recycled content.
Environmentalists would have you believe that plastic shopping bags are an environmental evil used for 5 minutes and then either littered and thrown in the garbage.
Reusable bags can perform better environmentally than the conventional plastic bag if reused repeatedly to justify the number of resources used to make the bag; reused 125 times per bag. But that is often not the case. Life Cycle Assessments (LCA) conducted world-wide have found scientifically that conventional plastic shopping bags are better for the environment, even if only used once.
The U.K. LCA found that:
- Paper bags would have to be used three times to lower their global warming potential to match that of a conventional HDPE plastic shopping bag being used just once.
- LDPE bags (thicker polyethylene bags for life) would have to be used four times; non-woven polypropylene bags 11 times; and cotton bags 131 times.
- A cotton reusable bag has to be reused 131 times to be as good environmentally as a plastic shopping bag used just one.
- The number of times each bag would have to be reused to match the environmental performance of conventional (HDPE) plastic carrier bags is shown in the table below (with and without secondary reuse of the conventional plastic bag).
Amount of Primary Use of Alternatives to Match the HDPE Conventional Bag Environmental Performance With or Without Secondary Reuse of the HDPE Bag
The Quebec LCA found:
- The LCA showed definitively that the thin 17-micron HDPE plastic shopping bag is the best bag environmentally and economically. It found that reusable bags have a much greater carbon footprint because of their resource intensity and require multiple reuses to match the environmental impact of the 17-micron thin bag used just once.
- According to the Quebec Government LCA, the Polypropylene (PP) woven, and PP non-woven bags need an equivalent number of reuses to equal one use of the thin plastic bag ranging from 16 to 98 reuses for the woven PP reusable and 11 to 59 reuses for the non-woven, depending on the environmental indicator.
Public Health Performance
Conventional plastic shopping bags are the more hygienic bag because they are a first-use bag that protects the health of Canadians from foodborne disease and pathogens like the coronavirus. As a first-use bag handed out for the first time at check out, the conventional plastic shopping bag provides a sterile environment for groceries. http://plasticbagsandyourhealth.ca/#publichealth
During the COVID-19 pandemic, plastic shopping bags were a critical public health tool used to stop the spread of the virus and when there was concern that reusables could transmit the virus on their surface. Science had shown that the coronavirus can survive on plastic for 72 hours. https://www.nejm.org/doi/full/10.1056/NEJMc2004973
The conventional plastic shopping bag provided an important level of protection for front line workers in grocery stores.
Their manufacture was declared essential in a number of provinces.
Reusable bags tend not to perform as well on public health – protecting the health of Canadians. Why? Because the majority of users do not clean their bags after every use so fungi, mold, viruses and bacteria can take up residence inside the bag and on the bag surface where they can cross-contaminate groceries carried in the bag with disease-causing pathogens. Most important during the pandemic, if not washed after every use, the reusable could become a transmission device for the coronavirus, so they were banned.
Reusable bags if washed/cleaned after every use can be as hygienic for use in store. Cleaning a reusable after every use removes 99% of all disease-causing pathogens.
However, a recent study by the plastics industry found 55% of reusable bag users never clean their reusable bag. http://allaboutreusablebags.ca/#polls