No, Reusable Shopping Bags Probably Won't Give You E. Coli. Here's What You Need To Know For The Bag Ban

The ultimate guide.

Last month, both Woolworths and Coles put an end to handing out single-use plastic bags.

Both chains are now instead offering alternatives such as the non-woven polypropylene (NWPP) "green" bags, canvas bags, and thick plastic reusable bags at a cost to consumers.

So, what are the most environmentally-friendly alternatives? And will your reusable "green" bags really poison you with E. coli?

Will reusable bags give you E. coli?

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Probably not – at least not the kind we should be worried about.

There is very little research on this topic and the studies that exist don't tell us a great deal about the possibility of harmful E. coli being spread by reusable bags.

The idea that reusable shopping bags could harbour dangerous bacteria first came from a University of Arizona study in 2010 that swabbed grocery bags at random in supermarkets in California and Arizona.

The researchers found that 8% of sampled bags tested positive for generic E. coli, which sounds very much like bad news. However, there are 45 known strains of E. coli and generic E. coli is not considered a pathogen (it doesn't cause disease).

Generic E. coli is typically found in our intestines and is considered a healthy part of our gut biome so while it does not spread disease itself, its presence can be indicative of faecal or meat contamination.

The authors of the study did not outline if any of the six strains of E. coli that can harm humans were present.

Then in 2012, a study was published from the University of Pennsylvania that demonstrated a significant rise in E. coli in the San Francisco area after the enforcement of a plastic bag ban.

The authors looked at data of E. coli-related emergency room visits in the San Francisco area as compared to the data from neighbouring Bay Area counties that did not enforce a bag ban.

They noted a jump in visits in San Francisco in the ten quarters following the plastic bag ban and concluded: "Our results suggest that the San Francisco ban led to, conservatively, 5.4 annual additional deaths."

However, the findings were refuted by San Francisco health officer Tomás Aragón, who penned an open letter to the authors and said that their study design did not allow them to make causal links.

Aragón also pointed out that the jump in E. coli cases was not unlike the increase witnessed throughout the United States, Canada, and Europe.

It should also be noted that the University of Arizona study found that machine or hand washing the reusable bags, even without bleach, "was effective in reducing coliform and other bacteria in the bags to levels below detection".

Are plastic bags actually bad for the environment?

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Yes! Moving on.

Seriously though, plastic bags can cause widespread problems through entire ecologies.

Mammals, birds, and reptiles can be harmed by becoming entangled in plastic bags or eating them. Sea turtles are particularly at risk of this because plastic bags can be so easily mistaken for jellyfish underwater and one 2001 study found that 13.2% of turtle deaths could be attributed to ingestion of human-made debris.

A 2012 report from the Convention on Biological Diversity in Montreal, Canada, said that all sea turtle species, 45% of marine mammals, and 21% of bird species can be harmed by plastic refuse through ingestion or entanglement.

Plastic bags can also become toxic by harbouring pollutants. Pesticides and industrial waste products have been found on plastic waste at concentrations 100 times that seen in the ground soil and one million times that seen in ocean water.

Plastic can cause harm at a cellular, systemic level because it is essentially indestructible and continues to break down into increasingly small pieces. Microplastic fragments (defined as anywhere under five millimetres in length) have been shown to enter living tissue and disrupt cellular activity. This can alter the food chain by reducing an animal's ability to escape predators.

The ability for microplastics to enter human bodies through the food chain has been speculated upon for several years. While there have been studies to show that microplastics are found in agricultural soil and freshwater sites, there is very little reliable data on how much there is in ocean water.

Studies have shown that humans can consume microplastics through tapwater (one study found 83% of water was contaminated with microplastics).

However, it's worth noting that the type of plastics that are used to make plastic bags specifically (high-density polyethylene and low-density polyethylene) do not contain molecules that are considered to cause either cancer or mutations in living organisms.

Would paper bags be any better?

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Nope. Turns out paper bags aren't a great single-use option to replace plastic bags unless they are both recycled and made from recycled material.

Paper bags release methane (a greenhouse gas) as they degrade in landfill and a 2007 report from Sustainability Victoria found that 39.5% of paper bags end their life cycle this way.

In terms of material and energy consumption to produce, paper bags are also far more demanding. An impact assessment study from the Scottish government found that single-use paper bags require four times the amount of water to produce than plastic bags.

Are supermarket "green" bags any more environmentally-friendly than plastic bags?

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Sure looks like it.

The 2007 Sustainability Victoria report that the "green" bag is the most sustainable and environmentally-friendly alternative.

The report concluded that if every Australian household switched to using the green bags, over the course of a year 24,100 tonnes of waste would be avoided, greenhouse gas emissions would be reduced by 42,000 tonnes, and 50,000 kilolitres of water would be saved.

However, the report also assumed that the bags could be used for two years (or 104 trips) to achieve these statistics.

It should be noted that these figures refer specifically to the "green" non-woven polypropylene bags and not canvas bags.

The energy and water consumption and environmental pollution to produce cotton canvas bags was assessed as having a greater environmental impact than conventional plastic bags in seven of nine categories in one British study.

Cotton plantations account for 2.4% of the world's cropland and manage to consume 24% of the global market for insecticides.