Bags of Bacteria

Bags of bacteria – the law of unintended consequences

Life-cycle Assessments of supermarket bags have been performed by Intertek and Franklin Associates, and an evaluation has been made by the Northern Ireland Assembly. https://www.biodeg.org/subjects-of-interest/life-cycle-assessments/ These studies examined single-use and reusable/bags-for-life type carrier bags, paper bags, bio-based plastic bags, heavy duty non-woven polypropylene bags and cotton reusable bags.  They concluded that plastic has the best LCA, and the best way to reduce the impact of plastic carrier bags is to re-use them as often as possible, and to make them with oxo-biodegradable technology.

However, the UK Food Standards Agency has recently issued a warning to anyone using reusable ‘Bags for life’  like the ones sold in Aldi, Tesco, Sainsbury’s etc., after studies revealed that dangerous bacteria were found in 99% of the bags, with coliform bacteria in 51% of the bags tested, and generic E.coli in 8%.  See https://www.sciencedirect.com/science/article/abs/pii/S0956713518306418  ; (2019) and Food Protection Trends, Vol. 31, No. 8, Pages 508–513 (2011); and Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA (2017)

When you consider that these bags are very rarely, if ever washed, and are often used to transport raw and fresh ingredients together in the same bag, it is not surprising that cross-contamination occurs and microbes which can be lethal are able to thrive.

Bacteria and viruses can survive for several days on surfaces, add a few hours in warm conditions in the boot of the car for good measure and the number of bacteria can multiply many times. You then have the potential for some very severe foodborne illnesses.

More and more retailers are switching away from plastic to paper bags, despite their dubious environmental credentials and the fact that they are not really fit for purpose. See https://www.biodeg.org/subjects-of-interest/paper-bags/ This is a problem that is likely to get worse, as people are forced into buying more bags for their food shopping.

Marks and Spencer recently introduced a new paper-based bag to consumers which they say can carry up to 15 kg and be reused up to 100 times.  However practical experience shows that these bags can split if knocked against something while laden, and they lose all their strength if they get wet.  Also, bags are usually used only once. Do consumers really think that paper bags are better than plastic, or is this just the result of clever marketing by the paper industry and some of the anti-plastic NGO’s?

When the consequence to human health are so serious, wouldn’t it be more responsible  to make the bags from proven antimicrobial technology that can be added to regular plastic to protect against dangerous microbes, including  bacteria, yeasts, moulds, fungi and viruses? See www.d2p.net

Adding d₂p at the manufacturing stage of the bag adds little or nothing to the cost and makes the plastic surface lethal to microbes.  Better still, the protection lasts for the lifetime of the product.

The plastic bags for life do appear to be the preferred option for shoppers, who can no longer get a lightweight carrier bag, and who know that paper is not the best option. So perhaps it’s  time for supermarkets to step-up and make their durable bags safer.  Prevention is definitely better than cure, and unless they take action, we may just be swapping one serious problem for another more serious one.