A Singapore-based research team has discovered that plastic has a potentially lower environmental footprint than cotton and paper bags.
Research from the Nanyang Environment and Water Research Institute (NEWRI) made headlines when the team revealed that single-use plastic bags can have a lower environmental footprint than single-use paper and multi-use cotton bags in countries with developed waste treatment systems like those in Singapore.
In terms of eco-friendliness, plastic bags made from high-density polyethylene plastic (HDPE) – the most used type of grocery plastic bag – was found to be second only to reusable plastic bags made from polypropylene non-woven plastic bags (PNB), but better than options such as cotton and kraft paper bags which are often assumed to be better for the environment.
“This is because we looked at the entire production process and life cycle of the bag, from raw material extraction to make the bag, to production, to transportation, all the way until its disposal,” explained head researcher and director of the NEWRI, professor Grzegorz Lisak.
“Our main message is that re-usable plastic bags are the best option, provided that they are re-used many times, over 50 times to be precise, but plastic bags, if treated properly afterwards, are less environmentally detrimental than the other types of bags in the study.”
The study looked at five types of bags: HDPE, HPB, kraft paper, cotton woven and biodegradable polymer.
The negative global warming potential was generally found to be 17 times higher for kraft paper, cotton woven and biodegradable polymer bags respectively when compared to PNB. Moreover, kraft paper or cotton woven bags demonstrated the highest negative impacts in terms of fossil depletion, marine ecotoxicities, human toxicity and acidification potentials.
The researchers stressed, however, that these results are only appliable in cities such as Singapore and possibly Tokyo, Hong Kong and Dubai which have good, confined waste management structures that minimise plastic waste leakage.