Scientists find reusable PET grocery bags a top choice to reduce plastic pollution in SA

Scientists find reusable PET grocery bags a top choice to reduce plastic pollution in SA
04 Aug 2020

Scientists find reusable PET grocery bags a top choice to reduce plastic pollution in SA

A recent study by South Africa’s Council for Scientific and Industrial Research (CSIR) has found that reusable polyester bags – made from PET plastic – are among the best grocery carrier bags for consumers who are looking to mitigate environmental plastic pollution.

The study compared sixteen different types of carrier bags offered by South African retailers in terms of their environmental and socio-economic performance across the bag’s life cycle. It found – when assuming that single-use bags are used just once and reusable bags are used every week for a year to fulfil annual grocery shopping requirements – that reusable high-density polyethylene (HDPE) and polyester bags* were most beneficial.

This was when assessing and comparing the various carrier bags against a broad range of environmental indicators, which included:

  • damage to human health, damage to ecosystems, and damage to resource availability;
  • socio-economic indicators that are particularly relevant in the South African context, namely impacts on employment, and affordability to consumers; and
  • a new indicator, namely persistence of plastic material in the environment which was used as a proxy for impacts associated with plastic pollution.

Overall rankings were calculated assuming an equal weighting across all these indicators. The study further assumed that single-use bags would only be used once each and that reusable bags would be reused continuously over a year.

The results indicate that the reusable, fossil-based plastic bags have a far lower environmental impact as compared to the single-use options (fossil-based or biodegradable), spread over one year’s shopping. The report finds that “in terms of affordability, contrary to what may have been expected, the reusable bags generally perform better than single-use bags over the course of a year.”

“Assuming that single-use bags are only used once, and that reusable bags are reused continuously to fulfil annual grocery shopping requirements, the reusable HDPE 70-micron (μm) bag [HDPE_70] is the top-performing bag overall; closely followed by the reusable non-woven [spun-bond and stitched] polyester bag [Polyester_NW],” the report states.

The HDPE_70 and Polyester_NW bags also rank in the top two positions across the following indicators: global warming, land use, water use, employment, and affordability. However, scientists noted that due to the weaker handles of HDPE 70 bags, they may not necessarily last a full year, in which case the polyester bags are the best choice.

“Assuming a longer lifespan as compared to HDPE_70, the Polyester_NW bag overtakes HDPE_70 as the top-ranked bag,” the report states.

In general, the analysis shows that for all types of bags, the more times a bag is reused, the better its performance – particularly from an environmental and affordability perspective. The number of times a bag is reused is the single largest contributing factor to its environmental performance, across all types of bags. Doubling the number of times a bag is used – for example, using a bag twice instead of just once – results in a halving of its environmental impact.

“Finally, only when all options for primary and secondary reuse have been exhausted, should bags be recycled or composted (as appropriate),” the report states.

*Specifically, HDPE_70 (70-micron HDPE bag), Polyester_NW (non-woven – spun-bond and stitched – polyester) and Polyester_W (woven fabric polyester) carrier bags

Read the full report here: