Forget paper bags. Reusable plastic bags are more eco-friendly in Singapore

Everyone is talking about not using plastic bags, and opting for
reusable bags.

But being an eco-friendly shopper in Singapore means opting for and
using a reusable plastic bag many times instead of using a cotton one, a new
study has found.

Forgot the plastic reusable bag? Then the next best option would be to
use a single-use plastic bag, instead of a paper one or one made of
biodegradable polymers.

These findings by researchers from Nanyang Technological University
(NTU) and their colleagues in Finland were published in August in the Journal
of Cleaner Production.

In the paper, the researchers noted that while plastic grocery bags are
one of the most common single-use packaging products, other options have been
gaining traction.

They include single-use bags made of paper or biodegradable plastic; or
reusable bags made of cotton or polypropylene non-woven plastic.

But how do they stack up against each other in terms of how
environmentally friendly they are here?

The latest study provides the answer, with the researchers modelling the
environmental impact of each type of bag based on a host of factors, such as
how the bags are made, transported, distributed, collected as waste, treated
and disposed of.

For example, the study took into account the quantities of natural
resources used to make each type of bag, and their transoceanic shipment from
where they were produced to Singapore.

The researchers found that if a reusable plastic bag made of
polypropylene non-woven plastic is used at least 50 times, it is the most
eco-friendly option here. This refers to the type of reusable bag commonly sold
at checkout counters at supermarkets for about $1.

A single-use plastic bag, such as those usually given out for free,
comes in as the second-most environmentally friendly option. But it still has
14 times the global warming potential of a reusable plastic bag used at least
50 times.

Global warming potential measures the environmental impact of various
greenhouse gases, which are produced in the manufacture, use and disposal of
the bags. It provides a common unit of measure.

Single-use biodegradable plastic bags are the third-most eco-friendly
option in Singapore, which incinerates most of its non-recyclable waste anyway.
This option has 16 times the global warming potential compared with a reusable
plastic bag.

Reusable cotton woven bags come in fourth with 17 times the global
warming potential, while single-use paper bags are the most environmentally
damaging, with 81 times the global warming potential.

The production of cotton involves pesticide use, and long-term heavy
metals being discharged into water. Paper bag production involves generation of
liquid waste, noted the authors.

Assistant Professor Grzegorz Lisak, director of Residues and Resource
Reclamation Centre at NTU's Nanyang Environment and Water Research Institute,
who led the research, said: "Our main message is that reusable plastic
bags are the best option, provided that they are reused many times - over 50
times to be precise."

Context is important, he added. This is because bags have to be
transported across different distances, depending on where they come from and
where the city that imports them is. Each country may also deal with waste
differently.

In Singapore, which has a closed waste management system with
incineration treatment, using plastic bags - both reusable and single-use types
- may be the best option that is currently available, he said.

"This is provided that there is no significant leakage of waste
into the environment," Prof Lisak added.

Plastic bags, if not disposed of properly, can contaminate the natural
environment and end up in the ocean, where they can ensnare wildlife or be
eaten by animals.

Singapore Youth for Climate Action member Alice Soewito said the
findings had to be communicated carefully, so people did not misinterpret them
as showing that plastic bags are eco-friendly.

"Such a message could be misleading, and it could distract from our
end goal of minimising or eliminating the use of these single-use
disposables," said Ms Soewito, an environment and sustainability major at
Cornell University.

To nudge consumer behaviour, she suggests that reusable plastic bags be
given to each household in a one-off distribution. A surcharge should also be
imposed on each single-use plastic bag taken by a customer.

"The battle should never be about swopping between different materials - like paper and plastic bags for single-use items. The question we should ask ourselves is why are we still using single-use items," she said.

Here's a list of commonly-used bags, from the most eco-friendly to the least.

Most eco-friendly: Reusable plastic bags

Credit: Cheryl Tan

1/5

Such bags refer to those often sold at the checkout counters in supermarkets for about $1. If each bag is used at least 50 times, it is the most eco-friendly option here.

2. Single-use plastic bags

Credit: Cheryl Tan

2/5

Fourteen times the global warming potential compared with reusable plastic bags, even though these bags, often given out for free at supermarkets, may be the second-most eco-friendly option here.

3. Single-use biodegradable plastic bags

Credit: 123rf

3/5

Sixteen times the global warming potential compared with reusable plastic bags.

4. Reusable cotton woven bags

Credit: Cheryl Tan

4/5

Seventeen times the global warming potential compared with reusable plastic bags. However, researchers say cotton bags that are reused hundreds of times would make them a superior choice over a single-use item.

Least eco-friendly: Single-use paper bags

Credit: 123rf

5/5

Eighty-one times the global warming potential compared with reusable plastic bags.

This article was first published in The Straits Times.