The author of a landmark study into plastic bags has likened to "religion" their impending removal from supermarkets, suggesting arguments against them are "complete furphies you can demolish in a few minutes of analysis".
Phillip Weickhardt, lead author of a 2006 Productivity Commission inquiry into waste management, said raising fines for littering made more sense.
"This is largely religion, deeply felt," he told The Weekend Australian. "Plastic bags are useful: hygienic, water proof. They have multiple uses and functions," he added.
Coles will join Woolworths in removing "single use" plastic bags from its stores next month, extending nationwide bans on the ubiquitous bags already in place across all states and territories except NSW and Victoria.
"The evidence plastic bags hurt marine life is very unpersuasive. When we looked at this we found that a lot of studies just cite each other; in fact we sourced it all back to some guy in Canada in the 1970s who'd done a study on the effect of fishing ropes on marine life," he said.
Woolworths surveyed 12,500 of its customers last month, finding more than three-quarters wanted plastic bags scrapped. The retail giant, which gave out 3.2 billion plastic bags last year, points to a CSIRO study that found up to a third of the world' s turtles and 43% of seabirds had eaten plastics.
The Productivity Commission in 2006 concluded:
"Plastic bags take up little landfill space, and their inert characteristics can actually help to reduce a landfill's potential for adverse environmental impacts. The true extent to which plastic-bag litter injures populations of marine wildlife, as opposed to individual animals, is likely to remain very uncertain because it is extremely difficult to measure," it added.
Mr Weickhardt said:
"Our conclusion generated the most angry vocal response from people who, with religious fervour, believe this is critical."
The retail giants will instead offer a range of reusable bags, including 15c recycled bags.
A recent study in Britain, where plastic bags are taxed, found reusable bags needed to be reused up to 173 times before they had a lower environmental impact than ordinary plastic bags.
"The environmental impact of all types of carrier bag is dominated by resource use and production," it found. "Whatever type of bag is used, the key to reducing the impacts is to reuse it as many times as possible and where reuse for shopping is not practicable, other reuse, eg store-place bin-liners, is beneficial," it said.
A 2012 University of Pennsylvania study found San Francisco's 2007 plastic bag ban killed people because reusable bags increased shoppers' exposure to harmful bacteria that can infest them. "The San Francisco ban led to, conservatively, 5.4 annual additional deaths," the authors concluded.
RMIT economist Sinclair Davidson said he was surprised Coles and Woolworths would "deliberately pursue a policy that they know will reduce the consumer satisfaction".
"How consumers react remains to be seen — I suspect we'll see less impulse purchasing," Professor Davidson said. "All-up, this is a virtue-signalling[Hypocritical] policy being adopted by Coles and Woolies; I suspect they have done their market research and are pretty confident they can impose their world view on consumers with little consequence."