Guest post by Rod Bogaards

It looks like a push is on to ban single-use plastic bags nationally according to the Courier-Mail. A ban has already been implemented in some of the smaller states and territories but not elsewhere. Perhaps there is good reason to be cautious.

In 2005, the Council of Australian Governments (COAG) agreed to phase out single-use plastic bags by 2008 because of the alleged problems that plastic bags pose for the litter stream and marine wildlife. Plastic bag litter is seen as a particularly undesirable because it:

• can be highly visible and long lasting, since plastic bags easily become airborne, are moisture resistant and take many years to decompose, and
• has the potential to injure or kill wildlife, particularly in the marine environment through ingestion or entanglement.

But the 2006 Productivity Commission (PC) inquiry into waste management found a wholesale ban on plastic bags was unlikely to address the problems identified, or solve the litter problem more generally. This is because a ban would penalise most uses of plastic bags, whereas the potential environmental benefit would only come from the less than 1% of bags that are littered.

The PC found that:

• Only a small proportion (0.8%) of plastic bags become litter (although available estimates suggest that in absolute terms, plastic bag litter is significant).
• Although the impact of plastic bag litter on marine life is uncertain, the available evidence suggests fishing-related debris, rather than land-based sources, is the principal source of litter hazardous to marine wildlife.
• Despite successful initiatives to reduce the use of plastic bags, particularly from supermarkets (the number of retail carry bags fell by 34% from 2002 to 2005), the decline did not appear to translate into a fall in plastic bag litter. The likelihood of a supermarket bag being littered is low as people use them to carry goods to their homes. Bags supplied for away-from-home uses – such as to carry takeaway food – are much more likely to be littered.
• A cost-benefit analysis, commissioned by the Environment Protection and Heritage Council (EPHC), considered eleven regulatory options (ranging from a ban or levy through to a new code of practice for retailers) and found that all of them would impose a net cost on the community.

The PC recommended an assessment of alternative approaches that specifically targeted litter, rather than all plastic bag uses and to focus on away from-home sources of litter entering marine environments. The subsequent EPHC Regulatory Impact Statement (RIS) acknowledged that targeting litter may be a more cost-effective solution to the plastic bag problem, but rejected the option because it was inconsistent with the commitment to phase out plastic bags. In April 2008, the EPHC decided not to endorse uniform regulatory action to ban or place a charge on plastic bags. However, four jurisdictions have implemented their own bans.

The reviews of plastic bag bans in SA, ACT and the NT show that there can be some perverse consequences when consumers modify their behaviour in response to a ban.

The SA Review found that previously many households used single-use plastic shopping bags to line their bins and, as a result of the ban, significantly more consumers have turned to purchasing bin liners:

… the purchase of bin liners by households has increased from 15% to 80%, raising some scepticism about the broader environmental benefit of the ban.

The ACT Review showed that an increase in reusable plastic shopping bags partially offset the decline in single-use plastic bags (by weight) following the ban:

… this review estimates that around 114 tonnes of boutique bags were sent to landfill in the period 1 May 2013 to 31 October 2013, compared to an estimated 182 tonnes of single-use plastic bags in the period 1 May 2011 to 31 October 2011.

The ACT Review did show a reduction in plastic bag litter following the ban but there are still too few data points to be confident in the results.

Finally, the NT Review indicated that both reusable plastic shopping bags and bin liner numbers increased significantly post ban (see table below of bag and bin liner numbers per year in the NT).

The review concluded, that despite a reduction of 10.3 million bags per year, given the diversity of bag types of varying thickness that were available, it was uncertain whether there was a reduction in overall plastic usage in the NT.

Overall, it remains unclear whether the benefits to the environment from plastic bag bans have been as large as anticipated, and worth the inconvenience and direct financial cost to consumers of purchasing alternative bags. It will be interesting to see what new evidence is put forward to Environment Ministers who are considering this issue at their next meeting in Sydney on Monday.

Rod Bogaards is an economist and former Director of the Productivity Commission.