Since the Anchorage Assembly’s decision to ban single-use plastic grocery bags in the municipality, there has been ongoing debate on the topic. In the Dec. 29 opinion column “Plastic bag pollution is more nuanced than the Assembly thinks,” author Sarah Jane Brown makes the case against the ban, but omits key information.
I spent a significant part of my career conducting project reviews for BP. One of the things we always had to watch for was missing data: Advocates for a project would not blatantly lie, but they would sometimes present only the numbers that supported their conclusions. We would usually see this in a lackluster project where a review of all the data could call into question its justification. When I read Ms. Brown’s opinion piece about the plastic bag ban, it took me back to my project review days. The author doesn’t present false numbers; she just does some judicious editing.
The author neglects to mention a key concern when it comes to single-use plastic bags, especially here in Alaska: the impact of these bags on marine life. Multiple studies have found that single-use plastic bags kill significant numbers of marine birds and mammals. How to weigh the wildlife impact of single-use plastic bags is a critical piece of the discussion, especially because Alaska’s culture and economy rely heavily on healthy oceans. To fail to mention the point entirely leaves a key piece of information out of the discussion.
On the broader topic of whether reusable bags have a lower overall environmental impact than single-use plastic bags, there is a more serious omission. The author points out that reusable bags consume more resources to manufacture, so they must be re-used a certain number of times for their environmental impact to be the same as single-use plastic bags. The author provides the re-use numbers from a recent Danish study: 7,100 times for cotton bags and 43 times for paper bags. What she neglects to include is the data for reusable polyester or polypropylene bags, by far the most common type of reusable grocery bags. That number from the Danish study is 35-50. An 2011 study in the UK found the number to be 11.
The numbers she provides suggest that consumers must re-use bags an impossible number of times to offset the environmental impacts of manufacturing them. However, re-using a polyester or polypropylene bag 50 times is routine. Assuming two trips to the store each week, reusable plastic bags have a positive environmental benefit after only 6 months. And these bags last and last; I’ve subjected some to heavy use for more than a decade and they are still going strong.
Policy topics such as the plastic bag ban are complex, and even with all information in hand, it is a challenge to adequately weigh the competing positions to arrive at a good decision. Presenting incomplete data in order to support a position is unhelpful to policymakers and a disservice to the public in general.
Sam Dennis is an engineer who formerly worked in oil and gas and now invests in renewable energy.
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