EA measures supermarket bags carbon footprint
Woven plastic bags need to be reused at least 11 times to have a lower carbon impact than single use carriers, according to research published for the first time.
According to work by the Environment Agency, published this week, lightweight single-use carriers have the lowest carbon footprint.
While standard 'bags for life', sold in most supermarkets, only need to be used four times to have a lower carbon footprint than single-use carriers.
The report Lifecycle Assessment of Supermarket Carrier Bags states paper, heavyweight plastic and cotton bags all use more resources and energy in their production.
The agency said other environmental impacts of single-use lightweight plastic bags such as litter - which weren't assessed by the study - also need to be taken into account.
The report, which was requested by the previous Labour Government, was part of an overall study carried out on how to reduce the environmental impact of retail and food packaging.
An agency spokeswoman said: "A significant part of the environmental impact of these bags is associated with the resources used in their production.
"All multi-use bags need to be reused as much as possible to reduce their relative environmental impact and be responsibly recycled at the end of their life."