From today English shoppers will have to pay 5p for plastic carrier bags at the checkout.

The new law makes England the last part of the UK to start charging for plastic carriers and is intended to reduce the number going to landfill.

Critics argue key exemptions may hinder the scheme’s effectiveness as certain categories of bag will not be charged and the law only applies to retailers hiring 250 or more full-time equivalent employees. Exemptions include uncooked meat and fish, unwrapped food for animal or human consumption or goods contaminated by soil, such as potatoes.

Similar legislation in Wales, Scotland and Northern Ireland has seen a significant drop in carrier bag usage, with Wales reporting an especially successful reduction of 79% in three years.

The number of single-use carrier bags handed out by major supermarkets in England has risen by 200 million over the last two years to 7.64 billion last year, averaging 140 per person and coming to a combined weight of 61,000 tonnes.

The government expects the scheme will reverse this rising trend by up to 80% in supermarkets and 50% on the high street generally.

Paper bags will continue not to be charged, but there is no exemption for biodegradable plastic carriers because, according to a report in The Independent, the government is unsure how to process them and whether they truly are better for the environment. The law is open to being amended in favour of biodegradables and the Department of the Environment, Food and Rural Affairs has been commissioned to submit a report to Parliament by 5 October.