Now, Breast Cancer UK has written to the UK subsidiaries of these companies, which include soup giant Campbell’s, for information about the extent of the use of BPA in cans in the UK. The charity is campaigning for a total ban on BPA in "food contact materials".

“There is a lot of evidence, and it’s growing, that BPA can have an affect on the human body even at very low levels,” says chief executive Lynn Ladbrook. “We believe there is no safe dose of BPA. That’s why we are writing to the UK subsidiaries of the companies in the US study, asking them to state their policy on BPA and the extent to which the chemical is used in the UK.”

Food Safety UK acknowledges that “minute” amounts of BPA can leach into food from cans and packaging, but says the chemical is “rapidly absorbed, detoxified, and eliminated by the body” and therefore “not a risk” to human health at current exposure levels. However, the subject is contentious among scientists.

What is BPA?

BPA stands for bisphenol-A, a man-made industrial chemical widely used to make hard, clear plastic including food and drinks packaging, microwave ovenware, storage containers, water and milk bottles as well as plastic tableware and cutlery. It is also used to make the epoxy resins that line cans of food, such as baked beans, soup and tomatoes and cans of fizzy and alcoholic drinks. The chemical is also found in a vast range of non-food products.

Is BPA safe?

It depends who you ask. BPA is classified as an endocrine disruptor, which means it can interfere with the hormone systems of mammals. But regulatory authorities around the world, including the European Food Safety Authority (EFSA), the US Food and Drug Administration and Health Canada, say our low exposure to the chemical is not harmful.

However, the scientific evidence that low doses can, in fact, impact on human health is growing. In France food packaging containing BPA is banned, although it can now be used in products made for export, following a legal challenge by plastics manufacturers.

Countries including Canada, the European Union, China and the UShave already banned BPA in baby bottles and baby food packaging, and in some case, children’s sippy cups.

What are some scientists concerned about?

Although the European Food Safety Authority investigated BPA in 2015 and declared it safe, this month it launched a fresh probe afterscientific evidence emerged from Holland that the chemical could impair the immune system of unborn and young children.

In February, the EU proposed classifying BPA as a category 1B reprotoxin; a substance presumed to have adverse effects on sexual function and fertility in men and women, as well problems in children. The EU is expected to ratify the proposal later this year, and anti-BPA campaigners say this could pave the way for the chemical to be phased out in consumer products.

Why are the main health concerns about BPA?

According to Breast Cancer UK, there is “a significant amount of evidence” that even low-level exposure to BPA can effect the development of breast tissue. Some studies have linked contact with BPA to breast cancer, prostate cancer, heart disease, obesity and diabetes.

The charity recommends that consumers opt for food products packaged in glass or other non-can materials wherever possible.

What do food manufacturers think?

Soup manufacturer Campbell’s has said that it will stop using BPA in cans by mid-2017. Nestle has already removed BPA from infant food packaging, and is “working towards” removing it from all its packaging.

A spokesman for the Metal Packaging Manufacturers Association (MPMA) said: “BPA is possibly the most researched chemical compound ever and the overwhelming weight of scientific evidence, as repeatedly verified by regulatory authorities across the world … shows that the use of BPA in can lining poses no threat to human health."