Image copyright Getty Images Image caption The health risks of chemicals in plastic bottles are the subject of some debate

Scientists say "far too little" is known about the health risks of chemicals used in food packaging, and some could cause cancer.

Research is needed to understand the effect on the human body and embryonic development of at least 4,000 chemicals used in packaging, they said.

Links between packaging and obesity, diabetes and neurological diseases need to be explored, scientists warned.

But critics have said that the call is alarmist.

Scientists Jane Muncke, John Peterson Myers, Martin Scheringer and Miquel Porta called for an investigation into the health risks of food packaging in a commentary piece published in the Journal of Epidemiology and Community Health.

'Lifelong exposure'

They noted that chemicals such as formaldehyde, which they said can cause cancer, were used in many materials, such as plastics used for fizzy-drink bottles and tableware.

Substances could leach into food, and they added that the risks of "lifelong exposure" to such chemicals were not documented, said the researchers.

"Whereas the science for some of these substances is being debated and policymakers struggle to satisfy the needs of stakeholders, consumers remain exposed to these chemicals daily, mostly unknowingly," they said.

But carrying out analysis would not be easy, they said, as there are no unexposed populations for comparison.

The call for research has attracted criticism.

Dr Ian Musgrave, senior lecturer in pharmacology at the University of Adelaide, said it was "very hard to take seriously" the claims that formaldehyde in plastic bottles could cause cancer.

He said it was present in many foods naturally, and to consume as much formaldehyde as that in an apple someone would have to drink "at least" 20 litres of plastic-bottled water.

Dr Musgrave added: "Obviously the concern about formaldehyde from food packaging is significantly overrated, unless we are willing to place 'potential cancer hazard' stickers on fresh fruit and vegetables."

'High levels of fat'

Jon Ayres, Professor of Environmental and Respiratory Medicine at the University of Birmingham, said the scientists painted an "alarmist" picture.

He said there was "no denying" that ingesting lower doses of some substances could "in principle" be harmful, but the issue was how to recognise and quantify any effect.

Prof Ayres added: "But can these effects really be anything other than modest at worst when few have been recognised to date?"

He said that simply calling for a different approach to the chemicals "does not really help".

Dr Oliver Jones, lecturer at the RMIT University in Melbourne, Australia, said: "More research is always welcome from a scientist's point of view.

"But I would hazard a guess that the high levels of fat, sugar and salt in a lot of today's processed food are more of a health concern than any migration of chemicals from the packaging."