Synthetic chemicals which are used in the processing, packaging and storing of the food we eat could be doing long-term damage to our health, environmental scientists warn.

The concerns have been raised in the Journal of Epidemiology and Community Health, part of the British Medical Journal group.

The scientists claim that tiny amounts of synthetic chemicals leach into food. While these minute quantities in themselves do no harm, no one knows how safe we are from a lifetime's exposure to the chemicals, such as formaldehyde, through eating food previously wrapped or stored in plastics.

In a commentary piece in the journal the scientists note that some of the chemicals that could cause concern are regulated but this does not prevent their being used widely in food packaging. They say that people who eat packaged or processed foods are likely to be chronically exposed to low levels of these substances throughout their lives.

Far too little is known about the long-term impact and especially about our exposure to such chemicals at critical points in human development, such as in the womb and during early childhood.

The writers, who include Jane Muncke, from the Food Packaging Forum Foundation, in Zurich, say there is cause for concern on several grounds. Chemicals known to be toxic, such as formaldehyde, a cancercausing substance, are legally used in these materials. Formaldehyde is widely present, albeit at low levels, in plastic fizzy drinks bottles and melamine tableware.

Other chemicals known to disrupt hormone production and used in food and drink packaging, include bisphenol A, tributyltin, triclosan, and phthalates. Altogether, more than 400 chemicals are involved.

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

They warn that potential cellular changes caused by food contact materials, and in particular, those with the capacity to disrupt hormones, are not even being considered in routine toxicology analysis. They suggest this "casts serious doubts on the adequacy of chemical regulatory procedures".

It will not be easy to monitor and assess the effects over decades of exposure to these chemicals, they say. There are no large groups of people who are not exposed to wrapped and processed and stored food.

Studies have shown that we all have traces of these chemicals in our bodies. That means it is not possible to carry out a study comparing people who have been exposed to them with people who have not.

But a population-based assessment is urgently needed as well as bio monitoring to establish any potential links between food-contact chemicals and chronic conditions such as cancer, obesity, diabetes, and neurological and inflammatory disorders, particularly given the known role of environmental pollutants, they argue.

"Since most foods are packaged, and the entire population is likely to be exposed, it is of utmost importance that gaps in knowledge are reliably and rapidly filled," they say.