The study by Jane Muncke also raises questions over the accuracy of commonly used testing methods to measure leaching of substances from food contact materials (FCMs) and suggests that children’s exposure is not “always realistically predicted”.
The wide-ranging paper, which appears in the Journal of Steroid Biochemistry and Molecular Biology, adds that exposure of whole populations to substances that have migrated into dry foods has been underrated.
The research further proposes that the effects of chemical contaminants should be assessed not just according to criteria such as mutagenicity and genatoxicity but also endocrine disruption, mixture and developmental toxicity.
Muncke said that the exposure assessment for chemicals leaching from food packaging is “currently estimated with apparent uncertainty”.
Firstly, given the complex nature of modern polymers it is not always possible to know what substances are incorporated into the final plastic material that could migrate into food. She added that current tests involving using stimulants to ape the chemical properties of foods can either over or underestimate exposure levels.
The study also raises concerns that analyses only assess monomers and additives rather than the whole leacheate. Taking items such as packaging inks and adhesives into account means “currently there is no systematic assessments of the whole packaging leacheate toxicity”, said the researcher.
Child exposure greater than estimated?
She adds that child exposure to contaminants could be greater than beleived as the amount of food they consume that has been affected by migration from FCMs is likely to be much higher than regulatory assesments. A British study found that on average children consume on average 1.6 times as much food from plastic food packaging as estimated by the current EU approach.
Moreover, the smaller packet sizes children more often use have a larger surface to volume ratio and therefore higher migration per kg of food. Such factors could mean that children are being exposed to contaminant levels above current tolerable daily intakes (TDI), said the research.
Toxicity in food packaging is assessed using a single substance approach but Muncke claims it has been established that “mixtures of chemicals with common biological endpoints can act additively”.
The paper outlines the current difference of opinion over the significance of low level exposure of intentionally added substances – particularly with regard to such an EDC like BPA. This determines whether regulatory bodies are obliged to carry out a reduced toxicity tests or additional analysis for reproductive toxicity.
Migration versus release
The study makes a distinction between migration and release – with the former being from chemicals that are intentionally added into food packaging and whose leaching is carefully assessed prior to authorisation.
But it adds there are substances that transfer into foods because of a range of unforeseen factors – such as environmental, reaction with foodstuffs and the effect of UV light and heat, which it calls ‘release’.
It cites the effect of hard water on polycarbonate bottles and how research has claimed this triggers a much higher rate of BPA transfer than is seen in lab tests used by regulators – where purified distilled water is employed.
Muncke acknowledges that risk assessment of FCM substances is a “challenging task”. But she states that the scientific findings she outlines in her paper suggest there are a number of key factors that are not presently being taken into account by authorities.
The real challenge for regulators, she concludes, is to “adopt recent scientific findings into systematic authorisation procedures for the benefit of public health”.
Endocrine disrupting chemicals and other substances of concern in food contact materials: An updated review of exposure, effect and risk assessment by Jane Muncke is published in the Journal of Steroid Biochemistry and Molecular Biology, doi:10.1016/j.jsbmb.2010.10.004