Food packaging and other food contact materials release compounds into food and expose consumers to low levels of chemicals on a daily basis. These compounds, called migrants, are present at very low concentrations (at parts per million, billion or trillion levels) but could still have negative impacts on human health. Chemical migration depends on the physiochemical properties of the migrating compound, the nature of the packaging material and food, processing and storage temperature, storage time and size of package in relation to the food volume. Chemical migration for inert materials (e.g. stainless steel, ceramic, glass) only occurs from the inside surface that is in indirect contact with food. For materials such as paper, paperboard and plastics, chemicals may migrate from within the package and even from outside the packaging.
Chemicals of Concern
In recent years several migrants from food packaging materials have received wide media coverage (e.g. Bisphenol A or BPA, phthalates, antimony, mineral oil hydrocarbons). Materials can have non-intentionally added substances as well as intentionally added substances (e.g. colour, processing and functional additives). For plastics the non-intentionally added substances can originate from break down products of the polymer or additives, impurities, side products and even contaminants from recycled materials.
A recent study identified 175 chemicals of concern (Food contact substances and chemicals of concern: a comparison of inventories, Food Additives & Contaminants: Part A, 2014, 31:8, 1438-1450). Chemical exposures have been linked to several chronic metabolic and reproductive disorders and cancer. This article estimates that up to 80 percent of food contact substances have insufficient toxicity evaluation.
Chemical Migration Testing
In Canada the safety of all food contact packaging is controlled under Division 23, Section B.23.001 of the Food and Drugs Act and Regulations. This regulation prohibits the sale of foods in packages that may impart harmful substances to their contents.
To test for the amount and type of chemicals migrating into the food, the package material is exposed to food stimulants (e.g.. food oil for fatty foods, 10 percent ethanol or 3 percent% acetic acid for water-based foods) using time and temperature parameters that relate to the application of the food product. The results are reported in milligrams of substance extracted per surface area of packaging material.
The identification and determination of “safe” levels of chemicals is challenging. There are a large number of compounds that could migrate from packaging. Determining the effects of these chemicals is complicated due to long-term / low-dose exposure and possible synergistic interactions among different chemicals. Variables such as temperature and contact time also affect the migration level. To complicate matters, chemicals may also be introduced from other food contact sources during production, processing, transportation and storage.
As studies have confirmed evidence of health concerns, industry and regulatory bodies around the world have reviewed and made changes to the regulations as well as adjustments to package material formulation. For example, Canada, the United States and the European Union have banned the use of polycarbonate baby bottles that contain BPA. Industry is also phasing out BPA containing epoxy liners for food cans.
What precautions can be taken to minimize the exposure to potentially hazardous substances? Manufacturers can avoid use of substances of concern, test for hazard properties during the research phase and proactively substitute chemicals with safer alternatives. Effort should be made to share data and increase regulatory harmonization of chemicals. With new insight on toxicity, exposure and metabolism, substances previously considered safe require re-evaluation using updated testing protocol.
Carol Zweep is the manager of packaging, food and label compliance for NSF International. Contact her via e-mail at firstname.lastname@example.org.