A scientific study published on 13 February 2013 in the peer-reviewed journal Food Additives & Contaminants: Part A assessed the levels of three different compound classes present in paperboard food packaging and their migration potential into packaged dry foods (Lorenzini et al. 2013). Scientists from Swiss and Italian institutes, including the Official Food Control Authority of the Canton of Zurich, obtained packaged muesli (16% fat content) and egg pasta (4% fat) immediately after filling. The muesli was packaged in an internal polyethylene plastic bag, while the egg pasta was in direct contact with the paperboard but had an external polypropylene plastic bag wrapping.
The packaged foods were stored in diverse ways, for different durations of time and at varying temperatures (Table 1). Before storage, levels of mineral oil saturated hydrocarbons (MOSH), mineral oil aromatic hydrocarbons (MOAH) and diisopropyl naphthalenes (DIPN) were measured in the paperboard packaging. One aim of the study was to understand the migration behavior of these compounds into food under real-life long-term storage conditions (> 1 month, room temperature) and during accelerated lab testing (10 days, 40°C).
Table 1: study design details
|Storage type||Storage temperatures||Storage duration, sampling times|
||4°C (refrigerated storage)20°C (room temperature)30°C (warm warehouse)40°C (migration testing)60°C (migration testing)||2 days after filling into packagingWeekly12 months|
Migration into food happened rapidly: after one week’s storage at 20°, MOSH content was 4 ppm (mg/kg food) in muesli and 5 ppm in the egg pasta. The internal plastic bag did not prevent migration. For the muesli, maximum migration was reached for MOAH and DIPN before the end of shelf life meaning that two of the three analyzed substance classes had transferred completely from the packaging into the food. The internal plastic bag thereby presented no migration barrier.
After 1 year free standing storage at room temperature, approximately half of the MOSH present in the packaging migrated to the food. For packs stored inside corrugated boxes migration was higher. For all substances, migration was highest in the boxed storage foods, followed by shelved and free standing storage. This is due to the volatility of the migrants that can evaporate to the air more freely if not boxed.
MOSH migration was highest for all three types of storage conditions. After 12 month storage at room temperature (20°C) the muesli contained 35 (boxed, 77% of paperboard concentration), 22.5 (shelved) and 18.9 mg MOSH /kg muesli (free standing) respectively. In egg pasta, MOSH migration was slightly lower.
For MOAH and DIPN, migration peaked after 8 months and ranged between 5.2 mg MOAH/kg muesli (8 months, boxed storage, 20°C) and 14.8 mg DIPN/kg egg pasta (8 months, free standing, 20°C).
Higher temperature migration test conditions of 40° are commonly used to simulate long term storage at room temperature but during actual shorter testing time. These storage conditions led to accelerated migration as expected, however also the type of migrants was different to actual room temperature storage during 1 year: hydrocarbons of higher molecular mass (>C28) increasingly migrated at the elevated temperature. This finding is important because commonly migration testing relies on higher temperatures for simulating longer storage conditions during a shorter time period. These results indicate that such test conditions lead to an imperfect representation of the real world conditions and in this case an overestimation of migration for higher molecular compounds.
Mineral oils commonly used as printing ink solvents can diffuse into foodstuffs when they migrate from paperboard food packaging. Not all food packaging printing inks contain mineral oils.However they can also be present in unprinted, recycled packaging material due to residues from newspaper and other sources of recycling. 2,6-iisopropyl-naphthalene (DIPN) is used as solvent in carbonless copy paper and enters paperboard food packaging through the recycling stream.
Due to a lack of toxicological data the European Food Safety Authority (EFSA) maintains the current acceptable daily intake (ADI) of 0.01 mg/kg bodyweight for mineral oil saturated hydrocarbons (MOSH) of the size C16 to C35 (EFSA 2012). This ADI was derived by the Joint Food and Agriculture Organization (FAO)/World Health Organisation (WHO) Expert Committee on Food Additives (JECFA 2002, 2012). Main health concerns related to MOSH are specific immune system responses (microgranuloma) that can impair organ functioning and lead to chronic disease. Mineral oil aromatic hydrocarbons (MOAH) are of greater concern since they contain known mutagenic and carcinogenic compounds. DIPN is not considered to be of toxicological concern.
Lorenzini, R., et al. (2013). “Migration kinetics of mineral oil hydrocarbons from recycled paperboard to dry food: monitoring of two real cases.” Food Additives & Contaminants: Part A: 1-11.
EFSA 2012 Scientific Opinion on Mineral Oil Hydrocarbons in Food, EFSA Journal 10(6):2704
JECFA 2002 Fifty-ninth report of the Joint FAO/WHO Expert Committee on Food Additives, JECFA 2002, p.11 ff
JECFA 2012 Seventy-sixth meeting of the Joint FAO/WHO Expert Committee on Food Additives: summary and conclusions, JECFA 2012, p.4