Plastic packaging materials (PPMs) protect food from contamination, maintain quality, and ease transportation and distribution. Additives included during the manufacturing and processing of PPMs improve flexibility, durability, barrier properties, and sometimes aid the processing itself. During processing, these additives, even the monomers used to produce the plastics, can produce side products or breakdown products as a result of degradation and various chemical reactions. These starting substances and reaction products include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), phthalates/phthalic acid esters, alkylphenols, and bis(2-ethylhexyl) adipate, which are considered endocrine-disrupting chemicals (EDCs) that may interfere with the human endocrine system and produce adverse reproductive, neurological, developmental, and immune effects. When in contact with food, EDCs can migrate into food if conditions are appropriate, thereby possibly jeopardizing food safety. Chemical risk assessment and regulatory control were developed to reduce human exposure to harmful migrated EDCs. This article gives an overview of the migration of EDCs from PPMs and control measures to reduce the risk of adverse impacts on human health.
A two-step solution based on the boundary conditions of Crank's equations for mass transfer in a film was developed. Three driving factors, the diffusion (D), partition (Kp,f) and convective mass transfer coefficients (h), govern the sorption and/or desorption kinetics of migrants from polymer films. These three parameters were simultaneously estimated. They provide in-depth insight into the physics of a migration process. The first step was used to find the combination of D, Kp,f and h that minimized the sums of squared errors (SSE) between the predicted and actual results. In step 2, an ordinary least square (OLS) estimation was performed by using the proposed analytical solution containing D, Kp,f and h. Three selected migration studies of PLA/antioxidant-based films were used to demonstrate the use of this two-step solution. Additional parameter estimation approaches such as sequential and bootstrap were also performed to acquire a better knowledge about the kinetics of migration. The proposed model successfully provided the initial guesses for D, Kp,f and h. The h value was determined without performing a specific experiment for it. By determining h together with D, under or overestimation issues pertaining to a migration process can be avoided since these two parameters are correlated.
Migration studies of chemicals from contact materials have been widely conducted due to their importance in determining the safety and shelf life of a food product in their packages. The US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) require this safety assessment for food contact materials. So, migration experiments are theoretically designed and experimentally conducted to obtain data that can be used to assess the kinetics of chemical release. In this work, a parameter estimation approach was used to review and to determine the mass transfer partition and diffusion coefficients governing the migration process of eight antioxidants from poly(lactic acid), PLA, based films into water/ethanol solutions at temperatures between 20 and 50°C. Scaled sensitivity coefficients were calculated to assess simultaneously estimation of a number of mass transfer parameters. An optimal experimental design approach was performed to show the importance of properly designing a migration experiment. Additional parameters also provide better insights on migration of the antioxidants. For example, the partition coefficients could be better estimated using data from the early part of the experiment instead at the end. Experiments could be conducted for shorter periods of time saving time and resources. Diffusion coefficients of the eight antioxidants from PLA films were between 0.2 and 19×10-14m2/s at ~40°C. The use of parameter estimation approach provided additional and useful insights about the migration of antioxidants from PLA films.