Managing Dual Use Additives Information Flow in Plastic Packaging Declarations
Dual use additive management demands specific identity flow from resin compounders to food packers to satisfy direct food additive maximum limits.
Worst Case Calculation
Meaning
Theoretical estimation methods assume the total migration of a substance from a polymer into the surrounding medium. A worst case calculation is used when experimental data is unavailable or when a screening step is needed to identify potential risks. Complete transfer of the additive or impurity is assumed regardless of the actual contact conditions.
Migration Limit
Comparison against legal thresholds determines if further testing is required. If a worst case calculation shows that the exposure is still below the permitted limit, the material is considered safe without further lab work. Preliminary screening saves time and cost during the initial phase of material selection.
Safety margins are maintained by the conservative nature of the assumption.
Content Depletion
Mathematical models use the initial concentration of the substance in the resin as the starting point. The worst case calculation does not account for the slow diffusion of molecules through the polymer matrix. Diffusion limits usually prevent the total exhaustion of an additive during normal product use.
Simplification allows for a rapid assessment that does not require knowledge of temperature or time variables.
Submission of
Submission of these figures is often the first step in a compliance file for a new part. If the worst case calculation fails to meet the safety criteria, the manufacturer must then perform specific migration testing. Most substances in high density polymers migrate at a much lower rate than this calculation suggests.
Filtering helps focus resources on the most important safety issues.