Toxicological Hierarchy
Chemical structure decision trees categorize low molecular weight organic migrants based on toxicological risk profiles without requiring full bioassay testing. In packaging compliance for paper and board, cramer classification assigns unstudied substances or non-intentionally added compounds into specific hazard classes to establish safe migration thresholds. Class one represents low oral toxicity potential, whereas class three contains structures that suggest toxicity or metabolic persistence.
The scheme uses chemical functional groups to set exposure limits.
Structural Evaluation
Screening procedures begin by evaluating functional groups, cyclic structures, and heteroatoms within the chemical molecule. When analyzing extractables from paperboard coatings or printing inks, cramer classification routes each identified molecule through a sequence of decision steps regarding functional reactivity and metabolic pathways. Simple aliphatic hydrocarbons pass directly to class one, whereas aromatic amines trigger immediate routing into class three.
Structural alerts dictate whether a compound requires rigorous analytical quantification down to sub-microgram levels. High-resolution mass spectrometry provides the empirical chemical formulas necessary to navigate these structural decision trees. Laboratories measure actual migration against these derived structural thresholds to confirm safety.
Regulatory Boundary
Compliance evaluations stop applying this structural decision tool when a compound exhibits clear genotoxic alerts. Genotoxic carcinogens require specific toxicological evaluations regardless of cramer classification outcome. Polymers, inorganic salts, and heavy metals lie outside the scope of this organic structural model.
The threshold approach establishes safe limits only for low-concentration migrants present in food contact substrates.
