Strength of association: Case studies and clinical data indicate clear health impacts in significant proportions of exposed groups. |
Consistency: Clinical data consistent with known toxic effects of organophosphates; and across varying aircraft types / countries. |
Specificity: Aerotoxic Syndrome is a syndrome (as is Acquired Immune Deficiency Syndrome; Multiple Chemical Sensitivity; Occupational Asthma; Gulf War Syndrome and Asperger’s Syndrome) and with common neurological/respiratory symptoms linked to oil leakage/pyrolysis products exposure in cabin air. |
Temporality: Aerotoxic Syndrome was never reported prior to the introduction of engine bleed air pressurization systems and cabin air contamination precedes linked health effects. |
Biological gradient: High contaminant exposure often causes greater health effects; but low dose effects also apparent, suggesting non-linearity. |
Plausibility: The known effects of organophosphates and other cabin air contaminants support a causal link. |
Coherence: Animal and human data support a causal link. |
Experiment: Some health effects are reversible after exposure cessation, especially for acute exposures. |
Analogy: Polychlorinated biphenyls; hot rubber fumes; welding fumes; traffic fumes, occupational asthma, leaded petrol, methyl mercury, organophosphate pesticides and tobacco smoke have relevant features. |