T = 0 No clinically significant systemic human toxicity documented under normal exposure. Ambrosia artemisiifolia is hazardous primarily through inhalant allergenicity rather than poisoning. No evidence for meaningful acute phytotoxic poisoning in humans comparable to toxic medicinal or alkaloid species.
A = 3 Moderate veterinary relevance. Pollen and plant material may contribute to allergic or inflammatory responses in animals, but lethal toxicity is not established. No evidence supports A≥4.
I = 4 Strong invasive behaviour documented throughout Europe. Species forms dense populations in disturbed habitats and agricultural land, causes major agricultural losses, suppresses native vegetation, and produces extremely high seed loads with persistent seed banks. Listed under EU Regulation 1143/2014 → BAN justified.
I=5 would require ecosystem-collapse level evidence comparable to the most destructive aquatic or transformer invasives; current evidence better supports I=4.