Invasive plants can pose real risks to human health.
Here are a few examples:
Injury: Chervil, wild parsnip and giant hogweed contain a phototoxic sap. When bare skin touches the plant and then is exposed to sunlight, the sap reacts and causes burns, blistering and skin discoloration.
Lyme disease: Invasive shrubs can increase populations of Lyme disease-carrying ticks. Heavy infestations of barberry - a thorny, multi-branching shrub - make particularly good hiding places for mice and cause populations to increase. Mice are an alternate host for Lyme disease. Larger mouse populations mean more Lyme disease-carrying ticks. A 2006 study in the Journal of Medical Entomology found twice as many adult ticks and nearly twice as many nymphs in plots dominated by exotic invasives. In some parts of the country, invasive barberry is treated solely to reduce rates of Lyme disease.
Elias, S.P, C.B. Lubelczyk, P.W. Rand, E.H. Lacombe, M.S. Holman, and R.P. Smith. 2006. Deer browse resistant exotic-invasive understory: An indicator of elevated human risk of exposure to Ixodes scapularis (Acari: Ixodidae) in Southern coastal Main woodlands. Journal of Medical Entomology 43(6): 1142-1152.
Lubelczyk, C. B., S. P. Elias, P. W. Rand, M. S. Holman, E. H. Lacombe, and R. P. Smith. 2004. Habitat associations of Ixodes scapularis (Acari: Ixodidae) in Maine. Environ. Entomol. 33: 900-906.
Williams, S.C., J.S. Ward, and T. Worthley. 2008. Increased blacklegged tick and white-footed mouse abundances in Japanese barberry infestations. Connecticut Invasive Plant Working Group – Invasive Plant Conference at the University of Connecticut. Poster Presentation.