With 650 million tourists crossing international borders annually, travel is a leading cause of unintended invasive-species introductions. Fungi, insects and seeds hitch rides in luggage, on food and clothing, even on our bodies. "The organisms...that we import intentionally pale in numbers beside the masses of smaller living things we set in motion incidentally," cautions Yvonne Baskin in A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions. And not without cost: In the U.S., invasive species have contributed to the decline of up to 46 percent of imperiled species.
Some countries require aircraft "disinsection" to crack down on alien invaders, forcing airlines to spray cabins with insecticides, including synthetic pyrethroids, which can spark asthma attacks. Passengers may be subject to in-flight spraying on some flights to Asia, Africa, the South Pacific and the Caribbean, while other countries spray planes immediately before passengers board.
What You Can Do: Travel Smart: Invasive Plants and Animals - The Green Guide