UC Davis Professor Emeritus Donald Crosby was 60 before contracting his first painful case of poison oak. But the experience spurred the environmental toxicologist to write a new book about plants that cause skin reactions -- "The Poisoned Weed."

The 266-page guide reveals a world full of plants that adversely affect human health by contact with the skin. Some itch- or rash-inducing plants may be surprising. Buttercups, chili peppers and figs, for instance, rank among the most dangerous "dermatoxic" plants in the United States.

In this comprehensive new book, Crosby reviews the history, occurrence, classification, poisonous constituents, hazards, toxicity and health aspects of the major allergenic and irritant plants. "The Poisoned Weed" is written for a broad cross-section of scientists and students but will also appeal to people involved with forestry, firefighting, utilities, parks, gardening, agriculture and outdoor recreation.

"The idea for this book began over many years as I watched my wife, Nancy, struggle with reactions to a series of toxic plants," Crosby said. "After my own experience with poison oak, I found while preparing for a classroom lecture that the only existing book on poison oak and poison ivy had been published in 1922. An update seemed long overdue."

As Crosby's research progressed, the scope of the book expanded to include other plants that cause similar dermatological reactions. Many common ornamental plants, food crops and garden weeds can produce toxic effects similar to poison oak.

More than two-thirds of the population is sensitive to poison oak, poison ivy and their relatives, exacting a huge economic toll. In California alone, more than 5,000 cases of occupational dermatitis from poison oak are reported each year. More than half the compensation claims from California agricultural workers during one five-year study period were caused by exposure to poison oak.

The book also discusses how allergenic plant compounds have become ubiquitous in typical grocery store items. They're in aftershave lotions, deodorants, fabric softeners, lipstick and furniture polish, to name a few. In fact, contact allergies are becoming recognized as a growing worldwide health problem, according to Crosby. Reactions can vary from mild itching to more serious rashes that require hospitalization.

Crosby taught at UC Davis and conducted research on toxic plants, their products and other toxic substances for more than 40 years. He helped found the campus's Department of Environmental Toxicology.

"The Poisoned Weed" is Crosby's fifth book and is published by Oxford University Press.