Contact between an agent and a target. Contact takes place at an exposure surface over an exposure period. Valerie Zartarian, Tina Bahadori and Tom McKone. Adoption of an official ISEA glossary. Journal of Exposure Analysis and Environmental Epidemiology (2005) 15, 1-5. doi: 10.1038/sj.jea.7500411 Published online 24 November 2004