The North American Free Trade Agreement (NAFTA) and the General Agreement o
n Tariffs and Trade (GATT) have focused attention on risk assessment of pot
ential insect, weed, and animal pests and diseases of livestock. These risk
s have traditionally been addressed through quarantine protocols ranging fr
om limits on the geographical areas from which a product may originate, pos
tharvest disinfestation procedures like fumigation, and inspections at poin
ts of export and import, to outright bans. To ensure that plant and animal
protection measures are not used as nontariff trade barriers, GATT and NAFT
A require pest risk analysis (PRA) to support quarantine decisions. The inc
reased emphasis on PRA has spurred multiple efforts at the national and int
ernational level to design frameworks for the conduct of these analyses. As
approaches to pest risk analysis proliferate, and the importance of the an
alyses grows, concerns have arisen about the scientific and technical condu
ct of pest risk analysis. In January of 1997, the Harvard Center for Risk A
nalysis (HCRA) held an invitation-only workshop in Washington, D.C. to brin
g experts in risk analysis and pest characterization together to develop ge
neral principles for pest risk analysis. Workshop participants examined cur
rent frameworks for PRA, discussed strengths and weaknesses of the approach
es, and formulated principles, based on years of experience with risk analy
sis in other setting and knowledge of the issues specific to analysis of pe
sts. The principles developed highlight the both the similarities of pest r
isk analysis to other forms of risk analysis, and its unique attributes.