Pages 41-68 in James Flynn, Paul Slovic and Howard Kunreuther (eds), Risk, media and stigma: understanding public challenges to modern science and technology. Earthscan Publications Ltd., London, England. 399 pages., Case study of a "radiating chain of stigma beginning with the accidental contamination of silage with oils containing polychlorinated biphenyls (PCBs), the consumption of the feed by dairy cows, the discovery of PCBs in cows milk bottled as a raw milk pro