[quote]

... to say nothing of the risk of contracting "mad cow" disease from eating beef brains from contaminated animals.</blockquote>


It seems that BSE may have been caused by organophosphate chemicals used to treat warble fly in cattle - and demanded to be the only method to treat the problem by the UK Ministry of Agriculture:
[quote]

Under the Warble Fly Order 1982 ... the Ministry required farmers to treat warble with organophosphorus ("OP") twice a year.</blockquote>


http://www.purdeyenvironment.com/bseinqui.htm


Nasty insecticides these are. Farmers and agricultural workers have been ill after exposure to them:


http://www.google.com/search?rls=en&q=organophosphates+farmers&ie=UTF-8&oe=UTF-8


... or dead:
[quote]

Despite being ill, Casillas attempted to ride his bike to work the next morning but lost consciousness and collapsed. By the time medical help arrived, he was dead, "with foam streaming from his nose."</blockquote>


http://www.thefreelibrary.com/Organophosphates,+friend+and+foe:+the+promise+of+m edical+monitoring...-a0203279204


They also seem to have a role in "Gulf War Syndrome":


http://en.wikipedia.org/wiki/Gulf_War_syndrome


The other animals to exhibit "madness" at around the same time as cattle were "mad cats". Cats were also treated with an organophosphate insecticide at that time. Makes you wonder.