fish might not be , cows are?

Ok we all know about BSE and that we are no longer allowed to be sold cows that were over 2.5 ? to 3 ? years old [legally].
Take a look at how the prions [ the bits of the cow that cause CJD- mad cow in humans] are produced - as I understand it.
Prions are mis-shaped proteins that accumulate in the brain and other tissues. These eventually overwhelm the normal operation of the brain and the brain starts to 'dissolve', causing death within 18 months [ in humans ] .
The keyword here is ACCUMULATE. The evidence is that cows who are slaughtered within 3 years [or earlier] do not show signs of BSE.
This is because not enough prions have formed to produce symptoms. You still eat what they have in their body.
Thus we are eating BSE contaminated products.
Doctors have stated that we would need to be 150 years old for us to be affected by this toxin and develop CJD or one of its variants.
Information given below is supposition on my part as I haven't seen the technical data, but..
1. This information is by necessity extrapolated from a very small database , so cannot be rigorous and must be subject to error. Without the technical data, it is impossible to speculate about the degree of uncertainty [in statistical terms] in that figure.
2. The physical figure of 150 years in 'lethal' terms is prone to massive error without the covering caveats/assumptions. Lethal doses in pharmaceutical terms are normally done using what is called LD50 - ie the dose required to kill 50% of the population exposed to the substance . The article I read had no such detail [it was a newspaper- so they do tend to miss out on these figures]. If it is an LD50 number then even ignoring the huge errors above in point 1 - if the standard deviation was something like 25 years[I have picked this number totally out of the air as it gives a number you can think of] , then we would lose something like about 1% [ I'm struggling here but isnt 3 sd= 1% ish ? ] of the population above 75 years old due to CJD- I know this is alarmist, but its broadly true.
3. A third way exists to extrapolate the data and that is to fit the data into a 'bell curve' . This is to say that the deaths that have occured already fit into a statistical normal distribution pattern.
This *can* produce a reasonable extrapolation if sufficient data points [deaths] exist, but they don't. Also this method fails to take into account of actions oustide the curve- like if showing the disease is a function of how many prions have been ingested and/or the time scale to be affected- then we could see HUGE parts of the population dying and would make AIDS look like a midge bite
The reason for hiding this fact from the population of the world ? So the UK did not have to slaughter its herd , is all. Frigtening aint it , what else has been swept under the carpet over the years....