When I studied marine biology and water (care?) A,B and C (Dont know the english names of all the courses),we learned the term "Point of no return" as a term describing when a water gets enough acids, that the heavy metals dissolve and kills everything, making it allmost impossible to restore.
I dont know if you use that term in the UK but it would be strange if you dont, since we used the term in english and not swedish.
Point of no return is, anyway a term used in many different subjects. It's a quite normal "chaos" term.
Let me get this straight, I do NOT think it is ok to have carps swimming around with leads. My point was that if I was the person losing leads all the time, I would check the rig to make the leads loosen only when fish snaggs, and not on normal takes.
I agree with you we shouldnt just discard leads,but as I said I would rather lose leads than teather fish.By the way I too have studied aquatic biology,and I studid the effects of lead in UKand EU waterways,and Im an active member of IFM so I can keep on top of current issues.