The plague of disintegrating diecasts

There seems to be a growing epidemic in recent years of diecast models simply crumbling to dust for no apparent reason, leaving many collectors perplexed and upset at the loss of a model through no fault of their own. Known variously as 'metal fatigue', 'zinc rot' or 'zinc pest', this is caused by impurities of lead and other metals in the zinc alloy used in diecasting and should be avoidable with modern production methods, but sadly it seems even expensive high-end models are not immune from it and there is no cure once it has taken hold.