is NOT unsafe and is still in very common use, it is a very potent and effective anti-hypertensive. The medical debate which is still going on, and is difficult for even some doctors to follow, is which BP drugs in the very long term give the most advantage, in terms of preventing heart attacks, strokes and deaths. NICE (national institute for clinical excellence) chooses diuretics and calcium channel blockers above B-blockers (atenolol). Not all BP guidelines agree with this.
Additionally there are significant numbers of patients where B-blockers are chosen because they also have other useful properties, suitable for that individual. By all means chat to your GP, he would not be wrong if he advises you to continue them.