Well I've had a good readup on the slug pellet issue. I believed that slug pellets were blue to ward off birds, which appears to be true. I've also found that birds, frogs, toads etc., do not eat dead slugs and snails. Slugs eat very little of the pellet(s) and if a bird etc., did eat a newly poisoned slug the poison level would be insufficient to cause it harm. Conservation organisations have not found evidence that pellets have harmed birds. Hedgehogs may eat many slugs and snails however, but they will eat only live ones so a build up of poison in their systems is unlikely.
I use very few, and will go on using them in the sparing way I do. In fact if you use too many the slugs and snails are put off, dont eat any pellets, and promptly go looking for plants that are less guarded. I may look for the ferrous pellets in future tho which do not contain melaldehyde but are based on an iron compound. One of the benefits being the slug does off and buries itself or hides until dead so fewer slimey results and virtually removing worries for wildlife.