Today I tasted a new batch that was done priming, the beer has a distinct but mild butter after taste, so I'm suspecting high Diacetyl levels, is it still safe to drink? Or should I throw it all?
Diacetyl is used as a food flavoring and is safe to ingest, It is not safe to inhale diacetyl when heated and/or vaporized, and causes popcorn lung.
There is no evidence in the available information on diacetyl or starter distillate that demonstrates or suggests reasonable grounds to suspect a hazard to the public when they are used at levels that are now current or that might reasonably be expected in the future.
Diacetyl is a FDA safe food additive. It's known for tasting almost exactly like butter. It's common on popcorn and candies. You can buy straight Diacetyl to flavor your food if you didn't get enough in your beer. If you don't like the way it tastes, dump it down the drain. We've all dumped many batches down the drain in our day.