timm,
There is no way to avoid the "bad stuff" such as tar and nicotine in any tobacco. Some are milder than others and you can employ moderation to reduce the harm, but there's no such thing as a harmless tobacco or that's what everyone would be smoking.
Truth be told, as others have noted, there is more "stuff" in aromatics than your average straight pipe tobacco... Odds are they are fairly benign additives like propylene glycol and artificial flavours but they are there in greater amounts.
Tobacco's chemical makeup and the simple combustion of plant matter are going to produce plenty of compounds that aren't ideal for your health. The only way to avoid it is to abstain, but that's not why we are all here!
Pipe smoking is a fairly enjoyable and relaxing pursuit - I think we all find positives in this pastime or we wouldn't take it up. If you like smoking your pipe, then these are the risks you take.
Colcolt is right on the money - some people are genetically predisposed to cancer and heart disease and respiratory ailments and tobacco may or may not be a trigger for them. There's really no way to know what is completely caused by genes, what's completely caused by lifestyle, or what's a combination of both.