contaminated starter

help! my starter may have been contaminated.

Henry is about 3 months old, was started on dark rye and has been fed dark rye it's whole life, 50g rye flour, 65g filtered water. from day 2 it has been very active, from about day 4 it's been doubling after feeding in about 3-4 hours, i feed it once a day, occasionally twice, sometimes once every 2 days, whenever I remember and can be bothered really. There was a time when I gave up on it and let it fester on the kitchen counter, it developed a dry skin which began growing little patches of mould. Soon after I noticed something had laid eggs on the inside of the jar.

At this point I decided I'd better do something about it. I gingerly peeled back the skin, to be hit in the face by a very strong smell of almost beery yeast. I scooped out about a teaspoon and started feeding it irregularly, and immediately it was as active as it ever was.

Now I assume this is all ok, my starter is active, smells of yeast, doubles in volume quite quickly... I know it's quite hard to kill a starter once you've got it going, but this isn't my concern.

I've never baked with it, I was intending to soon however, now I'm not so sure... I've just gone to feed it, and discovered the butt of a joint in there. I didn't discover this until I'd scooped out half, and mixed in the 65g of water.

I don't know how long it's been in there, or how it got there, but I imagine my flatmate forgot to tell one of his guests that the bins that are just outside the kitchen are not garbage bins. The joint end of it still had tobacco in it, as well as a little of the other stuff I presume. Is this something I should be worried about? I'm not so worried about the ash and plant matter, as after I start with a new jar from a teaspoon of my current starter, only trace amounts will remain, my concern is about the chemicals all over the tobacco, has anyone had a similar contamination? has it affected your starter at all? will I need to start again or am I panicking over nothing?