butane extraction (microbials)
DNA contamination

DNA is water-soluble and non-volatile (large molecules). You would not expect it to be present in a butane extract. However, traces of DNA are difficult to remove. If you look for DNA (using PCR, for example), you will probably find it. After all, it is a forensic molecule of choice.

Contamination with living microbes

I don't think living cell would survive the extraction. Fungal spores might, though.

Human consumption

There are lots of legal foods where the presence of microbes is desired - yoghurt, beer, cheese are just some examples. All fresh food has its share of microbes, and healthy humans have them too - on the skin and in our digestive tract. Many of these microbes have a role in keeping us healthy, but some make us sick.

As the laws concerning your project differ with location, and the opinions on benefits and risks of your product range widely, I won't comment on those except to say that residual butane would concern me more than traces of microbial DNA.