This comment from mitrovarr@Metafilter sums it up:

"It's really easy to contaminate PCR reactions with human DNA, on account of the technicians being human and thoughtlessly shedding DNA at all times. You can prevent it, of course, but most labs that usually deal with non-human taxa only don't bother to, because it doesn't matter and it's a tremendous hassle and significant expense to do so. Unless this was done in a forensics lab, that would be my guess as to the source of the human DNA in the reactions."

http://www.metafilter.com/154105/Quality-meat-No-fillers-Or-...

Occam's razor would suggest that hair or skin cells would account for most of it.

That's a pretty fair assumption. It would also mean that 2% of pretty much every food should contain a bit of human DNA, making hot dogs a moot target.

No, the article says "found human DNA in 2% of the samples", meaning 7 out of 345 samples had the DNA.

This implies it's not as common as you suggest.

I agree. This sounds sensationalized.

Though the submitter was the one that added the sensational headline. [edit: headline was changed]

They do say, "While some of these substitutions, hygienic issues, other variances, or off-label ingredients may be permitted by the FDA, our scientific disclosure allows you, as the consumer, to decide whether the variance or problems meet your personal standard in your buying decision."

Some of these problems like pork in pork-free products or having 10g protein as opposed to 25g seem to be big problems that need some sort of investigative follow-up like contacting the companies for a statement about the findings.

The report also doesn't state how it's detecting human DNA. I was under the impression that tests like these are reasonably unreliable, especially when dealing with big mixes of genetic materials...I can't say this with any authority though

Of interest:

>2/3 of the human DNA samples were [in] vegetarian products. >10% of Vegetarian products contained meat.

Sounds to me like the meat hotdogs are the better ones.

They tested “345 hot dogs and sausages,” and found 2% of them tested positive for human DNA. That's only 6–8 contaminated hot dogs. If 2/3 of those were vegetarian, that’s just 4 hot dogs. I wouldn't jump to any conclusions from such a tiny sample.

Also, if the human DNA was caused by sample contamination in the lab, it could just be that the contamination is more likely to be detected in a vegetarian sausage than in a meat one.

Soylent Green?

Squeeze hot dog juice into 23andMe test tube.

I think those type of questions are bit beyond the scope of this report.