I would think it certainly could. Whether it SHOULD, depends on the reason for testing blood alcohol levels:
Blood alcohol vis-a-vis alcohol intoxication: With widespread use of breathalyzers, I don't know if this technology would be an improvement. Having to get a tattoo to test for blood alcohol levels seems overkill (at least the tattoo would be necessary in the current stage of the technology's development). While not perfect, available technology (IMO) seems to be doing a sufficient job.
Liver disorders, cirrhosis, hepatitis, other liver disease: There are other diagnostics more appropriate than testing for blood alcohol content (BAC)for these. Ethanol is metabolized by the liver relatively quickly.
There may be applications for testing blood alcohol, but I don't think this technology is enough of an improvement to make it viable. A doctor may disagree. That is just my opinion.
Oh I was thinking the ink would be worth $$$ for tattoos that only show up when you're drinking - like little details like flames that appear around an otherwise unadorned area, etc.
