I have not drank alcohol in any form for 7 months. I had a recent peth test which was positive at 51 ng.
This is impossible!

I have not consumed alcohol inany fashion for 7 months. However, a peth test was done and showed a result of 51ng!

Do you have regular contact with products that contain alcohol? Wipes? Household products?/cleaning supplies?

It would seem you could have had some incidental exposure through products, or environment.