At very, very low concentrations. We're talking about concentrated nicotine extracted from tobacco. Not a baked potato lol.
I love aubergine.
nicotine, sadly, is a bit disappointing toxin. You can image the face of a guy who was trying to commit the suicide by consuming 4g of the pure nicotine, and sadly to him - survived (Schmidt 1931). the amount of ppl who survived the consumption f more than 60mg of nicotine is countless (Larson et al. 1961).
But yet again: highest concentration of the commercially available on the market nicotine is 7.2%. LD50 for nicotine is 0.8mg/kg. Regarding the skin absorption/penetration, we can argue here, but what is the point of re-discovering the America if someone else have done so?
From the article:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6322548/
you can find in the fig 3 there:
that the accumulation caused by penetration is pretty low for nicotine in PG/menthol ejuice, and higher for lemon ejuice.
But, in all cases, the critical factor is not the ejuice per se, but the time.
Therefore, I am assuming (and actually following this practice daily, while mixing with the 7.2% base my shortfills) that the basic hygiene, like the careful wash of the hands after mixing plays far more important role than having the gloves.
Gloves, by the way, can give a false safety feeling and it really depends from the used gloves material and thickness, as per:
https://pubmed.ncbi.nlm.nih.gov/23405605/
Consequently, going to conclusion:
yes, nicotine can be deadly if you would swim in it or if you would not hollow the basic hygiene principles.
Quod erat demonstrandum...