Request for help with interpreting nicotine dosages in two scientific papers

Hi

I would be very grateful indeed if someone could help me to understand something about each of the following two scientific papers:

According to Cancer Research UK and various other sources, nicotine on its own does not cause cancer. However, the above two papers seem to suggest otherwise.

I actually suspect that the truth is that it entirely depends upon the dosage.

In both of the above two papers, the nicotine was given to cell cultures, not multicellular organisms.

To be honest, I understand very little of what the above two papers are saying and It is not at all clear to me how to interpret the nicotine dosages used in them.

Does anyone here know how to translate cell culture dosages into equivalent dosages given to multicellular organisms, especially humans?

If yes then I would be very grateful indeed if you could examine the dosages used in each paper and then calculate for me (giving your workings) roughly how many milligrams of nicotine a human would need to consume in order for the nicotine exposure of their body’s cells to match the nicotine exposure of the cell cultures studied in the above two papers in which harmful effects were observed.

Thank you very much.

Kind regards

Tim