Railway sleepers to build a plinth

[Tebano]

Hi I got beautiful railway sleepers 200 x 100mm to start building my plinth but they are pressure treated Tonality E and also with Tanatone for colour. Can please anyone tell me if I should be worried?

[Toomulla]

I cannot see an issue unless you want to prep your pizza on the timber. It will never be subject to heat if the oven is correctly built