Yeah me too. But in biology labs (ex. microbiology and not jus a simple highschool lab) you have to disinfect with disinfectant on your bench before and after you work with bacteria ( ex. E.coli etc).

I think in highschool labs...you are jus disecting animals that were already perserved in a some kinda of perservative fluid. so the risk of bacterial on your bag is very minimal. Even in highschool chemistry, the concentrations students work with is very low.