How is this different than launches at Canaveral or elsewhere? Don’t those pads also have water deluge systems and service a variety of liquid fueled rockets?
Interestingly, ~70% of the water is evaporated during a launch.
SLS's main engine is hydrolox fueled, so it's byproducts should be water and hydrogen. But the SRBs have a lot of nasty ingredients like perchlorates.