The main issues with any prespray is the conditions where it is mixed and sprayed.
The primary route of entry to the body for the chemicals of concern is inhalation.
Have good ventilation when mixing.
When spraying, use the proper sized tip (04 is the smallest I would use, but I like 06 or 08 better. Larger droplets fall to the carpet immediately and don't drift around in the air.
Proper pressure also matters. 35 to 55 PSI for pump up or electric sprayers.
Keep the tip of the spray wand between 12" and 18" from the carpet. Too close and the spry bounces back into the breathable air space. Too far from the carpet and the droplets also get into the air.
Proper spraying technique will do more to improve health concerns that what chemical you use in most cases.
That being said, Bridgepoint makes Green Balance which has ingredients approved as safe for people and the environment (GRAS; US EPA DfE, etc.).
Wise man . Really need something to keep in the van at all times ( Winter is terrible here in Pa. ) . Procyon Plus can cover me for almost everything . Like all chems , you have to "work with it " but it does a fine job . Those of us in the colder parts of the U.S.A. need something versatile and a powder . Yes sir , there's a jar in my van right now .Procyon