Answer:
The active ingredient is Sodium percarbonate. Sodium percarbonate breaks down to Hydrogen Peroxide (an oxidizer) and Sodium carbonate, which acts as a laundry detergent booster, by acting as a water softener. Also there is some Sodium Silicate in there. This ingredient bonds to heavy molecules and pulls them out of the wash water.
It is fairly safe for the environment in moderate amounts. The carbonate is slightly caustic and hydrogen breaks down naturally.