the sole itself is resistant to oil and gasoline, but not necessarily the leather. As far as hazardous materials, that is hard to answer without knowing what chemicals you are exposing them to, but generally, if the hazardous materials are not made for skin contact, then it probably would not be good for the leather either.
The soles are oil and fuel resistant. Repeated exposure of the leather to fuel may harm the leather over time. As far as hazardous materials, while it does have resistance to chemicals, it depends on what hazardous materials you are exposing them to. Also, the chemical resistance is more protecting you and your skin with the CROSSTECH inner liner. Without knowing what you are exposing them to, it is hard to answer as far as the hazardous materials.