From the manufacturer:
The Standard for Studio Safety.
Gamsol is the safest solvent that allows artists to work in traditional and contemporary techniques without compromise. Gamsol can be used to thin oil colors and painting mediums, and for general studio clean-up. Gamsol is reusable and non-toxic when used as recommended.
At Gamblin, our mission is to lead oil painting into the future. To us this means crafting materials as they ought to be, not just as they have been. Our contemporary mediums are true to historic working properties, yet safer and more permanent.