Generally an eco solvent ink has little or no odour and doesn’t contain any harmful ingredients (such as cyclohexanone). The solvents within eco solvent inks are usually biodegrable and able to be broken down within the human body. However, just because an ink has no odour it does not automatically mean that it can be used in a normal indoor environment without extraction systems in place. You should always check the MSDS or with the manufacturer regarding ventilation requirements when using an eco solvent ink.
Solvent: this term is used to describe any ink that is not water-based. Piezo inkjet printers whose inks use petroleum or a petroleum by-product such as an acetone like carrier liquid. “Eco-Solvent” inks usually contain glycol esters or glycol ether esters and are slower drying.