The ferrofluid used in this product is a special formula designed for educational use. It is extremely messy, but will not harm you if you avoid prolonged exposure. The MSDS from the company who creates the ferrofluid used in this project can be viewed below:
According to the sheet, the fluid has minimal toxicity if ingested but to still seek medical attention. For this reason, I would suggest that the product not be handled by children under 16.
I'll also be including a MSDS as well for the suspension fluid with the final product, as well as a safety booklet with full disclaimers about the nature of the product. Please keep in mind that this product is not intended to be disassembled, and will be sealed to prevent tampering.