Going to start shredding various types of paper--no cardboard--and wondered if the various toners/inks would cause problems with the plants or if the plant would absorb the chemicals and I would end up eating them from the vegetables produced.
The inks from laser printers and ink jet printers are not considered to be toxic or problematic in the garden. Newspaper is also fine, but using the colored advertising inserts is discouraged.
If you are thinking of mixing it into the soil, the paper itself is a fine addition to a garden, in moderation. As the paper (or any other high carbon source) decomposes, it ties up nitrogen in the soil. Too much paper and the vegetable roots find themselves competing with decomposers for vital nitrogen.
Surface mulching with this paper is a fine way to keep weeds down or maintain moisture in the soil. Keeping the paper mulch on the surface will not impact nitrogen use of garden plants.
If you have a compost pile, paper can also be used in it as a carbon source, with the compost enriching your beds at a later point.