Toner

There is concern over the recent studies regarding nano-particles found in toner and laser printer emissions. Nano-particles are bad because they have the ability through barriers in the lungs that would normally block them.

Toner is not covered under the Basel Convention, and most companies like HP will not list the ingredients in toner. They say the ingredients are proprietary knowledge. Toner does have a level of flammability. Some incinerators will not handle this material because of that. This flammability issues could be interpreted has hazardous waste under the Basel Convention but is not at this time.

Clean-up

Toner can have static-electric charges and can ignite or explode when agitated inside a vacuum cleaner. Toner should not be sucked up by a normal vacuum cleaner. The small size of toner also allows it to pass through standard filters and become airborne.

According to Wikipedia "A special type of vacuum cleaner with an electrically conductive hose and a high efficiency (HEPA) filter may be needed for effective cleaning. These are called Electrostatic discharge-safe (ESD-safe) or toner vacuums."