Dear doctor, yesterday i have inhaled a cloud of black toner powder dust when repairing my printer cartridge. not knowing that black toner is dangerou?

Lungs: anything can be toxic to lungs, even too much Oxygen...having said that, a one time exposure to cartridge powder should cause no damage to ur lungs; prolonged exposure (ie. years) may cause damage however; Acutely, an exposure to any particular matter (ie dust) may cause a bronchospasm and sometime prolonged reaction; otherwise u should fine. Good Luck

I wouldn't worry: very much. The toxic components are additives, often titanium dioxide/amorphous silica. Studies have been done of depositing medium and high doses of toner directly into the trachea of lab rats/then studying them. Only with direct application of high concentrations was there evidence of lung damage. Moderate level exposure/instillation was determined to be "no observed adverse effect level."