Over the years, there have been studies done to evaluate the effects of inhalation around toner cartridges. One study by Xerox observed the effects of toner inhalation, where a person has frequent and long-term exposure to toner cartridges and similar materials, such as polymer dust. The study of toner inhalation was conducted with laboratory rats throughout most of their lifespan. According to the study, the results showed no evidence of upper respiratory toxins, lung tumors or deaths related to the exposure to toner cartridges. Xerox also examined a number of manufacturing and service employees with frequent and long-term exposure to toner cartridges. The company found no negative health associations related to toner inhalation.