title: Chronic inhalation exposure of rats for up to 104 weeks to a non-carbon-based magnetite photocopying toner.
abstract: Male and female Han Wistar rats were exposed for 6 h/day, 5 days/week for 13 or 104 weeks (whole body) to a magnetite photocopying toner. The toner contained 45% to 50% magnetite, with 45% to 50% styrene acrylic resin and less than 5% external additives, including hydrophobic amorphous silica and proprietary surface functional modifiers. Exposure levels were 1, 5, and 25 mg/m(3) for the 13-week study and 1, 4, and 16 mg/m(3) for the 104-week study. Lung toner burdens averaged 36, 288, and 604 microg per lung after 104 weeks' exposure at 1, 4, and 16 mg/m(3). The lung burdens were lower than have been reported in a similar study with a carbon-based toner. There were no significant effects on weight gain or food consumption in either study, or on clinical pathology parameters examined in the 13-week study. After 104 weeks' exposure at 16 mg/m(3), macroscopic examination revealed dark discoloration of the lungs and associated lymph nodes. Lung weights were significantly elevated by 21% and 14% for male and female rats, respectively. Microscopic findings indicative of a mild inflammatory response were similar in both studies, and included the presence of black-pigmented macrophages in the lungs and tracheobronchial and mediastinal lymph nodes; increased incidences of perivascular/peribronchiolar inflammatory cell infiltration; inflammation of the alveolar ducts (characterized by aggregations of black-pigmented alveolar macrophages and interstitial lymphocytic infiltration); increased cellularity of the bronchiole-associated lymphoid tissue; and a few instances of alveolar ciliated metaplasia. The 104-week study showed no increase in the incidence of pulmonary tumors.
authors.affiliation: DABT, ENVIRON International Corporation, 4350 North Fairfax Drive, Suite 300, Arlington, VA 22203, USA.
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Slesinski
authors.forename: Duncan
authors.initials: D
authors.lastname: Turnbull
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003308:Copying Processes; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D052203:Ferrosoferric Oxide / Q000633:toxicity*; D019570:Inhalation Exposure; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar
chemical_list: D052203:Ferrosoferric Oxide