Lung response to test toner upon 2-year inhalation exposure in rats.
SPF F-344 rats were exposed 6 h/day 5 days/wk for up to 24 months to a special test toner at 0, 1, 4 and 16 mg/m3 or TiO2 at 5 mg/m3, or SiO2 at 1 mg/m3, by the inhalation route. The animals were kept for an additional 6 weeks in filtered air. Surviving animals were sacrificed at 25.5 months after start of exposure. Life-span and causes of death were independent of treatment and in accordance with published values. No evidence for systemic toxicity or any upper-respiratory system effects were found in the toner-exposed groups. The incidence of lung tumors was comparable in the control, 3 toner and TiO2-exposed groups. An incidence of 18%, combined benign and malignant tumors was observed in the quartz-treated rats. A slight to moderate degree of fibrosis was observed at the toner high exposure level in all animals, while a very slight degree of fibrosis was noted in 20% of the animals at the toner middle (4 mg/m3) exposure level. The fibrogenic potency of the test toner was calculated to be comparable to TiO2. No pulmonary changes were seen at the toner low (1 mg/m3) and environmentally most relevant exposure level.
Muhle
H
H
Fraunhofer Institute of Toxicology and Aerosol Research, Hannover, FRG.
Mermelstein
R
R
Dasenbrock
C
C
Takenaka
S
S
Mohr
U
U
Kilpper
R
R
MacKenzie
J
J
Morrow
P
P
D000280:Administration, Inhalation; D000818:Animals; D005260:Female; D008175:Lung Neoplasms / Q000139:chemically induced / Q000473:pathology*; D008297:Male; D008689:Methacrylates / Q000008:administration & dosage / Q000493:pharmacokinetics; D011658:Pulmonary Fibrosis / Q000139:chemically induced; D011791:Quartz / Q000008:administration & dosage / Q000493:pharmacokinetics; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors; D014025:Titanium / Q000008:administration & dosage / Q000493:pharmacokinetics
D008689:Methacrylates; D011791:Quartz; C009495:titanium dioxide; D014025:Titanium