title: Manganese inhibition of sarcoma induction by benzo[a]pyrene in rats.
abstract: The effects of Mn and Cr dusts upon carcinogenesis by polycyclic aromatic hydrocarbons were tested in male Fischer 344 rats. In Experiment I, rats were given i.m. injections of benzo[a]pyrene (BP, 1.2 mg), Mn dust (4.4 mg), and Cr dust (4.4 mg), alone, and in various combinations. By 100 weeks, sarcomas occurred at the injection site in 17/20 rats that received BP alone, versus 10/19 rats that received BP plus Mn dust (P < 0.05). The sarcoma incidences were 0/20 in 3 control groups that received the vehicle, Mn dust alone, or Cr dust alone, and 20/20 in rats that received BP plus Cr dust. In Experiment II, rats were given i.m. injections of BP (0.6 mg), 7,12-dimethylbenz[a]anthracene (DMBA, 0.6 mg), Mn dust (4.4 mg), and Cr dust (4.4 mg), alone, and in various combinations. Local sarcomas occurred in 17/20 rats that received BP alone, versus 5/17 rats that received BP plus Mn dust (P < 0.001). Sarcoma induction was not inhibited when BP was injected in the right thigh and Mn dust in the left thigh (sarcoma incidence = 16/20). The sarcoma incidences were 0/19 in a vehicle control group; 0/18 in 2 control groups that received Mn dust or Cr dust alone; 18/20 in rats that received BP plus Cr dust; 14/20 in rats that received DMBA alone; 17/19 in rats that received DMBA plus Mn dust; and 13/18 in rats that received DMBA plus Cr dust. These experiments show that Mn dust inhibits the carcinogenicity of BP when the Mn dust and BP are administered to rats by a single i.m. injection. Under identical conditions, Mn dust does not affect the carcinogenicity of DMBA; Cr dust does not affect the carcinogenicity of BP or DMBA.
authors.affiliation: Department of Laboratory Medicine, University of Connecticut School of Medicine, Farmington 06032, USA.
authors.forename: F W
authors.initials: FW
authors.lastname: Sunderman
authors.forename: K S
authors.initials: KS
authors.lastname: McCully
authors.forename: S B
authors.initials: SB
authors.lastname: Taubman
authors.forename: P R
authors.initials: PR
authors.lastname: Allpass
authors.forename: M C
authors.initials: MC
authors.lastname: Reid
authors.forename: L A
authors.initials: LA
authors.lastname: Rinehimer
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000037:antagonists & inhibitors / Q000633:toxicity; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D001564:Benzo(a)pyrene / Q000037:antagonists & inhibitors* / Q000633:toxicity; D002273:Carcinogens / Q000037:antagonists & inhibitors* / Q000633:toxicity; D002857:Chromium / Q000494:pharmacology; D004347:Drug Interactions; D004391:Dust; D007273:Injections, Intramuscular; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D012513:Sarcoma, Experimental / Q000139:chemically induced / Q000517:prevention & control*
chemical_list: D016588:Anticarcinogenic Agents; D002273:Carcinogens; D004391:Dust; D002857:Chromium; D001564:Benzo(a)pyrene; D008345:Manganese; D015127:9,10-Dimethyl-1,2-benzanthracene