Document 3KN6LpMXvqRvexqR41JYadKJ

PIGMENT COATED MICA FLAKES The Pathogenic Action Resulting Prom Inhalation Exposure Male CROP Rats MR-582, H-2979, P-121 The proposed use for coated mica flakes is as a pigment in paints, inks, and plastics. The flakes are in the form of a golden-colored powder with the' following composition:; muscovite mica 67.2 per cent, Ti02 31.5 per cent, and Cr203, 1.3 per cent. Traces of impurities arise from Ti02 and include alumina. Iron oxide, sulfates, and various in organic compounds. The powder melts at 1000C. It is acid in reaction and possesses a specific gravity of approximately 3.00. It is insoluble in water, acetone, ethanol, and vegetable oil. Exposure of employees and consumers may occur by ingestion. Inhalation, or skin contact. Pour rats were caused to inhale the coated mica flakes suspended In dry air at a concentration of 20.1 milligrams per liter. AH rats survived the four-hour exposure period without symptoms. They were killed for study fourteen days later. The prevalence and severity of changes observed at necropsy are recorded In Table 1. Organ weights, and organbody weight ratios are presented in Tables 2 and 3, respectively. Comment The slight to moderate irregular congestion which was observed in the lungs of all animals, and the focal atelectasis and sub-pleural plaques occurring separately in two, may either represent effects of irritation from the N37288 2 inhaled flakes or reflect the presence of enzootic murine pneumonitis. No significant difference in weight of the lungs was noted when compared with control animals. Further indications that an ingredient of the mica flakes pigment may be biologically active are inferable from the deviations In the weights of the pancreas, adrenals, and thymus. Weight of the pancreas was moderately decreased in two rats and that of the thymus was moderately decreased in all four instances, while the adrenals showed a slight increase in weight in two instances. Since it seems unlikely that the mica particles could have travelled to these organs and because titanium dioxide is biologically inert, it is suspected that the ehrojjjic sesquioxide may be responsible for these changes. This problem may be resolved by histologic study. DAW:lJm Nov. 21, 1961 Pathologist DUP050041438 to* w O a $H OJ| P4 00 IT .. Vi I I qH <54 ir\ co * JVvOT ^OO '"J c0e 1 a> s s1? EH U VC <\ r~ < N37288.01 DUP050041439 IfPe. *<}D P) N37288.02 DUP050041440 OJ k Ijm :Hov. 22, 1961 Approved -fay; W '^ ^ G. W. H .S c Pathol COATED MICA FLAKE PIGMENTS Haskell Ho. 27~j? MR-582 TABLE 5 Differences In Per Cent Between Organ-Body Weight Ratios ____________ Exposed 'Versus Control Croups Organ Brain Heart Lungs Liver Pancreas Stomach Spleen Kidneys Testes Adrenals Thymus ORGAN-BODY WEIGHT RATIOS ________ GROUP ~ Exposed* Control* Per Cent Difference 52 55 -1.8 55 51 49 52 to 5 44l +6.4 -5.7 -8.1 24 29 -17 2 45 47 -8.5 20 21 -4.7 84 78 +7.6 86 84 +2.5 1.4 1.2 +16.6 17 24 -29.1 * Value 10 Prepared by: Donald A. Willkgan, D.V.M. Approved by: G... "UcKepers/ M. D\ Pathologist N37288.03 DUP050041441