SUBCHRONIC 10 DAY IMMUNOTOXICITY OF POLYDIMETHYLSILOXANE (SILICONE) FLUID, GEL AND ELASTOMER AND POLYURETHANE DISKS IN FEMALE B6C3F1 MICE

Millions of people have been exposed to silicones because of the wides pread use in consumer products such as cosmetics and toiletries, food products, household products and paints. Silicones have wide use in me dical practice, including lubricants in tubing and syringes, and as im plantable devices. The most prevalent silicone in medical use is polyd imethylsiloxane. This study was undertaken to determine the subchronic immunotoxicologic potential of the principal constituents of breast i mplants: silicone fluid, silicone gel and silicone elastomer. An alter native covering for devices containing silicons gels, polyurethane, wa s also included in the study. Silicone fluid and gel were injected sub cutaneously into female B6C3F1 mice (1 ml/mouse) and 6 mm disks of sil icons elastomer or polyurethane were implanted subcutaneously. There w ere no treatment-related deaths or overt signs of toxicity. None of th e tested materials had notable effects on body or organ weights, eryth rocytes or leukocytes in the blood, blood chemistries such as alanine aminotransferase, urea nitrogen, glucose, albumin or total protein The cellularity of the bone marrow and responses to CSF-GM and CSF-M were normal. The tested silcones did not alter the distribution of B cells and T cells in the spleen, but polyurethane perturbed the distributio n of CD4(+)CD8(+) and CD4(-)CD8(-) T cells. The antibody response to s heep erythrocytes was not markedly altered, nor were proliferative res ponses to concanavalin A, phytohemagglutinin, lipopolysaccharide or al logeneic cells. Reticuloendothelial function was normal, but polyureth ane evoked an enhanced phagocytosis of Covaspheres by adherent periton eal cells. Natural killer cell activity and serum complement were not altered. All silicone materials afforded modest protection to a challe nge with Listeria monocytogenes that killed 40 to 58% of control mice. Host resistance to Streptococcus pneumoniae or the B16F10 tumor was n ot affected by any of the treatments. There is a pattern indicative of some perturbation of T cell differentiation in mice implanted with a polyurethane disk.