IMMUNOTOXICITY OF 180 DAY EXPOSURE TO POLYDIMETHYLSILOXANE (SILICONE)FLUID, GEL AND ELASTOMER AND POLYURETHANE DISKS IN FEMALE B6C3F1 MICE

Millions of people have been exposed to silicones which are present in consumer goods such as cosmetics and toiletries, processed foods and household products. In addition, silicones have been used extensively in medical practice as a lubricant in tubing and syringes, and as impl antable devices. A silicone widely used in medical practice is polydim ethylsiloxane. This study was undertaken to determine the immunotoxico logic potential of long term exposure to the principal constituents of breast implants: silicone fluid, silicone gel and silicone elastomer. An alternative covering for devices containing silicone gels, polyure thane, was also included in the study. Silicone fluid and gel were inj ected subcutaneously into female B6C3F1 mice (1 ml/mouse) and 6 mm dis ks of silicone elastomer or polyurethane were implanted subcutaneously . There were no treatment-related deaths or overt signs of toxicity du ring the 180 day exposure. None of the tested materials had notable ef fects on body or organ weights, erythrocytes or leukocytes in the bloo d, blood chemistries such as alanine aminotransferase, urea nitrogen, glucose, albumin or total protein, or serum CH 50 or C3 levels. The ce llularity of the bone marrow and responses to CSF-GM and CSF-M were no rmal. The tested silcones and polyurethane marginally reduced the leve l of Ig(+) cells in the spleen but did not consistently alter the dist ribution of T cell surface markers. The antibody response to sheep ery throcytes was not markedly altered, nor were proliferative responses t o concanavalin A, phytohemagglutinin, lipopolysaccharide or allogeneic cells. Reticuloendothelial function was normal, as was phagocytosis o f chicken erythrocytes and Covaspheres by adherent peritoneal cells. N atural killer cell activity was depressed in all silicone treatment gr oups and in mice implanted with polyurethane. No silicone or polyureth ane treatment group displayed altered susceptibility to a challenge wi th Listeria monocytogenes, Streptococcus pneumoniae or the B16F10 tumo r. The only consistent effect of 180 day exposure to silicone material s or polyurethane was a modest depression of natural killer cell activ ity.