Total platinum concentration and platinum oxidation states in body fluids, tissue, and explants from women exposed to silicone and saline breast implants by IC-ICPMS.

Ion chromatography-inductively coupled plasma-mass spectrometry was used to determine the total platinum concentration and platinum oxidation states in samples from women exposed to silicone and saline breast implants. Samples included the following: whole blood, urine, hair, nails, sweat, brain tissue, breast milk, and explants. Mean Pt concentration in samples from women exposed to silicone breast implants were as follows: whole blood, 568.1 +/- 74.77 pmol/L (n = 9); urine, 1.77 +/- 0.847 mug/g of creatinine (n = 10); hair, 2.13 +/- 2.984 ng/g (n = 9); nails, 0.88 +/- 0.335 ng/g (n = 9); sweat, 1.90 +/- 1.691 ng/g (n = 9); breast milk, 1.09 +/- 0.316 mug/L (n = 6). Pt in explanted silicone breast implant gel (n = 9) occurred mainly in the +2, +4, and +6 oxidation states. Pt in whole blood (n = 7) and breast milk samples (n = 6) from women exposed to silicone breast implants occurred mainly in the +2 and +4 oxidation states. Saline breast implant fluid (n = 2) did not contain detectable levels of Pt. This is the most comprehensive report, to date, to show that women exposed to silicone breast implants have Pt levels that exceed that of the general population, and the first report, to date, to document the various Pt oxidation states present in samples from women exposed to silicone breast implants.

Gamma-glutamyl transpeptidase-deficient mice are resistant to the nephrotoxic effects of cisplatin.

We have proposed that the nephrotoxicity of cisplatin, a widely used chemotherapy drug, is the result of the binding of cisplatin to glutathione and the subsequent metabolism of the cisplatin-glutathione complex via a gamma-glutamyl transpeptidase (GGT)-dependent pathway in the proximal tubules. To test the hypothesis that GGT activity is essential for the nephrotoxicity of cisplatin, the effects of cisplatin were examined in wild-type and GGT-deficient mice. Mice were treated with 15 mg cisplatin/kg. Five days after treatment, renal histopathology, blood urea nitrogen levels, serum creatinine, platinum excretion, and platinum accumulation in the kidney were examined. Half the mice were supplemented with N-acetylcysteine, which has been shown to correct low levels of tissue glutathione in GGT-deficient mice. The data show that cisplatin was nephrotoxic in wild-type mice but not in GGT-deficient mice. The wild-type mice, with and without N-acetylcysteine supplementation, had significantly elevated levels of blood urea nitrogen, serum creatinine, and renal tubular necrosis. There was no evidence of nephrotoxicity in the GGT-deficient mice regardless of N-acetyl cysteine supplementation. No differences in platinum excretion were seen comparing wild-type and GGT-deficient mice, nor was there any significant difference in renal platinum accumulation. These data suggest that renal cisplatin toxicity is dependent on GGT activity, and is not correlated with uptake. The results support our hypothesis that the nephrotoxicity of cisplatin is the result of the metabolism of the drug through a GGT-dependent pathway.

Cyclosiloxanes produce fatal liver and lung damage in mice.

To examine the toxicity of cyclosiloxanes (CSs), the predominant low molecular weight cyclic silicones found in breast implants, we injected female CD-1 mice intraperitoneally with different doses of distillate (3.5-35 g/kg body weight) containing cyclosiloxane D3 (hexamethylcyclotrisiloxane; CS-D3), cyclosiloxane D4 (octamethylcyclotetrasiloxane; CS-D4), cyclosiloxane D5 (decamethylcyclopentasiloxane; CS-D5), and cyclosiloxane D6 (dodecamethylcyclohexasiloxane; CS-D6). The distillate was found to be lethal and all the mice injected with 35 g/kg died within 5-8 days. The median lethal dose (LD50) for distillate was estimated to be approximately 28 g/kg. These mice developed inflammatory lesions of the lung and liver as well as liver cell necrosis with elevated serum levels of alanine aminotransferase, aspartate aminotransferase, and lactic acid dehydrogenase. Administration of CS-D4 alone also produced lethality in these mice with an LD50 of 6-7 g/kg. CS-D4-treated mice also exhibited pulmonary and hepatic lesions and elevated serum enzymes. Analysis of LD50 data indicates that CS-D4 is about as toxic as carbon tetrachloride or trichloroethylene. We measured hydroxyl radical formation in CS-D4-treated mice and found increases of approximately 20-fold in liver and approximately 7-fold in lung on day 4 following injection. Our findings are significant because in vitro experiments have demonstrated that CSs can migrate out of breast implants, and in mouse experiments CSs have been shown to be widely distributed in many organs after a single subcutaneous injection and to persist for at least a year.

Low molecular weight silicones are widely distributed after a single subcutaneous injection in mice.

To examine the distribution of low molecular weight silicones in body organs, separate groups of female CD-1 mice were injected with either breast implant distillate composed primarily of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and tetradecamethylcycloheptasiloxane or a polydimethylsiloxane oil containing low molecular weight linear siloxanes. Mice were injected subcutaneously in the suprascapular area and killed at different times. Levels of individual low molecular weight silicones were measured in 10 different organs (brain, heart, kidney, liver, lung, mesenteric lymph nodes, ovaries, spleen, skeletal muscle, and uterus). In mice treated with the cyclosiloxane mixture and killed at 3, 6, or 9 weeks, highest levels of cyclosiloxanes were found in the mesenteric lymph nodes, ovaries, and uterus, but all organs examined contained cyclosiloxanes. In a cohort killed at 1 year, most organs contained measurable cyclosiloxanes with highest levels in mesenteric lymph nodes, abdominal fat, and ovaries. Of the individual cyclosiloxanes measured, selective retention of decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane relative to octamethylcyclotetrasiloxane was seen in all organs at all time points studied. Organs from animals receiving the linear siloxane mixture were harvested at 9, 12, and 15 weeks. We found maximum levels in the brain, lungs, and mesenteric lymph nodes, but all other organs contained measurable levels. These data are, to the best of our knowledge, the first demonstration that after a single subcutaneous injection silicones are widely distributed throughout the body and can persist over an extended period.

Release of low molecular weight silicones and platinum from silicone breast implants.

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was also observed to leak through intact implants into lipid-containing media at rates of approximately 20-25 micrograms/day/250 g of implant at 37 degrees C. The rates at which both LM-silicones and platinum have been observed to leak from intact implants could lead to significant accumulation within lipid-rich tissues and should be investigated more fully in vivo.

Detection and characterization of poly(dimethylsiloxane)s in biological tissues by GC/AED and GC/MS.

We have developed a sensitive method for the detection, characterization, and quantitation of low molecular weight silicones using gas chromatography coupled with atomic emission detection (GC/AED) and gas chromatography/ mass spectrometry (GC/MS). Using this approach, we have detected 12 distinct silicon-containing peaks in PDMS-V poly(dimethylsiloxane) oil by GC/AED, and we have used GC/MS analysis to identify some of the abundant peaks by MS spectral matching. Polydimethylpolysiloxanes contain 37.8% silicon; therefore, the amount of poly(dimethylsiloxane) in each peak can be calculated from its silicon content. The first three GC peaks from PDMS-V were identified as dodecamethylpentasiloxane, tetradecamethylhexasiloxane, and hexadecamethylheptasiloxane using Wiley Mass Spectral Library match (> 90%). Peaks 4-12 could not be matched unequivocally with the spectral library but showed ionic fragments characteristic of PDMS (73, 147, 221, 281, 295, and 369 amu). The detection limit for silicones using GC/AED and GC/MS systems was found to be 80 and 10 pg/microL, respectively. Studies were conducted using mouse liver homogenates spiked with varying amounts of PDMS-V, and the recovery was found to be greater than 90% over a wide range of PDMS-V concentrations. This method appears to work equally well for both linear and cyclic poly(dimethylsiloxane)s. Thus, the methodology described here has the potential to allow the measurement of less than 1 microgram of silicone/g of biological tissue. The overall goal of this research is to establish and validate a methodology by which the unequivocal identification and quantitation of poly(dimethylsiloxane)s can be accomplished.