Glycol Stearate and Glycol Stearate SE.

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 1982, along with updated information regarding product types and concentrations of use, and confirmed that Glycol Stearate and Glycol Stearate SE are safe as cosmetic ingredients in the practices of use and concentration as described in this report.

Development and in vivo evaluation of intranasal formulations of parathyroid hormone (1-34).

For efficient intranasal transport of parathyroid hormone (1-34) [PTH(1-34)], there is a great medical need to investigate permeation enhancers for intranasal formulations. In this study, the development of PTH(1-34) intranasal formulations was conducted. Based on conformation and chemical stability studies, the most preferable aqueous environment was determined to be 0.008 M acetate buffer solution (ABS). Subsequently, citric acid and Kolliphor® HS·15 were compared as permeation enhancers. The mechanisms of action of citric acid and Kolliphor® HS·15 were investigated using an in vitro model of nasal mucosa, and Kolliphor® HS·15 led to higher permeability of fluorescein isothiocyanate-labeled PTH(1-34) (FITC-PTH) by enhancing both the transcellular and paracellular routes. Moreover, citric acid showed severe mucosal toxicity resulting in cilia shedding, while Kolliphor® HS·15 did not cause obvious mucosa damage. Finally, Kolliphor® HS·15 was studied as a permeation enhancer using a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The results showed that 5% and 10% Kolliphor® HS·15 increased the bioavailability of PTH(1-34) to 14.76% and 30.87%, respectively. In conclusion, an effective and biosafe PTH(1-34) intranasal formulation was developed by using 10% Kolliphor® HS·15 as a permeation enhancer. Intranasal formulations with higher concentrations of Kolliphor® HS·15 for higher bioavailability of PTH(1-34) could be further researched.

Ninety-Day Nephrotoxicity Evaluation of 3-MCPD 1-Monooleate and 1-Monostearate Exposures in Male Sprague Dawley Rats Using Proteomic Analysis.

Fatty acid esters of 3-monochloropropane 1,2-diol (3-MCPD esters) are processing-induced food toxicants, with the kidney as their major target organ. For the first time, this study treated Sprague Dawley (SD) rats with 3-MCPD 1-monooleate at 10 and 100 mg/kg BW/day and 1-monostearate at 15 and 150 mg/kg BW/day for 90 days and examined for their potential semi-long-term nephrotoxicity and the associated molecular mechanisms. No bodyweight difference was observed between groups during the study. Both 3-MCPD 1-monooleate and 1-monostearate resulted in a dose-dependent increase of serum urea creatinine, uric acid and urea nitrogen levels, and histological renal impairment. The proteomic analysis of the kidney samples showed that the 3-MCPD esters deregulated proteins involved in the pathways for ion transportation, apoptosis, the metabolism of xenobiotics, and enzymes related to endogenous biological metabolisms of carbohydrates, amino acids, nitrogen, lipids, fatty acids, and the tricarboxylic acid (TCA) cycle, providing partial explanation for the nephrotoxicity of 3-MCPD esters.

Synthesis and Application of a New Amphiphilic Antioxidant.

A new amphiphilic antioxidant (tannyl stearate) derived from reaction of tannic acid with stearic acid was synthesized in order to improve tannic acid solubility in lipid materials. This reaction gives many products having different degree of esterification (tannyl mono, di, tri, tetra, penta, hexa, hepta……stearate) which were separated using silica gel column chromatography and tentative identification was carried out using thin layer chromatography (TLC). The intrinsic viscosities (η) were used to differentiate between the different molecular weight of the produced esters1). Tannyl penta stearate is assumed to be the most suitable amphiphilic antioxidant derivative, where those derivatives with less degree of esterification would be less soluble in fat, and those of higher degree of esterification would exhaust more hydroxyl group that cause decreases of antioxidant activity. The structure of tannyl penta stearate was approved depending on its chemical analysis and spectral data (IR, H1 NMR,). The emulsification power of tannyl penta stearate was then determined according to method described by El-Sukkary et al.2), in order to prove its amphiphilic property. Then tannyl penta stearate was tested for its antioxidant and radical scavenging activities in three different manners, those are, lipid oxidation in sunflower oil using Rancimat, (DPPH) free radical scavenging and total antioxidant activity. {Pure tannic acid (T), butylhydroxyanisol (BHA) and butylhydroxytoluene (BHT) were used as reference antioxidant radical saving compounds}. Then tannyl penta stearate was added to sunflower oil, frying process was carried out and all physicochemical parameters of the oil were considered, and compared to other reference antioxidant in order to study the effect of this new antioxidant toward oil stability. Acute oral toxicity of the tannyl penta stearate was carried out using albino mice of 21-25 g body weight to determine its safety according to the method described by Goodman et al.3). Also liver and kidney functions of those mice were checked. Thus it could be concluded that the addition of tannyl penta stearate to frying oils offers a good protection against oxidation. The effectiveness of tannyl penta stearate as lipid antioxidant has been attributed mainly to its stability at high temperature. And according to acute lethal toxicity test tannyl penta stearate was found to be a safe compound that can be used as food additive.

Inhibition of mTOR reduces lipotoxic cell death in primary macrophages through an autophagy-independent mechanism.

Macrophage dysfunction in obesity and diabetes is associated with persistent inflammation and poor wound healing responses. Relevant to these phenotypes, we have previously shown that macrophage activation in a high-fat environment results in cell death via a mechanism that involves lysosome damage. While searching for signaling pathways that were required for this response, we discovered that mTOR inhibitors, torin and rapamycin, were protective against lipotoxic cell death in primary peritoneal macrophages. The protective effect of mTOR inhibition was also confirmed by using genetic loss-of-function approaches. Given the importance of mTOR in regulation of autophagy we hypothesized that this pathway would be important in protection from cell death. We first demonstrated that autophagy was disrupted in response to palmitate and LPS as a consequence of impaired lysosome function. Conversely, the mTOR inhibitor, torin, increased macrophage autophagy and protected against lysosome damage; however, the beneficial effects of torin persisted in autophagy-deficient cells. Inhibition of mTOR also triggered nuclear localization of TFEB, a transcription factor that regulates lysosome biogenesis and function, but the rescue phenotype did not require the presence of TFEB. Instead, we demonstrated that mTOR inhibition reduces mitochondrial oxidative metabolism and attenuates the negative effects of palmitate on LPS-induced mitochondrial respiration. These results suggest that inhibition of mTOR is protective against lipotoxicity via an autophagy-independent mechanism that involves relieving mitochondrial substrate overload. On the basis of these findings, we suggest that therapies to reduce macrophage mTOR activation may protect against dysfunctional inflammation in states of overnutrition, such as diabetes.

Safety assessment of stearyl heptanoate and related stearyl alkanoates as used in cosmetics.

Stearyl heptanoate is an ester of stearyl alcohol and heptanoic acid that functions in cosmetics as a skin conditioning agent and is in the general class of chemicals called stearyl alkanoates. Stearyl caprylate, stearyl palmitate, stearyl stearate, stearyl behenate, and stearyl olivate are stearyl alkanoates with similar chemical structures, toxicokinetics, and functions in cosmetics. These water-insoluble stearyl alkanoates, when metabolized, yield stearyl alcohol and a corresponding fatty acid. The available information supports the safety of all of the related stearyl alkanoates. The Expert Panel concluded that stearyl heptanoate, stearyl caprylate, stearyl palmitate, stearyl stearate, stearyl behenate, and stearyl olivate are safe in the present practices of use and concentration.

Inner ear biocompatibility of lipid nanocapsules after round window membrane application.

Nanoparticle-mediated drug delivery represents the future in terms of treating inner ear diseases. Lipid core nanocapsules (LNCs), 50 nm in size, were shown to pass though the round window membrane (RWM) and reached the spiral ganglion cells and nerve fibers, among other cell types in the inner ear. The present study aimed to evaluate the toxicity of the LNCs in vitro and in vivo, utilizing intact round window membrane delivery in rats. The primary cochlear cells and mouse fibroblast cells treated with LNCs displayed dosage dependant toxicity. In vivo study showed that administration of LNCs did not cause hearing loss, nanoparticle application-related cell death, or morphological changes in the inner ear, at up to 28 days of observation. The cochlear neural elements, such as synaptophysin, ribbon synapses, and S-100, were not affected by the administration of LNCs. However, expression of neurofilament-200 decreased in SGCs and in cochlear nerve in osseous spiral lamina canal after LNC delivery, a phenomenon that requires further investigation. LNCs are potential vectors for the delivery of drugs to the inner ear.

A one-year oral toxicity study of sodium stearoyl lactylate (SSL) in rats.

The toxicity of sodium stearoyl lactylate (SSL) was examined in Wistar rats fed diets containing 0, 1.25, 2.5, and 5% SSL for one year, equivalent to mean daily intakes of 558, 1115, and 2214 mg/kg/day in males and 670, 1339, and 2641 mg/kg/day in females, respectively. SSL was well tolerated at these dietary levels as evidenced by the absence of toxicologically significant changes in the general condition and appearance of the rats, survival, neurobehavioral endpoints, growth, feed and water intake, ophthalmoscopic examinations, hematology and clinical chemistry parameters, urinalysis, or necropsy findings. The occurrence of uterine endometrial stromal polyps was the only finding of potential significance. Given the frequent occurrence of these benign tumors in rats, wide variability in the reported incidence of this type of polyps in rats, the lack of statistical significance and lack of biological evidence to suggest a mechanism for the slightly greater incidence in the groups fed 2.5 and 5% SSL, it was concluded that the endometrial stromal polyps observed in females fed SSL were not related to treatment. The no observed adverse effect level (NOAEL) of SSL was placed at 5%, the highest dietary level tested (equivalent to 2214 mg/kg/day for males and 2641 mg/kg/day for females).

Final report on the safety assessment of sodium cetearyl sulfate and related alkyl sulfates as used in cosmetics.

Sodium cetearyl sulfate is the sodium salt of a mixture of cetyl and stearyl sulfate. The other ingredients in this safety assessment are also alkyl salts, including ammonium coco-sulfate, ammonium myristyl sulfate, magnesium coco-sulfate, sodium cetyl sulfate, sodium coco/hydrogenated tallow sulfate, sodium coco-sulfate, sodium decyl sulfate, sodium ethylhexyl sulfate, sodium myristyl sulfate, sodium oleyl sulfate, sodium stearyl sulfate, sodium tallow sulfate, sodium tridecyl sulfate, and zinc coco-sulfate. These ingredients are surfactants used at concentrations from 0.1% to 29%, primarily in soaps and shampoos. Many of these ingredients are not in current use. The Cosmetic Ingredient Review (CIR) Expert Panel previously completed a safety assessment of sodium and ammonium lauryl sulfate. The data available for sodium lauryl sulfate and ammonium lauryl sulfate provide sufficient basis for concluding that sodium cetearyl sulfate and related alkyl sulfates are safe in the practices of use and concentration described in the safety assessment.

Final amended report on the safety assessment of Octyldodecyl Stearoyl Stearate.

Octyldodecyl Stearoyl Stearate is an ester that functions as a skin-conditioning agent and viscosity-increasing agent. It is reported to be used in 105 cosmetic products at concentrations from 2% to 15%. In an isolated human skin permeation and penetration study, 0.005% of the applied dose permeated the skin, around 3% was found in the epidermis, around 1.5% was in tape stripped skin layers, and around 95% stayed in the material applied to the skin. A formulation having 20.6% Octyldodecyl Stearoyl Stearate was classified as minimally to mildly irritating in an in vitro ocular irritation assay. Several tests of products containing from 7.5% to 12.7% Octyldodecyl Stearoyl Stearate using rabbits produced minimal to mild ocular irritation. One test of 100% Octyldodecyl Stearoyl Stearate (a trade compound) and another of 10% Octyldodecyl Stearoyl Stearate in corn oil using rabbits produced no ocular irritation. Tests using rabbits demonstrated that Octyldodecyl Stearoyl Stearate at use concentrations was non- to mildly irritating to skin; only one study reported moderate irritation. Octyldodecyl Stearoyl Stearate was not mutagenic, with or without S-9 activation, in an Ames test and did not produce a significant increase in micronucleated cells in a mouse in vivo study. In clinical single-insult patch tests at use concentrations, Octyldodecyl Stearoyl Stearate was nonirritating to mildly irritating; in a cumulative irritation study, it caused mild irritation. Octyldodecyl Stearoyl Stearate was nonsensitizing in clinical tests. Because few toxicity data were available on Octyldodecyl Stearoyl Stearate, summaries of data from existing safety assessments of related ingredients (Octyl Dodecanol, Stearic Acid, and Octyl Stearate) were included. Undiluted Octyl Dodecanol was nontoxic during acute oral and dermal studies using rats and guinea pigs. Stearic Acid was nontoxic to rats during acute oral studies, but caused toxicity during subchronic studies. Rabbits treated topically with the acid were not affected adversely, and mild erythema and slight induration were observed when Stearic Acid was administered intradermally to guinea pigs and rabbits. Octyl Stearate had very low acute oral toxicity in rats and mice. Octyl Dodecanol produced only transient mild ocular irritation in rabbits when administered at concentrations up to 100%. Octyl Dodecanol (30% and 100%) was nonirritating to skin in one study using rabbits. In another study using multiple species, 100% Octyl Dodecanol (described as technical grade) caused severe skin irritation in rabbits, moderate irritation in guinea pigs and rats, and no irritation in swine. Stearic Acid was non- to moderately irritating in animal studies, and did not cause photosensitization. In studies using rabbits, undiluted Octyl Stearate caused slight, transient ocular irritation, and minimal skin irritation. Stearic Acid did not induce mitotic crossovers and aneuploidy in Saccharomyces cerevisiae, and was nonmutagenic in the Ames test. In a feeding study using mice, Stearic Acid was noncarcinogenic at doses up to 50 g/kg/day. Mice given subcutaneous injections of the acid had low incidences of carcinomas, sarcomas, and lymphomas. In clinical studies, concentrations of up to 100% Octyl Dodecanol were non- to mildly irritating, nonsensitizing, nonphototoxic, and nonphotosensitizing. Stearic Acid was nonirritating at concentrations up to 100%, and at concentrations up to 13% it was nonsensitizing and nonphotosensitizing. Octyl Stearate (7.6%) in formulation was nonirritating, nonsensitizing, and nonphotosensitizing. Based on skin permeation and penetration data, the Panel does not expect any significant amount of Octyldodecyl Stearoyl Stearate to be systemically available. There is no evidence of systemic toxicity associated with any of the related chemicals reviewed in previous safety assessments. None of the available toxicology or clinical data suggest a concern about adverse skin reactions to Octyldodecyl Stearoyl Stearate, or to any of the related chemicals. There is no evidence of ocular toxicity, except for a mild, transient ocular irritation associated with Octyldodecyl Stearoyl Stearate and the related chemicals. Overall, Octyldodecyl Stearoyl Stearate was considered safe as used in cosmetics.

Alkylphosphocholine-induced glioma cell death is BCL-X(L)-sensitive, caspase-independent and characterized by massive cytoplasmic vacuole formation.

Alkylphosphocholines (APC) are candidate anticancer agents. We here report that APC induce the formation of large vacuoles and typical features of apoptosis in human glioma cell lines, but not in immortalized astrocytes. APC promote caspase activation, poly(ADP-ribose)-polymerase (PARP) processing and cytochrome c release from mitochondria. Adenoviral X-linked inhibitor of apoptosis (XIAP) gene transfer, or exposure to the caspase inhibitor, benzyloxycarbonyl-Val-Ala-DL-Asp-fluoro-methylketone zVAD-fmk, blocks caspase-7 and PARP processing, but not cell death, whereas BCL-X(L) blocks not only caspase-7 and PARP processing but also cell death. APC induce changes in Delta Psi m in sensitive glioma cells, but not in resistant astrocytes. The changes in Delta Psi m are unaffected by crm-A (cowpox serpin-cytokine response modifier protein A), XIAP or zVAD-fmk, but blocked by BCL-X(L), and are thus a strong predictor of cell death in response to APC. Free radicals are induced, but not responsible for cell death. APC thus induce a characteristic morphological, BCL-X(L)-sensitive, apparently caspase-independent cell death involving mitochondrial alterations selectively in neoplastic astrocytic cells.

Saturated fatty acids synergize with elevated glucose to cause pancreatic beta-cell death.

We have proposed the "glucolipotoxicity" hypothesis in which elevated free fatty acids (FFAs) together with hyperglycemia are synergistic in causing islet beta-cell damage because high glucose inhibits fat oxidation and consequently lipid detoxification. The effects of 1-2 d culture of both rat INS 832/13 cells and human islet beta-cells were investigated in medium containing glucose (5, 11, 20 mM) in the presence or absence of various FFAs. A marked synergistic effect of elevated concentrations of glucose and saturated FFA (palmitate and stearate) on inducing beta-cell death by apoptosis was found in both INS 832/13 and human islet beta-cells. In comparison, linoleate (polyunsaturated) synergized only modestly with high glucose, whereas oleate (monounsaturated) was not toxic. Treating cells with the acyl-coenzyme A synthase inhibitor triacsin C, or the AMP kinase activators metformin and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside that redirect lipid partitioning to oxidation, curtailed glucolipotoxicity. In contrast, the fat oxidation inhibitor etomoxir, like glucose, markedly enhanced palmitate-induced cell death. The data indicate that FFAs must be metabolized to long chain fatty acyl-CoA to exert toxicity, the effect of which can be reduced by activating fatty acid oxidation. The results support the glucolipotoxicity hypothesis of beta-cell failure proposing that elevated FFAs are particularly toxic in the context of hyperglycemia.

Final report on the safety assessment of Octyidodecyl Stearoyl Stearate.

Octyldodecyl Stearoyl Stearate functions as an occlusive skin-conditioning agent and as a nonaqueous viscosity-increasing agent in many cosmetic formulations. Current concentrations of use are between 0.7% and 23%, although historically higher concentrations were used. The chemical is formed by a high-temperature, acid-catalyzed esterification reaction of long-chain alcohols (primarily C-20) and a mixture of primarily C-18 fatty acids. Levels of stearic acid, octyldodecanol, and octylydocecyl hydroxystearate in the final product are 5% or less--no other residual compounds are reported. Only limited safety test data were available on Octyldodecyl Stearoyl Stearate, but previous safety assessments of long-chain alcohols and fatty acids found these precursors to be safe for use in cosmetic formulations. Octyldodecyl Stearoyl Stearate produced no adverse effects in acute exposures in rats. The chemical was mostly nonirritating to animal skin at concentrations ranging from 7.5% to 10%; one study did find moderate irritation in rabbit skin at a concentration of 7.5%. Clinical tests at a concentration of 10.4% confirmed the absence of significant irritation in humans. An ocular toxicity study in rabbits found no toxicity. No evidence of genotoxicity was found in either a mammalian test system or in the Ames test system, with or without metabolic activation. The available data on Octyldodecyl Stearoyl Stearate and the previously considered data on long-chain alcohols and fatty acids, however, did not provide a sufficient basis to make a determination of safety. Additional data needs include (1) chemical properties, including the octanol/water partition coefficient; and (2) if there is significant dermal absorption or if significant quantities of the ingredient may contact mucous membranes or be ingested, then reproductive and developmental toxicity data may be needed. Until such time as these data are received, the available data do not support the safety of Octyldodecyl Stearoyl Stearate as used in cosmetic formulations.

Final report on the safety assessment of Stearamide DIBA-Stearate.

Stearamide DIBA-Stearate is a substituted dihydroxyisobutylamine (DIBA) that functions in cosmetic formulations as an opacifying agent, a surfactant-foam booster, and a viscosity increasing agent. Stearamide DIBA-Stearate was reportedly used in four cosmetic formulations, at concentrations of 1% to 3%. Few data on this ingredient were available. Data on related ingredients, including Dibutyl Adipate, Diisopropyl Adipate, Stearamide DEA, and Stearamide MEA, were considered in the assessment of safety. A formulation containing 1.3% Stearamide DIBA-Stearate (further diluted to 4% of the formulation) was mildly irritating but nonsensitizing in an repeated-insult patch test (RIPT). The same dilution was noncomedogenic. At a concentration of 20%, Dibutyl Adipate had an oral LD50 of 2 g/kg. Subchronic dermal exposure of rabbits (1.0 ml/kg/day) caused a reduction in weight gain that was not observed at a dose of 0.5 ml/kg/day. In studies using rabbits, undiluted Dibutyl Adipate caused mild to moderate skin irritation and minimal ocular irritation. When pregnant rats were treated intraperitoneally with approximately 1.75 ml/kg Dibutyl Adipate during gestation, the incidence of fetal gross abnormalities was increased. No effect was observed at smaller doses. Diisopropyl Adipate had low acute oral and percutaneous toxicity, and was only a very mild ocular irritant. In skin irritation studies using rabbits, 5.0% to 100% Diisopropyl Adipate caused minimal to mild irritation; these results were also seen in clinical testing with only moderate cumulative irritation, and no sensitization or photosensitization. A formulation containing 5.27% Stearamide MEA was not toxic to rats when applied topically daily for 13 weeks. In studies using rabbits, Stearamide DEA (35% to 40%) was not a skin or ocular irritant, and Stearamide MEA (5.27%) was not an ocular irritant. At 17%, Stearamide MEA was not irritating to the skin, but caused minimal to moderate irritation to the eyes of rabbits. Stearamide MEA (5.27%) did not cause sensitization during a clinical study. It was not possible, however, to determine the relevance of these data on related ingredients. Therefore, it was concluded that the available data are insufficient. Additional data needs are (1) method of manufacture; (2) chemical characterization, including impurities; (3) dermal absorption; if significantly absorbed, then a 28-day dermal toxicity study and a reproductive and developmental toxicity study may be needed; (4) two genotoxicity assays, at least one in a mammalian system; if positive, then a 2-year dermal carcinogenesis study using National Toxicology Program (NTP) methods may be needed; (5) ultraviolet (UV) absorption data; if significant absorption occurs in the UVA or UVB range, photosensitization data are needed. Absent these data, it was concluded that the available data are insufficient to support the safety of Stearamide DIBA-Stearate as used in cosmetic products.

Non-adhesive cyanoacrylate as an embolic material for endovascular neurosurgery.

Endovascular neurosurgery is now becoming available as one of strategies for the treatment of cerebro-spinal arterio-venous malformations and aneurysms. For this treatment, a microcatheter is advanced into or close to a lesion and then an embolic material is administered through it to obliterate the lesion. N-butyl-2-cyanoacrylate (NBCA) has preferentially been used as an embolic material in Europe and America. However, its exceptionally strong adhesive force sometimes causes adhesion between the tip of the microcatheter and the artery. In this study, a new non-adhesive cyanoacrylate, isostearyl-2-cyanoacrylate (ISCA), was developed. It carries a long hydrophobic side isostearyl group with lower reactivity and adhesion than other cyanoacrylates. Its polymerization rate is, however, too low to obliterate a vascular lesion with a rapid blood flow. To increase the polymerization rate. ISCA was mixed with NBCA. As a result, the adhesive force of the mixture became extremely low, compared with that of NBCA. The viscosity of the mixture was low enough to allow its' use as an embolic material. Tissue reactions against the mixture was milder than those against NBCA. Radio-angiography became possible by mixing further with Lipiodol. The evaluation of this new embolic material with a rabbit renal artery showed that the obliteration effect of the mixture of ISCA and NBCA was excellent to use as an embolic material for clinical applications.

[The cytotoxic action of metal stearates and its correlation with the toxicity for animals]. / Tsitotoksicheskoe deistvie stearatov metallov i ego korreliatsiia s toksichnost'iu dlia zhivotnykh.

Toxic effects of lead, cadmium, barium, silver, zinc and calcium stearates on the Rh-type cells culture have been revealed. The expressiveness of the cytotoxic action correlated with the toxicity degree for laboratory animals. The strongest (r = 0,98; p less than 0,01) was the correlation between cytotoxicity parameter (the minimal cytoclastic concentration) and the inhalation toxicity parameter in animals (lim(ac)). The results permitted deriving formulae for predicting some toxicity parameters (intraperitoneal LD50, lim(ac)), hygienic regulations (MAC), and showed that the prediction based on cytotoxicity data is more reliable, than that based on toxicometric parameters in short-term experiments used for such purpose.

Magnesium stearate given perorally to rats. A short term study.

Magnesium stearate was fed to groups of 20 male and 20 female rats at levels of 0, 5, 10 and 20% in a semisynthetic diet for 3 months. Decreased weight gain was found in males in the 20% group. Urolithiasis was found in 8 males and in 7 females in the same group. Reduced relative liver weight was seen in males in the 10% and in the 20% groups, and an increased amount of iron was found in the livers of the 20% group. Nephrocalcinosis was reduced in females in the 20% group. In this experiment the no-effect-level is estimated to be 5% magnesium stearate in the diet, corresponding to 2500 mg/kg body wt/day.