Subchronic Toxicology Studies Research Articles

Deriving acceptable limits for non-mutagenic impurities in medicinal products – Durational adjustments

ICH Q3A/B guidelines are not intended for application during the clinical research phase of development and durationally adjusted qualification thresholds are not included. A central tenet of ICH Q3A is that lifetime exposure to 1 mg/day of an unqualified non-mutagenic impurity (NMI) is not a safety concern. An analysis of in vivo toxicology data from 4878 unique chemicals with established NO(A)ELs was conducted to determine whether durationally adjusted qualification limits can be supported. Although not recommended in ICH Q3A/B, a conservative approach was taken by using allometric scaling in the analysis. Following allometric scaling of the 5th percentile of the distribution of NO(A)ELs from available chronic toxicology studies, it was reconfirmed that there is a safety basis for the 1 mg/day qualification threshold in ICH Q3A. Additionally, allometric scaling of the 5th percentile of the distribution of NO(A)ELs from sub-acute and sub-chronic toxicology studies could support acceptable limits of 20 and 5 mg/day for an unqualified NMI for dosing durations of less than or greater than one month, respectively. This analysis supports durationally adjusted NMI qualification thresholds for pharmaceuticals that protect patient safety and contribute to 3Rs efforts for qualifying impurities using new approach methods.

Acute and Subchronic Toxicological Study of the Cocktail Extract from Curcuma xanthorrhiza Roxb, Phyllanthus niruri L. and Morinda citrifolia L.

Curcuma xanthorrhiza Roxb, Phyllanthus niruri L., and Morinda citrifolia L. are Indonesian medicinal herbs used empirically as traditional therapeutics for maintaining health. The cocktail extract of these three plants (CECPM) had been developed and demonstrated immunostimulant activity in rats. This study aimed to evaluate the acute and subchronic toxicity of CECPM in vivo. The acute toxicity assay was conducted by orally administering a range dose of CECPM (313, 625, 1250, 2500, or 5000 mg/kg body weight (bw) on female mice once and then evaluating the toxic symptom every day for 14 days later. The chronic toxicity test was carried out by giving various doses of CECPM (600, 800, and 1000 mg/kg·bw) to female and male rats orally continuously for 90 consecutive days. The signs of toxicities were evaluated at the 90- and 28 days postadministration. The acute oral toxicity assays showed that there was no toxic syndrome and mortality found during the period of the experiment. The lethal dose level (LD50) of CECPM was more than 5000 g/kg, which was categorized as practically non-toxic. Meanwhile, in the sub-chronic toxicity study, some parameters tested at 90 days postadministration and after 28 days of withdrawal, such as the body weight, relative organ weight, food intake, hematological and biochemical blood parameters, and also histopathological examination of five primary tissues (heart, liver, kidney, spleen, and lung) revealed no abnormalities. There was no-observed adverse effect level (NOAEL) for the present study of CECPM 1000 mg/kg·bw of the rat. Therefore, it is concluded that the orally administered CECPM was relatively nontoxic during acute and subchronic toxicology studies.

Assessment of safety through mutagenicity and subchronic toxicity studies with black pepper extract preparation.

Black pepper (Piper nigrum) is a rich source of natural and bioactive components such as N-trans-feruloyltyramine (NFT). In this paper, we discuss the results of the subchronic toxicity and mutagenicity studies conducted to understand the potential for adverse effects if any, of Black Pepper Extract Preparation (BPE). To evaluate mutagenicity, an Ames test was conducted with BPE in the presence and absence of S9 metabolic activation. Long-term safety was inferred through a 90-day subchronic toxicology study using adult rats. Dose levels were selected with expected human intake levels of NFT (120mg/kg/day), with an acceptable safety factor, for preclinical safety and tolerability. Sprague Dawley rats were fed diets targeting dietary intakes (doses) of 0, 125, 350, or 700mg/kg/day of BPE for 90days, an NFT dose level equivalent to 68, 190, and 380mg/kg/day. In vitro Ames test up to 5000µg/plate with and without S9 metabolic activation showed no BPE-related increases in revertant colony numbers and was non-mutagenic. There were no BPE-related changes in viability, clinical signs, body weight, food consumption, and organ weights. BPE dietary administration did not induce any treatment-related changes in hematology, clinical chemistry, other macroscopic or microscopic endpoints. The highest dose tested with BPE (700mg/kg/day) was the no-observed-adverse-effect level (NOAEL) that revealed no adverse effects. Based on toxicological endpoints evaluated, this NOAEL for BPE corresponded to a human equivalent NFT dose level of 380mg/kg/day, dependent upon a (∼50%) concentration of NFT in BPE.

Preclinical safety assessments of nicotinamide riboside hydrogen malate

Nicotinamide riboside (NR) is an analog of vitamin B3, which is naturally present in trace amounts in selected foods. Several B3 analogs are known precursors in the synthesis of nicotinamide adenine dinucleotide, including nicotinic acid (niacin) and nicotinamide (niacinamide). The safety of nicotinamide riboside hydrogen malate (NRHM), a salt of NR, was assessed in a bacterial reverse mutagenesis assay (Ames), in vitro micronucleus assay in human peripheral lymphocytes, a 14-day acute toxicology test (Sprague-Dawley rats), and a 90-day sub-chronic toxicology study in Sprague-Dawley rats. Based on the results of the 14-day study, the 90-day sub-chronic study was conducted comparing oral NRHM at 1000, 1500, and 3000 mg/kg/day with a vehicle control. No genotoxicity was observed. There were no mortalities or clinical observations attributed to the NRHM test substance administration over the course of the study. The no-observed-adverse effect level for NRHM was determined to be 3000 mg/kg bw/day in the female rats but 2000 mg/kg bw/day in the male rats due to a significantly lower body weight in males at the high dose. The results of this study imply that NRHM can be manufactured at a high level of purity, is not genotoxic, and is well-tolerated in in Sprague-Dawley rats.

Acute and Sub-chronic Toxicological Studies of Citrus aurantium Fruit Juice in Wistar Rats

Citrus aurantium remains an excellent source of vitamins and phytochemicals. C. aurantium has been associated with lots of medicinal uses ranging from weight management to the treatment of nausea, cardiovascular diseases and cancer. This study therefore aimed at determining the acute and sub-chronic toxic effects of C. aurantium (Lemon) fruit juice in Wistar rats. The median lethal dose (LD50) for the extract was determined by Lorke’s method. A total of 20 rats of mean weight of 125 ± 5 g randomized into 4 groups of five rats each was used for the study. Groups B, C and D were administered 2ml/kg, 4ml/kg and 8ml/kg bodyweight of the extract for 3 months while group A served as the control. Random blood glucose levels of rats were monitored on monthly basis. Blood samples were collected for various biochemical assays like kidney and liver functions, serum lactate dehydrogenase enzyme activity, lipid profile, lipid peroxidation and electrolyte levels using standard diagnostic methods. Results showed a lethal dose of 70ml/kg body weight. Creatinine and urea levels were observed to decrease markedly in groups C and D against control. Significant reductions in the liver function parameters were noted for the test groups when compared with the control with a comparative significant (p<0.05) increase in the activity of lactate dehydrogenase within the test groups. There was also a significant (p<0.05) decrease in the levels of total cholesterol, low-density lipoprotein, very low-density lipoprotein and triglycerides within the test groups as compared with the control. The findings suggest that prolonged administration of C. aurantium does not exert any serious chronic toxicity involving tissue and organ damage. It can also be inferred that the fruit juice of C. aurantium could be employed to remedy numerous maladies that affect the body based on the lethal dose.

Toxicological assessment of truebroc® glucoraphanin-rich broccoli seed extract

TrueBroc® Glucoraphanin-Rich Broccoli Seed Extract (TrueBroc®), is a hot water extract of Brassica oleracea var. Italica Plenck (Brassicaceae) seeds. The broccoli seeds are non-genetically modified and are tested and selected for their specific glucosinolate content. TrueBroc® contains greater than 99% of the aliphatic glucosinolate glucoraphanin and its precursor glucoerucin in the glucosinolate fraction. A battery of toxicology assays was conducted on TrueBroc® which includes in vitro and in vivo genotoxicity studies, an acute oral toxicity study in rats, a subchronic toxicology study in rats. The result from the subchronic rat study establishes a NOAEL of 1500 mg/kg/day.

A Complete In Vitro Toxicological Assessment of the Biological Effects of Cerium Oxide Nanoparticles: From Acute Toxicity to Multi-Dose Subchronic Cytotoxicity Study.

Engineered nanomaterials (ENMs) are of significant relevance due to their unique properties, which have been exploited for widespread applications. Cerium oxide nanoparticles (CeO2-NPs) are one of most exploited ENM in the industry due to their excellent catalytic and multi-enzyme mimetic properties. Thus, the toxicological effects of these ENMs should be further studied. In this study, the acute and subchronic toxicity of CeO2-NPs were assessed. First, an in vitro multi-dose short-term (24 h) toxicological assessment was performed in three different cell lines: A549 and Calu3 were used to represented lung tissue and 3T3 was used as an interstitial tissue model. After that, a sub-chronic toxicity assessment (90 days) of these NPs was carried out on a realistic and well-established reconstituted primary human airway epithelial model (MucilAir™), cultured at the Air–Liquid Interface (ALI), to study the long-term effects of these particles. Results showed minor toxicity of CeO2-NPs in acute exposures. However, in subchronic exposures, cytotoxic and inflammatory responses were observed in the human airway epithelial model after 60 days of exposure to CeO2-NPs. These results suggest that acute toxicity approaches may underestimate the toxicological effect of some ENMs, highlighting the need for subchronic toxicological studies in order to accurately assess the toxicity of ENM and their cumulative effects in organisms.

A Pathology Review of the Lower Gastrointestinal Tract in Relation to Ulcerative Colitis in Rats and Cynomolgus Macaques Treated With Ammonium Perfluorooctanoate.

Among many short-term, subchronic, and chronic toxicology studies with ammonium perfluorooctanoate (PFOA), the gastrointestinal tract has not been identified as a target organ for PFOA-related toxicity in laboratory animals where the corresponding serum PFOA concentrations typically approach several orders of magnitude higher than the general human population. These lack of gastrointestinal tract-related findings were in direct contrast to an epidemiological observation where a positive trend was observed for ulcerative colitis, an idiopathic chronic inflammatory condition of the gut, in a Mid-Ohio River community whose drinking water contained higher levels of PFOA. This study was conducted to perform a histological reevaluation of large intestine sections in laboratory animals from 2 long-term toxicological studies: one was with Sprague Dawley rats that received ammonium PFOA in their diet for 2 years and the other one was with cynomolgus macaques that received daily capsules of ammonium PFOA for 6 months. In both studies, there was a lack of histological evidence of treatment-related inflammatory lesions that was suggestive of the occurrence of ulcerative colitis in these laboratory animals even under the most rigorous treatment schedules. These findings do not offer support for the biological plausibility of the epidemiological associations reported.

Antidiabetic effect of Cordia morelosana, chemical and pharmacological studies.

CORDIA MORELOSANA: Standley (Boraginaceae) is commonly used in folk medicine for the treatment of diarrhoea, kidney inflammation, diabetes, lung pain, bronchitis, asthma, hoarseness, cough and fever. Current work was conducted to develop a bio-guided isolation of antidiabetic compounds from ethanolic extract of Cordia morelosana (EECm). The phytochemical bio-guided study was conducted by successive chromatographic techniques, and isolated compounds were characterized by 1D and 2D-NMR experiments. The in vivo antihyperglycemic and antidiabetic activities of EECm (100mg/kg), and methyl rosmarinate (MR, 50mg/kg) were determined on normoglycemic and diabetic murine models. Additionally, the in vitro activity was conducted to determine α-glucosidase inhibitory effect, and PPARs, GLUT4 and FATP expression on 3T3-L1 cells by RT-PCR. Acute and sub-chronic toxicological studies for EECm were conducted on rats, following the OECD guidelines (No. 420 and 407). EECm promotes significant α-glucosidase inhibition (55.6%) at 1mg/kg respect to the control. Also, EECm (100mg/kg) showed significant antihyperglycemic effect on oral glucose tolerance test (OGTT), and in non-insulin dependent type 2 diabetes (NIDD) model, had antidiabetic activity (p<0.001) compared to controls. The bio-guided isolation allowed to obtain four known compounds described as rosmarinic acid (RA), methyl rosmarinate (MR), nicotiflorine and 1-O-methyl-scyllo-inositol. On the other hand, MR showed significant antidiabetic and anthiyperglycemic activities (p<0.05), and overexpression of PPARγ, PPARα, GLUT-4 and FATP than control. Docking studies were conducted with PPARγ and PPARα, showing interesting binding mode profile on those targets. Finally, EECm displayed a LD50>2000mg/kg and sub-chronic toxicological study reveals no toxic signs in animals tested compared to control. EECm showed significant antihyperglycemic and antidiabetic actions being RA and MR the main antidiabetic metabolites.

Toxicological Studies of popular eye cosmetic used world wide

Background and Objective: Present research work was designed and conducted to verify the safe use of kajal, a popular eye cosmetic, which is widely used to beautify eyes throughout the world especially in South Asia and Middle East region.&#x0D; Material and Method: The toxicological studies were conducted in experimental animals for a period of 90 days to clarify misleading thoughts associated with its long term use including lead toxicity. The study was carried out in Albino rats of Wister strain and New Zealand White rabbits. Hashmi kajal dibya (net weight 4.25g), an eye cosmetic manufactured by M/s A.Q. and company international Pakistan was used as source for study. The ingredients claimed by the manufacturer are zinc oxide, wax, cinnamonum camphora, processed carbon black and clarified butter.&#x0D; Result: The elemental analysis resulted in presence of zinc 9.56%, lead 0.09% and total ash 41.01%, while sulfur, antimony, mercury and arsenic were not detected in the sample. The sub-chronic toxicological studies revealed that no toxicological effects were found in experimental animals. All the animals of test and control groups exhibited normal physiological activities and an increase in body weights. Lead and Zinc levels remained constant throughout the experimental period and no mortality was recorded. Furthermore, liver and kidney function tests were normal, indicating non-toxic effect of the kajal on vital organs.&#x0D; Conclusion: So it can be assumed that this eye cosmetic is non-toxic and can be used safely in humans.&#x0D; Bangladesh Journal of Medical Science Vol.18(1) 2019 p.118-123

Assessment of the Pig-a, micronucleus, and comet assay endpoints in rats treated by acute or repeated dosing protocols with procarbazine hydrochloride and ethyl carbamate.

The utility and sensitivity of the newly developed flow cytometric Pig-a gene mutation assay have become a great concern recently. In this study, we have examined the feasibility of integrating the Pig-a assay as well as micronucleus and Comet endpoints into acute and subchronic general toxicology studies. Male Sprague-Dawley rats were treated for 3 or 28 consecutive days by oral gavage with procarbazine hydrochloride (PCZ) or ethyl carbamate (EC) up to the maximum tolerated dose. The induction of CD59-negative reticulocytes and erythrocytes, micronucleated reticulocytes in peripheral blood, micronucleated polychromatic erythrocytes in bone marrow, and Comet responses in peripheral blood, liver, kidney, and lung were evaluated at one, two, or more timepoints. Both PCZ and EC produced positive responses at most analyzed timepoints in all tissue types, both with the 3-day and 28-day treatment regimens. Furthermore, comparison of the magnitude of the genotoxicity responses indicated that the micronucleus and Comet endpoints generally produced greater responses with the higher dose, short-term treatments in the 3-day study, while the Pig-a assay responded better to the cumulative effects of the lower dose, but repeated subchronic dosing in the 28-day study. Collectively, these results indicate that integration of several in vivo genotoxicity endpoints into a single routine toxicology study is feasible and that the Pig-a assay may be particularly suitable for integration into subchronic dose studies based on its ability to accumulate the mutations that result from repeated treatments. This characteristic may be especially important for assaying lower doses of relatively weak genotoxicants. Environ. Mol. Mutagen. 60:56-71, 2019. © 2018 Wiley Periodicals, Inc.

Re-evaluation of silicon dioxide (E551) as a food additive.

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of silicon dioxide (E 551) when used as a food additive. The forms of synthetic amorphous silica (SAS) used as E 551 include fumed silica and hydrated silica (precipitated silica, silica gel and hydrous silica). The Scientific Committee on Food (SCF) established a group acceptable daily intake (ADI) ‘not specified’ for silicon dioxide and silicates. SAS materials used in the available biological and toxicological studies were different in their physicochemical properties; their characteristics were not always described in sufficient detail. Silicon dioxide appears to be poorly absorbed. However, silicon‐containing material (in some cases presumed to be silicon dioxide) was found in some tissues. Despite the limitations in the subchronic, reproductive and developmental toxicological studies, including studies with nano silicon dioxide, there was no indication of adverse effects. E 551 does not raise a concern with respect to genotoxicity. In the absence of a long‐term study with nano silicon dioxide, the Panel could not extrapolate the results from the available chronic study with a material, which does not cover the full‐size range of the nanoparticles that could be present in the food additive E 551, to a material complying with the current specifications for E 551. These specifications do not exclude the presence of nanoparticles. The highest exposure estimates were at least one order of magnitude lower than the no observed adverse effect levels (NOAELs) identified (the highest doses tested). The Panel concluded that the EU specifications are insufficient to adequately characterise the food additive E 551. Clear characterisation of particle size distribution is required. Based on the available database, there was no indication for toxicity of E 551 at the reported uses and use levels. Because of the limitations in the available database, the Panel was unable to confirm the current ADI ‘not specified’. The Panel recommended some modifications of the EU specifications for E 551.

Acute and sub-chronic toxicological studies of the iridoid glycosides extract of Lamiophlomis rotata (Benth.) Kudo in rats

Lamiophlomis rotata(Benth.) Kudo is widely used in traditional Chinese medicine and its iridoid glycosides extract (IGLR) was the main active ingredient with hemostatic, antinociceptive and anti-inflammatory effects. This study was aimed to evaluate the safety of IGLR using acute and sub-chronic toxicity study methods on Sprague-Dawley rats. In acute toxicity test, IGLR caused slight diarrhea in three dose groups and a decreased of RBC and increased of MCH and Ret (P < .05) were observed in 16 g/kg group. In sub-chronic toxicity study, unscheduled deaths occurred in 1 and 3 rats at 0.40 and 1.00 g/kg groups, respectively. A slight diarrhea was observed in 1.00 g/kg group. Hemolytic anemia was the main toxicity effects of IGLR found in 0.40 and 1.00 g/kg groups, with a significant decrease of RBC, HGB (P < .05) and increase of Ret, MCV, MCH (P < .05) in hematological parameters, a significant decrease of ALT, Crea (P < .05) and increase of TBIL (P < .05) in biochemical parameters, and a significant increase of the percentage of rubricyte, normoblast (P < .05) in bone marrow. Overall, this study found IGLR has a potential toxicity considering with hemolytic anemia and diarrhea to rat. These results provide an important reference for further IGLR-related drug exploration.

Acute and 13-week subchronic toxicological evaluations of turanose in mice

BACKGROUND/OBJECTIVESTuranose, α-D-glucosyl-(1→3)-α-D-fructose, is a sucrose isomer which naturally exists in honey. To evaluate toxicity of turanose, acute and subchronic oral toxicity studies were conducted with ICR mice.MATERIALS AND METHODSFor the acute oral toxicity study, turanose was administered as a single oral dose [10 g/kg body weight (b.w.)]. In the subchronic toxicity study, ICR mice were administered 0, 1.75, 3.5, and 7 g/kg b.w. doses of turanose daily for 13 weeks.RESULTSNo signs of acute toxicity, including abnormal behavior, adverse effect, or mortality, were observed over the 14-day study period. In addition, no changes in body weight or food consumption were observed and the median lethal dose (LD50) for oral intake of turanose was determined to be greater than 10 g/kg b.w. General clinical behavior, changes in body weight and food consumption, absolute and relative organ weights, and mortality were not affected in any of the treatment group for 13 weeks. These doses also did not affect the macroscopic pathology, histology, hematology, and blood biochemical analysis of the mice examined.CONCLUSIONNo toxicity was observed in the acute and 13-week subchronic oral toxicology studies that were conducted with ICR mice. Furthermore, the no-observed-adverse-effect level is greater than 7 g/kg/day for both male and female ICR mice.

In Vivo Alkaline Comet Assay and Enzyme-modified Alkaline Comet Assay for Measuring DNA Strand Breaks and Oxidative DNA Damage in Rat Liver.

Unrepaired DNA damage can lead to genetic instability, which in turn may enhance cancer development. Therefore, identifying potential DNA damaging agents is important for protecting public health. The in vivo alkaline comet assay, which detects DNA damage as strand breaks, is especially relevant for assessing the genotoxic hazards of xenobiotics, as its responses reflect the in vivo absorption, tissue distribution, metabolism and excretion (ADME) of chemicals, as well as DNA repair process. Compared to other in vivo DNA damage assays, the assay is rapid, sensitive, visual and inexpensive, and, by converting oxidative DNA damage into strand breaks using specific repair enzymes, the assay can measure oxidative DNA damage in an efficient and relatively artifact-free manner. Measurement of DNA damage with the comet assay can be performed using both acute and subchronic toxicology study designs, and by integrating the comet assay with other toxicological assessments, the assay addresses animal welfare requirements by making maximum use of animal resources. Another major advantage of the assays is that they only require a small amount of cells, and the cells do not have to be derived from proliferating cell populations. The assays also can be performed with a variety of human samples obtained from clinically or occupationally exposed individuals.

&lt;em&gt;In Vivo&lt;/em&gt; Alkaline Comet Assay and Enzyme-modified Alkaline Comet Assay for Measuring DNA Strand Breaks and Oxidative DNA Damage in Rat Liver

Unrepaired DNA damage can lead to genetic instability, which in turn may enhance cancer development. Therefore, identifying potential DNA damaging agents is important for protecting public health. The in vivo alkaline comet assay, which detects DNA damage as strand breaks, is especially relevant for assessing the genotoxic hazards of xenobiotics, as its responses reflect the in vivo absorption, tissue distribution, metabolism and excretion (ADME) of chemicals, as well as DNA repair process. Compared to other in vivo DNA damage assays, the assay is rapid, sensitive, visual and inexpensive, and, by converting oxidative DNA damage into strand breaks using specific repair enzymes, the assay can measure oxidative DNA damage in an efficient and relatively artifact-free manner. Measurement of DNA damage with the comet assay can be performed using both acute and subchronic toxicology study designs, and by integrating the comet assay with other toxicological assessments, the assay addresses animal welfare requirements by making maximum use of animal resources. Another major advantage of the assays is that they only require a small amount of cells, and the cells do not have to be derived from proliferating cell populations. The assays also can be performed with a variety of human samples obtained from clinically or occupationally exposed individuals.

Toxicological assessment of polyhexamethylene biguanide for water treatment.

Polyhexamethylene biguanide (PHMB) is an antiseptic with antiviral and antibacterial properties used in a variety of products including wound care dressings, contact lens cleaning solutions, perioperative cleansing products, and swimming pool cleaners. There are regulatory concerns with regard to its safety in humans for water treatment. We decided to assess the safety of this chemical in Sprague-Dawley rats. PHMB was administered in a single dose by gavage via a stomach tube as per the manufacturer's instruction within a dose range of 2 mg/kg to 40 mg/kg. Subchronic toxicity studies were also conducted at doses of 2 mg/kg, 8 mg/kg and 32 mg/kg body weight and hematological, biochemical and histopathological findings of the major organs were assessed. Administration of a dose of 25.6 mg/kg, i.e. 1.6 mL of 0.4% PHMB solution (equivalent to 6.4x103 mg/L of 0.1% solution) resulted in 50% mortality. Histopathological analysis in the acute toxicity studies showed that no histopathological lesions were observed in the heart and kidney samples but 30% of the animals had mild hydropic changes in zone 1 of their liver samples, while at a dosage of 32 mg/kg in the subchronic toxicity studies, 50% of the animals showed either mild hepatocyte cytolysis with or without lymphocyte infiltration and feathery degeneration. Lymphocyte infiltration was, for the first time, observed in one heart sample, whereas one kidney sample showed mild tubular damage. The acute studies showed that the median lethal dose (LD50) is 25.6 mg/kg (LC50 of 1.6 mL of 0.4% PHMB. Subchronic toxicological studies also revealed few deleterious effects on the internal organs examined, as seen from the results of the biochemical parameters evaluated. These results have implications for the use of PHMB to make water potable.

Evaluation of the safety of primary metabolites of cyadox: Acute and sub-chronic toxicology studies and genotoxicity assessment

Cyadox (CYA) is a synthetic antimicrobial agent, belonging to quinoxaline (QdNO) family. Cy1 (bidesoxy cyadox), Cy2 (N4-desoxycyadox) and Cy10 (N1-desoxycyadox) are the primary metabolites of CYA. In our present study, an acute toxicity test, a sub-chronic toxicity test, and a battery of three genotoxicity tests were carried out according to standard protocols. The LD50 of the metabolites were above 5000 mg/kg b.w. The maximum tolerated dose (MTD) of Cy1 and Cy-M (mixture of Cy2 and Cy10) in rats, and the MTD of Cy1, Cy2 and Cy10 in mice were above 6000 mg/kg b.w./day. In subchronic study, rats were separately administered Cy1 and Cy-M at the dose levels of 0, 50, 150 and 2500 mg/kg diet for 90 days, with CYA (2500 mg/kg) as a control. Significant decreases in body weight and changes in clinical serum biochemistry were observed in the high-dose group of Cy1 and Cy-M, as well as CYA. Significant changes in relative weights of organs at 150 and 2500 mg/kg diet of Cy1 and CYA were noted. Additionally, the high-dose groups of Cy1, Cy-M and CYA showed pathological changes near the hepatic portal area. There was no evidence for genotoxic activity of any of the three metabolites in the bacterial reverse mutation test, mouse bone marrow micronucleus assay or an in vitro assay for clastogenicity. Based on the subchronic study, the target organ of the primary metabolites was the liver, and the no-observed-adverse-effect level for Cy1 and Cy-M was 150 mg/kg diet.

Toxicological and Genotoxicity Assessment of a Dihydroquercetin-Rich Dahurian Larch Tree (Larix gmelinii Rupr) Extract (Lavitol).

Safety assessment is reported of an orally ingested dihydroquercetin-rich extract (Lavitol) derived from the Dahurian larch tree, used as a food additive and as a dietary supplement ingredient. Dihydroquercetin, a potent antioxidant, is also known as taxifolin. The results of genotoxicity and toxicological tests (Comet assay, micronucleus test in human lymphocytes, chromosomal aberration test, subacute 7-day oral toxicity study, subchronic 90-day toxicology study with histopathologies, and, prenatal and postnatal developmental toxicity studies) on the extract provide further support for the safety of its consumption as a food supplement and food additive.

The health risk of chrysotile asbestos.

The word asbestos is a poorly attributed term, as it refers to two very different minerals with very different characteristics. One is the serpentine mineral of which the white asbestos, chrysotile, is the most common. The other is the amphibole asbestos, which includes the blue asbestos crocidolite and the brown asbestos amosite. Although today chrysotile is the only type used commercially, the legacy of past use of amphibole asbestos remains. This review clarifies the differences between the two mineral families referred to as asbestos and summarizes the scientific basis for understanding the important differences in the toxicology and epidemiology of these two minerals. Biopersistence and sub-chronic inhalation toxicology studies have shown that exposure to chrysotile at up to 5000 times the current threshold limit value (0.1 fibers/cm) produces no pathological response. These studies demonstrate as well that following short-term exposure the longer chrysotile fibers rapidly clear from the lung and are not observed in the pleural cavity. In contrast, short-term exposure to amphibole asbestos results quickly in the initiation of a pathological response in the lung and the pleural cavity. Significant progress has been made in understanding the factors that influence inhalation toxicology studies of fibers and epidemiological studies of workers. Evaluation of the toxicology and epidemiology studies of chrysotile indicates that it can be used safely under controlled use. In contrast, even short-term exposure to amphibole asbestos can result in disease.