Chronic Feeding Studies Research Articles

Oral ingestion of a novel oxygenating compound, Ox66™, is non-toxic and has the potential to increase oxygenation

Ox66™ is a novel solid state oxygenating compound. In order to support the use of Ox66™ as a potential oxygenating supplement to injured cells, this study evaluated the safety of Ox66™, its ability to withstand the conditions in the digestive tract, and its potential to increase oxygenation in the mesentery in rats. The toxicity of Ox66™ was evaluated by performing acute (10-day) and chronic (90-day) feeding studies on rats, the stability of the compound in the digestive tract was evaluated via ex vivo simulated digestion and subsequent CFDA viability assay on gut epithelial cells, and its capacity for oxygenation in the mesenteric microcirculation was determined by interstitial fluid pressure (PISF) O2 measurements upon injection into the small intestine of rats. No toxicity was found associated with acute or chronic oral administration of the compound in rats, and the compound was able to withstand the environment of the digestive tract in vitro. Based on the acute animal feeding study, the NOAEL was considered to be 1000 mg/kg/day. This proof-of-concept study further demonstrates the potential of Ox66™ to function as an oxygenating supplement that might be useful for treating either pathological hypoxic-related conditions or to improve oxygenation levels during or after exercise under healthy conditions.

1.22 Weight differences of honey bees after administration of sublethal doses of dimethoate

Background: The aim of this work was to assess honey bee body weight as a possible further parameter to detect effects in a 10 day chronic feeding study according to OECD 2451 following exposure to sublethal concentrations of a plant protection product (i.e. dimethoate). This investigation is based on the assumption that weight differences might be caused by chronic feeding of dimethoate. Two set of tests in two different laboratories (Lab 1 and Lab 2) were conducted in order to investigate possible weight changes of complete adult honey bees and/or parts of their body (honey stomach and intestine) following treatment of dimethoate. Bees were weighed before and after chronic feeding of sub-lethal concentrations of dimethoate. Results: Differences in the number of bees which lost weight following treatment of sublethal concentrations of dimethoate was found in Lab 1, but could not confirmed in Lab 2. The difference in weight between the control group and the dimethoate treatment could only be detected as a statistical significant difference in one lab at the highest concentration (0.4 mg/kg). Assessment of weight changes of parts of the bee body (honey stomach and intestine) shows a very high variation (CV) which makes interpretation of the data of the total body weight questionable. Conclusion: The results of the two laboratories were contradictory and no conclusive assessment can be done following the two sets of experiments. Assessment of bee body weight within a 10-day chronic feeding study is considered questionable for the detection of sublethal effects. Further work with other active ingredients is needed to clarify if body weight change of honey bees can be used as a parameter for sublethal effects.

Responses of Preterm Pigs Fed Bovine Colostrum and Formulas with either Lactose or Maltodextrin as the Sources of Carbohydrate

Enteral nutrition is restricted for neonatal preterm infants because of the increased risk of necrotizing enterocolitis (NEC), particularly when breast milk is not available. However, prolonged reliance on parenteral nutrition is associated with other adverse outcomes. Despite interest in providing aggressive enteral nutritional support to realize the growth potential of the preterm infant, delayed advancement to full enteral nutrition support is common. This is especially true for the increasing numbers of infants that are now surviving birth at 28 weeks of gestation and earlier and are at greater risk of food intolerance and NEC. A consequence is extrauterine growth restriction remains prevalent among preterm infants, increasing the risk of intellectual and developmental disabilities. There is a need to improve enteral nutrition support for neonatal preterm infants when breast milk is not available. Because of the ethical constraints associated with using preterm infants as test subjects, we used preterm pigs relevant to 32 week preterm infants to evaluate survival, NEC incidence and severity, and growth to 6–7 days of feeding bovine colostrum (control) or one of two formulas with either lactose or maltodextrin as the source of carbohydrate (120 ml/kg‐d). At conclusion of the feeding regimen blood chemistries, intestinal dimensions and gross pathology, and weights of other organs were recorded, and rates of intestinal glucose uptake were measured as an indicator of small intestine digestive functions. Feeding the formula with maltodextrin resulted in a 50% incidence of NEC with 30% mortality. NEC was not detected among pigs fed colostrum or the lactose‐based milk replacer. Growth of pigs fed bovine colostrum was minimal or even negative (−0.70 ± 0.26) and was lower than growth of surviving pigs fed the formulas with maltodextrin or lactose (0.77 ± 0.27 and 0.93 ± 0.18). Significant treatment differences were detected for the majority of measured analytes. Notably were the higher sodium, chloride, blood urea nitrogen, and serum lipids of pigs fed colostrum compared with the pigs fed the two milk replacers. Pigs fed colostrum had heavier small intestines (g/kg; P<0.05), but not higher total small intestine capacities to transport glucose. Our findings indicate colostrum protects preterm pigs against NEC, but does not promote body weight gain or enhance intestinal absorption, and should not be used as a control for chronic feeding studies. Using maltodextrin, but not lactose in formula increases NEC risk. Preterm pigs are a relevant and translational large animal model for evaluating how carbohydrates and other nutrients influence NEC risk, growth, health, and development after preterm birth.

An Overview on the Methods of Screening Antiobesity Activity

Purpose : The incidence of obesity around the world continues to increase and is considered a major cause of morbidity and mortality through various diseases. Various animal models can be used for the study of various compounds for the discovery of a novel treatment for the obesity. It can range from food intake studies in lean rodents to studies in obese animals due to high fat diet. The use of these animals helps us to determine whether the weight loss is due to fat loss or due to changes in other parameters. Various behavioral models can be used to study the food intake pattern and the effect of the drug on that pattern. These animal models have very good predictive validity as the effect of the drug on the animal models form the basis for the effect of the drug in humans. The drug induced weight loss in humans can be predicted to an extent from the studies carried out on these animal models. Approach : The published articles from Pubmed and other standard resources are used to study, review and compile the overview on screening methods used in Anti-obesity activity. Findings : The animal models of obesity can be used to study about the effects of parameters like insulin level, resistance and leptin levels in obesity. Acute and chronic feeding studies can be carried out. While studying about anti-obesity drugs the factors that lead to weight gain has to be considered. Conclusion : The obesity can be genetic or may be due to some other reason. The common cause for obesity is food intake with high calories and fat. So diet induced obese animal models are an important part of the studies. The animal models for the drug induced weight gain helps in the study of the effect of antiobesity drugs on the drug induced weight gain. All these models have been found to have utility in predicting the weight loss in obesity in man.

Evaluation of genotoxic and antigenotoxic effects of boron by the somatic mutation and recombination test (SMART) on Drosophila

Objective: In this study, different concentrations of boron have been evaluated for genotoxic and antigenotoxic properties by using the somatic mutation and recombination test (SMART) on Drosophila melanogaster. Study Design: The treatment concentrations were chosen to a pretest. Third-instar larvae trans-heterozygous for two genetic markers, multiple wing hair (mwh) and flare (flr3), were treated at different concentrations (0.1, 5, 10, 20, and 40 mg/mL) of boron. In addition to investigating antigenotoxic effects, the same boron concentrations were co-administered with 0.1 mM Ethyl Methane Sulfonate (EMS). Distilled water was used as a negative control; 0.1 mM of EMS was used as a positive control. For the chronic feeding study, small plastic vials were prepared with 1.5 g of dry Drosophila Instant Medium and 5 mL of the respective test solution. Hundreds of trans-heterozygous larvae were embedded into this medium. Feeding ended with pupation of the surviving larvae. After metamorphosis, all surviving flies were collected and stored in a 70% ethanol solution. Preparation and microscopic analyses of wing were made after the treatment. Then the observed mutations were classified according to size and type of mutation per wing. Results: Results indicated that there is no significant genotoxic effect with all of the boron concentrations. In addition, the antigenotoxic activities of boron against EMS were tested. Results indicated that all boron concentrations (0.1, 5, 10, 20 and 40 mg/mL) were able to abolish the genotoxic effects induced by the EMS. Conclusion: It is suggested that the observed effects can be linked to the antioxidant properties of boron. Moreover, these in vivo results will contribute to the antigenotoxicity database of boron.

Peregrine falcon egg pollutants

ABSTRACTThe role of the peregrine falcon (Falco peregrinus) as a bioindicator for the accumulation of organohalogen compounds and other persistent organic pollutants has been established in field studies. Biometric indices for damage caused by pollutants such as the shell thickness and the shell index were determined and the egg contents were analyzed for various pollutants by gas chromatography/mass spectrometry. A wide range of chemically activated luciferase expression (CALUX®) bioassays were performed on subsamples of the eggs.The following organohalogen compounds were found in the eggs of 2009: dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethane, heptachlor epoxide, hexachlorobenzene, dieldrin, hexachlorocyclohexane, polychlorobiphenyls and polychlorodibenzodioxins and polychlorodibenzofurans, polybromodiphenyl ethers, hexabromocyclododecane, tetrabromobisphenyl A, perfluoro compounds, and mercury. The DDT metabolite, dichlorodiphenyldichloroethene (DDE) (11,800 ng/g dry matter), was found to be the most highly concentrated egg contaminant followed by 2,2′,4,4′,5,5′-hexachlorobiphenyl (3800 ng/g). After a past general drop in pollution level, most egg contaminants presently plateau at levels that may still exceed limit values in foods of animal origin (DDE) or even toxicological thresholds (polychlorobiphenyls + polychlorodibenzodioxins, polybromodiphenyl ethers, perfluorooctanesulfonate, methylmercury).Accumulation of DDE could be shown in peregrine falcon eggs from the uplands of Southwest Germany with elevations up to 1500 m, presumably due to its global distribution and its cold condensation in higher altitudes. In contrast, the concentration of polychlorobiphenyls in falcon eggs decreases with elevation, indicating that these pollutants originate mainly from conurbations and local industrial sites.Significant negative correlations were found between both shell index and thickness and the concentration of Hg. A deleterious effect is also evident from a no-observed-adverse-effect level of 120 ng MeHg per gram egg determined by other authors in chronic feeding studies with ibises, which resulted in decreased egg productivity and male homosexual nesting and courtship behavior. The average Hg concentration in the peregrine falcon eggs from 2009 is almost four times higher than this level. MeHg accounted for 82.5% of the Hg present in the eggs of 2009 and 2010.The cell test DR CALUX® for screening of dioxin-like activities can be used to detect not only the 29 regulated dioxin-like substances but also many other persistent organic pollutants with dioxin-like potencies, such as mixed halogenated dioxins/biphenyls. In our case, the results of bioanalytical screening methods showed no additional effect of other compounds with dioxin-like activity.Ninety-three out of 177 analytes sought could be detected in the eggs. Chlorinated paraffins, organotin compounds, some pesticides that are still in use, and phthalic esters with the exception of traces of diethylhexyl phthalate could be excluded. All pollutants found in the eggs belong to substance classes banned by the Stockholm and Minamata Conventions.

Developing Ambient Water Quality Criteria for Mercury: A Probabilistic Site-Specific Approach

This project examined the development of ambient water quality criteria (AWQC) for the protection of wildlife for mercury. Mercury is considered a serious risk to wildlife in many areas. As a result, the Great Lakes Water Quality Initiative and others have developed AWQC. These AWQC have been controversial, however, because (1) the AWQC were single values that did not account for site-specific conditions; (2) derivation of the AWQC relied on a single NOAEL, and (3) the AWQC had an unknown level of conservatism because of reliance on both average and conservative assumptions and uncertainty factors. Rather than develop a single value AWQC for total mercury, we derive an AWQC model that explicitly incorporates factors controlling bioavailability, methylation rates and bioaccumulation in the aquatic environment (e.g., pH, DOC, sulfate). To derive our AWQC model, field data was collected including numerous water quality parameters and total mercury and methylmercury concentrations in whole body fish tissue from 31 lakes in Ontario and an additional 10 lakes in Nova Scotia. An independent dataset consisting of 51 water bodies in the United States was then used to confirm the validity and robustness of the AWQC model. Next we combined the results of chronic-feeding studies with similar protocols and endpoints, in a meta-analysis to derive a dose-response curve for mink exposed to mercury in the diet. Using this approach, one can derive an LD5 or other similar endpoint that can then be used as the basis for deriving -wildlife AWQC. In the final step, we used a probabilistic risk model to estimate the concentrations of methylmercury in water that would lead to levels in fish sufficient for there to be a 10% probability of exceeding the mink LD5. This analysis was repeated for various combinations of pH and DOC. The result is an AWQC model for mercury for the protection of wildlife that can be used for a variety of site-specific conditions. This title belongs to WERF Research Report Series ISBN: 9781843396376 (Print) ISBN: 9781780404028 (eBook)

Toxicological evaluation of smokeless tobacco: 2-year chronic toxicity and carcinogenicity feeding study in Wistar Han rats

A comprehensive 2-year oral chronic toxicity/carcinogenicity study was conducted with smokeless tobacco using modern toxicological test methods and well-accepted standards. The study included a 1-year interim subgroup to assess toxicity at that intermediate time point. Test groups consisted of a tobacco blend (B) used in snus, and an aqueous tobacco extract of that tobacco blend (E) administered at 0.2, 2, or 5mgnicotine/kg body weight/day via dosed feed to male and female Wistar Han rats. The dosages were selected to simulate potential exposure in humans ingesting smokeless tobacco or an aqueous extract of smokeless tobacco (the latter intended to simulate a snus extract, to enable bridging these data to snus epidemiology data). The following endpoints were evaluated: clinical observations, body weights, feed consumption (FC), ophthalmic exams, toxicokinetics, clinical pathology, gross pathology, and histopathology. During the 2-year study, clear treatment-related, dose-responsive effects included: (1) increases in plasma nicotine and cotinine (indicating that animals were appropriately exposed to levels relevant to human exposure) and (2) decreases in body weights with some alterations in FC. At the 2-year time point, two tumor types (in the highest B doses) displayed statistically significantly increased incidence trends vs. controls: (1) uterine carcinoma in females and (2) epididymal mesothelioma in males. Three tumor types displayed statistically significantly decreased incidence trends: (1) mammary gland adenomas in females, (2) skin basal cell carcinomas in females, and (3) thyroid follicular cell adenomas in males. These increases (and decreases) in tumor trends were interpreted as not being treatment-related because: (1) there were no preneoplastic or related non-neoplastic histopathological findings in the treated rats at the 1-year or 2-year time points to suggest that any of these neoplastic findings were treatment-related and (2) the tumor morphologies and incidences were generally within the expected range of historical controls for Wistar Han rats. Findings from this study indicate that chronic exposure of male and female Wistar Han rats to either a tobacco blend used in snus, or a tobacco extract of that blend does not lead to increased toxicity or carcinogenicity, based on the specified outcomes measured.

Dietary supplementation with cocoa flavanols does not alter colon tissue profiles of native flavanols and their microbial metabolites established during habitual dietary exposure in C57BL/6J mice.

Metabolism of flavanols (catechins, procyanidins) by gut microbiota has been extensively characterized. Comparatively little is known about accumulation of flavanols and their metabolites in the colon tissues, particularly during chronic exposure to low doses. Mice were fed low doses of cocoa flavanols for 12 weeks. Supplementation of the control diet with flavanols did not increase colonic tissue accumulation of flavanols nor microbial metabolites versus control. The type of cocoa flavanols did not affect colonic tissue accumulation of native flavanols or metabolites. Total phenolic content of the diets indicated that these results are not explained by background levels of undetected phenolics in the control diet. This is the longest known chronic flavanol feeding study to examine colonic tissue accumulation. Vast differences appear to exist between acute high doses and chronic low doses, to which gut microbiota and epithelium adapt. These results indicate that the fate of flavanols in the colon during chronic exposure is not fully understood.

An evaluation of the mode of action (MoA) and human relevance of rat liver tumours observed in a chronic rat feeding study with silthiofam

An evaluation of the mode of action (MoA) and human relevance of rat liver tumours observed in a chronic rat feeding study with silthiofam

Animals Models of Gastrointestinal and Liver Diseases. Animal models of alcohol-induced liver disease: pathophysiology, translational relevance, and challenges

Over the last four decades, chronic ethanol feeding studies in rodents using either ad libitum feeding or intragastric infusion models have significantly enhanced our understanding of the pathogenesis of alcoholic liver disease (ALD). Recently, we developed a chronic plus binge alcohol feeding model in mice that is similar to the drinking patterns of many alcoholic hepatitis patients: a history of chronic drinking and recent excessive alcohol consumption. Chronic+binge ethanol feeding synergistically induced steatosis, liver injury, and neutrophil infiltration in mice, which may be useful for the study of early alcoholic liver injury and inflammation. Using this chronic+binge model, researchers have begun to identify novel mechanisms that participate in the pathogenesis of alcoholic liver injury, thereby revealing novel therapeutic targets. In this review article, we briefly discuss several mouse models of ALD with a focus on the chronic+binge ethanol feeding model.

Pathology review of proliferative lesions of the exocrine pancreas in two chronic feeding studies in rats with ammonium perfluorooctanoate

Two chronic dietary studies, conducted years apart, with ammonium perfluorooctanoate (APFO) in Sprague Dawley rats have been previously reported. Although both included male 300 ppm dietary dose groups, only the later study, conducted in 1990–1992 by Biegel et al., reported an increase in proliferative lesions (hyperplasia and adenoma) of the acinar pancreas. An assessment of the significance of the differences between both studies requires careful consideration of: the diagnostic criteria for proliferative acinar cell lesions of the rat pancreas (for example, the diagnosis of pancreatic acinar cell hyperplasia versus adenoma is based on the two-dimensional size of the lesion rather than distinct morphological differences); the basis for those criteria in light of their relevance to biological behavior; and the potential diagnostic variability between individual pathologists for difficult-to-classify lesions. A pathology peer review of male exocrine pancreatic tissues from the earlier study, conducted in 1981–1983 by Butenhoff et al., was undertaken. This review identified an increase in acinar cell hyperplasia but not adenoma or carcinoma in the earlier study. Both studies observed a proliferative response in the acinar pancreas which was more pronounced in the study by Biegel et al. Definitive reasons for the greater incidence of proliferative lesions in the later study were not identified, but some possible explanations are presented herein. The relevance of this finding to human risk assessment, in the face of differences in the biological behavior of human and rat pancreatic proliferative lesions and the proposed mechanism of formation of these lesions, are questionable.

Chronic administration of dietary grape seed extract increases colonic expression of gut tight junction protein occludin and reduces fecal calprotectin: a secondary analysis of healthy Wistar Furth rats

Animal studies have demonstrated the potential of grape seed extract (GSE) to prevent metabolic syndrome, obesity, and type 2 diabetes. Recently, metabolic endotoxemia induced by bacterial endotoxins produced in the colon has emerged as a possible factor in the etiology of metabolic syndrome. Improving colonic barrier function may control endotoxemia by reducing endotoxin uptake. However, the impact of GSE on colonic barrier integrity and endotoxin uptake has not been evaluated. We performed a secondary analysis of samples collected from a chronic GSE feeding study with pharmacokinetic end points to examine potential modulation of biomarkers of colonic integrity and endotoxin uptake. We hypothesized that a secondary analysis would indicate that chronic GSE administration increases colonic expression of intestinal tight junction proteins and reduces circulating endotoxin levels, even in the absence of an obesity-promoting stimulus. Wistar Furth rats were administered drinking water containing 0.1% GSE for 21 days. Grape seed extract significantly increased the expression of gut junction protein occludin in the proximal colon and reduced fecal levels of the neutrophil protein calprotectin, compared with control. Grape seed extract did not significantly reduce serum or fecal endotoxin levels compared with control, although the variability in serum levels was widely increased by GSE. These data suggest that the improvement of gut barrier integrity and potential modulation of endotoxemia warrant investigation as a possible mechanism by which GSE prevents metabolic syndrome and associated diseases. Further investigation of this mechanism in high-fat feeding metabolic syndrome and obesity models is therefore justified.

Acute toxicity of chlorantraniliprole to non-target crayfish (Procambarus clarkii ) associated with rice-crayfish cropping systems

Chlorantraniliprole, a novel anthranilic diamide insecticide, was recently introduced into the United States where rice-crayfish crop rotations are practiced to control rice water weevil (Lissorhoptrus oryzophilus Kuschel) infestations. Chlorantraniliprole has high margins of mammalian safety and excellent insecticidal efficacy, but its toxicity to non-target crayfish is uncertain. In this study, the acute toxicity of chlorantraniliprole to the red swamp crayfish Procambarus clarkii Girard was determined using aquatic and feeding assays. The aquatic 96 h median lethal toxicity (LC(50)) data indicate that technical-grade chlorantraniliprole is highly toxic (US EPA category) to crayfish with an LC(50) of 951 microg L(-1) (95% CL = 741-1118 microg L(-1)). A no observed effect concentration (NOEC) of 480 microg L(-1) was recorded. Neither the 36 day chronic feeding study, where crayfish fed on chlorantraniliprole-treated rice seed in aquaria, nor the 144 h acute feeding test, where crayfish fed on rice seeds treated with chlorantraniliprole, produced mortality or abnormal behavior. Chlorantraniliprole is three orders of magnitude less acutely toxic to P. clarkii than lambda-cyhalothrin and etofenprox, two pyrethroid insecticides also used in rice, and is less likely to cause acute crayfish toxicity in rice pond ecosystems. Based on acute toxicity data, the use of chlorantraniliprole should be more compatible with rice-crayfish crop rotations than pyrethroids.

Chronic ingestion of 2-deoxy- d-glucose induces cardiac vacuolization and increases mortality in rats

Calorie restriction (CR), the purposeful reduction of energy intake with maintenance of adequate micronutrient intake, is well known to extend the lifespan of laboratory animals. Compounds like 2-deoxy- d-glucose (2DG) that can recapitulate the metabolic effects of CR are of great interest for their potential to extend lifespan. 2DG treatment has been shown to have potential therapeutic benefits for treating cancer and seizures. 2DG has also recapitulated some hallmarks of the CR phenotype including reduced body temperature and circulating insulin in short-term rodent trials, but one chronic feeding study in rats found toxic effects. The present studies were performed to further explore the long-term effects of 2DG in vivo. First we demonstrate that 2DG increases mortality of male Fischer-344 rats. Increased incidence of pheochromocytoma in the adrenal medulla was also noted in the 2DG treated rats. We reconfirm the cardiotoxicity of 2DG in a 6-week follow-up study evaluating male Brown Norway rats and a natural form of 2DG in addition to again examining effects in Fischer-344 rats and the original synthetic 2DG. High levels of both 2DG sources reduced weight gain secondary to reduced food intake in both strains. Histopathological analysis of the hearts revealed increasing vacuolarization of cardiac myocytes with dose, and tissue staining revealed the vacuoles were free of both glycogen and lipid. We did, however, observe higher expression of both cathepsin D and LC3 in the hearts of 2DG-treated rats which indicates an increase in autophagic flux. Although a remarkable CR-like phenotype can be reproduced with 2DG treatment, the ultimate toxicity of 2DG seriously challenges 2DG as a potential CR mimetic in mammals and also raises concerns about other therapeutic applications of the compound.

Toxicology and human health assessment of decabromodiphenyl ether

We evaluated the available pharmacokinetic data and human and animal toxicity data for 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) (CASRN 1163-19-5) with the objective of deriving a reference dose (RfD) based on the best available science. The available studies for deriving an RfD were first screened using the Klimisch criteria and further evaluated using the United States Environmental Protection Agency’s general assessment factors for data quality and relevance (i.e., soundness, applicability and utility, clarity and completeness, uncertainty and variability, and evaluation and review). The chronic 2-year dietary feeding study conducted by the United States National Toxicology Program (, Technical Report Series No. 309) was selected for RfD derivation. Hepatocellular degeneration in male rats was chosen as the critical endpoint in the development of an RfD. For dose-response characterization, we applied benchmark-dose modeling to animal data and determined a point of departure (the 95% lower confidence limit for a 10% increase in hepatocellular degeneration) of 419 mg/kg-day for oral exposures. Based on the similar pharmacokinetic characteristics of BDE-209 across species, this value was converted to a human equivalence dose of 113 mg/kg-day by applying a dosimetric adjustment factor based on body weight scaling to the ¾ power. An oral RfD of 4 mg/kg-day was calculated by using a composite uncertainty factor of 30, which consisted of 10 for intraspecies uncertainty, 3 for interspecies uncertainty (i.e., 3 for toxicodynamics × 1 for toxicokinetics), and 1 for deficiencies with the database. We consider the RfD to be adequately protective of sensitive subpopulations, including women, their fetuses, children, and people with hepatocellular diseases.

Final Amended Report on the Safety Assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as used in Cosmetic Products

Final Amended Report on the Safety Assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as used in Cosmetic Products

Acute and Chronic Effects of Honey and Its Carbohydrate Constituents on Calcium Absorption in Rats

The effects of honey and its carbohydrate constituents (glucose, fructose, and raffinose) on calcium absorption in rats were investigated in acute and chronic feeding studies. In the acute study, rats ( n = 120) were gavaged with an oral solution consisting of (a) 10 microCi (45)Ca, (b) 25 mg of calcium as calcium acetate, and (c) one of the following: 0 mg of honey (control), or 200, 500, or 800 mg of honey, a glucose-fructose mixture, 10.75 mg of raffinose, or 200 mg of raffinose. Another group received (45)Ca intraperitoneally. Femurs were collected 2 days later and analyzed for (45)Ca content. Rats given 500 and 800 mg of honey showed 25.5 and 33.6% increases in calcium absorption ( P<0.05), respectively, over the control group. Groups given the glucose-fructose mixture or 200 mg of raffinose had a significantly higher increase in calcium absorption than the control group (17.1 and 25.6%, respectively). In the chronic study, rats (n=96) were fed for 8 weeks with either 0% honey (control), 5% honey, 10% honey, or a glucose-fructose-raffinose (GFR) mixture. Femurs of GFR-fed rats had significantly lower calcium content, (45)Ca absorption, width, and BMD (at distal region) than control rats. Groups fed honey did not show the negative effects of GFR on bone, but had no advantage over the control group. No significant differences were observed in femur length, density, strength, or BMC among any treatment group compared to the control group. These results indicate that although a positive dose-response effect of honey and its carbohydrate constituents on calcium absorption was observed in the acute study, this effect disappeared upon long-term feeding in rats, implying adaptation had occurred.

A 104-Week Feeding Study of Genetically Modified Soybeans in F344 Rats

A chronic feeding study to evaluate the safety of genetically modified glyphosate-tolerant soybeans (GM soybeans) was conducted using F344 DuCrj rats. The rats were fed diet containing GM soybeans or Non-GM soybeans at the concentration of 30% in basal diet. Non-GM soybeans were a closely related strain to the GM soybeans. These two diets were adjusted to an identical nutrient level. In this study, the influence of GM soybeans in rats was compared with that of the Non-GM soybeans, and furthermore, to assess the effect of soybeans themselves, the groups of rats fed GM and Non-GM soybeans were compared with a group fed commercial diet (CE-2). General conditions were observed daily and body weight and food consumption were recorded. At the termination (104 weeks), animals were subjected to hematology, serum biochemistry, and pathological examinations. There were several differences in animal growth, food intake, organ weights and histological findings between the rats fed the GM and/or Non-GM soybeans and the rats fed CE-2. However, body weight and food intake were similar for the rats fed the GM and Non-GM soybeans. Gross necropsy findings, hematological and serum biochemical parameters, and organ weights showed no meaningful difference between rats fed the GM and Non-GM soybeans. In pathological observation, there was neither an increase in incidence nor any specific type of nonneoplastic or neoplastic lesions in the GM soybeans group in each sex. These results indicate that long-term intake of GM soybeans at the level of 30% in diet has no apparent adverse effect in rats.

Final Amended Report on the Safety Assessment of Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben as used in Cosmetic Products

Parabens is the name given to a group of p-hydroxybenzoic acid (PHBA) esters used in over 22,000 cosmetics as preservatives at concentrations up to 0.8% (mixtures of parabens) or up to 0.4% (single paraben). The group includes Methylparaben, Ethylparaben, Propylparaben, Isopropylparaben, Butylparaben, Isobutylparaben, and Benzylparaben. Industry estimates of the daily use of cosmetic products that may contain parabens were 17.76 g for adults and 378 mg for infants. Parabens in cosmetic formulations applied to skin penetrate the stratum corneum in inverse relation to the ester chain length. Carboxylesterases hydrolyze parabens in the skin. Parabens do not accumulate in the body. Serum concentrations of parabens, even after intravenous administration, quickly decline and remain low. Acute toxicity studies in animals indicate that parabens are not significantly toxic by various routes of administration. Subchronic and chronic oral studies indicate that parabens are practically nontoxic. Numerous genotoxicity studies, including Ames testing, dominant lethal assay, hostmediated assay, and cytogenic assays, indicate that the Parabens are generally nonmutagenic, although Ethylparaben and Methylparaben did increase chromosomal aberrations in a Chinese Hamster ovary cell assay. Ethylparaben, Propylparaben, and Butylparaben in the diet produced cell proliferation in the forestomach of rats, with the activity directly related to chain length of the alkyl chain, but Isobutylparaben and Butylparaben were noncarcinogenic in a mouse chronic feeding study. Methylparaben was noncarcinogenic when injected subcutaneously in mice or rats, or when administered intravaginally in rats, and was not cocarcinogenic when injected subcutaneously in mice. Propylparaben was noncarcinogenic in a study of transplacental carcinogenesis. Methylparaben was nonteratogenic in rabbits, rats, mice, and hamsters, and Ethylparaben was nonteratogenic in rats. Parabens, even at levels that produce maternal toxicity, do not produce fetal anomalies in animal studies. Parabens have been extensively studied to evaluate male reproductive toxicity. In one in vitro study, sperm were not viabile at concentrations as low as 6 mg/ml Methylparaben, 8 mg/ml Ethylparaben, 3 mg/ml Propylparaben, or 1 mg/ml Butylparaben, but an in vivo study of 0.1% or 1.0% Methylparaben or Ethylparaben in the diet of mice reported no spermatotoxic effects. Propylparaben did affect sperm counts at all levels from 0.01% to 1.0%. Epididymis and seminal vesicle weight decreases were reported in rats given a 1 % oral Butylparaben dose; and decreased sperm number and motile activity in F 1 offspring of rats maternally exposed to 100 mg/kg day -1 were reported. Decreased sperm numbers and activity were reported in F 1 offspring of female rats given Butylparaben (in DMSO) by subcutaneous injection at 100 or 200 mg/kg day -1 , but there were no abnormalities in the reproductive organs. Methylparaben was studied using rats at levels in the diet up to an estimated mean dose of 1141.1 mg/kg day -1 with no adverse testicular effects. Butylparaben was studied using rats at levels in the diet up to an estimated mean dose of 1087.6 mg/kg day -1 in a repeat of the study noted above, but using a larger number of animals and a staging analysis of testicular effects-no adverse reproductive effects were found. .