Acute and subchronic oral toxicity studies in rats with nanoscale and pigment grade titanium dioxide particles

Data generated using standardized testing protocols for toxicity studies generally provide reproducible and reliable results for establishing safe levels and formulating risk assessments. The findings of three OECD guideline-type oral toxicity studies of different duration in rats are summarized in this publication; each study evaluated different titanium dioxide (TiO₂) particles of varying sizes and surface coatings. Moreover, each study finding demonstrated an absence of any TiO₂ -related hazards. To briefly summarize the findings: 1) In a subchronic 90-day study (OECD TG 408), groups of young adult male and female rats were dosed with rutile-type, surface-coated pigment-grade TiO₂ test particles (d₅₀ = 145 nm − 21% nanoparticles by particle number criteria) by oral gavage for 90 days. The no-adverse-effect level (NOAEL) for both male and female rats in this study was 1000 mg/kg bw/day, the highest dose tested. The NOAEL was determined based on a lack of TiO₂ particle-related adverse effects on any in-life, clinical pathology, or anatomic/microscopic pathology parameters; 2) In a 28-day repeated-dose oral toxicity study (OECD TG 407), groups of young adult male rats were administered daily doses of two rutile-type, uncoated, pigment-grade TiO₂ test particles (d₅₀ = 173 nm by number) by daily oral gavage at a dose of 24,000 mg/kg bw/day. There were no adverse effects measured during or following the end of the exposure period; and the NOAEL was determined to be 24,000 mg/kg bw/day; 3) In an acute oral toxicity study (OECD TG 425), female rats were administered a single oral exposure of surface-treated rutile/anatase nanoscale TiO₂ particles (d₅₀ = 73 nm by number) with doses up to 5000 mg/kg and evaluated over a 14-day post-exposure period. Under the conditions of this study, the oral LD₅₀ for the test substance was >5000 mg/kg bw. In summary, the results from these three toxicity studies – each with different TiO₂ particulate-types, demonstrated an absence of adverse toxicological effects. Apart from reporting the findings of these three studies, this publication also focuses on additional critical issues associated with particle and nanotoxicology studies. First, describing the detailed methodology requirements and rigor upon which the standardized OECD 408 guideline subchronic oral toxicity studies are conducted. Moreover, an attempt is made to reconcile the complex issue of particle size distribution as it relates to measurements of nanoscale and pigment-grade TiO₂ particles. Clearly this has been a confusing issue and often misrepresented in the media and the scientific literature. It is clear that the particle-size distribution for pigment-grade TiO₂, contains a small (“tail”) component of nanoscale particles (i.e., 21% by particle number and <1% by weight in the test material used in the 90-day study). However, this robust particle characterization finding should not be confused with mislabeling the test materials as exclusively in the nanoscale range. Moreover, based upon the findings presented herein, there appears to be no significant oral toxicity impact contributed by the nanoscale component of the TiO₂ Test Material sample in the 90-day study. Finally, it seems reasonable to conclude that the study findings should be considered for read-across purposes to food-grade TiO₂ particles (e.g., E171), as the physicochemical characteristics are quite similar.     

Pharmacokinetic data reduce uncertainty in the acceptable daily intake for benzoic acid and its salts

The current acceptable daily intake (ADI) for benzoic acid and its salts as food additives is 0–5 mg/kg body weight. This accounts for a total uncertainty factor (UF) of 100, which includes a default factor of 10 for interspecies differences. Based on pharmacokinetic data in rodents and humans, we derived a chemical-specific adjustment factor (CSAF) of 2 for the pharmacokinetic component of the interspecies UF. Additional analyses indicate that this CSAF is conservative and interspecies differences between rats and humans are likely closer to unity. Human clinical studies indicate that the pharmacokinetics of benzoic acid and its salts are similar in children and adults, and that there is a lack of adverse events in humans at doses comparable to the no observed adverse effect level (NOAEL) in rodents; this suggests that the pharmacokinetic UF for intraspecies variability, as well as the pharmacodynamic components of the UFs, may also be reduced, although we did not calculate to what degree. In conclusion, the total UF can be reduced to 50 (2 for interspecies differences in pharmacokinetics, 2.5 for interspecies differences in pharmacodynamics, and 10 for intraspecies variability), which would increase the ADI to 0–10 mg/kg body weight.     

Acute and 13 weeks subchronic toxicological evaluation of naringin in Sprague-Dawley rats

Naringin is widely distributed in plant foods and has not previously been evaluated for safety through standard in vivo toxicological studies. In the present study, acute and subchronic oral toxicity studies of naringin were designed and conducted in Sprague-Dawley (SD) rats. Acute oral administration of naringin was done as a single bolus dose up to 16 g/kg and subchronic toxicity study for 13 weeks was done by oral administration at doses of 0 (control), 50, 250 and 1250 mg/kg in SD rats. There were no mortality, adverse clinical signs, abnormal changes in body weights or food consumption, toxicologically relevant changes in hematology, clinical biochemistry and macroscopic findings during 14 days of the acute toxicity study. During the subchronic oral toxicity study, no mortality and toxicologically significant changes in clinical signs, food consumption, opthalmoscopic examination, hematology, clinical biochemistry, serum sex hormone, macroscopic findings, organ weights and histopathological examination except for slight body weight decrease were noted and attributed to naringin administration. These observations suggest that naringin is practically non-toxic for SD rats in oral acute toxicity study and the no-observed-adverse-effect-level (NOAEL) of naringin in rats is greater than 1250 mg/kg/day when administered orally for 13 consecutive weeks.     

Evaluation of subchronic toxicity of SIM010603, a potent inhibitor of receptor tyrosine kinase,after 28-day repeated oral administration in SD rats and beagle dogs

SIM010603, a promising multi-targeted receptor tyrosine kinase (RTK) inhibitor, is now being considered for evaluation in phase clinical trial. In this work, the subchronic toxicity of SIM010603 in SD rats and beagle dogs have been characterized. Rats and dogs received SIM010603 orally (0–20 and 0–10 mg/kg/day, respectively) on a consecutive daily dosing schedule for 28 days following a 14 days recovery period. Sunitinib was used as a positive control. The No Observed Adverse Effect Level (NOAEL) of SIM010603 was 5 mg/kg/day for rats, and undefined for dogs. The treatment resulted in unscheduled mortality in dogs receiving 10 mg/kg of SIM010603 or Sunitinib. The adverse effects of SIM010603 on rats and dogs mainly included gastrointestinal toxicity, skeletal toxicity, myelosuppression, thymus atrophy, bronchopneumonia, cardiovascular dysfunction, and pancreatic toxicity. Similar observations have also been noted with this class of RTK signaling inhibitors and are consistent with pharmacologic perturbations of physiologic/angiogenic processes associated with the intended molecular targets. Most treatment-induced effects were reversible or showed ongoing recovery upon discontinuation of treatment. SIM010603 has shown comparable toxicity effect on beagle dogs, while better tolerability on SD rats when compared to Sunitinib.     

Repeated sub-chronic oral toxicity study of xylooligosaccharides (XOS) in dogs

In this study, Beagle dogs were administered xylooligosaccharide (XOS, CAS # 87099-0) at doses of 0, 1250, 2500, and 5000 mg/kg/day by oral gavage for 26 weeks. A 4-week recovery period was added to observe delayed or reversible toxicity. Measurements included body weight, food consumption, clinical observations, temperature, electrocardiogram (ECG), urinalysis, blood chemistry, hematology, organ weight, gross necropsy, and histopathological examination. Except for transient diarrhea or vomiting, no treatment-related adverse effects were noted. In the mid-dose groups, transitional diarrhea was observed in the initial 1–2 weeks. In the high-dose groups, diarrhea and/or vomiting were observed episodically over the duration of treatment. However, they disappeared after XOS was withdrawn in the recovery period. Although there was a tendency toward less weight gain in the high-dose group animal group, this is typical in animals and humans fed non-digestible carbohydrates. This chronic toxicity study demonstrated that the no observed adverse effect level (NOAEL) of XOS is 2500 mg/kg body weight (BW)/day. Based on body surface area (conversion factor of 0.54 for dogs to human), this corresponds to daily doses of 1350 mg/kg BW or 81–108 g XOS in human adults weighing 60–80 kg.     

Safety assessment of vitacoxib: Acute and 90-day sub-chronic oral toxicity studies

Vitacoxib, is a newly developed coxibs NSAID (selective inhibitors of cyclooxygenase-2). To date, no experimental data have been published concerning its safety for use as an additive in the human diet. In the present study, we assessed the acute and sub-chronic toxicity of vitacoxib administered by gavage. The acute toxicity tests in Sprague Dawley (SD) rats and ICR mice demonstrated that vitacoxib at a dose of 5000 mg/kg BW failed to alter any of the parameters studied. In the 90-day sub-chronic toxicity test, vitacoxib was administered to SD rats at the doses of 0 (control), 5, 10, 20, 30, and 60 mg/kg BW. The results demonstrated that there were no significant differences for most indexes of sub-chronic toxicity throughout the experiment at the dose of 5–20 mg/kg BW, indicating no apparent dose-dependent. However, there were significant histopathology changes in the liver and kidney, and alterations in some biochemical parameters in the 60 mg/kg BW group. Based on these findings, the gavage LD₅₀ was determined to be > 5000 mg/kg in SD rats and ICR mice, and the 90-day gavage no-observed-adverse-effect level (NOAEL) of vitacoxib was considered to be 20 mg/kg BW under the present study conditions.     

Six months chronic toxicological evaluation of naringin in Sprague–Dawley rats

Naringin is a flavonoid showing variable pharmacological properties and is distributed ubiquitously in plant foods. There is a paucity of reported data regarding its safety profile. In the present study, chronic toxicity studies of naringin was designed and conducted by oral gavage at doses of 0, 50, 250 and 1250 mg/kg in Sprague–Dawley (SD) rats for six months followed by 1-month recovery period. During the 6-month treatment period and one month recovery period, no mortality and toxicologically significant changes in clinical signs, opthalmoscopic examination, hematology, clinical biochemistry, serum sex hormone, macroscopic findings, organ weights and histopathological examination were noted and attributed to naringin administration. Although consecutive and/or isolated periods of significant body weights and food consumption decreases were relevant to naringin administration, they were not considered toxicologically significant. In addition, slight, non-pathological and reversible hair loss was noted during the 6-month treatment period and considered as a kind of change possibly relevant to naringin administration; however, it was not considered adverse change and to be of toxicological significance. Based on the results of this study, the no-observed-adverse-effect-level (NOAEL) of naringin in rats is greater than 1250 mg/kg/day when administered orally for 6 consecutive months.     

Subchronic,Reproductive, and Developmental Toxicity of a Fluorotelomer-Based Urethane Polymeric Product

A commercial fluorotelomer-based urethane polymeric dispersion, consisting of polymer, surfactant, and water, was evaluated in subchronic, reproduction, and developmental toxicity studies. The dispersion was administered daily by gavage to rats at dosages of 0, 50, 250, or 1000 mg polymer/kg/day or with 70 mg/kg/day of the sulfonate surfactant. Dose levels of 0, 50, 250, or 1000 mg polymer/kg/day were also used for the reproductive and developmental studies. Nasal olfactory epithelial degeneration and necrosis occurred in all dose groups in the 90-day study. Nasal adhesions were observed only in rats administered surfactant alone. Liver-enzyme alterations at 250 and 1000 mg/kg were considered to be potentially adverse effects. The subchronic no-observed-adverse-effects level (NOAEL) was 50 mg/kg. For the reproduction study, rats were dosed for 10 weeks prior to cohabitation and throughout mating, gestation, and lactation. There were no effects on reproductive function in males or females at any dosage. Thyroid weight was decreased in the 250 and 1000 mg/kg day F₁ groups unaccompanied by microscopic effects. In the developmental toxicity study, female rats were dosed from gestation days 6–20; there was no test-substance-related embryolethality, nor was there any dose-related increase in either fetal malformations. Fetal weight was minimally decreased at 1000 mg/kg/day in the presence of slight maternal toxicity; the NOAEL for developmental parameters was 250 mg/kg/day. The polymeric product was not a specific developmental or reproductive toxin.     

Subchronic and reproductive toxicity of whole dried Hoodia parviflora aerial parts in the rat

Hoodia parviflora is being developed commercially for use in weight loss food and dietary supplement products. As part of the safety assessment process for H. parviflora, a freeze dried powder preparation was tested in a 90-day oral toxicity study with reproductive/recovery component in rats. Groups of 10 male and female Sprague–Dawley rats were administered H. parviflora dried powder at doses of 0, 100, 250, and 350 mg/kg body weight/day by gavage for an 11-week pre-mating period and a 14-day co-habitation period, and for females, through lactation day 4. An additional 5 rats/sex/group received 0 or 350 mg/kg bw/day for 90 days and were sacrificed 28 days after cessation of treatment. Statistically significant, non-adverse reductions in body weight, body weight gain, food consumption and food efficiency were observed at 250 and 350 mg/kg/day in females. Food consumption was reduced in high-dose males. There were no adverse effects on hematological, blood biochemical, coagulation or urinalysis parameters or on the results of the functional observational battery and histopathological examinations. No evidence of any effect was noted on reproductive or developmental parameters. The NOAEL for dried H. parviflora powder was 350 mg/kg bw/day, the highest permissible dose tested, for both male and female rats.     

Subchronic, reproductive, and developmental toxicity of a fluorotelomer-based urethane polymeric product

A commercial fluorotelomer-based urethane polymeric dispersion, consisting of polymer, surfactant, and water, was evaluated in subchronic, reproduction, and developmental toxicity studies. The dispersion was administered daily by gavage to rats at dosages of 0, 50, 250, or 1000 mg polymer/kg/day or with 70 mg/kg/day of the sulfonate surfactant. Dose levels of 0, 50, 250, or 1000 mg polymer/kg/day were also used for the reproductive and developmental studies. Nasal olfactory epithelial degeneration and necrosis occurred in all dose groups in the 90-day study. Nasal adhesions were observed only in rats administered surfactant alone. Liver-enzyme alterations at 250 and 1000 mg/kg were considered to be potentially adverse effects. The subchronic no-observed-adverse-effects level (NOAEL) was 50 mg/kg. For the reproduction study, rats were dosed for 10 weeks prior to cohabitation and throughout mating, gestation, and lactation. There were no effects on reproductive function in males or females at any dosage. Thyroid weight was decreased in the 250 and 1000 mg/kg day F(1) groups unaccompanied by microscopic effects. In the developmental toxicity study, female rats were dosed from gestation days 6-20; there was no test-substance-related embryolethality, nor was there any dose-related increase in either fetal malformations. Fetal weight was minimally decreased at 1000 mg/kg/day in the presence of slight maternal toxicity; the NOAEL for developmental parameters was 250 mg/kg/day. The polymeric product was not a specific developmental or reproductive toxin.     

Acute and subchronic toxicity studies on Sel-Plex, a standardized, registered high-selenium yeast

Selenium has been recognized as an essential nutrient for human health; however, its bioavailability is primarily dependent upon the type of selenium, elemental versus organic. In geographic areas low in selenium, there is the potential for animals (including humans) to become selenium deficient and this potential deficiency can be remedied by consumption of exogenous selenium, including selenium-enriched yeast (Saccharomyces cerevisiae) that contains high levels of organic selenium (e.g., selenized yeast). The present studies were conducted to investigate potential oral toxicity of a unique selenized yeast preparation (Sel-Plex) when administered to (1) adult female CHS Swiss mice ICo:OFI (IOPS Caw); (2) adult female CHS Sprague-Dawley rats; and (3) adult male and female Sprague-Dawley CD rats. For the 28- and 90-day toxicity studies, (1) adult male and female Sprague-Dawley CRL:CD(R)(SD) IGS BR strain rats and (2) adult male and female 6- to 7-month-old Beagle dogs were used. The LD50 for mice was >or=2000 mg Sel-Plex/kg (>or=4.06 mg Se/kg) and for rats, was greater than >or=2000 mg Sel-Plex/kg (>or=4.06 mg Se/kg). In the two 28-day studies, for rats, the no observed adverse effects level (NOAEL) was 50 mg Sel-Plex/kg/day (0.1 mg Se/kg/day), and for the dogs, the NOAEL was 22.5 mg Sel-Plex/kg/day (0.045 mg Se/kg/day). For the two 90-day studies, for rats the NOAEL for Sel-Plex was 114 mg/kg/day (0.23 mg Se/kg/day), and for dogs, the NOAEL was 30 mg Sel-Plex/kg/day (0.06 mg Se/kg/day): the latter being the NOAEL in the most sensitive species.     

Toxicological evaluation of an olive extract,H35: Subchronic toxicity in the rat

The safety of olive extract H35 containing 35% hydroxytyrosol (HT) was tested in a 90-day oral gavage study in Wistar rats. H35 was administered at 0, 345, 691 and 1381 mg/kg bw/day, equivalent to 0, 125, 250 and 500 mg HT/kg bw/day. Reductions in terminal body weight (9%), and a statistically significant reduction in body weight gain (17%, P < 0.05) at week 13 were observed in high dose males, as well as a statistically significant increase in relative weights of the liver, heart, and kidneys of high dose males and females. These changes were not accompanied by pathological or clinical observations and a trend towards reversal was observed in the recovery phase. H35 was well-tolerated and no toxicologically significant treatment-related changes were observed in condition and appearance of rats, neurobehavioral outcomes, motor activity assessments, functional observational battery (FOB), food intake, ophthalmoscopic examinations, hematology, clinical chemistry, urinalysis, necropsy findings, sperm parameters or estrus cycle. The lowest observed adverse effect level (LOAEL) was the 500 mg HT/kg bw/day based on statistically significant reductions in body weight gain and decreased body weight in males. The no observed adverse effect level (NOAEL) was 250 mg HT/kg bw/day, equivalent to 691 mg/kg bw/day of H35 extract.     

Toxicological safety evaluation of the human‐identical milk oligosaccharide 6′‐sialyllactose sodium salt

Human milk oligosaccharides (HMOs) are abundant in breastmilk, but their presence in infant formula is negligible. Sialylated HMOs, such as 6′‐sialyllactose, constitute a significant portion of the HMO fraction of human milk and are linked to important biological functions. To produce infant formula that is more comparable with human milk, biosynthesized sialyllactoses known as human‐identical milk oligosaccharides (structurally identical counterparts to their respective naturally occurring HMOs in breastmilk) are proposed for use in infant formula and other functional foods for the general population. To support the safety of 6′‐sialyllactose sodium salt (6′‐SL), a 90‐day oral (gavage) toxicity study and in vitro genotoxicity tests were conducted. The 90‐day study is the first to be conducted with 6′‐SL using neonatal rats (day 7 of age at the start of dosing), thus addressing safety of 6′‐SL for consumption by the most sensitive age group (infants). In the 90‐day study, neonatal rats received 6′‐SL at doses up to 5000 mg/kg body weight (BW)/day and reference controls received 5000 mg/kg BW/day of fructooligosaccharide (an ingredient approved for use in infant formula) for comparison with the high‐dose 6′‐SL group, followed by a 4‐week recovery period. There was no evidence of genotoxicity in vitro. No test item‐related adverse effects were observed on any parameter in the 90‐day study, thus the high dose (5000 mg/kg BW/day) was established as the no‐observed‐adverse‐effect level. These results confirm that 6′‐SL is safe for use in formula milk for infants and in other functional foods for the general population.     

Evaluation of the inhalation toxicity of arecoline benzoate aerosol in rats

Arecoline is a pharmacologically active alkaloid isolated from Areca catechu. There are no published data available regarding the inhalation toxicity of arecoline in animals. This study aimed to evaluate the inhalation toxicity of arecoline in vitro and in vivo. For this purpose, arecoline benzoate (ABA) salt was prepared to stabilize arecoline in an aerosol. The MTT assay determined the half-maximal inhibitory concentration values of ABA and arecoline in A549 cell proliferation to be 832 and 412 μg/ml, respectively. The toxicity of acute and subacute inhalation in Sprague–Dawley rats was evaluated using the guidelines of the Organization for Economic Cooperation and Development. For acute inhalation, the median lethal concentration value of ABA solvent was >5175 mg/m³. After the exposure and during the recovery period, no treatment-related clinical signs were observed. In the 28-Day inhalation toxicity test, daily nose-only exposure to 2510 mg/m³ aerosol of the ABA solvent contained 75 mg/m³ ABA for male rats and 375 mg/m³ ABA for female rats, which caused no observed adverse effects, except for the decreased body weight gain in male rats exposed to 375 mg/m³ ABA. In this study, the no observed adverse effect level (NOAEL) for the 28-day repeated dose inhalation of ABA aerosol was calculated to be around 13 mg/kg/day for male rats and 68.8 mg/kg/day for female rats, respectively.     

Single and 14-day repeated dose inhalation toxicity studies of hexabromocyclododecane in rats

Limited toxicological information is available for hexabromocyclododecane (HBCD),a widely used additive brominated flame retardant. Inhalation is a major route of human exposure to HBCD. The aim of this study was to determine the acute inhalation toxicity and potential subchronic inhalation toxicity of HBCD in Sprague-Dawley rats exposed to HBCD only through inhalation. The acute inhalation toxicity of HBCD was determined using the limit test method on five male and five female Sprague-Dawley rats at a HBCD concentration of 5000 mg/m³. Repeated-dose toxicity tests were also performed, with 20 males and 20 females randomly assigned to four experimental groups (five rats of each sex in each group). There were three treatment groups (exposed to HBCD concentrations of 125,500, and 2000 mg/m³) and a blank control group (exposed to fresh air). In the acute inhalation toxicity study, no significant clinical signs were observed either immediately after exposure or during the recovery period. Gross pathology examination revealed no evidence of organ-specific toxicity in any rat. The inhalation LC_50(4 h) for HBCD was higher than 5312 ± 278 mg/m3 for both males and females. In the repeated dose inhalation study, daily head/nose-only exposure to HBCD at 132 ± 8.8, 545.8 ± 35.3, and 2166.0 ± 235.9 mg/m³ for 14 days caused no adverse effects. No treatment-related clinical signs were observed at any of the test doses. The NOAEL for 14-day repeated dose inhalation toxicity study of HBCD is 2000 mg/m³.     

Author Index to Volume 26

The toxicity profile of HIDROX? (Hydrolyzed Aqueous Olive Pulp Extract; OPE) was characterized in a series of toxicology studies. A limit dosage of 2000 mg/kg produced no toxicity in mice (acute oral NOAEL: 2000 mg/kg). In rats, an acute oral NOAEL of 2000 mg/kg was established, based on reductions in weight gains in both sexes at 5000 mg/kg. Reduced gains in female rats at 1500 and 2000 mg/kg were not significantly different from control values. Daily oral dosages of 1000, 1500 and 2000 mg/kg/day for 90 days produced small decreases in body weight gains at 2000 mg/kg/day in the male rats and in all groups of female rats. Feed consumption was comparable to controls. There were no adverse clinical, hematologic, biochemical, organ weight or gross necropsy effects. Focal, minimal or mild hyperplasia of the mucosal squamous epithelium of the limiting ridge of the forestomach occurred in some rats at 2000 mg/kg/day; this change was attributed to local irritation by repeated intubation of large volumes of viscous, granular dosing suspension. A NOAEL of 2000 mg/kg/day was established for the 90‐day study, based on the lack of significant adverse effects. Toxicokinetic data indicated that hydroxytyrosol (HT, the major component of OPE) was rapidly absorbed. Mean concentrations were measurable through 1 to 4 hours (t_last) at 1000 and 1500 mg/kg/day and through 8 hours at 2000 mg/kg/day. Dosages of OPE ranging from 500 to 2000 mg/kg/day did not adversely affect any of the mating, fertility, delivery or litter parameters investigated in an oral rat dosage‐range reproduction study. Adverse effects were also absent in a rat developmental toxicity study in which pregnant dams were treated with 1000, 1500 or 2000 mg/kg/day on days 6 through 20 of gestation. Plasma levels for pregnant and lactating rats were comparable to non‐pregnant rats; minimal levels crossed the placenta. Quantifiable levels were not identified in maternal milk or plasma from nursing pups. A bacterial reverse mutation and a CHO chromosome aberration assay revealed evidence of mutagenic activity at high dosages with S9 metabolic activation. However, three rat micronucleus evaluations performed after single and repeated (28‐day) dosages of up to 2000 mg/kg/day and dosages of 5000 mg/kg/day for 29 days resulted in negative findings; therefore, OPE was not considered to be mutagenic in this in vivo assay.     

A 28-day oral toxicity study of echimidine and lasiocarpine in Wistar rats

Pyrrolizidine alkaloids (PAs) are a class of naturally-occurring plant toxins. Echimidine is one of the predominant PAs found in honeys produced in Australia and New Zealand. There is a lack of information on the oral toxicity of echimidine on which to base regulatory decisions concerning the risk to humans of these honeys. This GLP study was conducted to assess the subchronic dietary toxicity of echimidine to rats compared to that of lasiocarpine as a positive control. Wistar rats, 10/sex, were fed diets containing 0, 0.6, 1.2 or 2.5 mg/kg bw echimidine. Positive control groups, 10/sex, were fed diets containing 0.6, 1.2 or 2.5 mg/kg bw lasiocarpine.Neither PA had any effect on survival, food consumption, clinical signs, gross lesions, or histopathology. Consumption of lasiocarpine, but not echimidine, decreased bodyweight gain in males at ≥ 1.2 mg/kg bw, and in females at 2.5 mg/kg bw. Slight alterations in white cell counts and serum ALT concentrations at 2.5 mg/kg bw of both PAs were not clinically significant, had no histological correlates, and were considered to be of equivocal relevance.In conclusion, the subchronic No Observed Adverse Effect Level (NOAEL) for echimidine is 2.5 mg/kg bw/day, whereas, on the basis of a treatment-related decrease in bodyweight gain in males at 1.2 mg/kg bodyweight, the NOAEL for lasiocarpine is 0.6 mg/kg bw/day.     

The toxicity profile of hydrolyzed aqueous olive pulp extract

The toxicity profile of HIDROX (Hydrolyzed Aqueous Olive Pulp Extract; OPE) was characterized in a series of toxicology studies. A limit dosage of 2000 mg/kg produced no toxicity in mice (acute oral NOAEL: 2000 mg/kg). In rats, an acute oral NOAEL of 2000 mg/kg was established, based on reductions in weight gains in both sexes at 5000 mg/kg. Reduced gains in female rats at 1500 and 2000 mg/kg were not significantly different from control values. Daily oral dosages of 1000, 1500 and 2000 mg/kg/day for 90 days produced small decreases in body weight gains at 2000 mg/kg/day in the male rats and in all groups of female rats. Feed consumption was comparable to controls. There were no adverse clinical, hematologic, biochemical, organ weight or gross necropsy effects. Focal, minimal or mild hyperplasia of the mucosal squamous epithelium of the limiting ridge of the forestomach occurred in some rats at 2000 mg/kg/day; this change was attributed to local irritation by repeated intubation of large volumes of viscous, granular dosing suspension. A NOAEL of 2000 mg/kg/day was established for the 90-day study, based on the lack of significant adverse effects. Toxicokinetic data indicated that hydroxytyrosol (HT, the major component of OPE) was rapidly absorbed. Mean concentrations were measurable through 1 to 4 hours (t(last)) at 1000 and 1500 mg/kg/day and through 8 hours at 2000 mg/kg/day. Dosages of OPE ranging from 500 to 2000 mg/kg/day did not adversely affect any of the mating, fertility, delivery or litter parameters investigated in an oral rat dosage-range reproduction study. Adverse effects were also absent in a rat developmental toxicity study in which pregnant dams were treated with 1000, 1500 or 2000 mg/kg/day on days 6 through 20 of gestation. Plasma levels for pregnant and lactating rats were comparable to non-pregnant rats; minimal levels crossed the placenta. Quantifiable levels were not identified in maternal milk or plasma from nursing pups. A bacterial reverse mutation and a CHO chromosome aberration assay revealed evidence of mutagenic activity at high dosages with S9 metabolic activation. However, three rat micronucleus evaluations performed after single and repeated (28-day) dosages of up to 2000 mg/kg/day and dosages of 5000 mg/kg/day for 29 days resulted in negative findings; therefore, OPE was not considered to be mutagenic in this in vivo assay.     

Acute toxicity, 28-day repeated-dose toxicity and toxicokinetic study of timosaponin BII in rats

Timosaponin BII (TBII), a major steroidal saponin isolated from Anemarrhena asphodeloides Bge., displays a variety of promising pharmacological activities, such as neuroprotection, enhancement of learning and memory, vascular protection and inhibition of platelet aggregation; therefore, it has been developed as a pharmaceutical for prevention or treatment of dementia. Given the safety concerns surrounding timosaponins and the absence of studies on the safety of TBII, the potential toxicity of TBII was evaluated in toxicity and toxicokinetic studies in rats. In the acute oral toxicity study, loose stools were observed in rats receiving 4000 mg/kg, and the symptoms recovered within 1 day. In the 28-day repeated-dose oral toxicity and toxicokinetic study, rats receiving 540 mg/kg showed loose stools and a slight deceleration of body weight growth in both sexes, and the females also showed a slight decrease in food consumption. Moreover, urinalysis indicated reversible treatment-related toxicity in rats receiving 540 mg/kg. The toxicokinetic study demonstrated a dose-dependent increase in systematic exposure to TBII after 28 successive days of oral treatment with TBII. The accumulation coefficients of TBII were 4.35, 1.70 and 1.81, respectively, in rats that received 60, 180 and 540 mg/kg. The no-observed-adverse-effect level (NOAEL) is proposed to be 180 mg/kg.     

Oral two-generation reproduction toxicity study with NM-200 synthetic amorphous silica in Wistar rats

Synthetic amorphous silica (SAS) like NM-200 is used in a wide variety of technological applications and consumer products. Although SAS has been widely investigated the available reproductive toxicity studies are old and do not cover all requirements of current OECD Guidelines. As part of a CEFIC-LRI project, NM-200 was tested in a two-generation reproduction toxicity study according to OECD guideline 416. Male and female rats were treated by oral gavage with NM-200 at dose levels of 0, 100, 300 and 1000 mg/kg bw/day for two generations. Body weight and food consumption were measured throughout the study. Reproductive and developmental parameters were measured and at sacrifice (reproductive) organs and tissues were sampled for histopathological analysis. Oral administration of NM-200 up to 1000 mg/kg bw/day had no adverse effects on the reproductive performance of rats or on the growth and development of the offspring into adulthood for two consecutive generations. The NOAEL was 1000 mg/kg body weight per day.