Toxicological safety assessment of a water extract of Lithocarpus litseifolius by a 90-day repeated oral toxicity study in rats.

Lithocarpus litseifolius although known as "Sweet Tea" (ST), has been traditionally accepted as a daily beverage and used as a folk medicine in southern China with little understanding of its potential toxicity. This study evaluated the safety of a water extract of ST by a subchronic toxicity study in Sprague-Dawley rats. A total of 80 rats were randomized divided into 4 groups with 10 males and 10 females in each group, treated with 2000, 1,000, 500 and 0 mg/kg body weight of ST extract by gavage for 90 days, respectively. The results of the study showed that ST extract did not induce treatment-related changes in the body and organ weight, food intake, blood hematology and serum biochemistry, urine indices, and histopathology in rats. The NOAEL of ST extract was observed to be 2000 mg/kg/day for rats of both sexes. These results indicated that ST extract was of low toxicity in the experimental conditions of the current study and had the potential for application in food-related products.

Subchronic oral toxicity study of the synbiotic mulberry in male and female Wistar rats.

Mulberry (Morus alba L) fruit is traditionally used in Chinese medicine and has several beneficial effects, such as hypoglycemic, hypolipidemic, and anti-oxidative effects. We previously developed the synbiotic mulberry (SM) containing probiotic Lactobacilli, prebiotic inulin, and mulberry powder. In food supplement development, toxicity is the most important criterion in food and drug regulations before commercialization. Thus, this study aimed to investigate the subchronic toxicity of SM in male and female Wistar rats to evaluate its biosafety. The subchronic toxicity study was conducted by daily oral administration of SM at doses of 250, 500, and 1000 mg/kgBW for 90 days. Male and female rats were evaluated for body weight, organ coefficients, biochemical and hematological parameters, and vital organ histology. The results showed no mortality or toxic changes in the subchronic toxicity study. These results suggested that no observed adverse effect level (NOAEL) of SM in male and female rats has been considered at 1000 mg/kgBW for subchronic toxicity study.

Toxicological evaluation and preliminary exposure assessment on glycerol monocaprylate.

As a commonly used food preservative, glycerol monocaprylate (GMC) has limited information and lacked a comprehensive risk assessment. In this study, we conducted in vitro genotoxicity tests, a 90-day subchronic toxicity study, and dietary exposure assessment in China. Rats (n = 10/sex/group) were orally administered GMC at doses of 1.02, 2.04, and 4.08 g/kg BW/day along with a water and corn oil for 90 days, including satellite groups (n = 5/sex/group) in the control groups and 4.08 g/kg BW dose group for observation after 90 days. Body weight, food consumption, hematology, serum biochemistry, urinalysis, endocrine hormone level and other metrics were examined. GMC did not exhibit genotoxicity based on the genotoxicity tests results, and an acceptable daily intake (ADI) of 40.8 mg/kg BW/day was established based on the 90-day subchronic toxicity study. Estimated daily intake of GMC for general population and consumer population in China were 0.99 mg/kg BW/day and 3.19 mg/kg BW/day respectively, which were significantly lower than the ADI. Our findings suggest that GMC does not pose a known health risk to Chinese consumers at the current usage level.

Subchronic Toxicity Evaluation of Idesia polycarpa Fruit Oil by 90-Day Oral Exposure in Wistar Rats.

Idesia polycarpa, belonging to the Flacourtiaceae family, is a tall deciduous tree, widely distributed in some Asian countries. It is famous for its high yield of fruit known as oil grape, which is rich of linoleic acid and linolenic acid, and so on. To provide evidences for its safe use as food, subchronic toxicity of I. polycarpa fruit oil and no observed adverse effect level were performed in male and female specific pathogen-free Wistar rats. Based on the Organization for Economic Co-operation and Development guidelines, the oil was orally administered to rats by gavage at 0, 1.0, 2.0, and 4.0mL/kg.bw/day for 90 days, followed by a 28-day recovery period. The results showed that no sign of oil-related toxicity, clinically or histologically, was observed in both male and female rats. Although there was a slight increase or decrease in some indicators such as hematology, serum chemistry, and so on, those changes were all within the normal ranges, and as presented in the 90-day study, the oil exhibited no toxic effect compared to the control rats. I. polycarpa might be a potential excellent and healthy vegetable oil resource.

Safety assessment and gastrointestinal retention of orally administered cerium oxide nanoparticles in rats.

Cerium oxide nanoparticles (CeO2 NPs, NM-212) are well-known for their catalytic properties and antioxidant potential, and have many applications in various industries, drug delivery, and cosmetic formulations. CeO2 NPs exhibit strong antimicrobial activity and can be used to efficiently remove pathogens from different environments. However, knowledge of the toxicological evaluation of CeO2 NPs is too limited to support their safe use. In this study, CeO2 NPs were orally administered to Sprague Dawley rats for 13 weeks at the doses of 0, 10, 100, and 1000 mg/kg bw/day, followed by a four week recovery period. The hematology values for the absolute and relative reticulocyte counts in male rats treated with 1000 mg/kg bw/day CeO2 NPs were lower than those in control rats. The clinical chemistry values for sodium and chloride in the treated male rat groups (100 and 1000 mg/kg/day) and total protein and calcium in the treated female rat groups (100 mg/kg/day) were higher than those in the control groups. However, these changes were not consistent in both sexes, and no abnormalities were found in the corresponding pathological findings. The results showed no adverse effects on any of the parameters assessed. CeO2 NPs accumulated in the jejunum, colon, and stomach wall of rats administered 1000 mg/kg CeO2 NPs for 90 days. However, these changes were not abnormal in the corresponding histopathological and immunohistochemical examinations. Therefore, 1000 mg/kg bw/day may be considered the "no observed adverse effect level" of CeO2 NPs (NM-212) in male and female SD rats under the present experimental conditions.

Toward a greener multifunctional pharmaceutical excipient: in vivo safety evaluation of nanofibrillated cellulose from tobacco stalk.

Tobacco stalk is a cellulose-rich material and a sustainable alternative to be applied as a plant-based nanofibrillated cellulose (NFC) source. NFC use has garnered attention in the development of oral pharmaceutical forms, despite concerns about its safety due to the adverse effects of nicotine on health. Therefore, we aimed at establishing the safety of NFC derived from tobacco stalk for its potential use as a novel pharmaceutical excipient, exploring its potential functions for tablet production. We conducted acute and subchronic oral toxicity tests in adult female Wistar rats. Initially, individual animals received sequential doses (175-5,000 mg·kg-1) for 24 hours followed by a careful observation of any toxic effects. Subsequently, 20 rats were divided into four groups for a subchronic assay, evaluating toxicity signs, body weight changes, hematological, biochemical, and histopathological parameters. No deaths or other clinical toxicity signs were observed in either the acute or the subchronic assays. We noticed a significant reduction in body weight gain (p < 0.05) after 14 days. We found statistical differences for hematological and biochemical parameters, unrelated to dosage. There were no observed toxic effects, and tobacco stalk ingestion did not adversely affect organ morphology in the histopathological evaluation. The oral administration of NFC at 5,000 mg·kg-1 per day for 28 days was well-tolerated by treated rats, with no reported deaths. In conclusion, NFC derived from tobacco stalk has shown to be a sustainable and safe alternative for use as an excipient at experimental doses, demonstrating compatibility with its proposed applications.

Toxicological evaluation of a pumpkin-derived pectin preparation: in vitro genotoxicity studies and a 13-week oral toxicity study in Sprague-Dawley rats.

The safety of a rhamnogalacturonan-I-enriched pectin extract (G3P-01) from pumpkin (Cucurbita moschata var. Dickinson) was evaluated for use as an ingredient in food and dietary supplements. G3P-01 was tested in a battery of genetic toxicity studies including reverse mutagenicity and in vitro micronucleus assay. In addition, Sprague-Dawley rats were randomized and orally dosed with G3P-01 incorporated in animal diet at concentrations of 0, 9000, 18,000, and 36,000 ppm daily for 13-weeks (n=10/sex/group) in line with OECD guidelines (TG 408). The results of the in vitro bacterial reverse mutation assay and micronucleus assay in TK6 cells demonstrated a lack of genotoxicity. The 13-week oral toxicity study in Sprague-Dawley rats demonstrated that the test article, G3P-01 was well tolerated; there were no mortalities and no adverse effects on clinical, gross pathology, hematology, blood chemistry, and histological evaluation of the essential organs of the animals. The present study demonstrates that G3P-01 is non-genotoxic and is safe when ingested in diet at concentrations up to 36, 000 ppm. The subchronic no-observed-adverse-effect level (NOAEL) for G3P-01 was concluded to be 36,000 ppm, equivalent to 1,899 and 2,361 mg/kg/day for male and female rats respectively.

Acute and subchronic oral toxicity study of Camelina sativa oil in Wistar rats.

Objective: The aim of these studies was to ascertain if Camelina sativa oil is harmful in both the acute and subchronic states. Methods: Wistar rats of both sexes were used in an acute toxicity test, and the fatal dosage (LD50) of oral Camelina sativa oil was greater than 27.6 g/kg bw. Rats were gavaged with Camelina sativa oil at dosages of 0.00, 0.92, 1.84, and 3.68 g/kg bw per day for 90 days. In addition, satellite groups were established in the control and high-dose groups for a 28-day recovery period. The following factors were assessed: mortality, clinical anomalies, body weight, food intake, hematological, serum biochemistry, urine, gross necropsy, and histology. Results: There were no observable toxicity-related changes in any of the three dosage groups. There is no toxicological relevance to the change in the high-dose hematological indicator PLT at the conclusion of the recovery period because it was within the usual range for this strain in our laboratory. The test material did not result in any pathological alterations, according to a pathological examination. Conclusion: Since the results of the current study, the no-observed-adverse-effect-level (NOAEL) for Camelina sativa oil in rats has been determined to be greater than 3.68 g/kg bw.

A toxicological assessment of spermidine trihydrochloride produced using an engineered strain of Saccharomyces cerevisiae.

Spermidine is a polyamine consumed in the diet, endogenously biosynthesized in most cells, and produced by the intestinal microbiome. A variety of foods contribute to intake of spermidine along with other polyamines. Spermidine trihydrochloride (spermidine-3HCl) of high purity can be produced using an engineered strain of Saccharomyces cerevisiae. Spermidine has a demonstrated history of safe use in the diet; however, limited information is available in the public literature to assess the potential toxicity of spermidine-3HCl. To support a safety assessment for this spermidine-3HCl as a dietary source of spermidine, authoritative guideline and good laboratory practice (GLP) compliant in vitro genotoxicity assays (bacterial reverse mutation and mammalian micronucleus assays) and a 90-day oral (dietary) toxicity study in rats were conducted with spermidine-3HCl. Spermidine-3HCl was non-genotoxic in the in vitro assays, and no adverse effects were reported in the 90-day oral toxicity study up to the highest dose tested, 12500 ppm, equivalent to 728 mg/kg bw/day for males and 829 mg/kg bw/day for females. The subchronic no observed adverse effect level (NOAEL) is 728 mg/kg bw/day.

Subchronic toxicity evaluation of Huobahuagen extract and plasma metabolic profiling analysis combined with conventional pathology methods.

Huobahua, namely, Tripterygium hypoglaucum (Levl.) Hutch, known as a traditional Chinese herbal medicine, especially its underground parts, has been widely developed into several Tripterygium agents for the treatment of rheumatoid arthritis and other autoimmune diseases. It has sparked wide public concern about its safety, such as multi-organ toxicity. However, the toxic characteristics and damage mechanism of Huobahuagen extract (HBHGE) remain unclear. In the present study, subchronic oral toxicity study of HBHGE (10.0 g crude drug/kg/day for 12 weeks) was performed in male rats. Hematological, serum biochemical, and histopathological parameters, urinalysis, and plasma metabolic profiling were assessed. The single-dose subchronic toxicity results related to HBHGE exhibited obvious toxicity to the testis and epididymis of male rats. Furthermore, plasma metabolomics analysis suggested that a series of metabolic disorders were induced by oral administration of HBHGE, mainly focusing on amino acid (glutamate, phenylalanine, and tryptophan) metabolisms, pyrimidine metabolism, glutathione metabolism, and steroid hormone biosynthesis. Moreover, it appeared that serum testosterone in male rats treated with HBHGE for 12 weeks, decreased significantly, and was susceptible to the toxic effects of HBHGE. Taken together, conventional pathology and plasma metabolomics for preliminarily exploring subchronic toxicity and underlying mechanism can provide useful information about the reduction of toxic risks from HBHGE and new insights into the development of detoxification preparations.

The food safety assessment of all-female common carp (Cyprinus carpio) (cyp17a1+/-;XX genotype) generated using genome editing technology.

There are several technical challenges and public issues concerning genome editing applications before they become viable in commercial aquaculture. Recently, we developed a novel strategy to generate all-female (AF) common carp, which exhibited a growth advantage over the control carp, using genetic editing through single gene-targeting manipulation. Here, we found that the body weight of the AF common carp was higher by 22.58% than that of the control common carp. Because the genotype of the AF common carp was cyp17a1+/-;XX, the contents of sex steroids were normally synthesized, as they were comparable to that of the control female carp. To evaluate the food safety of the AF carp, Wistar rats were fed a diet containing control female carp (control, C) or all-female (AF) carp at an incorporation rate of 5, 10 and 20% (w/w) for 90 days. Compared with those fed control carp, the rats fed AF common carp exhibited no significant difference in body weight, food intake, feed conversion ratio, hematology, serum biochemistry, urine test, relative organ weight, gross necropsy, and histopathological examination. This is the first food safety assessment of the farmed fish strain cultured using CRISPR/Cas9, which will further advance the fishery development of genome-edited animals.

Systemic subchronic toxicity and comparison of four selenium nutritional supplements by 90-day oral exposure in Sprague-Dawley rats.

To evaluate and compare the safety of four selenium supplements, namely Se-enriched peptides (SeP), yeast selenium (SeY), L-Se-methylselenocysteine (L-SeMc) and sodium selenite (Na2SeO3), the subchronic toxicity study was designed by 90-day gavage administration in Sprague-Dawley rats. The doses of SeP, SeY, L-SeMc and Na2SeO3 were 0.15, 0.30 and 0.60 mg/kg bw/day, with additional dose of 0.45 mg/kg L-SeMc (All dose calculated as Se). Symptoms like growling, hair loss and significant weight loss were found at 0.60 mg/kg of L-SeMc, but not in other groups. At the dose of 0.60 mg/kg, females in Na2SeO3, SeY and L-SeMc groups showed significant elevations in ALT and/or ALP. Pathologic manifestations such as bile duct hyperplasia and cholestasis were predominantly found in females at 0.6 mg/kg of L-SeMc and SeY groups, and in males at same dose of L-SeMc group showed marked testicular atrophy. 0.60 mg/kg of SeY and Na2SeO3, and 0.30, 0.45, 0.60 mg/kg of L-SeMc induced significant reductions in sperm motility rates, rapid movement and amount. In conclusion, the NOAEL of SeP, SeY, L-SeMc, Na2SeO3 was all 0.30 mg/kg for female, and 0.60, 0.30, 0.15 and 0.30 mg/kg for male respectively. Liver and reproductive organs are possible toxic target organs of hyper selenium.

Toxicity of a 90-day repeated oral dose of a collagen peptide derived from skate (Raja kenojei) skin: a rat model study.

Collagen peptides are widely employed as therapeutic materials due to their numerous beneficial properties, including for the following uses: antiaging, antioxidant applications, antibacterial applications, wound healing, tissue engineering, medication delivery, and cosmetics. Although collagen peptides are useful in these applications, to our knowledge, few published studies have been undertaken on their repeated-dose toxicity. We evaluated the possible subchronic toxicity of a collagen peptide derived from skate (Raja kenojei) skin (CPSS) in Sprague-Dawley rats by administering repeated oral doses over 90 days. Rats of both sexes were assigned randomly to one of four experimental groups, respectively receiving 0, 500, 1000, or 2000 mg/kg/day of CPSS. At all doses tested, repeated oral CPSS administration had no treatment-related adverse effects in terms of clinical signs, body weight, food consumption, detailed clinical observation, sensory reactivity, functional assessment, urinalysis, ophthalmic examination, gross pathology, hematology, serum biochemistry, hormone analysis, organ weight, and histopathology. Even though there were some alterations in hematologic parameters, serum biochemistry parameters, organ weight, and histopathological findings, these did not follow a dose-response pattern and were within historical limits for control rats. The oral no-observed-adverse-effect level (NOAEL) of the CPSS was 2000 mg/kg/day for both male and female rats in the applied experimental circumstances, and no target organs were identified.

Safety evaluation and maximum use level for transient ingestion in humans of allitol.

Allitol is a hexitol produced by reducing the rare sugar D-allulose with a metal catalyst under hydrogen gas. To confirm the safe level of allitol, we conducted a series of safety assessments. From the results of Ames mutagenicity assay using Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537, Escherichia coli strain WP2uvrA, and an in vitro chromosomal aberration test on cultured Chinese hamster cells, allitol did not show any significant genotoxic effect. No significant effects on general condition, urinalysis, hematology, physiology, histopathology, or at necropsy were observed at a dose of 1500 mg/kg body weight of allitol in the acute and 90-day subchronic oral-toxicity assessments for rats. A further study performed on healthy adult humans showed that the acute use level of allitol for diarrhea was 0.2 g/kg body weight for both men and women. The results of current safety assessment studies suggest that allitol is safe for human consumption.

Subchronic Microcystin-LR Aggravates Colorectal Inflammatory Response and Barrier Disruption via Raf/ERK Signaling Pathway in Obese Mice.

Microcystin-LR (MC-LR) is an extremely poisonous cyanotoxin that poses a threat to ecosystems and human health. MC-LR has been reported as an enterotoxin. The objective of this study was to determine the effect and the mechanism of subchronic MC-LR toxicity on preexisting diet-induced colorectal damage. C57BL/6J mice were given either a regular diet or a high-fat diet (HFD) for 8 weeks. After 8 weeks of feeding, animals were supplied with vehicle or 120 µg/L MC-LR via drinking water for another 8 weeks, and their colorectal were stained with H&E to detect microstructural alterations. Compared with the CT group, the HFD and MC-LR + HFD-treatment group induced a significant weight gain in the mice. Histopathological findings showed that the HFD- and MC-LR + HFD-treatment groups caused epithelial barrier disruption and infiltration of inflammatory cells. The HFD- and MC-LR + HFD-treatment groups raised the levels of inflammation mediator factors and decreased the expression of tight junction-related factors compared to the CT group. The expression levels of p-Raf/Raf and p-ERK/ERK in the HFD- and MC-LR + HFD-treatment groups were significantly increased compared with the CT group. Additionally, treated with MC-LR + HFD, the colorectal injury was further aggravated compared with the HFD-treatment group. These findings suggest that by stimulating the Raf/ERK signaling pathway, MC-LR may cause colorectal inflammation and barrier disruption. This study suggests that MC-LR treatment may exacerbate the colorectal toxicity caused by an HFD. These findings offer unique insights into the consequences and harmful mechanisms of MC-LR and provide strategies for preventing and treating intestinal disorders.

Oral toxicity evaluation of cannabidiol.

Use of cannabidiol (CBD) in humans has increased considerably in recent years. While currently available studies suggest that CBD is relatively safe for human consumption, data from publicly available studies on CBD conducted according to modern testing guidelines are lacking. In the current study, the potential for toxicity following repeated oral exposure to hemp-derived CBD isolate was evaluated in male and female Sprague Dawley rats. No adverse treatment-related effects were observed following administration of CBD via oral gavage for 14 and 90 days at concentrations up to 150 and 140 mg/kg-bw/d, respectively. Microscopic liver and adrenal gland changes observed in the 90-day study were determined to be resolved after a 28-day recovery period. CBD was well tolerated at these dose levels, and the results of this study are comparable to findings reported in unpublished studies conducted with other CBD isolates. The current studies were conducted as part of a broader research program to examine the safety of CBD.

Marine toxin C17-SAMT causes major structural damage to vital organs in mice following subchronic toxicity trials.

C17-sphinganine analog mycotoxin (C17-SAMT) has been characterized as the contaminant responsible for the atypical toxicity reported in mussels from the Bizerte lagoon (northern Tunisia) over the past decade. C17-SAMT exhibited common symptoms of toxicity in mice, including flaccid paralysis and severe respiratory distress, followed by rapid death. To determine the potential health risks of this neurotoxin, we assessed its subchronic toxicity according to the recommendations of OCDE n° 407. The body weight and the structural changes of vital organs were recorded. Biochemical and hematological parameters were also quantified. Macroscopic observations showed that mice treated with 0.9, 9, and 90 µg/kg C17-SAMT had significantly reduced stomach weights, swollen and fragile intestines, and signs of nephritis with renal abscesses. Transaminase assays pointed out that exposure to C17-SAMT can lead to transaminitis. Above-average lactate dehydrogenase values were recorded in both the treated and satellite groups. Hematology data showed a significant reduction in red blood cell counts in high-dose-treated group. Reductions in hemoglobin and hematocrit were also recorded. Mean leukocyte counts were significantly elevated in the high-, mid-dose treated and satellite groups. At the microscopic level, we noted myocardial atrophy and hyperemia. In the lungs, we noted necrosis associated with macrophages perivascular infiltration and congestion. The kidneys showed mild inflammation and glomerular atrophy. The stomach exhibited mucosal atrophy, while a thin colon and distended small intestine were observed in high-dose-treated group. The liver was affected by vascular congestion, inflammatory infiltration, and lobular necrosis that evolved into acute hepatitis. Lesions, such as inflammatory infiltration and mild necrosis of the liver, cortical abscess with central necrosis in the kidney, and mild congestion of cardiac tissue were recorded in the satellite group.

A 13-week subchronic toxicity study of heme iron in SD rats.

Heme iron (HI) has been widely used as a food additive and supplement to support iron fortification. However, no sufficient toxicological data to evaluate the safety of HI have been reported. In the current study, we performed a 13-week subchronic toxicity study of HI in male and female Crl:CD(SD) rats. Rats were orally administered HI in the diet at concentrations of 0%, 0.8%, 2%, and 5%. Observations of general condition, body weight (bw) and food consumption, urinalysis, hematology, serum biochemistry, and macroscopic and histopathological examination were performed. The results showed that HI had no adverse effects on any of the examined parameters. Therefore, we concluded that the no-observed-adverse-effect level (NOAEL) for HI was estimated to be 5% for both sexes (2,890 mg/kg bw/day for males and 3,840 mg/kg bw/day for females). Since the iron content of HI used in this study was in a range of 2.0-2.6%, iron content at NOAEL for HI was calculated to be 57.8-75.1 mg/kg bw/day for males and 76.8-99.8 mg/kg bw/day for females.

A 90-day rodent feeding study with grain for genetically modified maize L4 conferring insect resistance and glyphosate tolerance.

A 90-day rat feeding study was performed to conduct a safety assessment on L4, a multi-gene genetically modified maize, conferring "Bt" insect resistance and glyphosate tolerance. A total of 140 Wistar rats were assigned to seven groups, 10 animals/group/sex, which comprised three genetically modified groups fed diets containing different concentrations of L4, three corresponding non-genetically modified groups fed diets containing different concentrations of zheng58 (parent plants), and a basal diet group fed the standard basal diet for 13 weeks. The fed diets contained L4 and Zheng58 at w/w% percentages of 12.5%, 25.0%, and 50% of the total. Animals were evaluated on some research parameters, including general behaviour, body weight/gain, feed consumption/efficiency, ophthalmology, clinical pathology, organ weights, and histopathology. Throughout the feeding trial, all animals were in good condition. No mortality and no biologically relevant effects or toxicologically significant alterations were observed in the total research parameters of the rats in the genetically modified groups compared with those in the basal diet group or their corresponding non-genetically modified groups. No adverse effects were observed in any of the animals. The results indicated that L4 is as safe and wholesome as conventional, non-genetically modified control maize.

Subchronic toxicity study of ferric oxide nanoparticles through intragastric administration: A 94-d, repeated dose study in Sprague Dawley rats.

In this study, the toxicity of ferric oxide nanoparticles (Fe2O3 NPs) administered through gavage to Sprague Dawley (SD) rats for 94 d, consecutively and the recovery after Fe2O3 NPs withdrawal for 30 d were evaluated. The vehicle control group, low-, medium-, and high-dose groups were administered with the vehicle (0.5% sodium carboxymethyl cellulose [CMC-Na]), 125, 250, and 500 mg/kg of Fe2O3 NPs, respectively, administered every morning for 94 d. There was no significant difference in the body weight, food intake, hematological, blood biochemical, and urine indices of SD rats in each administration group and the control group (P > 0.05). There was no significant difference in organ weight, organ indices, and the coefficient of the visceral brain between the SD rats in the different dosage groups and the SD rats in the vehicle control group (P > 0.05). Histopathological observations showed that there was no correlation between the pathological lesions of the organs observed in this study and the dose of Fe2O3 NPs (P > 0.05). The no-observed-adverse-effect level (NOAEL) dose of Fe2O3 NPs was initially determined to be 500 mg/kg administered to SD rats through oral gavage for 94 d, consecutively, followed by recovery after Fe2O3 NPs withdrawal for 30 d.