General and histopathological results of a two-year study of rats fed semi-purified diets containing casein and soya protein

Re-evaluation of celluloses E 460(i), E 460(ii), E 461, E 462, E 463, E 464, E 465, E 466, E 468 and E 469 as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion re-evaluating the safety of microcrystalline cellulose (E 460(i)), powdered cellulose (E 460(ii)), methyl cellulose (E 461), ethyl cellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methyl cellulose (E 464), ethyl methyl cellulose (E 465), sodium carboxy methyl cellulose (E 466), enzymatically hydrolysed carboxy methyl cellulose (E 469) and cross-linked carboxy methyl cellulose (E 468) as food additives. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) 'not specified' for unmodified and modified celluloses. Celluloses are not absorbed and are excreted intact in the faeces; in addition, microcrystalline cellulose, powdered and modified celluloses could be fermented by the intestinal flora in animals and humans. Specific toxicity data were not always available for all the celluloses evaluated in the present opinion and for all endpoints. Given their structural, physicochemical and biological similarities, the Panel considered it possible to read-across between all the celluloses. The acute toxicity of celluloses was low and there was no genotoxic concern. Short-term and subchronic dietary toxicity studies performed with E 460(i), E 461, E 462, E 463, E 464, E 466 and E 469 at levels up to 10% did not indicate specific treatment related adverse effects. In chronic toxicity studies performed with E 460(i), E 461, E 463, E 464, E 465 and E 466, the no observed adverse effect level (NOAEL) values reported ranged up to 9,000 mg/kg body weight (bw) per day. No carcinogenic properties were detected for microcrystalline cellulose and modified celluloses. Adverse effects on reproductive performance or developmental effects were not observed with celluloses at doses greater than 1,000 mg/kg bw by gavage (often the highest dose tested). The combined exposure to celluloses (E 460-466, E 468 and E 469) at 95th percentile of the refined (brand-loyal) exposure assessment for the general population was up to 506 mg/kg bw per day. The Panel concluded that there was no need for a numerical ADI and that there would be no safety concern at the reported uses and use levels for the unmodified and modified celluloses (E 460(i); E 460(ii); E 461-466; E 468 and E 469). The Panel considered an indicative total exposure of around 660-900 mg/kg bw per day for microcrystalline, powdered and modified celluloses.

Cause-of-Death Analysis in Rodent Aging Studies

In research studies using rats or mice, the cause of death is often not evaluated or reported. An analysis of the causes of death is particularly valuable for aging and carcinogenesis studies. Comparing causes of death among the study groups is often an important adjunct to the biochemical, molecular, clinical, and histopathologic findings. The methods for evaluating causes of death, contributing causes of death, and comorbidities have been suggested in several publications. Surprisingly, in important mouse aging studies, causes of death are often not reported. Cause-of-death assignment in preclinical rodent model aging research suffers from a lack of a standardized approach and an understanding of the value that it can add to longevity and interventional studies. While assigning single cause of death may facilitate data analysis, defining and publishing data on contributing causes (comorbidities) provides more information on associated underlying chronic conditions and health span in mouse models. This article reviews factors that affect determination of cause of death and the methods for evaluating causes of death and comorbidities. The proposed systematic pathology analysis includes assigning cause of death and comorbidities to define total disease burden. The combination of pathology with in vivo data will fully characterize the effect of tested interventions on multiple chronic diseases and health span of aging mice with improved translation to human aging and age-associated lesions.

Successive Generations in a Rat Model Respond Differently to a Constant Obesogenic Environment

Research has shown that if a mother experiences a transitory perturbation to her environment during pregnancy or lactation, there are transgenerational consequences often involving a disordered metabolic phenotype in first generation offspring with recovery across subsequent generations. In contrast, little is known about the nature of the transgenerational response of offspring when a mother experiences a perturbation that is not transitory but instead persists across generations. Our study, using a rat model, subjected the parental generation to a change in environment and concomitant shift from a grain-based to obesogenic diets to generate an adipose phenotype in first generation offspring emulating a common scenario in human urbanisation and migration. We then investigated whether the obese phenotype was stable across generations when maintained in the transitioned environment, and whether dietary macronutrient balance affected the response. We found that second and third generation offspring had a reduced body fat to lean mass ratio and a reduced appetite relative to first generation offspring, irrespective of dietary macronutrient balance. The trajectory of this response is suggestive of a reduction in chronic disease risk across generations. This is one of the first studies, to our knowledge, to investigate the transgenerational response following parental transition to a persistent obesogenic environment, and to demonstrate that successive generations respond differently to this constant environment.

Feeding soy protein isolate and oils rich in omega-3 polyunsaturated fatty acids affected mineral balance, but not bone in a rat model of autosomal recessive polycystic kidney disease

Background

Polycystic kidney disease (PKD), a genetic disorder characterized by multiple cysts and renal failure at an early age. In children, kidney disease is often accompanied by disordered mineral metabolism, failure to achieve peak bone mass, and reduced adult height. Optimizing bone health during the growth stage may preserve against bone loss associated with early renal dysfunction in PKD. Dietary soy protein and omega-3 polyunsaturated fatty acid (n-3 PUFA) have been reported to ameliorate PKD and to promote bone health. The study objective was to determine the bone effects of feeding soy protein and/or n-3 PUFAs in a rat model of PKD.

Methods

Weanling female PCK rats (n = 12/group) were randomly assigned to casein + corn oil (Casein + CO), casein + soybean oil (Casein + SO), soy protein isolate + soybean oil (SPI + SO) or soy protein isolate + 1:1 soybean oil:salmon oil blend (SPI + SB) for 12 weeks.

Results

Rats fed SPI + SO diet had shorter (P = 0.001) femur length than casein-fed rats. Rats fed SPI + SO and SPI + SB diet had higher (P = 0.04) calcium (Ca) and phosphorus (P) retention. However, there were no significant differences in femur and tibial Ca, P or bone mass between diet groups. There were also no significant difference in bone microarchitecture measured by micro-computed tomography or bone strength determined by three-point bending test between diet groups.

Conclusions

Early diet management of PKD using SPI and/or n-3 PUFAs influenced bone longitudinal growth and mineral balance, but neither worsened nor enhanced bone mineralization, microarchitecture or strength.

Evidence for a role of proteins, lipids, and phytochemicals in the prevention of polycystic kidney disease progression and severity

Polycystic kidney disease (PKD) is a heritable disease characterized by renal cysts and is a leading cause of end-stage renal disease. Dietary intervention offers a potentially efficacious, cost-effective, and safe therapeutic option for PKD. The aim of this article was to review studies investigating the effect of dietary components on PKD and potential mechanisms of action. Low-protein diets are commonly recommended for PKD patients, but inconsistent findings in human and animal PKD studies suggest that the type rather the amount of protein may be of greater importance. Dietary soy protein has been shown to have renal protective effects in various animal models of PKD. Other than dietary proteins, studies investigating the role of the amount and type of dietary lipids on PKD progression are increasing. The omega-3 polyunsaturated fatty acids can alter multiple steps in PKD pathogenesis. Phytoestrogens and phytochemicals are other dietary compounds shown to attenuate cyst pathogenesis in animal studies. A better understanding of the role of nutrition in PKD can contribute to the development of dietary recommendations and diet-based therapies to reduce PKD progression and severity.

Krill for Human Consumption: Nutritional Value and Potential Health Benefits

The marine crustacean krill (order Euphausiacea) has not been a traditional food in the human diet. Public acceptance of krill for human consumption will depend partly on its nutritive value. The aim of this article is to assess the nutritive value and potential health benefits of krill, an abundant food source with high nutritional value and a variety of compounds relevant to human health. Krill is a rich source of high-quality protein, with the advantage over other animal proteins of being low in fat and a rich source of omega-3 fatty acids. Antioxidant levels in krill are higher than in fish, suggesting benefits against oxidative damage. Finally, the waste generated by the processing of krill into edible products can be developed into value-added products.

A 24-month dietary carcinogenicity study of DAG (diacylglycerol) in rats

Toxicologic and carcinogenic effects of DAG (diacylglycerol) oil, administered in diet for 24 months to Crl:CD((R))(SD)-IGS BR rats, were evaluated using diet-restricted and ad libitum-fed groups. All dietary fat (consistently 5.5%) was provided by DAG and/or the control article, TG (triacylglycerol) oil. Dietary concentrations (% DAG/% TG) were 0%/5.5%, 1%/4.5%, 2.75%/2.75% and 5.5%/0%. Separate groups were fed the 0%/5.5% and 5.5%/0% diets ad libitum. Another group received the standard rodent diet (fat content 4.5%) on the restricted feeding regimen. Clinical condition, ophthalmic findings, palpable mass occurrence, body composition, clinical pathology parameters and incidence of neoplastic lesions were unaffected by DAG in comparison to TG. Groups fed the 5.5% (DAG and/or TG) fat diet when compared to the 4.5% fat diet group displayed lower survival, higher body weights, organ weights, percent body fat, higher fat-related serum chemistry parameters, incidence of microscopic changes in the heart, kidneys, liver, bone marrow, spleen, and incidences of pituitary and mammary gland neoplasms. Parameters more affected in all the ad libitum groups than in the restricted diet groups (regardless of test article) fed the same diet included survival, body weights, body fat, fat-related serum chemistry parameters, and incidences of heart, kidney and liver microscopic changes. However, the DAG and TG ad libitum-fed groups were not different from one another. Thus, DAG-treated animals had no higher risk of carcinogenic effects than rats fed on similar feeding regimens with a diet in which all dietary fat came from TG.

A 24-month dietary carcinogenicity study of DAG in mice

This study evaluated the possible carcinogenic effects of DAG (diacylglycerol) oil when given in the diet at levels up to 6.0% for 24 months to mice. Dietary fat was provided by DAG and/or the control article, TG (triacylglycerol oil). Dietary concentrations (% DAG/% TG) were 0%/6.0% (TG control), 1.5%/4.5%, 3.0%/3.0%, and 6.0%/0%. An additional control group received the standard rodent diet (fat content 4.5%). The clinical condition of the animals, ophthalmic findings, palpable mass occurrence, body weights and gross and histopathologic findings were unaffected by DAG in comparison to TG. The findings in DAG-treated groups were no different than those observed in the TG control group. The standard basal diet had 4.5% fat content. Both TG and/or DAG, when presented separately or together in the diet at a total fat level of 6.0%, resulted in some differences relative to the basal diet control (lower survival, higher body weights, lower food consumption, and higher incidences of macroscopic and microscopic findings), presumably related to the higher dietary fat content and/or the semi-purified diet. However, these parameters were similar in groups fed a diet with 6.0% dietary fat that was either DAG or TG. Thus, DAG at dietary concentrations up to 6.0% for 24 months produced no signs of systemic toxicity and had no effect on the incidence of neoplastic findings.

Acute, subchronic and chronic safety studies with genistein in rats

Genistein is a phytoestrogen that occurs naturally in the diet, especially in soy based foods. There is wide spread interest in phytoestrogens as chemopreventive agents for a variety of diseases and cancers based on epidemiologic evidence. Although soy, and its constituents such as genistein, have been consumed at high levels in several Asian populations without apparent adverse effects, concern has been raised about potential adverse effects due to the estrogenic and other activities. Safety studies with genistein were conducted in the Wistar rat including two acute studies, two subchronic (4 weeks and 13 weeks) and a chronic 52-week dietary admix study. In the acute studies, genistein had a low order of toxicity. In the three repeated dose safety studies at doses up to 500 mg/kg/day, genistein was well tolerated. In all of the studies, decreased food consumption and body weight gain were observed at 500 mg/kg/day. The main hematological findings were decreased red blood cell parameters at 500 mg/kg/day with a compensatory increase in reticulocytes. For clinical chemistry, with the exception of a slight increase in gamma glutamyl transferase in male and female rats at the high dose, there were a number of other minor changes considered not toxicologically significant. At necropsy, there were relatively few macroscopic changes; in the 52-week study, dilation of the uterus with fluid at the high dose and cysts of the ovaries in treated animals were observed. Organ weight changes in male rats at the high dose of 500 mg/kg/day included increased kidney, spleen, adrenal and testes weights and for females included, increased liver, kidney, spleen, ovary and uterus weights. After 4 and 13 weeks of treatment with genistein, there were no treatment related histopathologic findings. After 26 and 52 weeks of treatment, histological changes were seen in the female reproductive organs (ovaries and uterus), and in males (epididymides and prostate), and bone, kidneys, heart, liver and spleen in both sexes. After 52 weeks of treatment of males, vacuolation of the epididymal epithelium at 500 mg/kg/day and inflammation of the prostate were recorded at a higher incidence at 50 and 500 mg/kg/day. In females, cytological changes in the uterus, squamous metaplasia at 50 and 500 mg/kg/day and hyperplasia at 500 mg/kg/day were observed. Furthermore, hydrometra of the uterus and findings in the vagina consisting of anestric or diestrus vaginal mucosa with vaginal mucification, hyperplastic epithelium and multifocal cystic degeneration were noted at 500 mg/kg/day. Atrophy of the ovaries increased in severity in animals at 50 and 500 mg/kg/day. Osteopetrosis (hyperostosis) was observed in male and female rats at 50 and 500 mg/kg/day along with a compensatory increase in extramedullary hemopoiesis in the spleen; females were more affected than males. Hepatocellular hypertrophy and minimal bile duct proliferation were recorded at a higher incidence in animals at 500 mg/kg/day. It is concluded that almost all of the treatment related findings in these studies are related to the estrogenic properties of genistein as a phytoestrogen and would be expected to occur with a compound with estrogenic activity. The hormonally related changes were considered to be functional in nature and thus not adverse effects. Most of the findings in these studies were limited to the high dose of 500 mg/kg/day and were reversible. The few findings observed at 50 mg/kg/day were relatively minor and in view of the functional (hormonally mediated) nature of the effects, were considered not adverse effects. The increased incidence of minimal bile duct proliferation and slightly increased gamma glutamyl transferase are indicative of a mild hepatic effect at the high dose of 500 mg/kg/day. The no observed adverse effect level (NOAEL) of genistein is considered to be 50 mg/kg/day based on the presence of mild hepatic effects at the high dose of 500 mg/kg/day. The no observed effect level (NOEL) is considered to be 5 mg/kg/day based on the hormonally induced functional changes at higher doses.

Dietary Omega-3 Fatty Acids May Be Associated with Increased Neuropathic Pain in Nerve-Injured Rats

Certain dietary proteins and oils are capable of decreasing chronic neuropathic pain levels in rats after partial sciatic nerve ligation injury. We tested, for the first time, the role of dietary polyunsaturated fatty acids in suppressing pain in partial sciatic nerve ligation-injured rats. Six groups of male Wistar rats were fed an identical casein-based, fat-free diet for 1 wk preceding partial sciatic nerve ligation injury and for 1 wk thereafter. In addition, rats received, via gavage, 1 mL/day of pure canola, corn, hemp, soy, or sunflower oil, differing significantly in their omega-3 and omega-6 polyunsaturated fatty acid content, or 1 mL of plain water. Responses to tactile and noxious heat stimuli were recorded before and after surgery and a difference score was calculated for each group by subtracting the preoperative from the post-partial sciatic nerve ligation values. Heat hyperalgesia, but not tactile allodynia, was significantly different among the dietary groups (P = 0.005). Heat hyperalgesia of rats fed hemp oil, developing the most robust response, was significantly larger compared with rats fed corn oil, developing the least pain model (difference score: 24.3 +/- 4.1 s versus 6.1 +/- 3.1 s, respectively; P < 0.001). These oils contain similar levels of omega-6 polyunsaturated fatty acids (hemp, 60%; corn, 58%) but their omega-3 levels are 28-fold different (20% versus 0.7%, respectively). A significant correlation was found among dietary levels of omega-3, but not omega-6 or the omega-3/omega-6 ratio, of the six dietary groups and heat hyperalgesia (P = 0.006). We conclude that dietary oil might predict levels of neuropathic pain in rats and that this effect may be associated with dietary omega-3 levels.

IMPLICATIONS

We found that certain commonly used oils can have a significant analgesic effect in rats with persistent pain after partial nerve injury. This effect may be associated with the amounts of omega-3 fatty acids consumed by rats.

Effects of diet and exposure to hindlimb suspension on estrous cycling in Sprague-Dawley rats

Various factors can disrupt the female reproductive cycle resulting in subfertility. The primary objective of this study was to determine whether physiological changes associated with exposure to hypogravity disrupt reproductive cycles. The hindlimb suspension (HLS) model was used to simulate the major physiological effects of hypogravity in female Sprague-Dawley rats. Also, to determine whether diet may influence reproductive results, rats were fed purified American Institute of Nutrition (AIN)-93G or chow diet. Rats (n = 9-11/group) subjected to HLS had lengthened estrous cycles due to prolonged diestrus, indicating hypoestrogenism. Interestingly, HLS rats fed AIN-93G but not chow diet had significantly reduced time spent in estrus and decreased plasma estradiol. Attenuation of hypoestrogenism in the chow-fed rats suggested that diet provided an exogenous source of estrogen. The mechanism involved in the disruption of estrous cycling remains to be determined. HLS increased urinary corticosterone (CORT) levels during the initial 4 days of HLS, suggesting that physiological responses to acute stress may be a potential mechanism in the disruption of estrous cycles. Higher basal urinary CORT was observed in rats fed chow vs. AIN-93G diet. HLS resulted in increased urinary CORT. However, two-way ANOVA indicated a significant HLS effect (P < 0.001) but no effect of HLS x diet effect on urinary CORT levels, suggesting that estrogenic activity associated with the chow diet did not enhance the stress response. The results of this study indicate that HLS, diet, and the combination of HLS and diet influence estrous cycling. This has important implications for future reproductive success in the hypogravity environment of space.

Comparison of AIN-76A and AIN-93G diets: a 13-week study in rats

Either purified or cereal-based diets may be used for toxicity testing in rats. Purified diets have advantages in terms of flexibility of formulation to meet specific study objectives and also assurance of relatively low levels of contaminants (e.g. heavy metals and pesticides). The American Institute of Nutrition recommended that the widely used purified diet AIN-76A be replaced by two newer diets, AIN-93G (for use during rapid growth, pregnancy and lactation) and AIN-93M (maintenance diet). The present study compared AIN-76A and AIN-93G by feeding these diets for 13 weeks to male and female rats. A cereal-based diet was also included for reference purposes. The groups fed purified diets had higher serum cholesterol and triglyceride levels than the chow-fed group. An increased incidence and severity of renal tubular mineralization in the purified diet groups was not observed in this study (in contrast to other published studies where rats were fed AIN-76A). Several histopathologic observations, including eosinophilic gastritis and mucification of gastric glands of the glandular stomach, occurred at higher rates in the AIN-76A group than the other dietary treatments. Hepatocellular fatty changes occurred in the purified diet groups at a significantly higher rate than in the chow diet group. In conclusion, AIN-93G is an appropriate diet for use in rat safety evaluation studies.

Soy-containing diet suppresses chronic neuropathic sensory disorders in rats

Partial sciatic nerve ligation (PSL) in rodents produces chronic neuropathic sensory disorders resembling neuropathic pain in humans. We previously reported that levels of allodynia and hyperalgesia after PSL injury were markedly attenuated by consumption of soy-containing diets. Here we aimed to show that dietary effect on pain behavior is not specific to a certain laboratory. For this purpose, experiments were conducted in a different laboratory (Baltimore rather than Jerusalem) and a different rat strain (Wistar rather than Sabra), with additional and different testing methods (radiant heat from a lamp rather than a CO(2) laser). Rats were fed two soy-free diets and a soy-containing one for 28 days. The sensitivity of rats to nonnoxious and noxious stimuli was determined before PSL injury, and levels of neuropathic sensory disorders were determined after it. We found that consuming the soy-containing diet prevented development of tactile and heat allodynia, but not mechanical hyperalgesia. This dietary effect was not correlated with calorie intake and weight gain or dietary concentration of fat and carbohydrates. We conclude that, regardless of experimental site, diet markedly affects chronic neuropathic sensory disorders in rats and should be standardized in animal models of pain.

IMPLICATIONS

Levels of chronic sensory disorders in a rat model of allodynia and hyperalgesia after partial sciatic nerve ligation depend on the consumption of a soy-containing diet. Further studies are needed to determine the role of diet in humans with chronic pain.

Soy of dietary source plays a preventive role against the pathogenesis of prostatitis in rats

This study examined the effects of diet on the development of prostatitis in male rats. Adult male rats were placed on either of two specially formulated diets which differed from one another by the presence or absence of soy as the protein source. A third group of rats (control) was fed standard laboratory rat chow which also includes soy as a source of protein. After 11 weeks, it was found that rats maintained on soy-free diet developed prostatitis mainly in the lateral lobe of the prostate. Increased severity and incidence of prostatitis in rats maintained on the soy-free diet coincided with a significant decrease in urinary excretion of various phytoestrogens. There was no evidence of prostatitis in rats maintained on soy-containing diets. Urinary excretion of phytoestrogens in rats maintained on soy-containing diet was also not different from controls. These results suggest that soy as a dietary source plays a protective role against the development of prostatitis in rats, and indicate that the ventral, lateral and dorsal lobes of the rat prostate have different sensitivities to alterations in dietary factors.

Comparison of cereal-based diet with purified diet by short-term feeding studies in rats, mice and hamsters, with emphasis on toxicity characteristics

Animal diets used in toxicity studies are prepared either from natural ingredients (cereal-based diet) or from more refined products (purified diet). The type of diet may influence both the outcome of the study and the values obtained with the various parameters in test and control animals. To detect the parameters sensitive to changes in diet composition, short-term (4-wk) studies were conducted in rats, mice and hamsters fed either a cereal-based diet or the AIN-76A purified diet supplemented with vitamins and minerals at the highest recommended levels for each of the species used. Although the purified diet was more palatable to rats and showed a higher protein quality, growth rate and food intake were generally slightly higher with the cereal-based diet in each of the species examined. The haematological values of the two diet groups were generally comparable. On the cereal-based diet the production of faeces was considerably higher than on the purified diet and was accompanied by a higher weight of the caecum. These findings were attributed to the relatively high level and mixed composition of the fibre fraction in the cereal-based diet. Blood levels of cholesterol and phospholipids were clearly lower on the cereal-based diet than on the purified diet. Because the differences were probably due to the level and composition of the fibre fraction, they support the suggestion to replace the 5% cellulose of the AIN-76A diet by a higher level of a more composite but well defined source of dietary fibre.

The toxicity of purified cellulose in studies with laboratory animals

The available literature has been reviewed for studies in laboratory animals using purified cellulose, as the production of purified cellulose may result in trace organochlorine contamination. The chronic ingestion of purified cellulose over the entire lifespans in rats and mice does not result in any increase in spontaneous disease or neoplasia. Further, purified cellulose does not display promotional activity in the mammary gland, the colon, or the bladder of rats and does not significantly alter the absorption or the metabolism of dietary components. No adverse effects were found on reproduction or neonate development in rats and mice. Therefore, no adverse health effects in humans are expected from exposure to purified cellulose.

Haemorrhages due to defective blood coagulation do not occur in mice and guinea-pigs fed butylated hydroxytoluene, but nephrotoxicity is found in mice

Groups of ten male Slc:ddY mice were fed a purified diet containing butylated hydroxytoluene (BHT) at levels of 0, 1.35, 1.75, 2.28, 2.96, 3.85 or 5.00%. They were kept in cages with soft-wood chips as bedding for 30 days. Groups of five Slc:ddY male mice were kept in cages with stainless-steel wire-mesh bottoms (without wood-chip bedding) and fed BHT at 0, 0.5, 1.0 or 2.0% in the diet for 21 days. Male Crj:Hartley guinea-pigs were given a purified ration containing BHT at levels of 0, 0.125 or 0.25% (five animals per group) for 14 days, or at 0, 0.5, 1.0 or 2.0% for 17 days (six animals per group). When BHT was given to mice housed in the mesh-bottomed cages there were one, one and two deaths during the experiment in the 0.5, 1.0 and 2.0% dose groups, respectively. Lung haemorrhages were observed in these dead mice, but in all other mice and guinea-pigs no haemorrhages were found. Indices of prothrombin time and kaolin-activated partial thromboplastin time were significantly decreased by up to 30 and 40%, respectively, in the mice kept on wood-chip bedding, and by up to 40 and 60% in the mice kept in cages with wire bottoms. In guinea-pigs, the prothrombin index was significantly reduced only in the 1.0% BHT group. We conclude that the BHT-induced lung haemorrhages in mice are not caused by a severe reduction in the coagulation process, as they are in rats, and that BHT does not cause bleeding like that observed in rats. However, dose-related toxic nephrosis was found in mice given 1.35-5.0% BHT in the diet. The nephrotoxic ED50(1 month) was 2.3 g/kg body weight/day. The results suggest that an extremely large dose of BHT can cause renal toxicity in mice.