EFFECTS OF SUBCHRONIC INHALATION EXPOSURE OF RATS TO EMISSIONS FROM A DIESEL ENGINE BURNING SOYBEAN OIL-DERIVED BIODIESEL FUEL

There is increasing interest in diesel fuels derived from plant oils or animal fats ("biodiesel"), but little information on the toxicity of biodiesel emissions other than bacterial mutagenicity. F344 rats were exposed by inhalation 6 h/day, 5 days/wk for 13 wk to 1 of 3 dilutions of emissions from a diesel engine burning 100% soybean oil-derived fuel, or to clean air as controls. Whole emissions were diluted to nominal NO x concentrations of 5, 25, or 50 ppm, corresponding to approximately 0.04, 0.2, and 0.5 mg particles/m 3, respectively. Biologically significant, exposure-related effects were limited to the lung, were greater in females than in males, and were observed primarily at the highest exposure level. There was a dose-related increase in the numbers of alveolar macrophages and the numbers of particles in the macrophages, as expected from repeated exposure, but no neutrophil response even at the highest exposure level. The macrophage response was reduced 28 days after cessation of the exposure. Among the high-level females, the group mean lung weight/body weight ratio was increased, and minimal, multifocal bronchiolar metaplasia of alveolar ducts was observed in 4 of 30 rats. Lung weights were not significantly increased, and metaplasia of the alveolar ducts was not observed in males. An increase in particle-laden macrophages was the only exposure-related finding in lungs at the intermediate and low levels, with fewer macrophages and fewer particles per macrophage at the low level. Alveolar histiocytosis was observed in a few rats in both exposed and control groups. There were statistically significant, but minor and not consistently exposure-related, differences in body weight, nonpulmonary organ weights, serum chemistry, and glial fibrillary acidic protein in the brain. There were no significant exposure-related effects on survival, clinical signs, feed consumption, ocular toxicity, hematology, neurohistology, micronuclei in bone marrow, sister chromatid exchanges in peripheral blood lymphocytes, fertility, reproductive toxicity, or teratology. This study demonstrated modest adverse effects at the highest exposure level, and none other than the expected physiological macrophage response to repeated particle exposure at the intermediate level.     

Effects of subchronic inhalation exposure of rats to emissions from a diesel engine burning soybean oil-derived biodiesel fuel

There is increasing interest in diesel fuels derived from plant oils or animal fats ("biodiesel"), but little information on the toxicity of biodiesel emissions other than bacterial mutagenicity. F344 rats were exposed by inhalation 6 h/day, 5 days/wk for 13 wk to 1 of 3 dilutions of emissions from a diesel engine burning 100% soybean oil-derived fuel, or to clean air as controls. Whole emissions were diluted to nominal NO(x) concentrations of 5, 25, or 50 ppm, corresponding to approximately 0.04, 0.2, and 0.5 mg particles/m(3), respectively. Biologically significant, exposure-related effects were limited to the lung, were greater in females than in males, and were observed primarily at the highest exposure level. There was a dose-related increase in the numbers of alveolar macrophages and the numbers of particles in the macrophages, as expected from repeated exposure, but no neutrophil response even at the highest exposure level. The macrophage response was reduced 28 days after cessation of the exposure. Among the high-level females, the group mean lung weight/body weight ratio was increased, and minimal, multifocal bronchiolar metaplasia of alveolar ducts was observed in 4 of 30 rats. Lung weights were not significantly increased, and metaplasia of the alveolar ducts was not observed in males. An increase in particle-laden macrophages was the only exposure-related finding in lungs at the intermediate and low levels, with fewer macrophages and fewer particles per macrophage at the low level. Alveolar histiocytosis was observed in a few rats in both exposed and control groups. There were statistically significant, but minor and not consistently exposure-related, differences in body weight, nonpulmonary organ weights, serum chemistry, and glial fibrillary acidic protein in the brain. There were no significant exposure-related effects on survival, clinical signs, feed consumption, ocular toxicity, hematology, neurohistology, micronuclei in bone marrow, sister chromatid exchanges in peripheral blood lymphocytes, fertility, reproductive toxicity, or teratology. This study demonstrated modest adverse effects at the highest exposure level, and none other than the expected physiological macrophage response to repeated particle exposure at the intermediate level.     

抗HER2靶点抗体偶联药物大鼠重复给药毒性研究

目的：通过对大鼠尾静脉重复注射给药重组抗HER2人源化单克隆抗体偶联美登素衍生物DM1,对其进行临床前安全性评价。方法：大鼠随机分成5个试验组,包括空白对照组、受试物低（5 mg·kg^-1）、中（11 mg·kg^-1）、高（22 mg·kg^-1）剂量组和已知对照药品组（22 mg·kg^-1,Kadcyla?）,每组30只动物,雌性各半。尾静脉注射给药,每周给药1次,连续给药3次,末次给药后恢复3周。研究期间,在不同时间点对动物临床症状、体重、摄食量、体温、尿液、血液学、血清生化及组织病理学等指标进行检测。结果：给药后,动物出现一定程度的不良反应,且作用强度呈剂量依赖性递增。毒副反应症状包括摄食量减少、尿液pH值改变;血液学检查发现,动物Lymph、RBC、HGB、HCT、MCV、MCH、MCHC、APTT下降,WBC、Neut、Mono、Eos、Baso、Retic计数升高;血清生化检查发现,动物TG、A/G、Na⁺、K⁺下降,ALT、AST、ALP、GGT、CHO、LDH、BUN、TP升高;骨髓检查发现,受试物影响动物红系细胞成熟分化;受试物引起动物肝脏、脾脏、肺（含支气管）重量增加,睾丸、附睾重量减少;组织病理学检查发现,肝脏、肾脏、脾脏、垂体、肾上腺、舌、皮肤细胞有丝分裂项增加,睾丸生精细胞数目减少和变性坏死,附睾精子减少和纤维组织增生。对照品组动物,给药后出现上述同样的改变。试验结果表明,受试物和已知对照药品两种药物的大鼠毒性研究结果具有相似性。结论：大鼠尾静脉重复注射给予重组抗HER2人源化单克隆抗体偶联美登素衍生物DM1后,毒性靶器官为肝脏、肾脏、脾脏、胸腺、肺（含支气管）、肠系膜淋巴结、十二指肠、睾丸、附睾、眼球、垂体、肾上腺、皮肤、舌、胸骨（骨髓）。未见毒性反应剂量（NOAEL ≤ 5 mg·kg^-1）。上述研究结果支持该药物成功获得临床试验批准,为后续开展临床研究提供了参考依据。     

Isopropanol 13-Week Vapor Inhalation Study in Rats and Mice with Neurotoxicity Evaluation in Rats

This study was conducted to evaluate the possible subchronictoxicity as well as neurobehavioral effects of isopropanol,a widely used industrial and commercial solvent. Five groups,each containing 10 Fischer 344 rats/sex and 10 CD-I mice/sex,were exposed for 6 hr/day, 5 days/week, for 13 weeks to isopropanolvapor at concentrations of 0 (control), 100, 500, 1500, or 5000ppm. An additional 15 rats/sex were assigned to the 0, 500,1500, and 5000 ppm groups for assessment of neurobehavioralfunction. No exposure-related mortalities occurred during thestudy. The narcotic effects of isopropanol were noted only duringexposures at 1500 and 5000 ppm. These signs, noted during exposures,were typically absent following exposures. The only clinicalsigns observed following exposures included swollen perioculartissue, perinasal encrustation, and ataxia for rats of the 5000ppm group. Neurobehavioral evaluations indicated no changesin any of the parameters of the functional observational battery;however, increased motor activity for female rats in the 5000ppm group was noted at Weeks 9 and 13. Decreases in body weightand body weight gain were observed for rats of the 5000 ppmgroup at the end of the first week of exposure. During the remainingweeks, increases in body weight and/or body weight gain wereobserved for rats of the 1500 and 5000 ppm groups. No exposure-relatedeffects on body weight were noted for male mice; however, increasedbody weight and body weight gain were observed for female miceof the 5000 ppm group. Increases or decreases in food and waterconsumption generally corresponded to changes in body weightand body weight gain. Various changes in clinical pathologyparameters were observed for rats and female mice of the 5000ppm group. The only organ weight effect noted was an increasedrelative liver weight in both sexes of rats of and female miceof the 5000 ppm group. At necropsy, three were no gross lesionsdetermined to be exposure related. Furthermore, the only microscopicchange observed was hyaline droplets within the kidneys of allmale rats (including controls). The size and frequency of thehyaline droplets were increased for the isopropanol exposuregroups compared to the control group. These differences werenot clearly concentration related, although this microscopicchange was most pronouced in the high-concentration group. Neuropatholo0gicexamination revealed no exposure-related lesions in the centralor peripheral nervous system of exposed rats. Thus, repeatedexposures to isopropanol for 13 weeks produced toxic effctsonly at the highest concentration and a kidney change in malerats of unknown biological significance.     

Subchronic hepatotoxicity evaluation of 1,2,4-tribromobenzene in Sprague-Dawley rats

Male Sprague-Dawley rats were exposed to 1,2,4-tribromobenzene (TBB) by gavage for 5 days, 2, 4, and 13 weeks at 0, 2.5, 5, 10, 25, or 75 mg/kg per d. There were no TBB exposure-related clinical signs of toxicity or changes in body weight. Liver weight increases were dose and exposure time related and statistically significant at ≥10 mg/kg per d. Incidence and severity of centrilobular cytoplasmic alteration and hepatocyte hypertrophy were dose and time related. The 75 mg/kg per d group had minimally increased mitoses within hepatocytes (5 days only). Hepatocyte vacuolation was observed (13 weeks) and was considered TBB exposure related at ≥25 mg/kg per d. Concentrations of blood TBB increased linearly with dose and at 13 weeks, ranged from 0.5 to 17 μg/mL (2.5-75 mg/kg per d). In conclusion, rats administered TBB doses of 10-75 mg/kg per d for 13 weeks had mild liver effects. A no observed adverse effect level of 5 mg/kg per d was selected based on the statistically significant incidence of hepatocyte hypertrophy at doses ≥10 mg/kg per d.     

Subacute toxicity assessment of carotenoids extracted from citrus peel (Nanfengmiju, Citrus reticulata Blanco) in rats

The mixture of carotenoids extracted from citrus peel (Nanfengmiju, Citrus reticulata Blanco) was tested for subacute oral toxicity. In this study, dose levels of 0, 200, 500 and 2000 mg/kg body weight/day were administered by gavage to 10 Wistar rats/sex/group for 28 days. No statistically significant, dose-related effect on food consumption, food efficiency, body weight gain, clinical signs or ophthalmoscopic parameters was observed in any treatment group. Urinalysis, hematological, blood coagulation and serum biochemical examination as well as necropsy or histopathology showed that no observed adverse effect was found. These findings suggested that the No-Observed-Adverse-Effect Level for the mixture of carotenoids extracted from citrus peel was at least 2000 mg/kg body weight/day.     

Safety assessment of yerba mate (Ilex paraguariensis) dried extract: results of acute and 90 days subchronic toxicity studies in rats and rabbits

Acute toxicity of yerba mate dried extract (YMDE) was investigated in Wistar rats (6/sex/group) from single dose of 2g/kg body weight by intragastric administration and 14days monitoring. Subchronic toxicity was investigated in Wistar rats, by intragastric administration (10/sex/group), and in New Zealand rabbits by oral administration (3/sex/group) of 2g/kg body weight for 12weeks. Toxicological parameters included clinical signs, body weight, water, and food consumption, hematological and serum parameters, and histopathological assessment. Acute YMDE administration showed no effects on survival, clinical observations, macroscopic examination of organs, body weight or food, and water consumption. Sub-chronic administration of YMDE did not change behavior, body weight, and histopatological assessment of stomach, kidney, liver, and small gut. Moreover, most of biochemical and hematological parameters remained unchanged. In summary, the results of our preclinical toxicological investigation are indicative that the YMDE is well tolerated for both single and chronic administration.     

13-WEEK INHALATION TOXICITY STUDY (INCLUDING 6- AND 13-WEEK RECOVERY PERIODS) WITH AMMONIUM PERSULFATE DUST IN ALBINO RATS

The subchronic inhalation toxicity of ammonium persulfate was characterized using Sprague-Dawley rats (20/sex/group) at respirable dust concentrations of 0, 5.0, 10.3, and 25 mg/m 3. Whole-body exposures were conducted 6 h/day, 5 days/wk for 13 wk. Gravimetric airborne test material samples were taken daily and particle size samples were taken weekly from each exposure chamber for analysis. Ten animals/sex/group were necropsied after 13 wk of exposure, and 5 animals/sex/group were held for 6- and 13-wk recovery periods. Animals were observed for clinical signs. Effects on body weight, food consumption, clinical chemistry and hematology, ophthalmologic parameters, organ weights, gross lesions, and histopathology were evaluated. There were no exposure-related deaths during the study. Rales and increased respiration rate were noted in both males and females in the 25 mg/m 3 group, and in a few animals in the 10.3 mg/m 3 group. The incidence of these clinical signs decreased to zero during the first few weeks of the recovery period. Body weights for both males and females in the 25 mg/m 3 group were significantly depressed during most of the exposure period compared to the control group. By the end of the recovery period, body weights for the exposed animals were similar to the control group values. Lung weights were elevated in the 25 mg/m 3 group after 13 wk of exposure, but were similar to controls at 6 wk postexposure. Irritation of the trachea and bronchi/bronchiole was noted microscopically after 13 wk of exposure to 25 mg/m 3. These lesions had recovered by 6 wk postexposure. Based on the results of this study, the no-observed-adverse-effect level (NOAEL) was 10.3 mg/m 3, while the no-observed-effect level (NOEL) for exposure of rats to a dust aerosol of ammonium persulfate was 5.0 mg/m 3 .     

Two-week aerosol inhalation study on polyethylene glycol (PEG) 3350 in F-344 rats

PEGs in the 3000 to 4000 MW range are used in many pharmaceutical and cosmetic applications; they produce little ocular or dermal irritation and have extremely low acute and subchronic toxicity by oral and dermal routes of administration. However, little information exists on the potential of aerosols of these materials to produce adverse health effects. F-344 rats were exposed to aerosols of PEG 3350 (20% w:w in water) at 0, 109, 567, or 1008 (highest attainable) mg/m3 for 6 hr/d, 5 d/wk for 2 wk. No exposure-related toxicity was found with regard to clinical signs, ophthalmology, serum chemistry, urinalysis, or gross pathology. Exposure-related effects included: a 50% increase in the neutrophil count (males only) at 1008 mg/m3; decreased body weight gain (16%) for both the 567 and 1008 mg/m3 groups (males only); absolute lung weights of both sexes were increased 10 and 18% for the 567 and 1008 mg/m3 groups, respectively. A slight increase in the number of macrophages in the alveoli was the only change observed histologically in all PEG 3350-exposed groups. Therefore, inhalation of aerosols of PEG 3350 at concentrations up to 1008 mg/m3 produced relatively little toxicity in rats, the lung was the target organ, and the no-observable-effect-level was between 109 to 567 mg/m3.     

A 90-day subchronic toxicity study of beta-calcium pyrophosphate in rat

β-calcium pyrophosphate has been used as a bone-graft extender. The present study evaluated the toxicity from the subchronic administration of β-calcium pyrophosphate to male and female Sprague-Dawley rats. Animals were divided into two groups consisting of 10 male and 10 female rats each and fed β-calcium pyrophosphate extract (30?mg/kg body weight/day) and saline, 7 days per week for 90 consecutive days. During the experiment, no deaths were observed in any groups, and there were no remarkable changes in clinical signs, body weight, food and water consumption, hematological and serum biochemical parameters, organ weight, and histopathological findings between the control and treated groups. The results show no adverse toxic effects of β-calcium pyrophosphate extract (30?mg/kg body weight/day) for rats of either sex.     

Arsenic levels in cooked food and assessment of adult dietary intake of arsenic in the Region Lagunera, Mexico.

The aim of this paper is to estimate the levels of arsenic (As) ingestion through cooked foods consumed in an arsenic endemic area and the assessment of their dietary intake of As. The study was conducted in two villages: a population chronically exposed to a high concentration of As via drinking water (410+/-35 microg/l) and to a low-exposure group (12+/-4 microg/l). A 24-h dietary recall questionnaire was applied to about 25 adult participants in each community. Samples of cooked food, ready for intake, were collected separately from each family's participants. To obtain the As estimate for each food item consumed, the mean quantity of food ingested in grams (wet weight) was calculated and the concentrations of total arsenic (TAs) in each cooked food were determined. The estimations of TAs intake were based on the sum over mean of As ingested from each food item consumed during the 24-h period for each participant. For the estimation of total daily As intake, we summed the mean obtained from food, plain water and hot beverage intakes. The TAs average intakes calculated for low-As-exposure group were 0.94 and 0.76 microg/kg body weight/day, for both summer and winter exposure scenarios, respectively. These values are 44.7 and 36% of the provisional tolerable daily intake (PTDI) for inorganic arsenic (2.14 microg/kg body weight/day), established by the World Health Organization (WHO) in 1989. The WHO reference value was obtained on a weekly basis intake estimation assuming an average body weight of 68 kg in adults. In contrast, for the high-exposure group the TAs average intakes were 16.6 and 12.3 microg/kg body weight/day for summer and winter, respectively. Ingestion via cooked food represented 32.5 and 43.9% of the total daily As intake in the high-exposure group; for summer and winter, respectively. None the less, the bioavailability of As through food can be different than via drinking water.     

Thirteen-week oral toxicity study of synthetic lycopene products in rats.

Synthetic crystalline lycopene provides an alternative to extracts of naturally occurring lycopene for use in dietary supplements and functional foods. BASF Lycopene 10 CWD and Lyco Vit 10% formulated products each contain approximately 10% synthetic lycopene. These products were evaluated for toxicological and behavioral effects during a 13-week oral dosing study with male and female Wistar rats. Doses of 0, 500, 1500 and 3000 mg/kg body weight/day Lycopene CWD and 3000 mg/kg body weight /day Lyco Vit, as well as 3000 mg/kg body weight /day of the matrices used to formulate and stabilize each product, were administered by gavage to 10 rats/sex/day. A satellite group of five rats/sex received 0 or 3000 mg/kg body weight /day of each formulated product for an interim evaluation at 4 weeks of feeding. No statistically significant, dose-related effects on body weight, body weight gain, food consumption, hematology, urinalysis, clinical chemistry or ophthalmoscopic parameters were seen in any of the lycopene product or lycopene formulation matrix groups in comparison to the vehicle control group after 4 or 13 weeks of dosing. No deaths attributed to the test articles occurred during the study and the only clinical finding and at necropsy was the presence of red pigment in the feces and gastrointestinal tract that was associated with the red-pigmented test materials. No significant or dose-related abnormalities were found at necropsy or in microscopic evaluations of tissues collected at termination. Rats evaluated in home cages or in open field tests for behavioral and sensorimotor effects during the final week of the study showed no signs of treatment-related effects. The no-observed-adverse-effect level (NOAEL) for this study was concluded to be 3000 mg/kg body weight/day for both Lycopene CWD and Lyco Vit. The results of this study thus demonstrate the absence of any significant toxicological findings with Lycopene CWD and Lyco Vit products even at very high dose levels.     

复方冰甲乳膏长期毒性试验研究

目的:观察复方冰甲乳膏对大鼠的长期毒性。方法:将80只SD大鼠,雌雄各半,随机分为4组,分别是空白对照组和受试药高剂量组(3.00 g·kg-1)、中剂量组(1.50 g·kg-1)、低剂量组(0.75 g·kg-1),每组20只,每天皮肤涂抹一次,每周6 d,连续给药13周,停药恢复2周。观察一般状况、体质量及进食量。同时检测大鼠的血常规、血生化、脏器系数和组织病理学改变。结果:各剂量组大鼠外观体征、行为活动等无明显异常,体质量、摄食量增加正常;血常规指标、血生化指标、脏器系数与对照组比较差异均无统计学意义(P>0.05),组织病理学检查未出现任何异常改变。结论:复方冰甲乳膏对SD大鼠皮肤涂抹给药13周,未出现明显的毒性作用。     

坤灵丸对雌性大鼠生育力及胚胎-胎仔发育影响的研究

目的 评价坤灵丸对雌性大鼠的生育力及胚胎发育的影响。方法 在生育力及早期胚胎发育毒性研究中,每组25只雌性SD大鼠从交配前14 d开始,每天ig给予1次坤灵丸（0.875、1.750、3.500 g制剂/kg）或去离子水至妊娠第7天,评价雌鼠症状、体质量、摄食量、生殖能力和早期胚胎发育情况;在胚胎-胎仔发育毒性研究中,每组25只雌性SD大鼠从妊娠第6~15天每天ig给予坤灵丸（0.875、1.750、3.500 g制剂/kg）或去离子水1次,评价妊娠母鼠的症状、体质量、摄食量、生殖能力及胎仔的体质量、性别和外观、内脏、骨胳发育的畸形或变异。结果 在生育力及早期胚胎发育毒性研究和胚胎-胎仔发育毒性研究中,坤灵丸给药剂量达到3.500 g/kg时未产生任何药物相关的母体毒性和胚胎毒性。结论 本试验条件下,雌鼠生育力及胚胎发育毒性的安全剂量为3.500 g/kg,按照体质量计算,该剂量相当于人用最大临床使用剂量的43.2倍。     

Subchronic toxicity studies of the aqueous extract of Aristolochiae fructus in Sprague-Dawley rats

The subchronic toxicity of Aristolochiae fructus containing aristolochic acids (AAs), a natural component in the Aristolochiaceae family, was investigated. The A. fructus was daily administered by gavage to male and female rats for 90 d at dose levels of 21.35, 213.5, and 2135 mg/kg (equivalent to 0.05, 0.5, and 5 mg/kg as AAs, respectively). During the test period, clinical signs, mortality, body weights, food and water consumption, hematology, serum biochemistry, organ weights, and histopathology were examined. Significant decreases in body weight gain were noted in the high-dose group receiving both the aqueous extract of A. fructus and AAs. Decreases in food consumption were noted beginning at 50 d and did not recover in the high-dose group of aqueous extract of A. fructus and AAs. Irrespective of dose, water consumption was not affected. There was no mortality or adverse clinical signs, hematology, or serum biochemistry in the treatment groups versus control. Nephrotoxicity and hyperplasia of epithelial cells in the forestomach were observed in rats receiving the highest dose of aqueous extract of A. fructus and at doses of >or= 0.5 mg/kg/day AAs. For both genders, the no-observed-adverse-effect level (NOAEL) for A. fructus based on this subchronic study in rats was considered to be 21.3 mg/kg/d.     

Effects of chronic haloperidol treatment on ingestive behaviour and body weight regulation in the rat

This study was designed to investigate the effects of two doses of haloperidol on body weight, food spillage and food and water intake using rats as subjects. In the first experiment, 12 male Wistar albino rats were observed in individual cages for 30 days, six receiving a daily injection of haloperidol (1 mg/kg IP in 1 ml/kg isotonic saline), while the other six received a control injection of isotonic saline in the experimental phase. In the second experiment, 12 rats were observed for 9 days in individual cages, six receiving a daily injection of 10 mg/kg haloperidol in 4 ml/kg isotonic saline in the experimental phase. In both studies, haloperidol depressed food intake and food spillage. With the lower dose of haloperidol (1 mg/kg), body weight was not depressed until several days after a significant reduction of food intake had been recorded. With the higher dose (10 mg/kg), body weight was depressed during the first 24 h, but quickly returned to normal, although food intake remained depressed. It is suggested that haloperidol may have a limited facilitatory effect on body weight.     

Safety evaluation of short-term exposure to chitooligomers from enzymic preparation.

Chitooligomers have significant application to the development of functional foods. This paper evaluated systematically the safety of chitooligomers, which were prepared by enzymatic depolymerization of chitosan. The oral maximum tolerated dose of this chitooligomes was more than 10 g/kg body weight in mice. It had no mutagenicity judged by negative experimental results of Ames test, mouse bone marrow cell micronucleus test and mouse sperm abnormality test. A 30-day feeding study shows that no abnormal symptoms and clinical signs or deaths were found in rats during the test. There were no significant difference in body weight, food consumption and food availability of rats in each test group. No significant differences were found in each hematology value, clinical chemistry value and organ/body weight ratio, either. No abnormality of any organ was found during histopathological examination. It is concluded that short-term ingestion of chitooligomers is of non-toxicity.     

Phenylsilsesquioxane fluid: developmental toxicity studies in rats and rabbits following oral administration

Phenylsilsesquioxane fluid (PSF) is used widely in the personal care industry and is a common component of skin and oral care products. The potential developmental toxicity of PSF was evaluated in rats and rabbits. Groups of 25 sperm-positive Sprague-Dawley rats (Taconic Farms) and 15 sperm-positive New Zealand White rabbits (HRP) were administered dose levels of 50, 500, or 1000 mg/kg PSF in corn oil. Vehicle control groups of equal size were administered corn oil alone. Rats were dosed daily (5 ml/kg) on gestation d 6-15 and sacrificed on gestation d 20, while rabbits were dosed daily (1.5 ml/kg) on gestation d 6-18 and sacrificed on gestation d 29. The fetuses were removed by cesarean section and examined for gross external, visceral, cephalic, and skeletal anomalies. No treatment-related clinical signs of toxicity were observed. No marked effects upon maternal food consumption, body weight, body weight gain, or uterus or liver weight were detected. Fetal viability and body weight, as well as developmental endpoints, were unaffected by treatment. Accordingly, exposure of pregnant rats or rabbits to 50, 500, or 1000 mg/kg of PSF during the period of major organogenesis did not result in any biologically significant adverse or teratogenic effects in the dams or fetuses.     

Evaluation of the developmental toxicity of formamide in Sprague-Dawley (CD) rats.

Timed-pregnant CD(R) outbred albino Sprague-Dawley rats received formamide (50, 100, or 200 mg/kg/day) or vehicle (5 ml/kg deionized/distilled water, po) on gestational days (gd) 6 through 19. Maternal food and water consumption (absolute and relative), body weight, and clinical signs were monitored at regular intervals throughout gestation. At termination (gd 20), confirmed-pregnant females (21-23 per group) were evaluated for clinical status and gestational outcome; live fetuses were examined for external, visceral, and skeletal malformations and variations. There were no maternal deaths and no dose-related clinical signs. At 200 mg/kg/day, maternal body weight on gd 20, weight gain, and gravid uterine weight were significantly decreased. Maternal weight gain, corrected for gravid uterine weight, liver weight (absolute or relative), and food and water consumption (absolute or relative), were not affected. Formamide did not affect prenatal viability or incidences of fetal malformations or variations. Average fetal body weight/litter was decreased at 100 and 200 mg/kg/day. Fetal body weight was affected at lower daily doses than in previously published studies, possibly due to the longer total exposure period and/or lack of a recovery period between cessation of exposure and termination. In summary, the maternal toxicity no-observed-adverse-effect level (NOAEL) was 100 mg/kg/day and the low observed adverse effect level (LOAEL) was 200 mg/kg/day under the conditions of this study. Similarly, the developmental toxicity NOAEL was 50 mg/kg/day and the LOAEL was 100 mg/kg/day.     

Subchronic thyroid toxicity evaluation of 4,4'-methylenebis(N,N'-dimethyl)aniline in Fischer 344 rats

Female F344 rats were exposed to 4,4'-methylenebis(N,N'-dimethyl)aniline (MDA) by dietary feed at concentrations of 0, 50, 200, 375, 500, or 750 ppm for 5 d, 2 wk, 4 wk, and 13 wk duration. Endpoints evaluated included clinical observations, body weights, thyroid weights, serum thyroid hormones, blood MDA, gross pathology, and thyroid histopathology. There were no MDA exposure-related clinical signs of toxicity. Mean body weight decreased 5% compared to control in the 750 ppm group during study wk 6 through 13. Serum TSH increased and serum T4 and T3 levels decreased with increasing feed concentrations of MDA and time of exposure. Thyroid weight increases were both concentration- and exposure time-dependent and statistically significant at ≥375 ppm. Incidence and severity of decreased colloid, follicular cell hypertrophy and follicular cell hyperplasia were also related to MDA concentration and exposure time. A no-observed-adverse-effect level (NOAEL) of 200 ppm was selected based on the statistically significant increase in incidence of follicular cell hyperplasia at concentrations ≥375 ppm.