Evaluation of the Reproductive and Developmental Toxicity of a Fluoroalkylethanol Mixture

The objective of these studies was to evaluate the reproductive and developmental toxicity of a commercial fluoroalkylethanol mixture, which is an intermediate in the production of fluorotelomers. The test substance was administered daily by gavage to Sprague–Dawley rats as a suspension in 0.5% aqueous methylcellulose. In a one-generation reproductive toxicity study, rats (20 per sex per group) were given dosages of 0, 25, 100, or 250 mg kg^{? 1} day^{? 1} for a period of 74 days prior to cohabitation, and during mating, gestation, and lactation. Body weights, feed consumption, clinical signs, gross pathology, sperm parameters, estrous cyclicity, and reproductive performance were evaluated for the P₁ generation. The F₁ offspring were evaluated during the lactation period for growth and survival and given a gross pathology examination at weaning. A subset of the offspring were retained; body weights, feed consumption, clinical signs, and age at onset of vaginal opening and preputial separation were evaluated, and gross pathology was performed on postnatal day 60. In the developmental toxicity study, groups of time-mated Sprague–Dawley female rats were given the test substance as a suspension in 0.5% aqueous methylcellulose at daily dosages of 0, 50, 200, or 500 mg kg^{? 1} day^{? 1} by gavage on gestation days 6–20. During the in-life portion of the study, growth parameters and clinical observations were made. On gestation day 21, dams were euthanized, and the thoracic and abdominal viscera were examined. The uterine contents were removed and examined, and fetuses were evaluated for any alterations. In the reproduction study, litter size at birth, number of live pups per litter on day 0 and 4 of lactation, and pup weights during lactation were reduced in groups administered ≥ 100 mg kg^{? 1} day^{? 1}. No other reproductive parameters were affected. There were no adverse reproductive effects observed at 25 mg kg^{? 1} day^{? 1}. In the developmental toxicity study, reduced maternal body weight parameters, increased perineal fur staining, and increased fetal skeletal alterations were observed at 500 mg kg^{? 1} day^{? 1}. There was no maternal or developmental toxicity at 50 or 200 mg kg^{? 1} day^{? 1}. Under the conditions of the studies, the no-observed adverse effect levels for this mixture were 25 mg kg^{? 1} day^{? 1} for subchronic toxicity and reproductive parameters and 200 mg kg^{? 1} day^{? 1} for developmental toxicity end points. No functional reproductive or developmental effects were observed at dose levels that did not adversely affect adult animals.     

Evaluation of the Developmental Toxicity of 8-2 Telomer B Alcohol

The potential maternal and developmental toxicity of 8-2 Telomer B Alcohol was assessed in rats. Groups of 22 time-mated female Crl:CD (SD)IGS BR rats were administered oral gavage doses as suspensions of 8-2 Telomer B Alcohol in aqueous 0.5% methylcellulose from day 6 through 20 of gestation (G) at daily doses of either 0, 50, 200, or 500 mg/kg. Under the conditions of this study, adverse maternal toxicity was produced at 500 mg kg^{? 1} day^{? 1} and consisted of maternal mortality, decreased body weights and body weight gains, and increased clinical observations of toxicity. One litter at 500 mg kg^{? 1} day^{? 1} consisted of one early resorption and was believed to be secondary to overt maternal toxicity, although single conceptus litters occur historically in this strain of rats. Developmental toxicity at 500 mg kg^{? 1} day^{? 1} consisted of increased fetal skeletal variations (delayed pelvic bone ossification and wavy ribs). At 200 and 500 mg kg^{? 1} day^{? 1}, there were transient reductions in maternal feed consumption. In addition, there were slight increases in the incidence of delayed fetal skull bone ossification at 200 and 500 mg kg^{? 1} day^{? 1}. The no-observed-adverse-effect level (NOAEL), defined as the highest dose at which adverse effects attributable to the test substance were not detected, for both maternal and developmental toxicity, is considered to be 200 mg kg^{? 1} day^{? 1}. Thus, 8-2 Telomer B Alcohol is not considered to be a selective developmental toxicant in rats. The transient and quantitative nature of the observations in the 200 mg/kg group supports the conclusion that these findings were not adverse.     

Reproductive and Developmental Toxicity Screening Study of 4-Aminophenol in Rats

Twelve male and female rats per group were given 4-aminophenol (PAP) by gavage at 0, 20, 100, or 500 mg/kg/day. Males were dosed for a total of 49 days, beginning 14 days before mating. Females were dosed for a total of 40–60 days, from 14 days before mating to Day 3 of lactation throughout the mating and gestation periods. Four males and 2 females died at 500 mg/kg/day, and all surviving males and females showed brown urine at 100 mg/kg/day and above. Body-weight gain was lower in males and females at 500 mg/kg/day, and food consumption was decreased in males at 500 mg/kg/day and in females at 100 and 500 mg/kg/day. Absolute and relative weights of the testes and epididymides were decreased at 500 mg/kg/day. Histopathological examinations revealed decreased spermatocyte and spermatid levels in the testis, debris of germ cell in the epididymis lumen, basophilic tubules in the kidney, and deposits of hemosiderin in the red pulp and extramedullary hematopoiesis in the spleen in males at 500 mg/kg/day. Longer gestation period, decreased delivery index, and lower body weight of pups on postnatal day (PND) 0 and increased number of stillborns at 500 mg/kg/day were also observed. At this dose, the viability of pups on PND 4 was decreased markedly. No adverse effects on reproduction or development were detected at 20 and 100 mg/kg/day. These findings indicate that PAP is general and reproductive/developmental toxic, but is unlikely to be teratogenic, in rats.     

Reproductive and Developmental Toxicity of Phthalates

The purposes of this review are to (1) evaluate human and experimental evidence for adverse effects on reproduction and development in humans, produced by exposure to phthalates, and (2) identify knowledge gaps as for future studies. The widespread use of phthalates in consumer products leads to ubiquitous and constant exposure of humans to these chemicals. Phthalates were postulated to produce endocrine-disrupting effects in rodents, where fetal exposure to these compounds was found to induce developmental and reproductive toxicity. The adverse effects observed in rodent models raised concerns as to whether exposure to phthalates represents a potential health risk to humans. At present, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and butyl benzyl phthalate (BBP) have been demonstrated to produce reproductive and developmental toxicity; thus, this review focuses on these chemicals. For the general population, DEHP exposure is predominantly via food. The average concentrations of phthalates are highest in children and decrease with age. At present, DEHP exposures in the general population appear to be close to the tolerable daily intake (TDI), suggesting that at least some individuals exceed the TDI. In addition, specific high-risk groups exist with internal levels that are several orders of magnitude above average. Urinary metabolites used as biomarkers for the internal levels provide additional means to determine more specifically phthalate exposure levels in both general and high-risk populations. However, exposure data are not consistent and there are indications that secondary metabolites may be more accurate indicators of the internal exposure compared to primary metabolites. The present human toxicity data are not sufficient for evaluating the occurrence of reproductive effects following phthalate exposure in humans, based on existing relevant animal data. This is especially the case for data on female reproductive toxicity, which are scarce. Therefore, future research needs to focus on developmental and reproductive endpoints in humans. It should be noted that phthalates occur in mixtures but most toxicological information is based on single compounds. Thus, it is concluded that it is important to improve the knowledge of toxic interactions among the different chemicals and to develop measures for combined exposure to various groups of phthalates.     

Assessment of a Short-Term Reproductive and Developmental Toxicity Screen

Short-term tests for reproductive and developmental toxicityare needed to provide preliminary data on the toxicity of chemicals about which little or no data exist. An ideal design wouldtest all aspects of reproduction and identify the target processin a short time period. One potential design has been evaluatedusing four chemicals of varying reproductive/developmental toxicity.Swiss mice were mated for 3 days prior to chemical exposureto produce time-mated females for gestational exposure and toascertain fertility of the untreated males. The group of time-matedfemales was treated during Gestation Days 8–14 and allowedto litter for observations through Postnatal Day (PND) 4. Endpointsobserved included pup number and body weights on PND 0, 1, and4 and number of uterine implantation sites on PND 4. A secondgroup of females was dosed daily for 19 days. After 7 days,these females (n = 10/group) were cohabited with male mice whohad been treated for 5 days prior to this second mating. Dailychemical dosing continued during the 5-day cohabitation. Thissecond group of females was killed after 19 days of treatmentand the number of live and dead fetuses and implantation siteswas recorded. After 17 days of dosing, male mice were killedand the reproductive system evaluated by organ weights, totalepididymal sperm counts and motility, and testicular histology.All four chemicals tested, boric acid, ethylene glycol, ethyleneglycol monomethyl ether, and theophylline, were found to betoxic to development or reproduction when tested previouslyby conventional developmental toxicity or continuous breedingprotocols. This short-term (21 day) design correctly identifiedthree of these four chemicals as reproductive and developmentaltoxicants and distinguished the potent toxicants from the lesseffective compounds. This design can be used to prioritize chemicalsfor further study, or to delineate the relative toxicities ofstructurally related chemicals, and to identify the proper doserange for subsequent toxicity studies.     

生物技术药物的发育和生殖毒性评价

由于生物技术药物与小分子药物本身存在差异,发育和生殖毒性(DART)评价应考虑受试物的种属特异性、免疫原性、生物活性和暴露情况,并采取灵活、个案处理和基于科学的方法进行研究.当传统种属(如啮齿类、兔)不是药理学相关物种时,DART评价首选非人灵长类动物模型.若生物技术药物只与人或黑猩猩产生交叉反应,DART评价可使用针对传统种属开发的同源蛋白(替代分子)作为受试物.此外,还可使用转基因动物进行DART评价.     

Acute, Subchronic, and Developmental Toxicity and Genotoxicity of 1,1,1-Trifluoroethane (HFC-143a)

The toxicity potential of 1,1,1-trifluoroethane (HFC-143a),a CFC alternative, was evaluated in several acute, subchronic,and developmental toxicity studies by the inhalation route andin genotoxicity studies. HFC-143a has a very low acute inhalationtoxicity potential as shown by a 4-hr LC50 of >540,000 ppmin rats. HFC-143a has a low potential to induce cardiac sensitizationin experimental screening studies in dogs; only the highestconcentration tested—300,000 ppm—elicited a cardiacsensitization response. In an initial 4-week nose-only inhalationstudy, male and female rats were exposed 6 hr/day, 5 days/weekat concentrations of 0, 2000, 10,000, or 40,000 ppm. Femalesshowed no evidence of toxicity at any exposure level; male ratsdid exhibit degenerative changes only in the testes at all exposurelevels. However, because of exposure system irregularities,which resulted in excessive temperature conditions and stressin the HFC-143a-exposed groups, the study was repeated in malerats exposed by whole-body inhalation. In this repeat studyno toxicity was observed at 40,000 ppm. Moreover, a subsequent90-day whole-body inhalation study in rats exposed 6 hr/day,5 days/week at 0, 2000, 10,000, or 40,000 ppm resulted in noevidence of toxicity at any exposure concentration. The resultsof the second 4-week and the 90-day studies using whole-bodyexposures indicate that the findings from the first 4-week studywere related to the stress induced by excessive temperaturesand nose-only restraint. Therefore, the no-observed-effect level(NOEL) for rats repeatedly exposed up to 90 days was consideredto be 40,000 ppm. In developmental toxicity studies with ratsand rabbits, an increase in visceral variations or skeletalmalformations was observed, respectively, at HFC-143a concentrationsof 2000, 10,000, or 40,000 ppm (rat) or at the low and highconcentrations (rabbit). Because of the unusually low controlincidence of variations (1.6% per litter in the control versus6.8–16.8% for historical control values), the lack ofa clear dose-response relationship, and the lack of other developmentaleffects, these findings were not considered related to HFC-143aexposure. In adition, results from genotoxicity studies (Ames,chromosomal aberration with human lymphocytes, mouse micronucleus)demonstrated that HFC-143a Was not mutagenic.     

Reproductive and Developmental Toxicity of N,N-Diethyl-m-toluamide in Rats

N,N-Diethyl-m-toluamide (mDET, DEET) is widely used as a topicalinsect repellent. It is the active ingredient in many consumerformulations, which usually contain 10–25% mDET in analcohol base. More concentrated consumer products are also available,including some that are pure technical grade mDET. Persons livingor employed in mosquito-infested areas may have very high seasonalexposures to mDET. Because contradictory reports had been publishedon the reproductive and developmental toxicity of mDET, a seriesof studies was conducted in male and female Sprague-Dawley rats.All treatments were administered by daily subcutaneous injectionsof undiluted mDET. A dose finding study was done using 12 time-matedfemales per group treated on Gestational Days (GD) 6–15with 0.50, 0.62, 0.78, 0.92, or 1.2 ml mDET /kg/day. No femalessurvived 10 days of mDET dosing with 1.2 ml/kg/day. Deaths occurredin all other groups except the low dose (0.50 ml/kg/ day). Pregnantfemales treated on GD 6–15 with 0 or 0.30 ml/ kg/day wereused for the teratology study. Half of each group was euthanizedon GD 20: the second half was singly housed in nesting boxesand allowed to deliver litters. Live pups were counted and weighedsoon after birth on Postnatal Day (PD) 0 and again on PD 3,9, and 14. Proven fertile males were treated 5 days/week for9 weeks with 0, 0.30, 0.73, 1.15, or 1.80 ml mDET /kg/day fora male dose-finding study. Each group consisted of 20 males.No males survived the 1.80 ml/kg/day. Deaths occurred in allremaining dose groups except the 0.30 ml/kg/ day and controlgroup. Immediately following the final treatment of the maledose study, 11 males were randomly selected from the 0.30 and0.73 ml/kg/day groups. They were cohabited for 7 days with 4females per male during post-treatment Weeks 1 and 2. Half ofthe females were euthanized 12–14 days after the lastday of cohabitation for a dominant lethal study; the remainingfemales were singly housed in nesting boxes and allowed to deliverlitters. Live pups were counted and weighed on PD 0 and 3. Therewas no evidence of reproductive or developmental toxicity inany of these assays, but there were signs of neuro-toxicityin treated adult male and female rats, which may relate to reportsof neurotoxicity in humans heavily exposed to mDET -containinginsect repellents, o 1992 society of Toxicology.     

Oral Toxicity Study of 2-Pentenenitrile in Rats with Reproductive Toxicity Screening Test

A combined repeated-dose toxicity study with reproduction was conducted with 2‐pentenenitrile (2-PN). Rats (10/sex per dose level) were dosed with 2-PN once daily by gavage at dose levels of either 0, 1, 3, or 10 mg kg^?1 day^?1 for 28 days, prior to and during cohabitation, and through day 3 of lactation. General clinical observations were recorded daily; body weights were recorded weekly. A neurobehavioral evaluation consisting of a functional observational battery and motor activity was conducted in all parental rats (10/sex per group). Clinical pathology parameters (hematology, clinical chemistry, coagulation) were measured in parental rats. Pup weights and clinical signs were recorded at birth and on lactation day 4. Parental rats were given a gross pathological examination, organ weights were obtained, and histological examination was conducted for the control and 10 mg kg^?1 day^?1 groups. No effects were seen with regard to mortality, clinical signs, functional observational battery and motor activity, hematology, or organ weights. Females receiving 10 mg/kg and males from all dose groups showed lower body weight gains and feed efficiency. Increased albumin concentrations were seen in both sexes given 10 mg/kg. Females in the 10 mg/kg group showed degeneration of the olfactory mucosa. No effects on the numbers of pups born, number surviving to lactation day 4, pup weight, and no gross anatomical development changes were observed. Under the conditions of this study, the no-observed-effect level (NOEL) for systemic toxicity in rats was 3 mg kg^?1 day^?1, based on degeneration of olfactory mucosa in females at 10 mg kg^?1 day^?1. The NOEL for reproductive and neurobehavioral toxicity in rats and for toxicity to offspring was 10 mg kg^?1 day^?1, the highest dose level tested.     

Subchronic feeding study of grain from herbicide-tolerant maize DP-Ø9814Ø-6 in Sprague-Dawley rats

This 13-week feeding study conducted in Sprague-Dawley rats evaluated the potential health effects from long-term consumption of a rodent diet formulated with grain from genetically modified (GM), herbicide-tolerant maize DP-Ø9814Ø-6 (98140; trade name Optimum^® GAT^® (Optimum^® GAT^® is a registered trademark of Pioneer Hi-Bred)). Metabolic inactivation of the herbicidal active ingredient glyphosate was conferred by genomic integration and expression of a gene-shuffled acetylase coding sequence, gat4621, from Bacillus licheniformis; tolerance to acetolactate synthase (ALS) inhibiting herbicides was conferred by overexpression of a modified allele (zm-hra) of the endogenous maize ALS enzyme that is resilient to inactivation. Milled maize grain from untreated (98140) and herbicide-treated (98140+Gly/SU) plants, the conventional non-transgenic, near-isogenic control (091), and three commercial non-transgenic reference hybrids (33J56, 33P66, and 33R77) was substituted at concentrations of 35–38% w/w into a common rodent chow formula (PMI^® Nutrition International, LLC Certified Rodent LabDiet^® 5002) and fed to rats (12/sex/group) for at least 91 consecutive days. Compared with rats fed diets containing grain from the conventional near-isogenic control maize, no adverse effects were observed in rats fed diets containing grain from 98140 or 98140+Gly/SU maize with respect to standard nutritional performance metrics and OECD 408-compliant toxicological response variables [OECD, 1998. Section 4 (Part 408), Health Effects: Repeated Dose 90-Day Oral Toxicity Study in Rodents, Guideline for the Testing of Chemicals. Organisation of Economic Co-operation and Development, Paris, France]. These results support the comparative safety and nutritional value of maize grain from genetically modified Optimum^® GAT^® and conventional, non-transgenic hybrid field corn.     

Subchronic 3-month oral toxicity study of grape seed and grape skin extracts

Meganatural™ brand grape seed extract (GSE) and grape skin extract (GSKE), containing proanthocyanidin (PAC) polyphenolic compounds, are intended for use in food as functional ingredients exhibiting antioxidant activity. Proanthocyanidins, as well as the minor constituent phenolic compounds in GSE and GSKE, are present naturally in many foods such as fruits, vegetables, chocolate, tea, etc., and on average people consume 460–1000 mg/day of these combined substances. Although humans have ingested PACs for centuries without reported adverse effects, the current toxicology literature contains relatively little formal evidence regarding their safety. Accordingly, as part of a program to investigate the safety of GSE and GSKE, these products were incorporated into chow and fed to rats for at least 3 months in a GLP-compliant subchronic toxicity study. Groups of CD^® (Sprague–Dawley) Crl:CD^® IGS BR rats (20 males and 20 females per group) were fed diets containing GSE at concentrations of 0, 0.63, 1.25 or 2.5% (w/w); GSKE was fed at 2.5% (w/w) only. Clinical observations were recorded and body weight and feed consumption measured throughout the study. After 1 month, blood was obtained from 10 rats/sex/group by retrobulbar puncture for interim measurement of clinical pathology. At the end of the study the rats were subjected to a full necropsy, aortic blood samples were collected for clinical pathology, selected organs were weighed and a complete list of tissues was preserved from all animals. Histologic examination was performed on all tissues from control and high-dose GSE and GSKE groups. There were no treatment-related changes that were considered to be of toxicologic significance. Therefore, a dietary concentration of 2.5% GSE or 2.5% GSKE was considered to be a no-observed-adverse effect level (NOAEL). This was equivalent to a time-weighted average dose over the course of the study of approximately 1.78 g/kg body weight/day GSE or GSKE in male rats and 2.15 g/kg body weight/day in female rats.     

Acute, Subacute, and Subchronic Inhalation Toxicity Studies of Respirable Polymeric Methylene Diphenyl Diisocyanate (Polymeric MDI) Aerosol in Rats

Short-term inhalation toxicity studies with respirable polymericmethylene diphenyl diisocyanate (polymeric MDI) aerosol wereperformed in rats. The 4-hr LC50 was found to be 490 mg polymericMDI/m³ (95.5% <4.3 µm). Exposure of (4-week-old) ratsto 0, 2.2, 4.9, or 13.6 mg polymeric MDI/m³ (95% < 5 µm)for 2 weeks resulted in mortality, severe growth retardation,and elevated lung weights at 13.6 mg/m³ at 4.9 mg/m³ slightgrowth retardation and slightly elevated lung weights were observed.A 13-week study with 6-week-old rats exposed to 0.35, 1.4, or7.2 mg polymeric MDI/m³ (95% < 5 µm) revealed transientgrowth retardation and a slightly increased number of pulmonaryalveolar macrophages occasionally accompanied by increased numbersof mononuclear cells and fibroblasts in alveolar septa onlyat 7.2 mg/ m³ In a second 2-week study with 4 or 6-week-oldrats exposed to 14.1 mg polymeric MDI/m³ (95% < 5 µm),4-week-old rats died earlier and in greater numbers than 6-week-oldrats. In a second 13-week study with 6-week-old rats, usingexposure concentrations of 0, 4.1, 8.4, and 12.3 mg polymericMDI/ m³ (95% < 5 µm) and including a 4-week recoveryperiod, 12.3 mg/ m³ induced mortality, growth retardation, severerespiratory distress, increased lung weights, degeneration andhyperplasia of the nasal epithelium, accumulations of macrophagesin the lungs and mediastinal lymph nodes, and focal inflammatorychanges in the lungs. Rats exposed to 8.4 mg/ m³ showed respiratorydistress, lower body weights in males, increased lung weights,and similar, but much less severe, histopathological changesin the respiratory tract and mediastinal lymph nodes. Most ofthe histopathological changes seen at the higher concentrationswere also seen at 4.1 mg/m³ but to a very minor degree and ina few rats only. At the end of the 4-week posttreatment periodthe microscopical changes in nose, lungs, and mediastinal lymphnodes were still present but generally to a much less degreethan at the end of the exposure period. It was concluded thatthe dose-effect curve for repeated exposures of rats to respirablepolymeric MDI is very steep, and that the "no-observed-adverse-effectlevel" of polymeric MDI was 1.4 mg/m³ the actual no-adverse-effectlevel being lower than but most probably very close to 4.1 mg/m³.     

Reproductive and Developmental Toxicity Studies of a Linear Alkylbenzene Mixture in Rats

Alkylate 215, a mixture of linear decyl- to tridecylbenzenes,is an intermediate in the manufacture of detergent sulfonates.A two-generation reproduction study and a developmental toxicitystudy were conducted using single daily doses given by gastricintubation in a corn oil vehicle. In the reproduction study,groups of 30 rats/sex/group were given doses of 0, 5, 50, or500 mg/kg/day. F₀ animals received a 10-week premating treatmentperiod and were then mated to produce a single litter; F₁ adultswere selected from the F₁ litters. F₁ animals were dosed for11 weeks before mating to produce a single litter. Adults andweaned pups received a gross postmortem examination. Histopathologystudies were conducted on reproductive tissues, tissues withgross lesions, and the pituitary gland taken from each adultin the control and high dose groups. In the developmental toxicitystudy, groups of 24 mated female rats were given 0, 125, 500,or 2000 mg/kg/day on Days 6 through 15 of gestation. Dams wereterminated on gestation Day 20 and fetuses were examined forexternal, soft tissue, and skeletal defects. Results of thereproduction study were as follows. At 50 mg/kg/day, pup weightswere decreased at Day 7 in the F₁ litter. At 500 mg/kg/day,decreases were found in the F₁ females in premating and earlylactation weight gains; in both generations in premating weightgains in males and in weight gains during gestation in females;and in litter size, pup viability at birth, Day 0–4 sur vival, and pup weights on Days 14 and 21. The NOAEL for reproductiveeffects was 5 mg/kg/day. The developmental toxicity study foundeffects on several parameters. The only effect noted at 125mg/kg/day was a slight decrease in maternal weight gain. Maternalweight gains were depressed to a greater extent at 500 and 2000mg/kg/day. Ossification variations and delayed ossificationwere increased significantly at 2000 mg/kg/day and were abovecontrol levels at 500 mg/kg/day. The NOAEL for developmentaltoxicity was 125 mg/kg/day. Alkylate 215 did not have any unusualor selective reproductive or developmental toxicity.     

Subchronic feeding study of herbicide–tolerant soybean DP-356Ø43-5 in Sprague–Dawley rats

Optimum™GAT™ ¹ soybean is a genetically modified (GM) soybean containing event DP-356Ø43-5 (356043) that was produced by integration of the coding sequences of the GAT4601 and GM–HRA proteins. In planta expression of these proteins confers tolerance to glyphosate and sulfonylurea/imidazolinone herbicides, respectively. This paper reports the results from a subchronic rat feeding study conducted with 356043 soybeans. Dehulled/defatted toasted meal and toasted ground hulls were prepared from soybeans from untreated plants (356043), herbicide-treated plants (356043 + Gly/SU), non-transgenic isoline control (091), and three commercial non-transgenic reference varieties (93B86, 93B15, and 93M40). Individual diets conforming to standard certified rodent chow formulation (Purina Rodent LabDiet^® 5002) were prepared with 20% meal (w/w) and 1.5% hulls (w/w). Diets were fed to young adult Sprague–Dawley rats (12/sex/group) for at least 93 days. Compared with rats fed the isoline control or conventional reference diets, no biologically-relevant, adverse effects were observed in rats fed diets containing 356043 or 356043 + Gly/SU soybean with respect to body weight/gain, food consumption/efficiency, clinical signs, mortality, ophthalmology, neurobehavioral assessments (sensory response, grip strength, motor activity), clinical pathology (hematology, coagulation, serum chemistry, urinalysis), organ weights, and gross and microscopic pathology. The results from this study indicate that 356043 soybeans are as safe and nutritious as conventional non-GM soybeans.     

Developmental and reproductive toxicity evaluation of toluene vapor in the rat II. Developmental toxicity

The developmental toxicity of toluene was evaluated via whole body inhalation exposure, in pregnant Sprague Dawley rats exposed to toluene (99.9% pure) from gestation day (GD) 6–15 inclusive, 6 h/day, at concentrations of 0, 250, 750, 1500 and 3000 ppm (0, 938, 2812, 5625 and 11250 mg/m³). Doses were selected from a preliminary study performed over a range of concentrations from 0 to 5000 ppm, in which maternal and fetal toxicity were observed at 2000 ppm and above. This study has been cited in various regulatory documents and is presented here to allow greater accessibility to results and conclusions.

Toluene induced clinical signs in pregnant dams (ataxia, hyper-responsivity, increased water intake, decreased food consumption) at 3000 ppm, ataxia and hyper-responsivity at 1500 ppm, and reduced maternal body weight gain at 1500 during the exposure period only and at 3000 ppm from initiation of exposure to GD20. At Caesarean section on GD20, no adverse effects on implantation, number and viability of fetuses, or fetal sex distribution were observed. Litter weight and mean fetal weight was reduced at 3000 ppm and mean fetal weight was reduced at 1500 ppm. Instances of reduced or unossified skeletal elements occurred at the same dose levels. Mean fetal weight was also reduced at 250 ppm but not at 750 ppm. Extensive statistical analysis of fetal body weight data support the conclusion that there is no toxicologically significant dose-related effect on fetal body weight at or below 750 ppm. Low incidences (≤2.5%) of various malformations occurred in the 250, 1500, and 3000 ppm groups; there was no increase in the incidence of specific or total malformations with increased exposure and thus these were not attributed to toluene.

In this Toluene study, the maternal toxicity NOAEL was 750 ppm with a defined maternal and developmental toxicity LOAEL of 1500 ppm.     

Subchronic toxicity and toxicokinetics of long-term intranasal administration of bencycloquidium bromide: a 91-day study in dogs

The subchronic toxicity and toxicokinetics of Bencycloquidium bromide (BCQB) were evaluated after 91-day intranasal administration in dogs at daily dose levels of 2.5, 5.0, and 10.0 mg/kg. Following repeated exposure to medium- or high-dose of BCQB, apparent changes were observed in the levels of blood glucose, creatinine or blood urea nitrogen in both male and female dogs. The no-observed-adverse-effect level (NOAEL) of BCQB was considered to be 2.5 mg/kg/day under the present study conditions. There were no significant gender differences in most indexes of subchronic toxicity throughout the experimental period with the exception of food consumption and body weight, or in the parameters of plasma toxicokinetics after either single-dose or repeated administrations of BCQB at each dosage. In dog, BCQB did not accumulate in blood plasma, while much higher concentrations of BCQB residues were found in most tissues examined (especially the kidney) following 91-day repeated exposure relative to a single dose. In all tissues except the reproductive organs, BCQB concentrations reverted to low levels by 2 weeks post-dosing. The results indicate that blood glucose levels and renal function should be closely monitored when BCQB is used in long-term therapy.     

Subchronic toxicity and toxicokinetics of LZB, a new proton pump inhibitor, after 13-week repeated oral administration in dogs

The subchronic toxicity and toxicokinetics of a novel proton pump inhibitor, pymeprazole (LZB), were investigated in beagle dogs by daily oral administration for 13 consecutive weeks. Three test groups received doses of 30, 100 and 300 mg/kg/day of LZB. Rabeprazole of 60 mg/kg/day was used as positive control. The 13-week repeated oral doses of LZB resulted in objective signs of mild gastrointestinal disturbance for high-dose group animals. One individual dog of high-dose group was found to be lethargy and astasia at the last month of administration; for hematology, mild anemia was observed at high-dose females; for clinical chemistry, higher cholest, trigly and gastrin were observed at high-dose females, higher ASAT, ALAT, cholesterol, triglyceride and gastrin at high-dose males were also observed; for histopathology, the primary effects of LZB were related to gastric mucosa of high-dose group seen by H and E or Grimelius stain. Impairment of surface epithelium was observed by SEM. The treat-related effects basically were reversible for a 4-week drug-free period. As for positive control group, 13-week oral administration of rabeprazole resulted in more severe toxicity than high-dose group of LZB although much lower dose was employed. The accumulation of LZB after 13-week oral administration was not notable at the toxic dose of 300 mg/kg/day. The toxic dose was considered to be 100mg/kg/day and the no-observed-adverse-effect level (NOAEL) to be 30 mg/kg/day, which is much higher than other PPIs. The toxicological target could be stomach, liver, hematological system and nervous system.     

The Reproductive and Developmental Toxicity of Indium in the Swiss Mouse

Indium is increasingly used in a variety of industries, andwhile there are few studies of its developmental toxicity, thereare no reports of its potential reproductive toxicity. Thesestudies were undertaken to investigate the possible reproductivetoxicity of indium and to determine the relative vulnerabilityof males and females. We used, initially, a 21-day combineddevelopmental/reproductive toxicity protocol. Oral exposuresto InCl₃ (250 mg/kg) were without effect on the male reproductivesystem or liver. A kidney effect was demonstrated in males bya decrease in urinary N-acetyl glucosaminidase. The abilityof females to become pregnant was unaffected. However, fetaldevelopment was adversely affected, manifested as increasedintrauterine deaths in the presence of reduced maternal weightgain. A developmental toxicity study identified no increasein fetal malformations, but verified the increased fetal deaths,in the absence of effects on adjusted maternal body weight.In vitro toxicity studies showed that the embryolethality wasat least in part a result of direct toxicity to the conceptus,with effective doses in the low micromolar range. A limiteddisposition study showed that fetuses contained low micromolarconcentrations of indium, more indium than maternal liver, andcomparable to levels that were toxic in vitro. Although studiesof greater exposure duration are required for risk assessment,these data indicate that fetal development is likely to be moreaffected by indium than female or male reproduction, with adverseeffects occurring at low micromolar levels in vivo and at exposuresthat may or may not affect body weight.     

Combined Treatment Potentiates the Developmental Toxicity of Ibuprofen and Acetazolamide in Rats

Aspirin (ASA), an irreversible cyclooxygenase (COX) inhibitor, induces ventricular septal defect (VSD) and diaphragmatic hernia (DH) in rat fetuses when administered on gestation days (GDs) 9–10, a critical period for cardiovascular (CV) and midline development. Evaluation of a spectrum of nonsteroidal antiinflammatory drugs (NSAIDs; reversible COX inhibitors) showed that while some NSAIDs induced VSD in rats, none of the NSAIDs evaluated produced DH. In addition to inhibiting COX, ASA also inhibits carbonic anhydrase. The purpose of this study was to determine whether concurrent inhibition of COX and carbonic anhydrase would produce a teratogenic profile that includes both VSD and DH. To inhibit both COX and carbonic anhydrase, ibuprofen (COX inhibitor) and acetazolamide (carbonic anhydrase inhibitor) were coadministered on GDs 9–10. Groups of 20 female Crl:CD(SD)IGS BR rats were given either 300 mg kg^{? 1} day^{? 1} ibuprofen, 1000 mg kg^{? 1} day^{? 1} acetazolamide, or both (combination of ibuprofen and acetazolamide). Fetuses were evaluated on GD 21 for external and visceral development. Ibuprofen induced VSD in 3.7% of fetuses per litter; no defects in appendicular skeletal development were noted. Acetazolamide induced VSD in 5.9% of the fetuses per litter and appendicular defects in 41% of the fetuses per litter. Coadministration of ibuprofen and acetazolamide produced VSD in 18.7% of the fetuses per litter and appendicular defects in 77% of the fetuses per litter; however, there were no DH. Therefore, while concurrent inhibition of COX and carbonic anhydrase did not produce DH, potentiation was noted for the induction of VSD and appendicular anomalies.     

Developmental Toxicity Studies of Methyl Ethyl Ketoxime (MEKO) in Rats and Rabbits

Abstract

The developmental toxicity of methyl ethyl ketoxime (MEKO), an industrial antioxidant used primarily as an antiskinning agent in alkyd paint, was investigated in rats and rabbits. Following preliminary dose range finding studies, groups of 25 pregnant rats or 18 pregnant rabbits were dosed by gavage with aqueous solutions of MEKO at 0, 60, 200, or 600 mg/kg (rats) or 0, 8, 14, 24, or 40 mg/kg (rabbits) on gestation days 6–15 or 6–18, respectively. In rats, dose-dependent clinical signs of maternal toxicity including reduced body weight gains were noted at 200 and 600 mg/kg. At 60 mg/kg and above enlarged spleens were observed at necropsy. The preliminary study found methemoglobin formation and reticulocytosis indicative of anemia at these dose levels. No treatment-related gestational effects, malformations or developmental variations were observed in the rats. In rabbits, 3 females aborted and 8 females were found dead at 40 mg/kg between gestation days 11 and 24. Clinical signs of maternal toxicity were present in surviving doses at this dose level. Body weight gains were reduced at 24 and 40 mg/kg. The preliminary study indicated maternal hematological effects in the rabbits similar to the rats at dose levels as low as 10 mg/kg. MEKO was not considered to have produced any treatment-related gestational effects, malformations or developmental variations in the rabbit at dose levels at or below 24 mg/kg. Because of excessive maternal mortality and abortions at the 40 mg/kg dose level, only 6 rabbits produced litters. The severe maternal toxicity and limited number of litters precluded a full assessment of developmental toxicity at 40 mg/kg. Nonetheless, MEKO did not appear to be teratogenic to the rabbit at this dose level.