Reproductive and developmental toxicity screening test of tetrahydrofurfuryl alcohol in rats

Twelve male and female rats per group were given tetrahydrofurfuryl alcohol (THFA) by gavage at 0, 15, 50, 150 or 500 mg/kg/day. Males were dosed for 47 days, beginning 14 days before mating, and females were dosed for 42–52 days beginning 14 days before mating to day 4 of lactation throughout the mating and gestation period. Changes in locomotor activity, inhibition of body weight gain, and/or histopathological changes in the thymus, spleen, testes and/or epididymides were observed in males and females at 150 mg/kg and above. No effects of THFA were found on the copulation index, fertility index, or the number of corpora lutea and implantations in pregnant females. At 500 mg/kg, no pregnant females delivered any pups. At 150 mg/kg, gestation length was prolonged, and the total number of pups born and the number of live pups on postnatal days 0 and 4 was markedly decreased. No effects of THFA were found on the sex ratio and body weight of live pups, or the incidence of pups with malformations or variations. Based on these findings, the NOAELs for parental and reproductive/developmental toxicity of THFA were concluded to be 50 mg/kg/day in rats.     

Reproductive and developmental toxicity screening study of 2,4-dinitrophenol in rats

Rats were treated by gavage once daily with 2,4-dinitrophenol (DNP) at 0 (control), 3, 10, or 30 mg/kg bw. Males were dosed for 46 days, beginning 14 days before mating, and females were dosed for 40-47 days, from 14 days before mating to day 3 of lactation. No deaths were observed in males and females of any group. A significant decrease in body weight gain and significant increase in liver weight were found in males and females at 30 mg/kg bw/day. The number of live pups on postnatal days (PNDs) 0 and 4, live birth index, and body weight of live male and female pups on PNDs 0 and 1 were significantly lowered at 30 mg/kg bw/day. External and internal examinations of pups revealed no increased incidence of malformations in DNP-treated groups. On the basis of these findings, we concluded that DNP has general and reproductive/developmental toxicity, but not teratogenicity, under the present conditions. The NOAEL of DNP is considered to be 10 mg/kg bw/day in rats.     

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 screening test of basic rubber accelerator, 1,3-di-o-tolylguanidine, in rats

Twelve male and female rats per group were exposed to the rubber accelerator 1,3-di-o-tolylguanidine (DTG) by gavage at 0, 8, 20 or 50 mg/kg bw/day. Males were dosed for a total of 49 days beginning 14 days before mating. Females were dosed for a total of 40-49 days beginning 14 days before mating to day 3 of lactation throughout the mating and gestation period. At 50 mg/kg bw/day, deaths were observed in two males and three females. Lowered body weight gain and food consumption were noted in males at 50 mg/kg bw/day and females at 20 and 50 mg/kg bw/day. Mydriasis, decreased locomotor activity, bradypnea, prone position, tremor and/or salivation were observed in males and females at 20 and 50 mg/kg bw/day. No effects of DTG were found on the estrous cyclicity, precoital interval, copulation, fertility and gestational indices, numbers of corpora lutea and implantations, or gestation length. A significant decrease in the number, body weight and viability of offspring and increase in the incidence of fetuses with external malformations were found at 50 mg/kg bw/day. Oligodactyly, anal atresia and tail anomalies were observed. These data suggest that DTG may be teratogenic. The NOAELs of DTG for general and developmental toxicity in rats are 8 and 20 mg/kg bw/day, respectively.     

Reproduction/developmental toxicity screening test in rats with orally-administered 1-hexene

This study was conducted to provide screening information concerning the potential systemic, reproductive and developmental toxicity of 1-hexene when administered orally, by gavage, to male and female rats using a modified OECD 421 protocol. 1-Hexene was administered at doses of 100, 500, and 1000 mg/kg/day in corn oil; the control group received the vehicle at an equivalent volume. The males were treated for 28 days prior to mating and until euthanasia (44 days of dosing). The females were treated for 14 days prior to mating and during mating, gestation, and lactation until euthanasia (41-55 total days of dosing). Females were allowed to deliver and rear their offspring until lactation day 4. The parental rats were subject to a gross and microscopic examination. Viability and development of the pups were followed through lactation day 4. There was no mortality, and there were no clinical signs of toxicity or differences in body weights, weight gain, feed consumption or organ weights. Copulation and fertility indices, precoital intervals, gestation lengths and pregnancy rates were comparable among the groups, and no signs of prolonged delivery or unusual nesting behaviors were noted. Pup viability, body weights, external observations and necropsy data were comparable among the groups. Pitted kidneys were observed at necropsy for two parental males in the 500 mg/kg/day group and three males in the 1000 mg/kg/day group. Microscopic changes in the kidneys of some male rats from the 100, 500, and 1000 mg/kg/day groups consisted of dose-related accumulations of hyaline droplets in the epithelial cells of the proximal convoluted tubules of the kidneys. In summary, the only treatment-related effect noted in this study was hydrocarbon nephropathy in male rats, which is not considered relevant for human health. The NOAEL for systemic and reproductive toxicity was 1000 mg/kg/day, excluding the finding of male rat hydrocarbon nephropathy.     

Reproductive and developmental toxicity studies of pyridostigmine bromide in rats

These studies were performed to evaluate the reproductive and developmental toxicity of pyridostigmine bromide (PB) in rats. Separate male and female fertility/reproductive performance studies, a perinatal/postnatal study and a teratology study were conducted. Dose levels were sufficient to result in overt cholinergic tremors at the high dose in each study. PB did not affect male or female fertility/reproductive performance. Pups born to treated dams did show slight, transient decreases in body weight gain, apparently secondary to the nursing behavior of dams demonstrating overt tremors. PB did not result in an increase in visceral or skeletal malformations. A slight increase in delayed ossification and early resorption were seen at the highest dose tested and were considered secondary to maternal stress/toxicity.     

Combined repeated-dose and reproductive/developmental toxicity screening test of 1-tert-butoxy-4-chlorobenzene in rats

We have carried out animal toxicity tests of chemicals for a chemical safety program implemented by the Ministry of Economy, Trade, and Industry of Japan. Here, we tested 1-tert-butoxy-4-chlorobenzene in a combined repeat-dose and developmental and reproductive toxicity test. The test chemical was administered daily by gavage to 9-week-old Crl:CD (SD) rats at doses of 0, 20, 100, and 500 mg/kg/d. Males were treated for 42 d beginning 14 d before mating. Females were treated from 14 d before mating to day 4 of lactation. Decreased spontaneous locomotion, decreased respiratory rate, and incomplete eyelid opening were observed at 500?mg/kg/d (both sexes), but resolved within 30?min of administration, suggesting central nervous system depression. No notable changes were observed in body weight, food consumption, functional battery tests, or blood test. Increased liver weight with centrilobular or diffuse hepatocyte hypertrophy was observed at 100 and 500?mg/kg/d (both sexes). There were no biochemical or histopathological changes related to hepatotoxicity. Increased kidney weight with basophilic tubules, tubule dilatation, and increased hyaline droplets were observed in males dosed at 100 and 500?mg/kg/d. Immunohistochemical staining indicated α_2u-globulin nephropathy, a male rat-specific toxicity. Although kidney weight was also increased in females dosed at 500?mg/kg/d, it was not considered to be an adverse effect because there were no histopathological changes. Pup weights on postnatal day 0 were decreased at 500?mg/kg/d and still decreased on postnatal day 4. Our data indicated the no-observed-adverse-effect-level for repeated-dose and reproductive/developmental toxicity for 1-tert-butoxy-4-chlorobenzene was 100?mg/kg/d.     

Reproductive and developmental toxicity of inhaled 2,3-dichloro-1,3-butadiene in rats

Inhalation developmental and reproductive toxicity studies were conducted with 2,3-dichloro-1,3-butadiene (DCBD), a monomer used in the production of synthetic rubber. In the reproductive toxicity study, Crl:CD^®(SD)IGS BR rats (24/sex/group) were exposed whole body by inhalation to 0, 1, 5, or 50 ppm DCBD (6 h/day) for approximately 10–11 weeks total, through premating (8 weeks; 5 days/week), cohabitation of mating pairs (up to 2 weeks, 7 days/week), post-cohabitation for males (7 days) and from conception to implantation (gestation days 0–7 [GD 0–7]), followed by a recovery period (GD 8–21) for presumed pregnant females. Estrous cyclicity was evaluated during premating (last 3 weeks) and cohabitation. Reproductive organs and potential target organs, sperm parameters, and GD 21 fetuses (viability, weight, external alterations) were evaluated. In the developmental study, pregnant Crl:CD^®(SD)IGS BR rats (22/group) were exposed whole body by inhalation to 0, 1, 10, or 50 ppm DCBD (6 h/day) on GD 6–20; dams were necropsied on GD 21 (gross post-mortem only) and fetuses were evaluated (viability, weight, and external, visceral and skeletal exams). During the in-life portion of the studies, body weight, food consumption, and clinical observation data were collected. At 50 ppm, gasping and labored breathing occurred in both studies during the first few exposures; body weight and food consumption parameters were affected in parental animals from both studies, but were more severely affected in the developmental study. Fetal weight was decreased in the developmental study at 50 ppm. Degeneration of the nasal olfactory epithelium was observed in the reproduction study at 50 ppm. There were no effects on reproductive function, embryo–fetal viability, or increases in fetal structural alterations in either study. The no-observed-adverse-effect level (NOAEL) for reproductive toxicity was 50 ppm. The NOAEL for systemic toxicity in the reproduction study was 5 ppm based on adverse effects on body weight and food consumption parameters and nasal olfactory epithelial toxicity at 50 ppm in parental rats. The NOAEL for maternal and developmental toxicity was 10 ppm based on reduced maternal weight gain and food consumption and reduced fetal weight at 50 ppm in the developmental toxicity study.     

Combined repeated dose and reproductive/developmental toxicity screening test of 4-methoxy-2-nitroaniline in rats

4-Methoxy-2-nitroaniline (4M2NA) is widely used as an intermediate for the synthesis of dyes, pigments and other chemical compounds. Since 4M2NA has amino-group and nitro-group on the benzene ring, it was expected that it induced obvious hemolytic anemia. We conducted a combined repeated dose and reproductive/developmental toxicity screening test according to Organisation for Economic Co-operation and Development (OECD) Test Guideline No. 422 (OECD TG 422) to enrich the toxic information and ensure the safety of 4M2NA. 4M2NA was administered to Crl:CD(SD) male and female rats by gavage at 0, 12.5, 75 or 450?mg/kg/day for 42 to maximum of 54 days through pre-mating, mating, pregnancy and lactation periods. An extramedullary hematopoiesis and congestion in spleen, and higher reticulocyte ratio were noted in only females at 450?mg/kg/day without decreased anemic parameters in the hematological examination. Hypertrophy of centrilobular hepatocytes in both sexes was observed with increased relative liver weight at 450?mg/kg/day. Furthermore, the diffuse follicular cell hypertrophy of the thyroid was observed in females at 450?mg/kg/day. No abnormalities were detected in the reproductive indices of copulation, delivery or fetal viability. We concluded the no-observed-adverse-effect level (NOAEL) for repeated-dose toxicity was 75?mg/kg/day based on the trace evidences of hemolytic anemia, and the NOAEL for reproductive/developmental toxicity as 450?mg/kg/day based on no toxicological concerns for reproductive endpoints. The hemolytic anemia was much milder than expected. Thus, we discussed the reason of this much less hemolytic effect from the point of view of the structural characteristics of 4M2NA.     

Evaluation of OECD screening tests 421 (reproduction/developmental toxicity screening test) and 422 (combined repeated dose toxicity study with the reproduction/developmental toxicity screening test)

The Advisory Committee on Existing Chemicals (BUA) of the Federal Republic of Germany convened a panel with expertise in reproductive and developmental toxicology to evaluate the OECD Screening Tests 421 (Reproduction/Developmental Toxicity Screening Test) and 422 (Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test) with respect to their ability to unmask any potential toxic effects on reproduction. The original assignment for that panel was to "validate" those screening tests. However, the panel members recognized beforehand that this was actually an impossible task because of lack of a sufficient database. Only five chemicals with known reproductive toxicity had been examined following the OECD Screening Test Guidelines 421 or 422. A comparison of these test results with those of the definitive OECD Test Guidelines 414, 415, 416, or additional investigations could, therefore, only have been made with this very limited number of chemicals that had also undergone evaluation by one of the test guidelines cited. In each case biological properties relevant to reproductive toxicity were also indicated by the OECD Screening Tests 421 or 422. This communication reviews the main differences in study design of OECD Screening Test Guidelines 421 and 422 compared to those definitive test guidelines of similar study design for reproduction or developmental toxicity (especially with the one-generation study, OECD Test Guideline 415). The very limited possibilities of detecting late postnatal and postlactational manifestations are emphasized, as is the low statistical power of the OECD Screening Tests 421 and 422. Furthermore, the very limited ability to unmask teratogenicity is delineated. The outcome of screening tests was evaluated based on the results of 57 studies conducted according to the OECD Test Guideline 421 or 422. The test results were categorized according to the incidence of toxic effects on reproduction in the parent animals or their offspring and related to general toxic effects. Based on the ranking of these results, recommendations regarding setting rational priorities for further evaluations of existing chemicals' reproductive hazards are made. In general, the reviewer panel supports the OECD position that the screening tests are useful for initial hazard assessment and can contribute to the decision-making process on setting priorities for further test requirements. The panel also agrees with the OECD statement that the OECD Screening Tests 421 and 422 are neither an alternative to definitive tests (i.e., OECD Test Guidelines 414, 415, and 416) nor are they intended as their replacement.     

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.     

Combined repeated-dose toxicity study of silver nanoparticles with the reproduction/developmental toxicity screening test

Combined repeated-dose toxicity study of citrate-capped silver nanoparticles (7.9 ± 0.95 nm) with reproduction/developmental toxicity was investigated in rats orally treated with 62.5, 125 and 250 mg/kg, once a day for 42 days for males and up to 52 days for females. The test was performed based on the Organization for Economic Cooperation and Development test guideline 422 and Good Laboratory Practice principles. No death was observed in any of the groups. Alopecia, salivation and yellow discolouration of the lung were observed in a few rats but the symptoms were not dose-dependent. Haematology, serum biochemical investigation and histopathological analysis revealed no statistically significant differences between control group and the treated groups. Toxicity endpoints of reproduction/developmental screening test including mating, fertility, implantation, delivery and foetus were measured. There was no evidence of toxicity.     

Reproductive and developmental toxicity of ethylene glycol in the mouse

The effects of ethylene glycol on reproduction of CD-1 mice were tested in a protocol which permitted continuous breeding during a specified interval. The dosage amounts of 0, 0.25, 0.5, or 1% ethylene glycol by continuous administration in drinking water for male and female mice were selected from the general toxic responses observed in a 14-day pilot study. After the first week of administration, begun at 11 weeks of age, the animals were housed one male and one female per cage for 14 weeks during which time any offspring were examined, sexed, weighted, and killed to allow continuous mating of the first generation. At the end of the 14-week cohabitation period, the males and females were separated and any litters delivered after that time were kept until weaning. Those second-generation animals were mated at about 70 days of age. Slight, but statistically significant, decreases were found in the numbers of litters per fertile pair and live pups per litter in the 1% dose group and live pup weight at the 1% dose groups compared to control F0 mice. Facial anomalies were noted in a number of offspring of high-dose-treated mice and an examination for skeletal defects demonstrated a pattern including reduction in the size of bones in the skull, fused ribs, and abnormally shaped sternebrae and vertebrae in the high-dose-treated, but not the untreated, mice. Neither the 0.25 nor 0.5% dose groups were significantly affected. No clinical signs of toxicity or significant adverse effects on body weight or water consumption were seen at the doses used, but two deaths occurred at the 0.5% quantity which may have been related to oxalate crystal deposition in the kidney.     

Reproductive and developmental toxicity of hydrofluorocarbons used as refrigerants

The present paper summarizes data on the reproductive and developmental toxicity of hydrofluorocarbons (HFCs), including pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), difluoromethane (HFC-32) and 1,1,1,3,3-pentafluoropropane (HFC-245fa), used as refrigerants, published in openly available scientific literature. No developmental toxicity of HFC-125 was found even at 50,000 ppm in rats or rabbits. Although HFC-134a exhibited no dominant lethal effect or reproductive toxicity in rats, it caused low body weight in pre- and postnatal offspring and slightly retarded skeletal ossification in fetuses at 50,000 ppm in rats. No maternal or developmental toxicity was noted after exposure to HFC-143a even at 40,000 ppm in rats or rabbits or HFC-152a even at 50,000 ppm in rats. HFC-32 is slightly maternally and developmentally toxic at 50,000 ppm in rats, but not in rabbits. HFC-245fa caused decreases in maternal body weight and food consumption at 10,000 and 50,000 ppm and fetal weight at 50 000 ppm. No evidence of teratogenicity for these HFCs was noted in rats or rabbits. There is limited information about the reproductive toxicity of these HFCs. Animal studies remain necessary for risk assessments of chemicals because it is difficult to find alternative methods to determine the toxic effects of chemicals. It is required to reduce emissions of organic vapors containing HFCs to reduce the risk of exposure.     

Reproductive and developmental toxicity study of T-3762 in rats administered intravenously during the period of organogenesis

A teratogenicity study of T-3762, an injectable new quinolone antibacterial agent, was conducted in Sprague-Dawley rats to determine the effects on dams and next generations. T-3762 was administered intravenously to pregnant rats at the dose levels of 26, 78 and 156 mg/kg/day from day 7 to day 17 of gestation, during the organogenesis. 1. In the dams, there were no effects on general condition, food intake, water intake and body weight in the T-3762 treated groups. There were no abnormal findings on the autopsy at the end of gestation and lactation periods in the T-3762 treated groups. 2. In the fetuses, there were no effects on the number of dead and live fetuses, sex ratio and body weight in the T-3762 treated groups. No external, visceral and skeletal abnormalities attributed to T-3762 were observed. 3. In the offspring, there were no effects on birth rate, viability, differentiation of external development, body weight, sensory function, emotionality, learning ability and reproductive performance in the T-3762 treated groups. From these results, no-toxic dose levels of T-3762 are considered to be 156 mg/kg for the general toxicity and the reproductive toxicity of parents and for the development of next generation, respectively.     

Reproductive and developmental toxicity of arsenic in rodents: a review

Arsenic is a recognized reproductive toxicant in humans and induces malformations, especially neural tube defects, in laboratory animals. Early studies showed that murine malformations occurred only when a high dose of inorganic arsenic was given by intravenous or intraperitoneal injection in early gestation. Oral gavage of inorganic arsenic at maternally toxic doses caused reduced fetal body weight and increased resorptions. Recently, arsenic reproductive and developmental toxicity has been studied in situations more similar to human exposures and using broader endpoints, such as behavioral changes and gene expression. For the general population, exposure to arsenic is mostly oral, particularly via drinking water, repeated and prolonged over time. In mice and rats, methylated or inorganic arsenic via drinking water or by repeated oral gavage induced male and female reproductive and developmental toxicities. Furthermore, at nonmaternally toxic levels, inorganic arsenic given to pregnant dams via drinking water affected fetal brain development and postnatal behaviors. However, arsenic given by repeated oral gavage to pregnant mice and rats was not morphologically teratogenic. In this review of arsenic reproductive and developmental toxicity in rats and mice, the authors summarize recent in vivo studies and discuss possible underlying mechanisms. The influences of folate, selenium, zinc, and arsenic methylation on arsenic reproductive and developmental toxicity are also discussed.     

Reproductive toxicity of acrylamide-treated male rats

Acrylamide content is elevated in fried, baked and heat-processed starchy foods. The present experiment was conducted to investigate the reproductive toxicity of oral acrylamide in male rats. Thirty weaned SD male rats of 21-day-old were randomly allotted to three groups, and acrylamide was administered to each group at doses of 0, 5 and 10 mg/kg-d for 8 consecutive weeks. The results indicated that the growth of rats treated with acrylamide was retarded (P < 0.05), but relative weights of testes and epididymides compared to body weight were not significantly different (P > 0.05). Our results also indicate that the epididymal sperm reserves decreased significantly (P < 0.05), suggesting partial depletion of germ cells. In addition, histopathologic lesions were also present in the testes of treated rats. Furthermore, distinct expression patterns of sGC heterodimers were observed in this animal model. This may suggest different physiologic roles for sGC subunits in spermiogenesis and steroidogenesis.     

Reproductive and developmental toxicities of zinc supplemented rats

Reproductive and developmental toxicities of zinc supplementation in F(0) rats and F(1) progeny were examined. Rats were treated by gavaging with zinc chloride (ZnCl(2)) at 0.0, 7.5, 15 and 30 mg/kg-d. ZnCl(2) treatment was associated with deficient energy imbalances, reduced number of live pups/litter, decreased live birth index, increased mortality and increased fetal resorption. Changes in serum clinical chemistry and hematologic parameters were sex-related. In F(0) females, ZnCl(2) was associated with increased liver/body weight ratios, reduced creatinine and reduced alkaline phosphatase concentrations. In F(0) males, ZnCl(2) significantly increased relative liver weight and elevated γ-GGT. In addition, at birth, F(1) males exhibited, a significant (p<0.05) increase in anogenital distance, whereas ZnCl(2) hastened the time of eye opening and incisor eruption in males and females. These results indicate that excess ZnCl(2) supplementation before and during pregnancy and during lactation could pose some health risk concerns to pregnant mothers and their offspring.