Reproductive Toxicity of Boric Acid in Swiss (CD-1) Mice: Assessment Using the Continuous Breeding Protocol

Reproductive Toxicity of Boric Acid in Swiss (CD-1) Mice: AssessmentUsing the Continuous Breeding Protocol. FAIL P. A., GEORGE,J. D., SEELY, J. C., GRLZZLE T. B., AND HEINDEL J. J. (1991).Fundam. Appl. Toxicol. 17, 225–239. The potential reproductivetoxicity of boric acid (BORA) in CD-1 mice (Swiss) was evaluatedusing the Reproductive Assessment by Continuous Breeding (RACB)Protocol. BORA was administered in the feed for 27 week to maleand female Swiss (CD-1) mice at concentrations of 0, 1000, 4500,or 9000 ppm. Estimated doses. based on feed consumption andbody weight, averaged 152, 636, and 1262 mg/kg body wt duringWeek 1 for males for 1000, 4500, and 9000 ppm, respectively.During 14 weeks of cohabitation, fertility of F₀ mice was partiallyreduced at 4500 ppm and totally eliminated at 9000 ppm. No litters,dead or alive, were produced by 9000 ppm cohabited pairs. Amongthe litters born at 4500 ppm, live litter size and body weightwere significantly reduced. A crossover mating trial of controland 4500 ppm groups confirmed the male as the affected sex,with fertility rates and the mating Index significantly lowerin the 4500 male ? 0 ppm female group. At nmopsy, after 27 weeksof BORA exposure, dose-related changes were present in F₀ malesfor reduced body and reproductive organ weights, increased incidenceof abnormal sperm, decreased sperm concentration and motility,and seminiferous tubule degeneration. In the 4500 ppm females,dietary BORA for 27 weeks caused significantly decreased weightsof kidney/adrenals and livers; kidney/adrenal weight was alsoreduced In 4500 ppm males. The last litters of the control and1000 ppm females, born in the 14-week breeding phase, were rearedto 74 days of age and then mated in nonsibling pairs withintreatment groups. These F₁ mice had normal fertility, but theadjusted mean body weight of F₂ pups was decreased. These dataestablish the reproductive toxicity of BORA in CD-1 mice anddemonstrate that the male is the most sensitive sex.     

Two-generation reproductive toxicity study of the flame retardant hexabromocyclododecane in rats

Male and female rats were fed a diet containing flame retardant hexabromocyclododecane (HBCD) at 0, 150, 1500 or 15,000 ppm throughout the study beginning at the onset of a 10-week pre-mating period and continuing through the mating, gestation and lactation periods for two generations. The mean daily intakes of HBCD during the whole period of administration were 10.2, 101 and 1008 mg/kg bw in F0 males, 14.0, 141 and 1363 mg/kg bw in F0 females, 11.4, 115 and 1142 mg/kg bw in F1 males, and 14.3, 138 and 1363 mg/kg bw in F1 females for 150, 1500 and 15,000 ppm, respectively. The incidence of rats with decreased thyroid follicles size was increased in F0 and F1 males and females at 1500 ppm and higher. Serum TSH levels were increased in F0 and F1 females at 1500 ppm and higher, and serum T4 levels were decreased in F0 males and females at 15,000 ppm. The number of the primordial follicles in the ovary of F1 females was reduced at 1500 ppm and higher. There were increases in the absolute and relative weights of the liver in male adults and male and female weanlings at 1500 ppm and higher, and in female adults at 15,000 ppm, and of the thyroid in male and female adults at 15,000 ppm. Decreased body weight and body weight gain associated with reduced food consumption were found in F1 males and females at 15,000 ppm. Decreases were found in the viability index of F2 pups and the body weight of male F1 and F2 pups and female F2 pups at 15,000 ppm. In F2 pups, there were low incidences of the completion of eye opening in males at 15,000 ppm and in females at 1500 ppm and higher, and of completed mid-air righting in females at 15,000 ppm. The data indicate that the NOAEL of HBCD in this study was 150 ppm (10.2mg/kg bw/day). The estimated human intake of HBCD is well below the NOAEL in the present study.     

Assessment of the Reproductive Toxicity of a Complex Mixture of 25 Groundwater Contaminants in Mice and Rats1

The potential reproductive toxicity of a mixture of 25 chemicals(MIX) formulated to simulate contaminated groundwater suppliesnear hazardous waste dumps was evaluated in CD-1 Swiss miceand Sprague-Dawley rats using the reproductive assessment bycontinuous breeding protocol. Male and female mice and ratswere exposed to MIX in the drinking water at concentrationsof 1, 5, and 10% of a technically achievable stock solution.For mice, body weight and feed consumption were not affectedby MIX but water consumption was decreased for both the 5 and10% MIX groups in both F₀ and F₁ animals. For F₀ mice, the numberof live pups/litter was decreased at 10% MIX and the numberof females/litter was decreased 10 and 17% at the mid and highMIX dose, respectively. Vaginal cytology was normal, as weretestis weight and testicular spermatid head count. For F₁ mice,fertility was unaffected, but there was a decreased number offemale pups/litter (19%) and a decreased adjusted live pup weightat 10% MIX. At necropsy, cauda epididymal sperm concentrationand spermatid head count were reduced (20%) in the presenceof normal testis, epididymis, prostate, seminal vesicle, liver,and kidney/adrenal weight. Female estrous cyclicity was alteredat 5 and 10% MIX with nor mal kidney/adrenal, uterus, and ovary%oviductweight. For rats, F₀ body weight and feed consumption were notaffected by MIX but water consumption was decreased 10, 30,and 40% in the low-, medium-, and high-dose MIX groups, respectively,and 39% in the high-dose MIX F animals. Rat fertility was normalbut there was a decreased number of male pups/litter (11%) anda decreased live pup weight (6%) at 10% MIX. Male and female.     

Carisoprodol: Reproductive Assessment by Continuous Breeding in Swiss Mice

Carisoprodol (CARI), a commonly prescribed neuromuscular relaxant,was evaluated for reproductive toxicity in Swiss CD-1 mice usingthe Reproductive Assessment by Continuous Breeding (RACB) protocol.Male and female mice were given CARI in corn oil suspensionby daily gavage at doses of 0, 300, 750, and 1200 mg/kg bodywt/day. Clinical signs of general toxicity in Fo animals includedsedation, primarily in the high-dose group during the firstweek of exposure, and reduced body weight in high-dose females.CARI administration for 14 weeks did not affect the abilityof the F₀ animals to produce litters. However, decreases inproportion of pups born alive (4%) and absolute (5%) and adjustedlive pup weight (7%) were observed at 1200 mg/kg CARI when comparedto controls. In a crossover mating trial to determine the affectedsex, there were no significant differences in the measured reproductiveparameters. CARI at the high dose increased the proportion oftime spent in proestrus and estrus, but cycle length was unaffected.At F₀ necropsy (Week 27 of treatment), all sperm parameterswere normal. Right epididymis and liver weights, relative tobody weight, were increased (12 and 23%, respectively) overthe control group for high-dose males. A mating trial to determinethe fertility and reproductive competence of the F₁ generationshowed no effect of CARI on indices of mating, pregnancy, orfertility, the proportion of F₂ pups born alive, the sex ratioof live F₂ pups, live F₂ pup weight, or gestation length. However,decreases in the number of F₂ pups per litter (22%) and adjustedlive F₂ pup weight (8%) were observed in the high-dose group.Indications of generalized toxicity in the F₁ generation includeddecreased survival through Postnatal Day 21 at 750 (5%) and1200 (9%) mg/kg CARI, and transiently decreased body weightsduring postnatal development and as adults for males and femalesat all dose levels. At necropsy, there was no effect of treatmenton the relative weight of any male or female reproductive organs;testicular spermatid concentration was reduced at all levelsof CARI. Relative liver weight was increased for females at300 mg/kg and for males and females at both 750 and 1200 mg/kg.In summary, CARI produced generalized toxicity and moderateeffects on the reproductive processes of F₀ and F₁ generationSwiss mice during chronic exposures of up to 1200 mg/kg/day.     

Reproductive Toxicity Evaluation of Acetaminophen in Swiss CD-1 Mice Using a Continuous Breeding Protocol

Acetaminophen (APAP) was evaluated for reproductive toxicityin Swiss CD-1 mice using a continuous breeding protocol. APAPwas administered in the diet at 0, 0.25, 0.5, and 1.0% (w/w),which represented average daily intakes of 0, 357, 715, and1430 mg APAP/kg/day, respectively. Exposure of parental (P)breeding pairs to 1% APAP in the diet for 14 weeks during cohabitationsignificantly decreased the number of litters per pair, andreduced, although not significantly, the number of live pupsper litter. Importantly, 6 of 19 high-dose P pairs failed toproduce a fifth litter, and this fully accounted for the diminishednumber of litters in this group. In addition, the fifth litterthat was produced by the 13 high-dose P pairs averaged onlyabout 9 live pups per litter, which correspondingly reducedthe overall group average for this parameter. In comparison,the control and two lower-dose P pairs produced 11 or 12 livepups per litter on average. Although the birth weights for F₁pups in the final litter were unaffected by prenatal APAP exposure,postnatal growth was adversely affected as evidenced by retardedweight gain as measured at 28 and 74 ± 10 days of agefor all three dietary levels. At 1% APAP this weight gain effectwas more pronounced at Day 28 than at Day 74 ± 10, suggestingthat nursing pups may have been exposed to higher concentrationsor may be more sensitive to APAP and/or an active metabolitethan were the young adults. A mating trial of F₁ pairs at 74± 10 days of age indicated that mating, fertility, andreproductive performance were normal, except that the birthweight of F₂ pups was significantly depressed at 1% APAP. Thislatter effect may have been attributable to maternal toxicityin that body weight and relative pituitary weight were significantlydecreased, and relative brain and liver weight significantlyincreased, in high-dose F₁ females. In addition, body weightwas significantly reduced in the high-dose F₁ males at necropsy.No treatmentrelated effects on reproductive organ weights andno gross or histological changes in the reproductive tissuesof the high-dose F₁ male and female mice were observed. Continuousexposure of F₁ males at 1% APAP, however, significantly increasedthe percentage of abnormal epididymal sperm, while sperm densityand percentage of motile sperm were unaffected. Collectively,these data indicated that continuous exposure to 1% APAP viathe diet (1.43 g/kg/day) led to cumulative effects on reproductionin the P pairs, to retarded growth and abnormal sperm in theF₁ mice, and to reduced birth weight of F₂ pups.     

Toxicology and carcinogenesis studies of transplacental AZT (Cas No. 30516-87-1) in Swiss (CD-1®) mice (in utero studies)

3'-Azido-3'-deoxythymidine (AZT) is the most widely used and evaluated chemotherapeutic agent for the treatment of persons with acquired immune deficiency syndrome (AIDS) and persons seropositive for human immunodeficiency virus (HIV). The study in this report was conducted to obtain information on AZT transplacental carcinogenicity at doses that were lower than those used in previous NCI studies and analogous to therapeutic doses. Male and female Swiss (CD-1(R)) mice were exposed to AZT (greater than 99% pure) during all of gestation. Genetic toxicology studies were conducted in mouse peripheral blood erythrocytes. Groups of 22, 28, 34, or 46 female mice (F(0) generation) were administered AZT in 0.5% methylcellulose by gavage at doses of 50, 100, 200, or 300 mg AZT/kg body weight 7 days per week for 29 to 39 days (day of delivery). A vehicle control group of 22 female mice received methylcellulose alone. Each female group was divided into two groups with dosing started 1 week apart in order to facilitate cohabitation, mating, and delivery. Groups of six, six, seven, nine, or twelve undosed male mice were cohabited with the vehicle control and 50, 100, 200, and 300 mg/kg dosed females, respectively, on study days 9 to 13 and then discarded. Pups (F(1) generation) were culled (0, 50, and 100 mg/kg groups) to yield a maximum of five pups/sex per litter on postnatal day 4; no more than four pups/sex per litter were used in the study. On postnatal day 25, all surviving 200 and 300 mg/kg pups were placed on study. After culling and randomization to cage groups, the 0, 50, 100, 200, and 300 mg/kg groups consisted of 50, 50, 50, 37, and 32 male pups and 50, 50, 50, 40, and 42 female pups, respectively. Decreased litter size and fertility rates were observed in the 200 and 300 mg/kg F0 dams. Survival of all exposed groups of F(1) mice was similar to that of the vehicle controls. Mean body weights of 200 mg/kg males were generally less than those of the vehicle controls after week 29. Mean body weights of 300 mg/kg males were less during the first year of the study, but these mice recovered and body weights were generally similar to those of the vehicle controls at the end of the study. The incidences of alveolar/bronchiolar carcinoma and of adenoma or carcinoma (combined) in 200 and 300 mg/kg males were significantly greater than those in the vehicle controls. The incidences of histiocytic cellular infiltration of the lung in 200 and 300 mg/kg males were significantly increased. GENETIC TOXICOLOGY: The NTP conducted a number of studies of the genetic toxicity of AZT, independent of this transplacental carcinogenicity study. In these genetic toxicity studies, AZT (50, 75, 100, or 150 mg/kg) administered to pregnant Swiss (CD-1(R)) dams, beginning prior to conception and continuing throughout gestation and lactation, induced high levels of micronucleated polychromatic erythrocytes (PCEs) in pups sampled on postnatal days 1 and 4. Direct gavage treatment of these transplacentally and lactationally exposed pups, beginning on postnatal day 4, resulted in further increases in the frequencies of micronucleated PCEs on postnatal days 8 and 21. The percentage of PCEs among erythrocytes in pups was significantly elevated over normal adult levels, indicating a high rate of erythropoiesis in neonatal mice. The percentage of PCEs was decreased in all pups exposed to AZT, consistent with treatment-related bone marrow toxicity. CONCLUSIONS: Under the conditions of this study, there was clear evidence of carcinogenic activity in F(1) male mice exposed transplacentally to AZT based on increased incidences of alveolar/bronchiolar neoplasms. There was no evidence of carcinogenic activity in F(1) female mice exposed transplacentally to AZT at 50, 100, 200, or 300 mg/kg. Reproductive toxicity in the form of decreased litter size and fertility rates was observed in dams in the 200 and 300 mg AZT/kg dose groups.     

Nitrofurazone: Reproductive Assessment by Continuous Breeding in Swiss Mice

Nitrofurazone (NTFZ), a nitrofuran antibiotic, was evaluatedfor reproductive toxicity in Swiss CD-1 mice using the ReproductiveAssessment by Continuous Breeding protocol. Male and femalemice were cohabited for 15 weeks and exposed to NTFZ in feedat concentrations of 0, 100, 375, and 750 ppm (14–102mg/kg/day). F₀ 750-ppm breeding pairs had significantly reducedfertility after 7 days of exposure to NTFZ (17% fertile comparedto 98% for control pairs) and were infertile after the secondlitter. F₀ mid-dose pairs had progressively decreasing fertility(47% by the fifth litter), reduced litter size, and reducedproportion of pups born alive. Crossover breeding of controland high-dose F₀ animals confirmed infertility in high-dosemales and reduced litter size and pup weight in high-dose femaleswhen compared to the controlxcontrol group. At necropsy, therewere no effects on body weight, but F₀ males had reduced testisweight at the high dose and reduced epididymal sperm concentrationand abnormal sperm morphology at all doses of NTFZ. Increasedliver as well as kidney and adrenal weights (combined) wereobserved at 375 and 750 ppm; hepatic hypertrophy was noted microscopicallyat 750 ppm. F₀ females had reduced body weight, hepatic hypertrophy,and altered estrous cycles at 750 ppm and reduced ovarian weightat all doses. In the second generation, F₁ mice at 375 ppm hadreduced postnatal survival and body weight and produced smallerF₂ litters compared to control mice. At necropsy, F₁ males hadreduced testes weight and epididymal sperm concentration, abnormalsperm morphology, hepatic hypertrophy at 375 ppm, and borderlinenephropathy at 100 and 375 ppm. F₁ females had decreased body,liver, and ovarian weight at 375 ppm and altered estrous cyclesat 100 and 375 ppm. Thus, NTFZ at 100 ppm ( 14 mg/kg/day) causedadverse reproductive effects in F⁰ male and female and F₁ femalemice in the presence of relatively mild systemic toxicity.     

Evaluation of the reproductive and developmental toxicity of aluminium ammonium sulfate in a two-generation study in rats

Aluminium ammonium sulfate (AAS) was tested for reproductive/developmental toxicity in a two-generation study. Male and female rats were continuously given AAS in drinking water at 0, 50, 500 or 5000 ppm. Water consumption was decreased in all AAS-treated groups, and the body weight of parental animals transiently decreased in the 5000 ppm group. In either generation, no compound-related changes were found in estrous cyclicity, sperm parameters, copulation, fertility and gestation index, number of implantations and live birth pups, sex ratios of pups or viability during the preweaning period. Male and female F1 pups in the 5000 ppm group showed a lower body weight on postnatal day 21, while there were no differences in the birth weight of F1 and F2 pups between the control and AAS-treated groups. Preweaning body weight gain in F2 males and females indicated a similar decreasing tendency at 5000 ppm. In F1 and F2 weanlings, the weight of the liver, spleen and thymus decreased at 5000 ppm, but no histopathological changes were found in these organs. In F1 females in the 5000 ppm group, vaginal opening was delayed slightly. There were no compound-related changes in male preputial separation or in other developmental landmarks. In behavioral tests conducted for F1 animals at 4-6 weeks of age, no compound-related changes were found in spontaneous locomotor activity and performance in a water-filled multiple T-maze. In conclusion, the NOAEL of AAS for two-generation reproductive/developmental toxicity was considered to be 500 ppm in rats. Considering the aluminium content in the basal diet, the total ingested dose of aluminium from drinking water and food in this 500 ppm group was calculated to be 5.35 mg Al/kg bw/day.     

Reproductive Effects of 4-Vinylcyclohexene in Swiss Mice Assessed by a Continuous Breeding Protocol

4-Vinylcyclohexene (VCH), a dimer of 1,3-butadiene, was evaluatedfor reproductive toxicity in Swiss (CD-l) mice using the continuousbreeding protocol (NTP, 1989). VCH in corn oil was administeredby gavage at doses of 0, 100, 250, and 500 mg/kg/day to animalsthat were housed in same sex pairs for 1 week and then cohabitedin breeding pairs for 14 weeks. During cohabitation, newbornlitters were euthanized immediately after evaluation on postnatalDay (PND) 0. Litters born after Week 15 were reared until PND21, when all F₀ animals and low- and mid-dose F₁ weanlings werehumanely killed without a necropsy. At PND 74 ± 10, controland high-dose F animals were cohabited within groups for 1 weekand necropsied after delivery of the litters. In F breedingpairs, VCH did not affect measures of reproductive competence,including initial fertility, litters per pair, live litter size,or the proportion of pups born alive. Pup weight was decreased(4%) in the high-dose group relative to controls. High-doseF females exhibited slight general toxic ity, manifested asan 8% difference in body weight compared to controls. VCH didnot adversely affect preweaning growth or survival in the F₁generation. VCH had no effect on the reproductive competenceof the F₁ generation. High-dose F adult males and females haddecreased body weight. At necropsy, in creased relative liverweight (males 9% and females 8%) and sperm motility (althoughnot thought to be biologically significant) were observed inthe 500 mg/kg VCH group. Relative to controls, testicular spermatidcount was decreased by 17% by 500 mg/kg VCH treatment in thepresence of normal epididy mal sperm number and testis and epididymisweight. VCH treated females had significantly reduced numbersof primordial (33% decrease), growing (55% decrease), and antraloocytes(33% decrease) compared to controls, but ovarian weight andestrus cyclicity were unaffected. In summary, VCH, at doseswhich resulted in slight generalized toxicity (500 mg/kg/day),reduced the gamete pool in both the ovary (markedly) and testis(slightly) but had no significant adverse effect on the abilityto reproduce in either the F or F, generation.     

Effects of dietary genistein exposure during development on male and female CD (Sprague-Dawley) rats

Genistein is a naturally occurring isoflavone that interacts with estrogen receptors and multiple other molecular targets. Human exposure to genistein is predominantly through consumption of soy products, including soy-based infant formula and dietary supplements. A dose range-finding study was conducted as a prelude to a multigeneration bioassay to assess potential toxicities associated with genistein consumption. Genistein was administered in a soy- and alfalfa-free diet at 0, 5, 25, 100, 250, 625, or 1250 ppm to pregnant dams starting on Gestation day 7 and continuing throughout pregnancy. Dietary exposure of the dams continued through lactation, and pups were maintained on the same dosed feed as their mother after weaning until sacrifice at Postnatal day 50. Body weight and feed consumption of the treated dams prior to parturition showed a decreasing trend with a significant reduction at the highest dose. Litter birth weight was depressed in the 1250 ppm dose group, and pups of both sexes in that dose group had significantly decreased body weights relative to controls at the time of sacrifice. The most pronounced organ weight effects in the pups were decreased ventral prostate weight in males at the 1250 ppm dose and a trend toward higher pituitary gland to body weight ratios in both sexes. Histopathologic examination of female pups revealed ductal/alveolar hyperplasia of the mammary glands at 250 to 1250 ppm. Ductal/alveolar hyperplasia and hypertrophy also occurred in males, with significant effects seen at 25 ppm and above. Abnormal cellular maturation in the vagina was observed at 625 and 1250 ppm, and abnormal ovarian antral follicles were observed at 1250 ppm. In males, aberrant or delayed spermatogenesis in the seminiferous tubules relative to controls was observed at 1250 ppm. There was a deficit of sperm in the epididymis at 625 and 1250 ppm relative to controls, although testicular spermatid head counts and epididymal spermatozoa counts did not show significant differences from controls at these doses. Both sexes showed an increase in the incidence and/or severity of renal tubal mineralization at doses of 250 ppm and above. Dietary genistein thus produced effects in multiple estrogen-sensitive tissues in males and females that are generally consistent with its estrogenic activity. These effects occurred within exposure ranges achievable in humans.     

Lifetime toxicity/carcinogenicity studies of FD & C Blue No. 1 (brilliant blue FCF) in rats and mice

FD & C Blue No. 1 was fed to Charles River CD rats and CD-1 mice as a dietary admixture in lifetime toxicity/carcinogenicity studies. The rat study was conducted with an in utero phase in which the compound was administered to the F0 generation rats (60/sex/group) at dietary concentrations of 0.0%, 0.0%, 0.1%, 1.0% or 2.0%. After randomly selecting the F1 animals, the lifetime phase was initiated at the same levels with 70 rats/sex/group, including two control groups. The maximum exposure times were 116 and 111 wk for males and females, respectively. The no-observed-adverse-effect levels are dietary concentrations of 2.0% for males (1072 mg/kg body weight/day), and 1.0% for females (631 mg/kg/day) based on a 15.0% decrease in terminal body weight and decreased survival in the high-dose females compared with the combined control groups. Charles River CD-1 mice (60/sex/group) were fed FD & C Blue No. 1 as a dietary admixture at levels of 0.0%, 0.0%, 0.5%, 1.5% or 5.0% in a lifetime toxicity/carcinogenicity study. The maximum exposure time was 104 wk for both males and females. No consistent, significant compound-related adverse effects were noted. The no-observed-adverse-effect level established in this study is a dietary concentration of 5.0% (7354 mg/kg/day and 8966 mg/kg/day for male and female mice, respectively.     

Reproductive Toxicity of Tricresyl Phosphate in a Continuous Breeding Protocol in Swiss (CD-1) Mice

Reproductive Toxicity of Tricresyl Phosphate in a ContinuousBreeding Protocol in Swiss (CD-I) Mice. CHAPIN, R. E., GEORGE,J. D., AND LAMB, J. C. IV. (1988). Fundam. Appl. Toxi-col. 10,344-354. The effects of a mixture of tricresyl phosphate isomerson reproductive performance in Swiss (CD-I) mice were evaluatedusing a continuous breeding protocol. Tricresyl phosphate (TCP)was mixed into the feed at 0, 0.05, 0.1, and 0.2% by weight.Although the fertility index was not changed in the animalsconsuming the high-concentration feed, the number of littersper pair decreased in a dose-related fashion, and the proportionof pups born alive, and their weight, was significantly decreasedin the high-dose group. A crossover mating trial found impairedfertility in both males and females exposed to 0.2% TCP, witha greater effect in females. Histopathology of the Fo pairsrevealed dose-related seminiferous tubule atrophy, and decreasedtestis and epididymal weights in the high-dose males, whilethe female reproductive tract showed no histopathologic changes.There were dose-related changes in the adrenals of both sexes,and body weight was depressed in both sexes at the highest concentration.The last litter born in the 98-day breeding phase was rearedto age 74 days and then mated within the control and two ofthe treatment groups (0.0,0.05, and 0.1 % TCP; there were toofew offspring in the 0.2% group). There was a decrease in thefertility index in the 0.1% TCP group, and a decreased proportionof liveborn and number of liveborn pups per litter. In the F,males at necropsy, sperm concentration and morphology were normalat termination, although motility was decreased in both the0.05% and the 0.1% groups compared to controls. These data showthat TCP impaired fertility in both sexes of mice in the Fogeneration and affected sperm motility at even the lowest dosein F, males.     

Tetrahydrofuran: two-generation reproduction toxicity in Wistar rats by continuous administration in the drinking water.

In a two-generation reproduction toxicity study, 25 male and 25 female Wistar rats per dose group and generation were exposed continuously to tetrahydrofuran in the drinking water for at least 70 days prior to and during mating, gestation, parturition and lactation to weaning, at concentrations of 0, 1000, 3000 or 9000 ppm (approximately 100, 300 and 700 mg/kg/day in males and females premating, 100, 300 and 800 mg/kg/day in females during gestation, and 200, 500 and 1300 mg/kg/day in females during lactation) through two successive generations. In both generations and sexes, water consumption was dose-relatedly reduced at all doses; food consumption and body weight were reduced at 9000 ppm. Necropsy kidney weights were increased in 9000 ppm F0 males. Pup body weight gain during lactation was reduced in both generations (F1 and F2 pups) and eye opening delayed in the first generation (F1 pups) at 9000 ppm; there were no treatment-related malformations. The NOAEL of tetrahydrofuran in drinking water is 9000 ppm for parental fertility and reproductive performance, and 3000 ppm for systemic parental and developmental toxicity.     

Reproductive Toxicity of 2,2-Bis(bromomethyl)-1,3-propanediol in a Continuous Breeding Protocol in Swiss (CD-1) Mice

The effect of 2,2-bis(bromomethyl)-1,3-propanediol (BMP) onreproduction in Swiss CD-1 mice was evaluated by use of a continuousbreeding protocol. BMP was administered in the feed at 0.1,0.2, and 0.4% concentrations. Both male and female F₀ mice (20pairs per treatment group, 40 pairs of control animals) weredosed 7 days prior to and during a 98-day cohabitation period.Although the fertility index was unchanged in the highdose group,BMP exposure significantly decrased the numbers of litters perpair, pups born alive per litter, and pup weight when adjustedfor litter size. Crossover mating between treated and controlF₀ animals indicated a specific effect only on female reproductivecapacity. At the highest dose, BMP caused a body weight decreasein the F₀ animals of both sexes with no effect on relative organweights. Sperm concentration, motility, morphology, and estrualcyclicity were unaffected by BMP exposure. Histopathology inthe F₀ animals revealed specific kidney lesions in both sexes;males were more sensitive than females. The last litter bornin the 98-day breeding phase was reared to age 74 days and thenmated to nonsiblings of the same treatment group. The effectof highdose BMP exposure on F₁, fertility, body and organ weights,sperm parametem, and estrual cyclicity was the same as thatfor the F₀ animals, with the exception of the lack of renallesions seen in the F₁, females. These data show that BMP impairedfertility in female mice in both generations in the absenceof an effect on reproductive organ weights and estrual cyclicity.     

Assessment of a two-generation reproductive and fertility study of mercuric chloride in rats.

Effects of mercuric chloride (MC) on the reproductive performance of two successive generations of rats was evaluated. F(0) rats were exposed to 0.0:0.0 (males:females), 0.50:0.75 (males:females), 1.00:1.50 (males:females) and 1.50:2.50 (males:females) mg/kg/day MC. Selected parental F(1) males and females were exposed to the same doses received by their parents (F(0)). Significant differences resulting from exposure of the F(0) generation to MC were found in implantation efficiency, fertility, live births and day 4 survival indices, litter size, and the body weight of F(1) pups. However, the continued exposure of the F(1) generation to MC did not affect fertility index or litter size, but did significantly affect implantation efficiency, live births and day 4 survival indices. In F(0) males, body weight and weights of the kidneys, testes, epididymides, prostate and seminal vesicles were significantly different, while in F(1) males, body weight, kidney weight, brain weight, liver weight and the weights of the testes, prostate and seminal vesicles were significantly different. In F(0) females, body weight and the weights of the kidneys, brain and liver were significantly different, while in F(1,) females, body weight, as well as the weights of the kidneys, liver, adrenals, uterus and ovaries were significantly different. These data showed that exposure to MC resulted in more adverse reproductive effects in the first generation and that these effects moderated in the second generation.     

Maternal exposure to anti-androgenic compounds, vinclozolin, flutamide and procymidone, has no effects on spermatogenesis and DNA methylation in male rats of subsequent generations

To verify whether anti-androgens cause transgenerational effects on spermatogenesis and DNA methylation in rats, gravid Crl:CD(SD) female rats (4 or 5/group, gestational day (GD) 0 = day sperm detected) were intraperitoneally treated with anti-androgenic compounds, such as vinclozolin (100 mg/kg/day), procymidone (100 mg/kg/day), or flutamide (10 mg/kg/day), from GD 8 to GD 15. Testes were collected from F1 male pups at postnatal day (PND) 6 for DNA methylation analysis of the region (210 bp including 7 CpG sites) within the lysophospholipase gene by bisulfite DNA sequencing method. F0 and F1 males underwent the sperm analysis (count, motility and morphology), followed by DNA methylation analysis of the sperm. Remaining F1 males were cohabited with untreated-females to obtain F2 male pups for subsequent DNA methylation analysis of the testes at PND 6. These analyses showed no effects on spermatogenesis and fertility in F1 males of any treatment group. DNA methylation status in testes (F1 and F2 pups at PND 6) or sperms (F1 males at 13 weeks old) of the treatment groups were comparable to the control at all observation points, although DNA methylation rates in testes were slightly lower than those in sperm. In F0 males, no abnormalities in the spermatogenesis, fertility and DNA methylation status of sperm were observed. No transgenerational abnormalities of spermatogenesis and DNA methylation status caused by anti-androgenic compounds were observed.     

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

The reproductive toxicity of toluene was evaluated in a 2-generation test in which male and female Sprague–Dawley rats, parental (F0) and first generation (F1), were exposed to toluene via whole body inhalation, 6 h/day, 7 days/week for 80 days premating and 15 days of mating at concentrations of 0, 100, 500 and 2000 ppm (0, 375, 1875 and 7500 mg/m³). Toluene was administered at 2000 ppm to both sexes, or to females or males only to be mated with untreated partners. Pregnant females at all dose levels were exposed from gestation day (GD) 1–20 and lactation day (LD) 5–21. At LD5, females were removed from their litters for daily exposure and returned when 6 h of exposure was completed. F1 pups selected to produce the F2 generation were treated for 80 days beginning immediately after weaning (LD21) and initially mated at a minimum of 100 days of age. F2 pups were not exposed to toluene by inhalation.

Toluene exposure did not induce adverse effects on fertility, reproductive performance, or maternal/pup behaviors during the lactation period in males and females of the parental or first generation, but did inhibit growth in F1 and F2 offspring in the 2000 ppm (both sexes treated) and 2000 ppm (females only treated) groups. Caesarean section of selected 2000 ppm (both sexes treated) dams at GD20 showed reduced fetal body weight and skeletal variations. Exposure to toluene caused decreased pup weights throughout lactation in F1 and F2 2000 ppm (both sexes treated), and 2000 ppm (females only treated) groups. Exposure at 2000 ppm to male parents only did not induce similar weight inhibition in offspring. The toluene offspring NOAEL is 500 ppm in groups in which maternal animals were exposed, and 2000 ppm for male only treated groups.     

Octyl methoxycinnamate: two generation reproduction toxicity in Wistar rats by dietary administration.

Wistar rats continuously received octyl methoxycinnamate (OMC) in the diet through two successive generations at nominal doses of 0, 150, 450 or 1000 mg/kg bw/day. OMC had no adverse effects on estrous cycles, mating behavior, conception, parturition, lactation and weaning, sperm and follicle parameters, macropathology and histopathology of the sexual organs. 1000 mg/kg bw/day reduced parental food consumption and body weight (-14% to -16% in males, -4% to -5% females), increased liver weight, produced hepatic cytoplasmic eosinophilia and erosion/ulceration of glandular stomach mucosa. and led to a slightly decreased implantation rate in the top dose F0 and F1 dams. The high dose F1 and F2 pups had reduced lactation weight gain and organ weights and delayed sexual maturation landmarks. There was no evidence of a selective influence of the test compound on pups' sexual landmarks. The NOAEL (no observed adverse effect level) is 450 mg/kg bw/day for fertility and reproductive performance, for systemic parental and developmental toxicity.     

Effect of oral administration of 1,3-diphenylguanidine on sperm morphology and male fertility in mice.

An oral testicular toxicity and male fertility study was carried out in CD-1 mice with 1,3-diphenylguanidine (99.9% purity). 1,3-Diphenylguanidine was administered to male mice by daily gavage at dose levels of 0, 0.06, 0.25, 1, 4 and 16 mg/kg body wt. per day during an 8-week premating period. Females were not dosed at any time during the study. Sperm abnormality evaluation was performed in approximately half the males, randomly selected from the control and 16-mg/kg dose group on completion of dosing. The remaining males in the control, 4- and 16-mg/kg body wt per day groups were mated with non-dosed females. Reproductive performance, necropsy findings and litter data were recorded. No differences were found between control and dosed groups in body weight gain during the dosing period, macroscopic observations and organ weights at necropsy. Microscopic examination of the testes and determination of the frequency of total sperm abnormalities in the 16-mg/kg body wt per day group, did not show any effect due to 1,3-diphenylguanidine dosing when compared to the control group, except for a slight increase in sperm with folded tails but normal heads. Male and female fertility as well as reproduction performance were comparable in the groups examined (0, 4 and 16 mg/kg body wt per day). Maternal necropsy findings and litter data did not reveal any dose-related effect. It was concluded that under the conditions of the present study, 1,3-diphenylguanidine did not exert any significant adverse effects on fertility, reproductive capacity or embryonic/fetal development in CD-1 mice when administered to males at levels up to 16 mg/kg body wt per day.     

Two-generation reproductive toxicity study of the rubber accelerator N,N-dicyclohexyl-2-benzothiazolesulfenamide in rats

Male and female Crl:CD(SD) rats were fed a diet containing rubber accelerator N,N-dicyclohexyl-2-benzothiazolesulfenamide (DCBS) at 0, 80, 600 or 4500ppm throughout the study beginning at the onset of a 10-week pre-mating period and continuing through the mating, gestation, and lactation periods for two generations. At 4500ppm, decreases in the body weight, body weight gain, and food consumption were found in F0 males and females. No changes in the estrous cyclicity, copulation index, fertility index, gestation index, delivery index, number of implantations, precoital interval, or gestation length were observed in any generation at any dose of DCBS. Delayed preputial separation at 4500ppm as well as delayed vaginal opening and higher body weight at the age of vaginal opening at 600 and 4500ppm were found in the F1 generation. A transient change in performance in a water-filled multiple T-maze was found at 600 and 4500ppm in F1 females. There were no compound-related changes in number of pups delivered, sex ratio of pups, viability of pups, anogenital distance, surface righting reflex, negative geotaxis reflex, mid-air righting reflex, pinna unfolding, incisor eruption, or eye opening in the F1 and F2 generations. The body weight of F1 and F2 male and female pups was lowered at 4500ppm. Reduced uterine weight of the weanlings was noted in the F1 generation at 4500ppm and in the F2 generation at 600 and 4500ppm. The data indicate that the NOAEL of DCBS for two-generation reproductive toxicity is 80ppm (5.2mg/kgbw per day) in rats.