N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Dose descriptor:

NOAEL

22.5 mg/kg bw/day

Additional information

In an early three-generation study Charles River CD rats were treated with 77DP for three successive generations (Monsanto Co. 1980). 77PD was administered in the diet at concentrations of 30, 100 and 300 ppm (ca. 2.25, 7.5, 22.5 mg/kg bw/day). Groups of 8 male and 16 female F0 rats were administered test diets for 11 weeks. Administration continued through mating, gestation and lactation for two successive litters (F1aF1b). A10 day rest period was allowed between litters. Groups of 8 males and 16 females were retained at weaning from the second litters of each dose level as parental animals for succeeding generation. Growth and reproduction procedures described for F0 generation were repeated for the F1 and F2 generations.

Parental animals were observed daily for mortality or abnormal reactions. Body weights were measured weekly during 11 week growth period. Food consumption was measured at three intervals during the F0 growth period. Pups were observed daily for mortality, were counted on day 0, 1, 4, 12 and 21 of lactation; and were weighed on day 21 of lactation. Parental animals were sacrificed after weaning of their second litter. All litters were culled on day 4 of lactation to 10 pups/litter. All other pups except those selected for production of succeeding generations were sacrificed two weeks post-weaning. Animals selected for preservation of tissue or animals exhibiting abnormal development were subject to gross pathology examination. Tissues were preserved from 8 male and 8 female parental animals from each generation and from 10 male and 10 female pups of the F3b litters. Body weights were measured and organ weights were determined for brain, gonads, heart, kidneys, liver, and spleen of parental animals. Histopathologic evaluations of about 30 selected tissues were conducted on 5 male and 5 female parental animals from F0, F1 and F2 generation and 10 male and 10 female pups from the F3B3 generation, all from control and high dose groups, and on abnormal tissues preserved from parental animals in low and mid dose level group. Limited histopathologic evaluation was also conducted on tissues from animals which died during the study.

Mortality of parental animals was high throughout the study. However, this mortality occurred in all study groups and was not considered related to treatment.

Postmortem pathologic evaluation revealed as common findings in the lungs lesions associated with chronic murine pneumonia, suppurative bronchopneumonia and absesses. The lessions of chronic murine pneumonia were present in most animals of the sacrificed, moribund sacrifice and death groups of animals of the F0, F1 and F2 generations. However, lesions of suppurative bronchopneumonia, graded as moderately severe to severe, were present in many animals that died in these three generation study. Pathologic evaluations revealed suppurative bronchopneumonia in most of the dead animals. The authors of the pathologic study report suggested that severity of the suppurative bronchopneumonia lesions was considered to be related to the most probable cause of death for many of the animals that died.

No unusual behavioural reactions related to treatment were observed during the study. A number of treated and control F0 animals were reported as possibly having respiratory infection (as discussed above). Reduced body weight gains were reported for parental animals in the high dose group for each parental generation. Final body weights were lower for parental animals in these groups also. No consistent weight gain reductions were noted for the animals fed either 30 or 100 ppm. At week 9 animals of the 300 ppm group showed reduced food intake compared to the lower dose groups and control. The authors suggested poor palatability of the 300 ppm dietary mixture.

Mating indices, fertility indices, and the incidence of parturition were comparable between control and treated groups throughout the study. The number of pups delivered and weaned by treated and control animals, was comparable for F0, F1 and F2 generations. The number of pups surviving to weaning in the F1b, F2a, F2b, F3a and F3b high dose litters and the number surviving in F2a, F3a and F3b mid dose litters was reduce; survival indices for these litters were reduced accordingly. Survival indices calculated for the low dose group were comparable to control values. Body weights of weanlings from the high dose group were significantly reduced for F1b males and for F2 and F3 litter males and females. Pup weights were slightly reduced for mid-dose group litters. No unusual behavioural reactions considered related to treatment were noted for offspring during the study.

Gross necropsy observations of F0, F1and F2 adults sacrificed after weaning of their second litters did not reveal any adverse effects related to the test material administration. For high dose animals, kidney weights were reduced in the F0, F1 and F2 generations, and liver weights were reduced for F1 and F2 generation animals. No other statistical differences in organ weights were noted for F0, F1 or F2 parental animals in any treatment group. No treatment-related gross pathologic alterations or external structural malformation were noted in offspring of treated animals. Microscopic examination of tissues from selected F0, F1 and F2 parental animals and F3b pups from control and high dose groups, and from selected animals from low and mid dose groups, revealed no abnormalities associated with treatment.

In conclusion, test substance concentration of 30, 100 and 300 ppm administrated in the diet to male and female rats for three successive generations produced no adverse effects on foetal survival or on mating or fertility indices. Survival during lactation of pups from high and mid dose groups was reduced in F1, F2 and F3 litters. Body weights of pups from high dose and mid-dose groups and from parental animals from the high dose group were reduced during the study; because of the limited documentation the relevance of these findings are unclear.

Organ weights for kidney and liver from high dose animals were reduced. Necropsy evaluation of animals from the study and histopathologic evaluation of tissues from parental animals and F3b pups indicated no treatment related effects from administration of test material.

Based on findings of this study, a NOAEL fertility of 300 ppm (ca. 22.5 mg/kg bw/day, highest dose tested) and a NOAEL maternal toxicity of 100 ppm are suggested.

Short description of key information:
The effect of 77PD on fertility was evaluated in an early three-generation study (Monsanto Co. 1980). Rats were treated with 77PD concentrations of 30, 100 and 300 ppm in the diet for three successive generations. No adverse effects on foetal survival or on mating or fertility indices were indicated. However, survival during lactation of pups from high and mid dose groups was reduced in F1, F2 and F3 litters. In addition, body weights of pups from high dose and mid-dose groups and from parental animals from the high dose group were reduced during the study. Organ weights for kidney and liver from high dose animals were reduced. Necropsy evaluation of animals from the study and histopathologic evaluation of tissues from parental animals and F3b pups indicated no treatment related effects from administration of test material. Based on the data from the early three-generation study a NOAEL fertility of 300 mg/kg (ca. 22.5 mg/kg bw/day, highest dose tested) is suggested. The NOAEL for parental toxicity is 100 ppm and based on body weight changes and reduction in kidney and liver weights observed at 300 ppm. No effects on foetal development and on foetal survival were indicated. However the body weights of mid- and high dose pups as well as the survival during lactation were reduced; because of the limited documentation the relevance of these findings are unclear.

Effects on developmental toxicity

Description of key information

The developmental toxicity of the test substance 77PD was evaluated in a teratology study (Monsanto Co. 1986).  Pregnant Charles River CD® rats (25 per group) were administered orally with 0, 25, 75 and 150 mg/kg bw and day on day 6 through 15 of gestation. Cesarean sections were performed on all surviving females on gestation day 20 and the foetuses were removed for teratologic evaluation. Maternal toxicity was observed at 75 and 150 mg/kg bw and day, indicated by death, clinical signs, reduced body weight and/or body weight gain. No adverse effects were noted on dams or foetuses at Cesarean section. No relevant differences were observed in number of viable foetuses, number of implantations, post-implantation loss, number of corpora lutea and foetal sex distribution in treated animals compared to control. However, the mean foetal body weight value at 25 mg/kg/day was significantly higher than the control but was attributed to inherent biological variation. Malformations that were observed in the treated groups occurred in low incidence and were not considered treatment related. No meaningful differences were noted between the incidence of developmental variations seen in the treated groups and those in the control group. Based on the findings from this study a NOAEL developmental toxicity of 150 mg/kg bw and day (highest dose tested) and a NOAEL maternal toxicity of 25 mg/kg bw and day are suggested. 

Effect on developmental toxicity: via oral route

Dose descriptor:

NOAEL

150 mg/kg bw/day

Additional information

The developmental toxicity of the test substance 77PD was evaluated in a teratology toxicity study (OECD TG 414) (Monsanto Co. 1986). Pregnant Charles River CD® rats (25 per group) were used to determine the teratogenic potential of the test substance. Dosage levels of 0, 25, 75 and 150 mg/kg bw and day were administered orally by gavage as a single daily dose on day 6 through 15 of gestation. The control group received the vehicle (corn oil) only. Cesarean sections were performed on all surviving females on gestation day 20 and the foetuses were removed for teratologic evaluation. Mortality occurred in females of the mid (1/25) and high dose group (4/25). The high dose group females died between gestation days 16 and 17 and the mid dose group female died on gestation day 17. All control and 25 mg/kg/day females survived to scheduled sacrifice.

Clinical signs were noted in all treated animals. Antemortem abnormalities noted among the females that died included blood around and/or expelled from vaginal opening; blood under the cage; stained, wet and/or matted haircoat; hypothermia and ptyalism. For the mid dose female that died during treatment only ptyalism was noted; the necropsy observations of the animals that died were not meaningfully different from those of the control animals. Observation of high dose females that survived to scheduled sacrifice revealed an increased incidence of stained, wet and/or matted haircoat predominantly in the anogenital region. Ptyalism was apparent at all treated dosage levels although the incidence was very low. No treatment-related gross internal lesions were noted at necropsy. Body weight loss was observed during the initial subinterval of treatment (gestation days 6 to 9) at the 150 mg/kg/day dose level. Moreover, body weight gains during both the overall treatment and gestation intervals (gestation days 6-15 and 0-20, respectively) were reduced, relative to the control, at the 75 and 150 mg/kg/day dosage levels. Treatment-induced differences in body weight gain were not evident at the 25 mg/kg/day dose level.

No differences attributable to treatment were observed in the dams or foetuses at Cesarean section. No relevant differences were observed in number of viable foetuses, number of implantations, post-implantation loss, number of corpora lutea and foetal sex distribution in treated animals compared to control. However, the mean foetal body weight value at 25 mg/kg/day was significantly higher than the control and was attributed to inherent biological variation for lack of similar findings at the 75 and 150 mg/kg/day dose levels. Malformations that were observed in the treated groups occurred in low incidence and were not considered treatment related (total fetuses (litters) with malformations: control: 2 (2), low dose: 0 (0), mid-dose: 2 (2), high dose: 1 (1)). One high-dose foetus had anophthalmia, one mid-dose and two control foetuses had microphthalmia and another mid-dose foetus had ectopia cordis and scernoschisis. No meaningful differences were noted between the incidence of developmental variations seen in the treated groups and those in the control group (total fetuses (litters) with variations: control: 77 (22), low dose: 57 (20), mid dose: 68 (17), high dose: 64 (17)).

Based on the findings of this study, the authors suggested a NOAEL developmental toxicity of 150 mg/kg bw and day (highest dose tested). Maternal toxicity was observed at 75 and 150 mg/kg bw/day, indicated by mortality, clinical signs and reduced body weights and/ or body weight gain; based on these findings a NOAEL maternal toxicity of 25 mg/kg bw and day is suggested.

In an early and limited documented teratology study female New Zealand albino rabbits were treated with 77PD (Monsanto Co. 1980). The animals were dosed with 3.0 or 10.0 mg/ kg bw test substance included in gelatine capsules. The concurrent control group received empty gelatine capsules. All does were treated from gestation days 6 through 18 and were sacrificed on gestation day 29. The day of artificial insemination was defined as gestation day 0. Both treatment groups and the control group exhibited decreased body weights during the dosing period (gestation day 6 to 18), while only the control group showed mean body weight at study termination compared to the body weight on gestation day 0. Reproduction data included total number of implantation sites, total number of resorption sites (early and late), total number of live pups, number of abortions and number of resorption sites and live pups per 100 implantation sites. Four does of the high dose group aborted during the study; however three of these does aborted and were found dead. Gross examination of these three animals revealed ulcerated mucosa of the stomach. The authors concluded that these deaths were not treatment-related; because none of the other treated animals showed these effects. No control or low dose group does aborted during the study. The number of resorption sites per 100 implantation sites was slightly higher in the control group compared to the treated animals. No-treatment related effects were noted on the number of implantation sites. No clinical signs were noted in any of the does during the study. Examinations for foetal external abnormalities revealed one high dose foetus with bilateral talipomanus; however talipomanus has been observed in control foetuses in this laboratory (no additional data given). Because of the low incidence (1/72 fetuses and 1/8 pups in the litter) and the occurrence of talipomanus in historical control data the authors concluded that this finding is not relevant. According to the authors, the incidences other external abnormalities were within the range of the current negative control or within the historical control data (no data given). No internal abnormalities were seen in any of the evaluated foetuses. No differences in foetal body weights were noted; however the survival of high dose foetuses were reduced after 24 hour incubator time.

The relevance of these findings is limited because of limitation of study documentation and performance and should only be used for supporting reasons.