4-[3-(1-naphthylamino)propyl]morpholine

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

good

System:

haematopoietic

Organ:

thymus

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The purpose of this study was to evaluate the potential effects on general toxicity, neurological and reproductive function, and prenatal/early neonatal growth and offspring survival in rats following repeated oral gavage administration of 4-(3-(1-naphthylamino)propyl)morpholine. This study evaluated 4-(3-(1-naphthylamino)propyl)morpholine in the OECD 422 design.

Groups of 12 male and 12 female Crl:CD(SD) rats were administered 4-(3-(1-naphthylamino)propyl)morpholine in propylene glycol daily, by gavage at dose levels of 0 (control), 10, 50, or 200 mg/kg/day. Females were dosed once daily for four weeks prior to breeding, through breeding (two weeks), gestation (three weeks), and through postpartum day 13. Females were necropsied on postpartum day 14. Males were dosed four weeks prior to breeding and continuing through breeding (two weeks) until necropsy (test days 59-60). Effects on general systemic toxicity, neurobehavioral activity, clinical chemistry, hematology, coagulation, thyroid hormone levels, urine parameters, gonadal function, estrous cyclicity, mating behavior, conception, development of the conceptus, parturition and early postnatal growth and survival were evaluated. In addition, a gross necropsy of the adults was conducted with extensive histopathologic examination of tissues. Litter size, pup survival, sex, body weight, anogenital distance, nipple retention, and the presence of gross external morphological alterations were assessed in the offspring.

Male and female rats administered 10, 50, or 200mg/kg/day 4-(3-(1-naphthylamino)propyl)morpholine had no treatment-related effects in clinical signs orneurobehavioral endpoints whencompared to control animals. There were no treatment-related effects of 4-(3-(1-naphthylamino)propyl)morpholine on reproductive function, or survival of the offspring at any dose level tested.

Gestation body weight gains were statistically identified and 14.5% lower from GD 0-20 in females given 200 mg/kg/day when compared to controls. Body weights were statistically identified and 7% lower on GD 20 in females given 200 mg/kg/day when compared to controls. These decreases were associated with decreased feed consumption throughout gestation. There was a treatment-related decrease in lactation body weights (4-6% throughout lactation) in females given 200 mg/kg/day. There were no corresponding decreases in feed consumption or body weight gains during lactation in this group, and therefore, the lower body weights likely reflect the lower body weights and body weight gains during gestation. There were no treatment-related differences in the body weights of females at any dose level tested during the pre-mating period or in body weight gains during the lactation period. There were no treatment-related differences in body weights of females in the 10 or 50 mg/kg/day groups during lactation. No significant differences in body weights were observed for males at any dose level when compared to controls.

There was a treatment-related decrease in feed consumption of 43% from TD 1-3, 16% from TD 3-8, and 11% from TD 15-22 in females given 200 mg/kg/day when compared to controls. There was treatment-related decreased feed consumption throughout gestation of 7-9% in females given 200 mg/kg/day compared to controls. In males given 200 mg/kg/day, there was a treatment-related decrease in feed consumption of 26% from TD 1-3 and 11% from TD 3-8 compared to controls. There were no treatment-related effects on feed consumption throughout lactation. There were no significant differences in the amount of feed consumed by males or females at 10 or 50 mg/kg/day when compared to their respective controls throughout the study.

There were no treatment-related effects on litter size. Male and female pup body weights were decreased on PND 4, 7 and 13 (statistically identified in females on PND 4(AC), 7, and 13 and in males on PND 13) in litters from dams given 200 mg/kg/day. Decreases in pup body weights were associated with decreases in maternal gestation body weights and body weight gains in the 200 mg/kg/day dose group. There were no treatment-related effects on pup body weights in pups from dams given 10 or 50 mg/kg/day.

Males and females given 200 mg/kg/day had treatment-related higher mean reticulocyte counts, which were interpreted to be a regenerative response to hemolysis of the red blood cells at this dose level. The hemolysis and associated reticulocytosis were interpreted to be non-adverse effects. Treatment-related very slight polychromasia of red blood cells was present in males and females given 200 mg/kg/day, and was interpreted to be reflective of a non-adverse regenerative response to the hemolytic anemia. Males given 200 mg/kg/day had a statistically significant treatment-related higher mean white blood cell count, and treatment-related higher percent neutrophils, and lower percent lymphocytes. These alterations in white blood cell parameters were non-adverse. There were no treatment-related effects on prothrombin time in male or female rats administered10, 50, or
200mg/kg/day.

Males and females given 200 mg/kg/day had treatment-related higher mean total bilirubin concentrations, which were interpreted to be caused by hemolysis. Males given
200 mg/kg/day had a statistically significant treatment-related higher mean phosphorus concentration. Females given 200 mg/kg/day had treatment-related higher mean cholesterol and triglyceride concentrations, lower mean albumin and glucose concentrations, lower alanine aminotransferase (ALT) activity, and a statistically significant higher mean potassium concentration. The alterations in albumin, glucose, ALT, and potassium were interpreted to be treatment related. None of the alterations in clinical chemistry parameters were interpreted to be indicative of adverse effects.

Males given 10, 50 or 200 mg/kg/day had a treatment-related and dose-responsive increase of bilirubin in the urine. Additional treatment-related alterations in males given
200 mg/kg/day consisted of the presence of moderate amounts of protein, trace amounts of glucose, and increases in the concentration of urobilinogen in the urine. None of the alterations in urinalysis parameters were interpreted to be indicative of adverse effects.

There were no treatment-related changes in the serum concentrations of T3 or T4 in PND 4 culled pups, PND 13 males or females, nor in adult males, at any dose level. There was a treatment-related and statistically identified decrease in the mean T4 concentration of LD 14 dams given 200 mg/kg/day. There was no treatment-related effect on T3 at any dose level or T4 concentrations at 10 or 50 mg/kg/day in LD 14 dams.

Females given 200 mg/kg/day had a treatment-related 8.1% lower mean final body weight, relative to controls. The final body weights of females given 10 or 50 mg/kg/day and of males given 10, 50 or 200 mg/kg/day were similar to controls.

Males given 10, 50 or 200 mg/kg/day had dose-dependent higher absolute and relative mean kidney weights, which were interpreted to be treatment related, and corresponded to the presence of very slight increased hyaline droplet formation in males given 50 or
200 mg/kg/day, and the presence of increased hematogenous pigment (consistent with

 

bilirubin) in females given 50 or 200 mg/kg/day. Females given 200 mg/kg/day had higher mean relative kidney weights that were interpreted to be reflective of the lower mean final body weight of females at this dose level.

Males and females given 200 mg/kg/day had treatment-related higher mean absolute and relative liver weights (19.9% and 23.2% higher for males, respectively and 9.9% and 19.7% higher for females, respectively). Treatment-related higher mean absolute and relative liver weights (not statistically identified) were also present in males given 50 mg/kg/day (8.4% and 5.6% higher than controls, respectively). The higher liver weights in males and females given 200 mg/kg/day, and in males given 50 mg/kg/day, corresponded to very slight or slight hypertrophy of centrilobular/midzonal hepatocytes, with increased cytoplasmic eosinophilia. Females given 50 mg/kg/day had a 5.9% increase in relative liver weight, which was interpreted to be treatment related, but lacked a histopathologic correlate.

Males given 50 or 200 mg/kg/day had treatment-related higher mean absolute and relative spleen weights. The higher spleen weights in males given 200 mg/kg/day corresponded to slight congestion of the red pulp, very slight or slight increased erythrocytic and granulocytic extramedullary hematopoiesis, and very slight or slight increased amount of pigment (hemosiderin)-laden macrophages. The higher spleen weights in males given
50 mg/kg/day corresponded to very slight increased erythrocytic extramedullary hematopoiesis, and very slight increased amount of pigment (hemosiderin)-laden macrophages.

Males given 200 mg/kg/day had treatment-related higher mean absolute and relative thyroid weights. The higher thyroid weights in males given 200 mg/kg/day did not have a histopathologic correlate, and were not accompanied by alterations in serum T3 and T4 concentrations.

Females given 200 mg/kg/day had treatment-related statistically identified lower mean absolute and relative thymus weights. The lower mean thymus weights corresponded to very slight atrophy of lymphoid tissue in the cortex of the thymus.

A treatment-related histopathologic liver effect consisted of hypertrophy of centrilobular/midzonal hepatocytes, with increased cytoplasmic eosinophilia, in males given 50 mg/kg/day and in males and females given 200 mg/kg/day, which was interpreted to be a non-adverse and adaptive effect.

A treatment-related histopathologic kidney effect consisted of a very slight increase compared to controls in hyaline droplet formation in the proximal convoluted tubules of males given 50 or 200 mg/kg/day. The occurrence of increased amounts of amounts of hyaline droplets was interpreted to be a non-adverse effect. Another treatment-related histopathologic kidney effect was a very slight increase in hematogenous pigment in the renal tubules of females given 50 or 200 mg/kg/day. The pigment was present in the cytoplasm of cortical tubules, and was weakly positive for bilirubin with Fouchet’s bile stain, and negative for iron with Prussian blue stain. The presence of bilirubin in the renal cortical tubules was interpreted to be a non-adverse effect.

Treatment-related histopathologic effects of the spleen were the following: an increased incidence of slight congestion of the red pulp in males and females given 200 mg/kg/day; very slight or slight increased erythrocytic extramedullary hematopoiesis in males given
50 mg/kg/day and in males or females given 200 mg/kg/day; very slight increased granulocytic extramedullary hematopoiesis in males given 200 mg/kg/day; and very slight or slight increases in pigment-laden macrophages in males and females given 10, 50 or
200 mg/kg/day. The macrophages stained positive for iron with Prussian blue stain, and were therefore consistent with the presence of hemosiderin. All of the histopathologic alterations of the spleen were interpreted to be non-adverse.

Treatment-related very slight to moderate subacute to chronic inflammation in the mucosa and submucosa of the cecum was present in males given 200 mg/kg/day. Males with slight or moderate inflammation of the cecum also had slight focally extensive or diffuse edema in the submucosa of the cecum. The male with moderate inflammation of the cecum also had slight, multifocal necrosis of mucosal epithelial cells. The inflammation, edema, and mucosal necrosis of the cecum were interpreted to be adverse locally irritating effects of treatment.

Treatment-related atrophy of the lymphoid tissue of the thymus was present in females given 200 mg/kg/day. The thymic atrophy was interpreted to be a stress-induced adverse effect.

A treatment-related increase in the incidence of very slight hypertrophy of follicular cells of the thyroid gland was present in females given 200 mg/kg/day.

Treatment-related histopathologic effects of the nasal tissues and/or pharyngeal duct were present in males and females given 200 mg/kg/day, and females given 10 or 50 mg/kg/day. The effects were randomly distributed within the nasal passages, and consisted of variable incidences and severities of the following: degeneration in the olfactory, respiratory, transitional and/or pharyngeal duct epithelium; fibrinopurulent exudate; chronic active inflammation in areas of epithelial degeneration; squamous metaplasia of the respiratory, transitional and/or pharyngeal duct epithelium; ulcers of the respiratory and/or pharyngeal duct epithelium, and synechia of the turbinates. All of the nasal tissue/pharyngeal effects were interpreted to be adverse and reflective of direct irritation due to inadvertent reflux of the test material into the pharyngeal duct and nasal passages during oral gavage administration.

Pigment-laden macrophages (brown pigment) were present in the mucosa and/or submucosa of the duodenum, jejunum, ileum, cecum and/or colon of males and females given 50 or
200 mg/kg/day. Pigment-laden macrophages (brown pigment) were also present in the mesenteric lymph nodes in males given 50 or 200 mg/kg/day and females given 10, 50, or 200 mg/kg/day. The pigment-laden macrophages were interpreted to be reflective of absorption of the test material, which was brown in color, and not an adverse effect of treatment.

A no-observed-effect level (NOEL) for general toxicity could not be determined for male or female rats due to the occurrence of treatment-related effects at all dose levels. Based on adverse locally irritating effects in the cecum and nasal tissues of males given
200 mg/kg/day, the no-observed-adverse-effect level (NOAEL) for males was
50 mg/kg/day. However, there were no adverse systemic effects in males at any dose level. Based on adverse locally irritating effects in the nasal tissues and/or pharynx of some females at all dose levels, a NOAEL for females was not determined. However, adverse systemic effects in females were stress-induced lymphoid atrophy of the thymus and decreased body weight gain, body weight and feed consumption during gestation in rats given 200 mg/kg/day. Therefore the NOAEL for systemic toxicity was 200 mg/kg/day for males, and 50 mg/kg/day for females. 

Justification for classification or non-classification

In the available repeated dose toxicity study, the observed toxicological effects were limited to local signs of irritation in male animals at the top dose group; no systemic toxicological effects were observed up to the top dose of 200 mg/kg

In females, the critical effect (other than irritation of the nasal tissues) was a stress induced lymphoid atrophy of the thymus and a decreased bodyweight/bodyweight gain, leading to a NOAEL for systemic toxicity of 50 mg/kg bw.

These findings are not consistent with the type of effects required to trigger a repeated dose toxicity classification. Therefore it is concluded that this substance does not require classification for repeated dose toxicity.