N-[3-(dimethylamino)propyl]docosanamide

Endpoint summary

Description of key information

- subacute 4-week study; oral (gavage), rat (Sprague-Dawley); 5 rats/dose/sex in the groups treated with 30 and 60 mg/kg bw/d, 10 rats/dose/sex in the control group and in the group treated with 120 mg/kg bw/d., OECD TG 407, GLP; NOAEL = 60 mg/kg bw/day (based on lower food intake and slight reduction in body weight gain at 120 mg/kg bw/day); read-across: N-[3-(dimethylamino)propyl] C12-C18 alkylamide

- Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test, 10 Wistar rats/sex/dose by gavage at dose levels of 0, 5, 15 and 45 mg/kg bw/d; Males were exposed for 28 days, Females were exposed for 54 days, according to OECD guideline 422, GLP; NOAEL(reproduction/development) = 45 mg/kg; NOAEL(parental toxicity) = 15 mg/kg bw/d (increased salivation, reduced body weight gain at 45 mg/kg bw/d); read-across: N-[3-(dimethylamino)propyl] C12-C18 alkylamide

 

- subchronic 90 d study; oral (gavage), rat (Crl:WI (Han)); 10/sex/dose; 0, 15, 30, 60 mg/kg bw/d; OECD TG 408, GLP; NOAEL systemic effects: 60 mg/kgbw/day (no signs of systemic toxicity); NOAEL local effects: 15 mg/kg bw/day (local effects in the non-glandular stomach) ; read-across: N-[3-(dimethylamino)propyl] C12-C18 alkylamide

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: tertiary amines, amides, and fatty acid chains with comparable length and degree of saturation (corresponding to scenario 2 of the read-across assessment framework)

The read-across hypothesis is based on structural similarity of target and source substances. The target and source chemicals have a very similar structure in that they are comprised of a hydrophobic (alkyl) and hydrophilic (amine headgroup) end. Due to this motif they form micelles (colloidal dispersions) and have surfactant properties.
Based on available experimental data, including key physicochemical properties and data from genotoxicity studies, the read-across strategy is supported by a similar toxicological profile of all substances.

Therefore, read-across from the existing toxicity studies conducted with the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A justification for read-across is attached to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See justification for read-across attached to IUCLID section 13.

3. ANALOGUE APPROACH JUSTIFICATION
See justification for read-across attached to IUCLID section 13.

4. DATA MATRIX
See justification for read-across attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Species:

rat

Strain:

other: Crl:WI (Han)

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

corn oil

Duration of treatment / exposure:

90 d

Frequency of treatment:

daily

Dose / conc.:

15 mg/kg bw/day (actual dose received)

Dose / conc.:

30 mg/kg bw/day (actual dose received)

Dose / conc.:

60 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No clinical signs of toxicity were noted during the study period and no additional findings were noted during the arena observations.
Salivation seen after dosing among 30 and 60 mg/kg bw/day animals was not considered toxicologically relevant, taking into account the nature and minor severity of the effect and its time of occurrence (i.e. after dosing). This sign was considered to be a physiological response related to taste of the test item rather than a sign of systemic toxicity.
Any other clinical signs noted during the treatment period occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this study and did not show any apparent dose-related trend.
One 30 mg/kg bw/day female displayed piloerection on a few occasions, however at the incidence observed, these were considered to be unrelated to treatment.

Mortality:

no mortality observed

Description (incidence):

No mortality occurred during the study period.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Body weights and body weight gain of treated animals remained in the same range as controls over the study period.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Food consumption before or after correction for body weight remained similar to the control level over the study period.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

no effects observed

Description (incidence and severity):

The nature and incidence of ophthalmology findings noted was similar among the groups, and occurred within the range considered normal for rats of this age and strain. These findings were therefore considered to be unrelated to treatment with the test item.

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Statistically significantly higher relative eosinophil counts were recorded for 60 mg/kg bw/day females.
Other statistically significant changes in haematology parameters were considered to be unrelated to treatment as these occurred in the absence of a dose-related trend. These included changes in mean corpuscular haemoglobin (MCH) (30 mg/kg bw/day males), mean corpuscular haemoglobin concentration (MCHC) (30 and 60 mg/kg bw/day males), neutrophil and lymphocyte (30 mg/kg bw/day females) levels.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Clinical biochemistry parameters were considered unaffected by treatment.
Any statistically significant changes in clinical biochemistry parameters were considered to be unrelated to treatment as these occurred in the absence of a dose-related trend. This included changes in sodium and chloride levels in 15 and 30 mg/kg bw/day males and females, in albumin and inorganic phosphate levels of 30 mg/kg bw/day males, and total bilirubin levels of 15 mg/kg bw/day females.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Grip strength and motor activity were similar between treated and control groups. Regarding motor activity, all groups showed a similar motor activity habituation profile with a decreasing trend in activity over the duration of the test period.
Hearing, pupil reflex (left), pupil reflex (right), and static reflex were not recorded. However, it was considered unlikely that treatment related changes had occurred in these parameters since there were no signs of toxicity in related observations, such as clinical signs, arena observations, ophthalmoscopy, grip strength, and motor activity.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no test item-related alterations in organ weights.
All organ weight differences observed, including those that reached statistical significance, were considered incidental and unrelated to the administration of the test item.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test item-related microscopic findings after treatment with the test item were noted in the nonglandular stomach of 15, 30, and 60 mg/kg bw/day males and females.
A dose-dependent increase in incidence and severity of hyperplasia, squamous cell was recorded in the non-glandular stomach (forestomach) in males and females of 15, 30 and 60 mg/kg bw/day animals from a minimal to slight level, and to a moderate level in 60 mg/kg bw/day males. Related to this finding, hyperkeratosis and undulations at the basement membrane zone were often observed concomitantly. In two males treated with 30 mg/kg bw/day, and one male and one female treated with 60 mg/kg bw/day, signs of slight cellular atypia were noted. There were no other test item-related histological changes observed. The remainder of the recorded microscopic findings were within the range of background pathology encountered in rats of this age and strain.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Details on results:

Oral administration of the test item resulted in local proliferative lesions in the non-glandular stomach (the forestomach) in all treatment groups, with an increasing incidence and severity (see Table 1 in "Any other information on results including tables" for incidence and severity) (20, 75 and 90% of the animals affected at 15, 30 and 60 mg/kg bw/day respectively). The lesions were characterized by areas of a thickened epithelial layer, frequently accompanied by hyperkeratosis (5, 60 and 70% of the animals affected at 15, 30 and 60 mg/kg bw/day, respectively) and undulations at the basement membrane zone (10, 55 and 70% of the animals affected at 15, 30 and 60 mg/kg bw/day, respectively). Undulations are believed to be caused by the space occupying expansion of the epithelial layer of the forestomach and considered a secondary
change. In a single male treated with 60 mg/kg bw/day the lesion became slight papillary. Signs of slight cellular atypia were noted in few males treated with 30 mg/kg bw/day and in a male and female treated with 60 mg/kg bw/day. The finding of obvious squamous cell hyperplasia (with early signs of atypia in some cases) in the non-glandular stomach of rats treated with 30 or 60 mg/kg bw/day is considered an adverse finding. Lesion in the non-glandular stomach of rodents however are considered clinically irrelevant since humans do not have a forestomach equivalent.

Key result

Dose descriptor:

NOAEL

Remarks:

For systemic toxicity

Effect level:

>= 60 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: As no signs of systemic toxicity were observed, the NOAEL for systemic toxicity is 60 mg/kg bw, the highest dose tested in this study.

Dose descriptor:

NOAEL

Remarks:

For local effects

Effect level:

15 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

30 mg/kg bw/day (actual dose received)

System:

gastrointestinal tract

Organ:

stomach

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

no

Conclusions:

In a GLP-compliant OECD guideline 408 study, the NOAEL for local toxicity was set at 15 mg/kg bw/day, based on the local proliferative lesions (including squamous cell hyperplasia with early signs of atypia in some cases) in the forestomach. As no signs of systemic toxicity were observed, the NOAEL for systemic toxicity is 60 mg/kg bw, the highest dose tested in the study conducted with the source substance. This result is applicable also to the target substance DIMAPDO.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

60 mg/kg bw/day

Study duration:

subchronic

Species:

rat

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

Experimental data on repeated dose toxicity is not available for the target substance DIMAPDO. For the assessment of effects of DIMAPDO after repeated exposure the results of a subacute 28-day study, theCombined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Testand a subchronic 90 d study conducted with the structurally similar source substance N-[3-(dimethylamino)propyl] C12-C18 alkylamide are taken into consideration. A justification for read-across is attached to IUCLID section 13.

 

Subacute toxicity

In a subacute toxicity study N-[3-(dimethylamino)propyl] C12-C18 alkylamide was administered daily for 29 days by oral route (gavage) to two groups of 5 male and 5 female Sprague-Dawley rats at dose-levels of 30 or 60 mg/kg bw/d and to one group of 10 male and 10 female rats at the dose-level of 120 mg/kg bw/d under a constant dosage-volume of 5 mL/kg bw/d. An additional group of 10 male and 10 female rats received the vehicle only, corn oil, under the same experimental conditions and acted as a control group. An additional satellite group was included in the control and high-dose groups for observation of reversibility, persistence or delayed occurrence of systemic / irritative effects for 4-week post-treatment.

On completion of the treatment period, the principal animals were sacrificed and the last five control and high-dose animals per sex were kept for a 4-week treatment-free period. The test item was administered as a solution in the vehicle. On completion of the treatment or treatment-free period, the animals were humanely sacrificed and subjected to a full macroscopic post-mortem examination.

No unscheduled deaths occurred during the study. Treatment with the test item induced mainly ptyalism, loud breathing and piloerection. Ptyalism was observed in all treated animals except two females receiving the 30 mg/kg/d dose. In the 60 and 120 mg/kg/d groups, loud breathing was noted in all but one male. All but one female experienced also loud breathing in the 120 mg/kg/d group while only one female in the 60 mg/kg/d group showed this clinical sign. Loud breathing was observed in 1 out of 5 males treated at 30 mg/kg/d. Piloerection was recorded in 3 out of 10 high-dose males. These findings were not observed in controls animals and were reversible during the recovery period. There were no signs of disturbance of neurobehavior in any of the test item-treated animals.

A trend towards a lower body weight gain was noted in treated animals associated with a decrease in food consumption in high-dose animals when compared to controls. These effects were reversible during the recovery period. Hematological, blood biochemical and urinary parameters did not reveal any toxicologically significant effect of the test item. There were no treatment-related changes in the mean organ weights of animals sacrificed at the end of treatment and treatment-free periods. White discoloration in the forestomach of most of the animals given 60 or 120 mg/kg/d was observed at necropsy and considered to be associated with the test item. No test item-related changes were observed at necropsy at the end of the treatment-free period. Microscopic examination revealed signs of pronounced irritation in the forestomach of animals given 60 or 120 mg/kg/d. These consisted of acanthosis, hyperkeratosis, erosion/ulcer, edema with mixed infiltrate of inflammatory cell in the submucosa and correlated with the white discoloration seen at necropsy. At 30 mg/kg/d, changes in the forestomach were present with lower severity and incidence. These changes were considered to be adverse. Compared with controls, there was a marginal and not dose-related increase in the incidence of edema and infiltrate of mixed inflammatory cells in the glandular stomach of the treated animals. This was considered to represent extension of the inflammatory process. Following a 4-week treatment-free period, acanthosis and hyperkeratosis were observed in the forestomach but with lower severity than observed at the end of the treatment period. The lower incidence and severity of changes observed in the forestomach after a 4-week treatment-free period were indicative of a pronounced but not totally complete recovery.

Based on the experimental conditions of this study the NOAEL of N-[3-(dimethylamino)propyl] C12-C18 alkylamide with respect to systemic toxic effects was considered to be 60 mg/kg bw/d because of lower food intake and slight reduction in body weight gain observed in animals treated at 120 mg/kg bw/d, and the NOAEL with respect to local effects could not be established because of irritation observed in the forestomach of all treated groups. However, in the absence of a similar structure in the stomach from human beings, the effect was not considered relevant for Human health.

 

A Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test (adopted 22 March 1996) in accordance with OECD TG 422 was performed with the source substance of N-[3-(dimethylamino)propyl] C12-C18 alkylamide. The test item was administered by gavage to three groups, each of ten male and ten female Wistar rats, for up to eight weeks (including a two week maturation phase, pairing, gestation and early lactation for females), at dose levels of 5, 15 and 45 mg/kg/d. A control group of ten males and ten females was dosed with vehicle alone (Corn oil). Clinical signs, behavioural assessments, body weight change and food and water consumption were monitored during the study. Extensive functional observations were performed on five selected males from each dose group after the completion of the mating phase, and for five selected parental females from each dose group on Day 4 postpartum. Haematology and blood chemistry were evaluated prior to termination on five selected males and females from each dose group. Males were terminated on Day 43, followed by the termination of all surviving females and offspring on Day 5 post partum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Results: There were no unscheduled deaths that were related to treatment. Episodes of increased salivation were evident in animals of either sex treated with 45 mg/kg/d throughout the treatment period. An isolated incident of noisy respiration was also evident in one male treated with 45 mg/kg/d on Day 4. No toxicologically significant effects were detected in animals of either sex treated with 15 or 5 mg/kg/d. There were no treatment-related changes in the behavioural parameters measured, no toxicologically significant changes in functional performance and no treatment-related changes in sensory reactivity. Females treated with 45 mg/kg/day showed a reduction in body weight gain during the premating period, with four females showing actual body weight losses during the first week of treatment whereas this was the case for two animals of the control group. However, this difference was not statistically significant, nor was there any difference in body weight visible during the remainder of the study. No body weight effects were detected in males treated with 45 mg/kg/d or animals of either sex treated with 15 or 5 mg/kg/d.

No adverse effect on food or water consumption or food efficiency was detected. There were no toxicologically significant effects detected in the haematological or in the blood chemical parameters measured. No treatment related effects were detected in the organ weights measured. One male treated with 45 mg/kg/d had a raised limiting ridge in the stomach. No toxicologically significant effects were detected in females treated with 45 mg/kg/d or in animals of either sex treated with 15 or 5 mg/kg/d. Basically, the only toxicologically relevant finding was the observation of slight to marked findings of erosion/ulceration and hyperplasia/hyperkeratosis in the forestomach which is considered a consequence of local corrosive/irritating properties of the dosed formulation.

The oral administration of the test item to rats by gavage, at dose levels of 5, 15 and 45 mg/kg/d, resulted in treatment related effects detected in animals of either sex treated with 45 mg/kg/d. These effects are considered local in nature, to be caused by the corrosive/irritant properties of the dosed formulation. As no real systemic effects have been observed, the 'No Observed Adverse Effect Level' (NOAEL) for systemic toxicity can therefore considered to be 45 mg/kg/d.

 

Subchronic toxicity

In a GLP-compliant OECD guideline 408 study, groups of 10 male and female Crl:WI (Han) rats were administered N-[3-(dimethylamino)propyl] C12-C18 alkylamide in corn oil by oral gavage at dose levels of 0, 15, 30 and 60 mg/kg bw/d for 90 days. There were no mortalities or relevant clinical signs. Body weights, body weight gains and food consumption were unaffected. There were no adverse changes on ophthalmological, haematological or clinical chemistry parameters and no macroscopic changes or organ weight changes observed at gross necropsy. Histopathological examination revealed the presence of local proliferative lesions in the forestomach in all treatment groups, with an increasing incidence and severity. The lesions were characterized by areas of a thickened epithelial layer, frequently accompanied by hyperkeratosis and undulations at the basement membrane zone. Undulations are believed to be caused by the space occupying expansion of the epithelial layer of the forestomach and considered a secondary change. Signs of slight cellular atypia were noted in few males treated with 30 mg/kg/day bw/d and in a male and female treated with 60 mg/kg bw/d. The finding of obvious squamous cell hyperplasia (with early signs of atypia in some cases) in the non-glandular stomach of rats treated with 30 or 60 mg/kg bw/d is considered an adverse finding. Lesion in the non-glandular stomach of rodents however are considered clinically irrelevant since humans do not have a forestomach equivalent. The relevant NOAEL for systemic toxicity is 60 mg/kg bw/d, the highest dose tested in this study.

 

There are no data gaps for the endpoint repeated dose toxicity. No human data are available. However, there is no reason to believe that these results from rat would not be applicable to humans. 

Justification for classification or non-classification

Based on the available data, DIMAPDO does not need to be classified for repeated dose toxicity according to the criteria given in regulation (EC) 1272/2008. Thus, no labelling is required.