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Description of key information

A 28 d repeated dose oral toxicity study conducted with the read across substance amides, C12-18 (even numbered) and C18-unsatd., N,N-bis(hydroxyethyl in rats yielded a NOAEL of >750 mg/kg bw/day based on the absence of treatment-related effects at any of the dose levels tested. A 90 d oral study conducted on the test substance N,N-bis(2-hydroxyethyl)dodecanamide from which a NOAEL of 50 mg/kg bw/day was established, showed effects at higher dose levels. However, it is unclear whether the effects noted were related to the test substance itself or as a result of nutritional deficiencies due to the unpalatability of the diet (evidenced by scattering of food). Therefore, the 28 d NOAEL of >750 mg/kg bw/day was retained for risk assessment purposes.

In 13 week and 2 year studies conducted with the test substance via the dermal route of application, the following dose descriptors were derived:

       Sub-chronic dermal mouse: LOAEL for systemic effects: 50 mg/kg bw/d based organ weight changes at ≥50 mg/kg bw/d; LOAEL for local effects: 50 mg/kg bw/d based on non-neoplastic lesion of the skin

       Sub-chronic dermal rat: NOAEL (systemic effects): 100 mg/kg bw/d based on body weight, organ weight and clinical chemistry alterations at the ≥200 mg/kg bw/d; NOAEL (local effects): 25 mg/kg bw/d based on non-neoplastic lesions of the skin at ≥50 mg/kg bw/d.

       Chronic dermal mouse: NOAEL (systemic effects): 15 mg/kg bw/d based on body weight changes; LOAEL (local effects): 15 mg/kg bw/d based on non-neoplastic lesions of the skin.

       Chronic dermal rat: NOAEL (systemic effects): 50 mg/kg bw/d based on BW changes at the LOAEL; LOAEL (local effects): 50 mg/kg bw/d based on non-neoplastic lesion of the skin at all tested doses.

Giving preference to rat species and considering the highest NOAEL below the lowest LOAEL, the NOAEL for systemic effects of 50 mg/kg bw/d from the 2 year study in rat was carried forward for risk assessment purposes.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
750 mg/kg bw/day
Study duration:
subacute
Species:
rat
Quality of whole database:
The information requirements for this tonnage band is sufficiently met with the available data.

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:
adverse effect observed
Dose descriptor:
NOAEL
50 mg/kg bw/day
Study duration:
chronic
Species:
rat
Quality of whole database:
The information requirements for this tonnage band is sufficiently met with the available data.

Additional information

Oral

A study was conducted to determine the repeated dose oral toxicity of the read across substance, amides, C12-18 (even-numbered) and C18-unsatd., N,N-bis(hydroxyethyl), to rats. Groups of 10 male and 10 female rats were orally gavaged with the substance diluted in olive oil, 5 d/wk for 28 d at doses of 0, 70, 250, 750 (Days 1-14) and 1500 (Days 15-28) mg/kg bw/d. Clinical signs, bodyweight, hematology, clinical chemistry, urinalysis, gross and microscopic pathology were recorded. Additional groups of 5 male and 5 female rats were kept for a 4 month recovery period. No treatment-related adverse effects were observed at any of the doses. Changes in the forestomach at some doses including controls were attributed to the use of olive oil and found to be reversible after end of exposure. Under the conditions of the study, the 28 d NOAEL to rats was therefore considered to be greater than 750 mg/kg bw/d (Potokar, 1983).

A study was conducted to evaluate the subchronic oral toxicity of the read across substance, N,N-bis(2-hydroxyethyl)dodecanamide, in Carworth Farm E rats. The rats were administered test substance concentrations of 0, 0.1, 0.5, 1 and 2% in diet for 90 d. The animals were observed daily for clinical signs. Body weight were recorded weekly and haematological, clinical chemistry and urine examinations were carried out at termination. Gross and histopathological examinations were also performed at termination. No adverse effect on the appearance or condition of the animals was observed. Growth retardation was associated with diminished food intake from the dose level of 0.5%. Food refusal was demonstrably due to an effect of the test material on palatability of the diet. Terminal haematological examination revealed a reduction in the haemoglobin level, haematocrit and red cell count at the 1 and 2% dose levels in females but less pronounced effects were seen in males. Serum levels of glutamic-oxaloacetic transaminase were elevated at 0.5% and above in females but only at 0.5 % in males. No untoward effect was observed in the renal function tests. The principal organ weight changes were: increases in the relative kidney weight in all test groups except at 0.1% in females and at 0.1 and 0.5% in males, and increases in the relative liver weight in females on the two highest levels. The types and incidence of histological lesions were comparable in control and test groups. Under the study conditions, the 90 d NOEL was considered to be 0.1% in diet, equivalent to 50 mg/kg bw/day (Gaunt, 1965).

Dermal

13 week studies

A study was conducted to evaluate the effects of repeated dermal exposure to the test substance in B6C3F1 mice. Groups of 10 male and 10 female mice were dermally exposed to 0, 50, 100, 200, 400 or 800 mg/kg bw/day in ethanol at a frequency of 5 d/wk for a period of 13 weeks. Mortality, clinical findings, body weight and histopathology were evaluated at specific time intervals. All male and female mice except one 800 mg/kg bw/day male survived until the end of the study. Final mean body weights and body weight gains of 800 mg/kg bw/day males and females and 400 mg/kg bw/day females were significantly lower than those of the vehicle controls. Clinical findings in dosed mice included irritation of the skin at the site of application. Irritation occurred in all surviving dosed males and in most females administered ≥100 mg/kg bw/day. The heart weights of 400 and 800 mg/kg bw/day males and females and 200 mg/kg bw/day females and the kidney weights of 50, 100, and 400 mg/kg bw/day males were significantly greater than those of the vehicle controls. Relative to the vehicle controls, the liver weights were increased in all dosed groups. A dose-dependent increase in the incidences of non-neoplastic skin lesions included epidermal hyperplasia, parakeratosis, suppurative epidermal inflammation, chronic active dermal inflammation, sebaceous gland hypertrophy and ulcer. Under the conditions of the study, the LOAEL for both systemic and local effects was considered to be 50 mg/kg bw/day (Irwin, 1999).

A study was conducted to evaluate the effects of repeated dermal exposure to the test substance in F344/N rats. Groups of 10 male and 10 female rats were dermally exposed to 0, 25, 50, 100, 200, or 400 mg test substance/kg bw/day in ethanol at a frequency of 5 d/wk for a period of 13 weeks. Survival, clinical findings, body weight, hematology, clinical chemistry and histopathology were evaluated at specific time intervals. All animals survived until study termination. The final mean body weights and body weight gains of 200 and 400 mg/kg bw/day males and the mean body weight gain of 400 mg/kg bw/day females were significantly lower than those of the vehicle controls. The only treatment-related clinical finding was irritation of the skin at the site of application in most males administered 100 mg/kg bw/day or greater and in all females administered 50 mg/kg bw/day or greater. Segmented neutrophil counts and alkaline phosphatase concentrations were increased significantly on specific days in the 200 and/or 400 mg/kg bw/day male and female groups. Kidney weights of 200 and 400 mg/kg females were significantly greater than those of the vehicle controls. There was a dose-dependent increase in the incidence of non-neoplastic lesions of the skin at the site of application, including epidermal hyperplasia, parakeratosis, chronic active dermal inflammation, suppurative epidermal inflammation and sebaceous gland hypertrophy in dosed rats. However, these effects were minimal in the 50 mg/kg bw/day dose group. Hence, under the conditions of the study, the NOAELs for systemic and local effects can be considered to be 100 and 25 mg/kg bw/day, respectively (Irwin, 1999).

2 year studies

A study was conducted to evaluate the effects of chronic exposure to the test substance in B6C3F1 mice. Groups of 50 male and 50 female mice were dermally exposed to 0, 15 or 30 mg/kg bw/day in ethanol at a frequency of 5 d/wk for a period of 105 weeks. 5 males and 5 females were considered for the 3 month interim assessment. Survival, clinical findings, body weight and histopathology were evaluated at specific time intervals. Survival of the dosed male and female rats was similar to that of the vehicle control groups. The mean body weights of females (Week 76 onwards) were reduced than those of the vehicle control group at 30 mg/kg bw/day. The only significant treatment-related clinical finding was irritation of the skin at the site of application in 30 mg/kg bw/day males. The incidences of epidermal hyperplasia, sebaceous gland hyperplasia and chronic active inflammation of the dermis in all dosed groups were significantly increased relative to the vehicle controls at 3 months and at 2 years. The increased incidences of hyperkeratosis in dosed males at 3 months and in dosed males and females at 2 years, of parakeratosis in 30 mg/kg bw/day males at 3 months and 2 years, and of ulcer in 30 mg/kg bw/day males and exudate in 30 mg/kg bw/day males and females at 2 years were also attributed to the test substance administration. No significant neoplastic lesions or evidence of carcinogenic activity was observed at any tested dose levels in skin and lymph nodes. Under the test conditions, the NOAEL for systemic effects can be considered to be 15 mg/kg bw/d and for local effects, the LOAEL can be considered to be 15 mg/kg bw/d (Irwin, 1999).

A study was conducted to evaluate the effects of chronic exposure to the test substance in F344/N rats. Groups of 50 male and 50 female rats were dermally exposed to 0, 50 or 100 mg/kg bw/day in ethanol at a frequency of 5 d/wk for a period of 104 weeks. Survival, clinical findings, body weight and histopathology of different organs were assessed at specific time intervals. Survival of the dosed male and female rats was similar to that of the vehicle control groups. The mean body weights of males and females (Week 24 onwards) were reduced than those of the vehicle control group at 100 mg/kg bw/day. A dose dependent increase in irritation (mild to moderate) and non-neoplastic lesions (minimal to moderate) of the skin were observed at the site of application in all animals. The non-neoplastic lesions included epidermal hyperplasia, sebaceous gland hyperplasia, hyperkeratosis, parakeratosis, chronic active dermal inflammation and ulcer. No significant neoplastic lesions or evidence of carcinogenic activity was observed at any tested dose levels in skin, testis and thyroid gland. Under the conditions of the study, the NOAEL for systemic effects can be considered to be 50 mg/kg bw/d and the LOAEL for local effects can be considered at the lowest dose of 50 mg/kg bw/d (Irwin, 1999).

Justification for classification or non-classification

Based on the NOAEL derived from an oral subacute study in rat (>750 mg/kg bw/day) in which no treatment-related effects were observed, and observed effects in a chronic dermal study in rat (NOAEL of 50 mg/kg bw/day for systemic effects and LOAEL of 50 mg/kg bw/day for local effects), the test substance is not considered to meet the requirements for repeated dose toxicity classification according to CLP (EC 1272/2008) criteria.