tetraethyl N,N'-(methylenedicyclohexane-4,1-diyl)bis-.sc.dl.sc.-aspartate

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral

Remarks:

other: two-generation study

Type of information:

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

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP guideline study with deviations: This study was originally planned as a one-generation study and later enhanced to a two-generation study. As deviation to the guidelines of a two-generation study histopathology of F1 parental rats was done only in liver and kidneys.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 416 (Two-Generation Reproduction Toxicity Study) (2001)

Species:

rat

Strain:

Wistar

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Duration of treatment / exposure:

Total duration of in-Life Phase: 281 days (day 1 = first day of administration). The test substance or vehicle was administered to the animals from the first day of the study (F0) or from Day 29 after birth (F1) until spontaneous death, moribund sacrifice or until scheduled necropsy.
F0 animals were pretreated with the test substance for about 10 weeks, then the mating period of 3 weeks followed. After a gestation period of about 22 days litters were born and the dams were allowed to rear them. F0 females were killed and necropsied when about 28 days old F1 pups had been weaned. The weaned F1 offspring was treated further with the substance for at least 10 weeks premating period. The procedures during the mating, gestation and lactation period of F1 rats were the same as described for F0 rats.

Frequency of treatment:

once daily

Remarks:

Doses / Concentrations:
40, 200 and 1000 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

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

Sex:

male/female

Dose descriptor:

LOAEL

Remarks:

general toxicity

Effect level:

1 000 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: Mild kidney effects (basophilic tubules, focal tubular dilation/hyaline casts) in F0 male rats combined with elevated absolute and/or relative kidney weights in F0 males and females and F1 rats

Critical effects observed:

not specified

In males of F0-generation basophilic tubules were slightly increased by severity at 1000 mg/kg and minimal focal tubular dilation/casts were slightly more frequent at 1000 mg/kg.

 

		0 mg/kg	40 mg/kg	200 mg/kg*	1000 mg/kg
Male animals without kidney findings		3	-	1	-
Male animals with Basophilic Tubules	Grade 1	18	18	18	6
	Grade 2	4	6	5	16
	Grade 3	-	-	-	2
	Grade 4	-	1	-	-
Male animals with Foc. Tub. Dil./Casts	Grade 1	8	7	10	13
	Grade 2	1	-	-	3

                                                       *in total kidneys of 24 animals examined

 

Although basophilic tubules and focal tubular dilation/hyaline casts are common spontaneous findings in male rats of this age these findings were concluded to be adverse, since they correlated with statistically significantly elevated absolute and/or relative kidney weights, evident for F0 and F1 rats at 1000 mg/kg. For F0 females slightly more frequent slight non-adverse tubular change of inner renal cortex were found at 1000 mg/kg and for F1 rats kidney histopathology was inconspicuous.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

A short term oral toxicity study (28-days; Bomhard, Bayer AG, 1992b) with the read across substance revealed no toxicological effects. The derived NOAEL was 1000 mg/kg bw/day. In a two-generation reproductive toxicity study mild kidney effects (basophilic tubules and focal tubular dilation/hyaline casts) were seen in males only at a dose of 1000 mg/kg bw/day. The basophilic tubules and focal tubular dilation/hyaline casts are common spontaneous findings in male rats of this age but as a worst case assumption these findings were concluded to be adverse, since they correlated with statistically significantly elevated absolute and/or relative kidney weights, evident for F0 and F1 rats at 1000 mg/kg. Thus, 1000 mg/kg turned out to be a LOAEL and 200 mg/kg a NOAEL in the study based on such kidney responses. It is not expected that a 90-days repeated dose toxicity study according to OECD TG 408 would substantially change the assessment of the substance, therefore the available information on repeated dose toxicity meets the tonnage driven data requirement of REACH.

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

An oral subacute dose study (OECD TG 407; Bomhard, Bayer AG, 1992b) with the structural analogue aspartic acid, N,N'-[methylenebis(2-methyl-4,1-cyclohexanediyl)]bis-,1,1',4,4'-tetraethyl ester was conducted on 5 male and 5 female rats at doses of 0 (vehicle control), 40, 200 and 1000 mg/kg bw per day. Additional 10 animals (5 per sex) were used for further observation in a 2 -weeks post exposure period following treatment with 0 and 1000 mg/kg bw/day.

No mortality, no clinical signs and no effects on food-/water-consumption or body weight gain were observed. Hematology and histopathology revealed no conclusive signs of toxicologic relevance on blood and hematopoetic organs.

Neither clinical chemistry nor gross/histopathology revealed signs indicating substance-related metabolic or organ impairment.

Thus, the NOAEL was determined to be 1000 mg/kg bw/day.

Also available is a two-generation reproductive study (OECD 416) with the structural analogue. In this study groups of 25 male and 25 female F0 and F1 rats received once daily doses of 0, 40, 200 and 1000 mg/kg via gavage during a pre-mating period of about 10 weeks, a mating period of up to 3 weeks, and, for female animales, during gestation (~ 22 days) and weaning (~ 28 days).

At 1000 mg/kg only for males of F0-generation basophilic tubules were slightly increased by severity and minimal focal tubular dilation/casts were slightly more frequent at 1000 mg/kg. Although basophilic tubules and focal tubular dilation/hyaline casts are common spontaneous findings in male rats of this age these findings were concluded to be adverse, since they correlated with statistically significantly elevated absolute and/or relative kidney weights, evident for F0 and F1 rats at 1000 mg/kg. For F0 females slightly more frequent slight non-adverse tubular change of inner renal cortex were found at 1000 mg/kg and for F1 rats kidney histopathology was inconspicuous. No other test substance related findings were reported. Thus, the LOAEL for general toxicity of the study is 1000 mg/kg and the NOAEL is 200 mg/kg, based on mild effects in male rats only.

The studies were performed with aspartic acid, N,N’-[methylenebis(2-methyl-4,1-cyclohexanediyl)]bis-, 1,1',4,4'-tetraethyl ester which is a structural analogue to aspartic acid, N,N’-(methylenedi-4,1-cyclohexanediyl)bis-, 1,1',4,4'-tetraethyl ester. Both substances are diethyl esters of aspartic acid linked to a dicyclohexylmethyldiamine moiety. The difference between these two substances is merely the presence of two methyl groups connected to the cyclohexane rings. This structural analogy was confirmed by the Member State responsible for the notification of both substances under the NONS regulation. The Member State decided that test results obtained for one substance can be transferred to the other substance and that testing of both substances is usually not required. This decision is in accordance with the grouping of substances and read-across approach in Annex XI, 1.5 of the REACH Regulation.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
A subacute (28 days) repeated dose study is available for the read across substance showing no toxicological effects up to the highest dose tested (NOAEL = 1000 mg/kg). A two-generation toxicity study (subchronic) reveals a LOAEL of 1000 mg/kg (NOAEL = 200 mg/kg), due to mild effects on male rats kidney. This value is used for risk assessment.

Justification for classification or non-classification

No classification required according to EU-Directive 67/548/EEC, Annex I

No classification required according to Regulation (EC) No 1272/2008, Annex VI.