Aspartic acid, N,N'-(2-methyl-1,5-pentanediyl)bis-, 1,1',4,4'-tetraethyl ester

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

433-260-2

EC Name:

-

Cas Number:

168253-59-6

Molecular formula:

C22H40N2O8

IUPAC Name:

1,5-bis[1,2-bis(ethoxycarbonyl)ethylamino]-2-methylpentane

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann, Borchen, Germany
- Strain: Hsd Cpb:WU (SPF)
- Age at study initiation: animals of the weigth class used are 2-3 months old
- Housing: singly
- Diet and Water: ad libitum
- Acclimation period: at least 5 days

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber volume: internal volume 3.8 L
- Mode of exposure: directed flow nose-only exposure
- Generation of athmospheres: In order to increase the efficiency of the generation of respirable particles and to prevent larger particles from entering the chamber a preseparator/baffle system was used. Under dynamic conditions the test substance was nebulized into a baffle (pre-separator) from which the substance was conveyed into the intake of the cylindrical inhalation chamber. The test substance was nebulized using a binary nozzle with conditioned compressed air.

TEST ATMOSPHERE
- Samples taken from breathing zone: yes
- Brief description of analytical method used: gravimetric and analytical. For analytical method: The test atmosphere was determined by gas chromatography after sampling on Florisil.

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: analysed using a Berner-Type Aeras low-pressure critical orifice cascade impactor. Aerosol mass < 3 µm:80.7%.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.73 µm/1.89

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

5000 mg/m³ (target concentration)
4492 mg/m³ (analytical concentration)
4923 mg/m³ (gravimetrical concentration)

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Body weights measured before exposure, on days 3 and 7, and weekly thereafter. Appearance and behaviour of each rat examined carefully several times on the day of exposure and at least once daily thereafter, except on weekend (once daily).
- Necropsy of survivors performed: yes
- Other examinations performed: examinations of reflexes, rectal temperature (directly after cessation of exposure)
- Control animals: exposed to conditioned air.

Statistics:

Analysis of variance (ANOVA).
For necropsy findings: pair-wise Fisher test after the R x C chi-squared test, in accordance with Gad and Weil (1982).

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4 923 mg/m³ air

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

other: NO(A)EL

Effect level:

< 4 923 mg/m³ air

Exp. duration:

4 h

Remarks on result:

other: basis for effect level: mild and transient irritation on the respiratory tract

Mortality:

No mortality was observed after exposure to concentrations up to and including 4923 mg/m³.

Clinical signs:

other: Clinical signs were reduced motility, piloerection, ungroomed hair-coat, bradypnea, and labored breathing pattern. All signs resolved within the first three postexposure days.

Body weight:

Compared to control animals the test substance caused a mild and transient decrease in body weigth gain.

Gross pathology:

Necropsy findings were unobtrusive.

Other findings:

A mild statistically significant decrease in body temperature was observed, giving further evidence for a mild upper respiratory tract irritation potential of the substance (reflex changes in breathing pattern induced by upper respiratory tract irritants are associated with a decline in the metabolic rate and body temperature of rodents based on published evidence; see Jaeger and Gearhart, Toxicology 25, 299-309, 1982; Mautz and Bufalino,Respiration Physiology, 76, 69-78, 1989).

Applicant's summary and conclusion

Executive summary:

An acute inhalation toxicity study with the test item was performed on Wistar rats according to OECD TG 403. In this study the animals were nose only exposed to the aerolized substance at the targeted limit concentration of 5000 mg/m³ (gravimetrical concentration 4923 mg/m³). Animals exposed to conditioned air under otherwise identical conditions served as control. The test substance aerosol was of adequate respirability (MMAD 1.73 µm; GSD 1.89).

No mortality occurred in the course of the study. Signs (reduced motility, piloerection, ungroomed hair-coat, bradypnea, labored breathing pattern, decrease in body weight gain, and mild decrease in body temperature) were transient and resolved within the first three postexposure days. Necropsy findings were unobtrusive. Experimental evidence suggests that the aerosol is apparently a mild upper respiratory tract irritant (characteristic reflex changes in breathing patterns). Based on this study the LC50 (4h) of the substance is > 4923 mg/m³ and the NO(A)EL (4 h) < 4923 mg/m³.