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Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 17 - September 05 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1993
Report Date:
1993
Reference Type:
publication
Title:
The inhalation toxicity of di- and triethanolamine upon repeated exposure.
Author:
Gamer AO, et al.
Year:
2008
Bibliographic source:
Food and Chemical Toxicology, 46(6), 2173-2183
Reference Type:
secondary source
Title:
Sub-acute Inhalation and Neurotoxicity of Triethanolamine (TEA)
Author:
Gamer AO, et al.
Year:
1998
Bibliographic source:
unpublished

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
Principles of method if other than guideline:
Groups of 10 Wistar rats/sex were head-nose exposed to clean air (control ) and target concentrations of 0.02; 0.1 and 0.5 mg/l Triethanolamine (test groups). The substance was administered as a 1 i quid aerosol during a period of 28 days (20 exposures). Based on the recommendation of 0ECD Guidelines for the "Testing of Chemicals", method 412, clinical, hematological, clinicochemical examinations were carried out. Furthermore, neurofunctjonal tests (functional observational battery) were performed before and 4 times at about weekly intervals during exposure period. At the end of the study 3 animals/sex and group were perfusion fixed for eventual further neuropathology which, however, was not performed because no neurotoxic findings were observed clinically and in routine histopathology of brain and sciatic nerve. The remaining 7 animals/sex and group were subjected to conventional necropsy. 7 animals per sex of the high concentration group and of the controls were subjected to hi stopathol ogi cal examination, the scope of organs of 0ECD 412 being extended by brain and peripheral nerve.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Triethanolamine; Substance No. 89/711
- Physical state: liquid/colourless
- Analytical purity: 98.9 %
- Date of manufacture: June 29, 1989
- Lot/batch No.: Probe 912
- Stability under test conditions: ensured
- Storage condition of test material: under nitrogen

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Dr. K. Thomae GmbH, Biberach
- Age at study initiation: 7 weeks
- mean weight at study initiation: males: 239; females 168 g
- Fasting period before study: none
- Housing: individually
- Diet: KLIBA rat/mouse/hamster Iaboratory diet 24-343-4 10 mm pellets, KlingentalmuehIe AG, Kaiseraugst, Switzerland ad libitum
- Water: tap water ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
nose/head only
Vehicle:
other: unchanged (no vehicle)
Details on inhalation exposure:
Generation of an inhalation atmosphere:

The substance to be tested was supplied to a two-component atomizer by means of a continuous infusion pump and was atomized with compressed air. Having passed a glass separator, the liquid aerosol was diluted with conditioned blast air which was conducted via a glass bottle filled with bidist. water for humidification and was supplied to the exposure apparatus. In order to decrease the viscosity of the substance the two-component atomizers were warmed.
The following amounts of air were set:

Test group Compressed air [m³/h] Blast air [m³/h] Exhaused air [m³/h]
0 - 3.0 ± 0.3 2.7 ± 0.3
1 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3
2 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3
3 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3

Test group Substance flow atomizer [ml/h] Atomizer temperature [° C]
1 0.2 38.9 – 41.2
2 1.2 – 4.0 38.7 – 39.9
3 20 - 35 38.2 – 39.9

Generation of an inhalation atmosphere:

The substance to be tested was supplied to a two-component atomizer by means of a continuous infusion pump and was atomized with compressed air. Having passed a glass separator, the liquid aerosol was diluted with conditioned blast air which was conducted via a glass bottle filled with bidist. water for humidification and was supplied to the exposure apparatus. In order to decrease the viscosity of the substance the two-component atomizers were warmed.
The following amounts of air were set:

Test group Compressed air [m³/h] Blast air [m³/h] Exhaused air [m³/h]
0 - 3.0 ± 0.3 2.7 ± 0.3
1 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3
2 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3
3 1.5 ± 0.3 1.5 ± 0.3 2.7 ± 0.3

Test group Substance flow atomizer [ml/h] Atomizer temperature [° C]
1 0.2 38.9 – 41.2
2 1.2 – 4.0 38.7 – 39.9
3 20 - 35 38.2 – 39.9

Head-nose exposure system
The head - nose exposure technique was preferably selected for this inhalation study to minimize fur contamination of the animals with the substance, which cannot be avoided during whole-body exposure. Fur contamination may lead to an additional dermal- and oral uptake (animals preen as their fur becomes contaminited). Thus an estimation of a nominal dose, taken up by the animals and its correlation to a toxic effect becomes more difficult.

Furthermore, by using the dynamic mode of operation with a Iow-volume chamber, the equilibrium characteristic of this exposure technique is favorable: t99 (the time to reach 99% of the final target concentraiion) is shorter as compared with whole - body chambers with a higher chamber volume.

The aerosol was generated inside an aerodynamic exposure appalatus (INA 20; volume V ~ 55 I, BASF Aktiengesellschaft). The apparatus consists of a cylindrical inhalation chamber of stainless steel sheeting and coneshaped outlets and inlets. The rats were restrained in exposure tubes (glass tubes), their snouts projected into the inhalation chamber and they thus inhaled the aerosol. The apparatus was also connected to an exhaust air system. The exhaust air system was set lower than the supply air system (positive pressure). This ensured that the aerosol in the breathing zones of the animals was not diluted by laboratory air.

In order to accustom the animals to the exposure conditions they were exposed to supply air in head-only exposure systems under comparable flow conditions on 5 days before the exposure period ( preflow period) . Then alI test groups were exposed for 6 hours on workdays over a time period of 28 days (285 days test). The number of exposures was 20.
The animals did not have access to water or feed during the exposure.
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
28 days
Frequency of treatment:
6 hrs/day, 5 days/week
Doses / concentrations
Remarks:
Doses / Concentrations:
0.02; 0.1; 0.5 mg/l (Aerosol)
Basis:
analytical conc.
No. of animals per sex per dose:
10
Control animals:
yes
Details on study design:
Post-exposure period: none
Positive control:
not done

Examinations

Observations and examinations performed and frequency:
Body weight data
The body weight of the animals was checked at the beginning of the prefolw, one day before beginning of the exposure peride and then once a week alwasy at the same time of the day.

Clinical signs and findings:
The bahaviour and state of health of the test animals were checked on workdays at least 3 times on exposure days and one during the preflow period and the post observation days.

Mortality:
A check for dead animals was made daily.

Neurofunctional tests:
The evaluation on neurofunction was performed on all animals before the beginning of exposure on study days 0, day 1, 8, 14, and 27 (last exposure).

The examination was performed using a functional observational battery which includes various parameters of sensoric and motoric function as follows:
tremors, convulsions, piloerection, lacrimation, secretion of pigmented tears, salivation, pupil size, diarrhea, vocalization, paresis, paralysis, ataxia, general appearance, body tone, posture, animal body (appearance), locomotor activity, respiration, urination, skin color, righting reflex, behavior, grip strenght, pupillary reflex, winking reflex, vision, audition, olfaction, sensitivity of the body surface, pain perception (hot plate test), , tail pinch, toe pinch, visual placing response, miscellaneous.

Clinical chemistry and Hematology
Blood was taken from the retroorbital venous plexus in the morning from non-fasted, not anesthetized animals. The blood samplings and the subsequent analysis of blood and serum was carried out in a randomized sequence. The assays were performed under internal lab quality conditions with commercial reference controls to assure reliable test results.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
Means and standard deviation
Statistical relevance was established using methods of AN0VA and DUNNETT
KRUSKALWALLIS test
MANN-WHITNEY U test

Results and discussion

Results of examinations

Details on results:
CLINICAL SIGNS AND MORTALITY
During the whole study period the animals of test groups 0 to 2 showed no abnormal clinical signs and findings.
Reddish crusts on nasal edges (blood test positive) were detected in the animals of test group 3 after exposure during the second half of exposure period (males on days 21 to 23, 26 and 27, females on days 14 to 16, 20 to 23, 26 and 27).

No deaths were recorded throughout the study.

BODY WEIGHT AND WEIGHT GAIN
Body weight and body weight change of male and female animals from alI test groups showed no statistically significant difference when compared to the control group

HAEMATOLOGY
No substance-induced changes were observed in the hematological parameters or in clotting analysis of both sexes.

CLINICAL CHEMISTRY
No substance-induced changes were observed in the enzyme activities or the blood chemistry parameters of both sexes.

NEUROBEHAVIOUR
The statistjcally significant increased grip strength of forelimbs in males of test group 2 on day 14 and decreased grip strength of hind limbs in females of test group 3 on day 1 were judged to be not substance related because there was no concentration or time dependence. AlI other parameters examined during neurofunctional testing did not show any difference between animals exposed to the test substance and controls. Therefore functional observational battery did not reveal any substance-induced neurofunctional impairment in the treated groups when compared to control.

HISTOPATHOLOGY: NON-NEOPLASTIC
Local effects were characterized histopathologically by focal inflammatory changes in the submucosa of the larynx region, which seems to be the most sensitive part of the respiratory tract after aerosol exposure to Triethanolamine. There was a tendency to concentration dependent increase in incidence and severity of the lesion from mid to high concentration in both sexes. The effect was found in females to a lesser extent. In this sex 0.02 ng/l did not cause larynx irritation anymore. In male animals however minimal to slight effects were observed in the low concentration similar to the mid
concentration. Because of this simiIar grade of the lesion it is concluded that just below 0.02 ng/l no irritation should be present anymore

OTHER FINDINGS
There is a statistically significant inter-group difference between the red blood cells of the male animals of the control and those of test group 2. This deviation is marginal, inconsistent, when compared with the other sex, and lacking dosage-relationship. Accordingly, this finding is considered to be of no toxicological significance.

Effect levels

open allclose all
Dose descriptor:
NOAEC
Remarks:
systemic effects
Effect level:
0.5 mg/L air
Sex:
male/female
Basis for effect level:
other: no effects at highest concentration tested
Dose descriptor:
NOAEC
Remarks:
local effects
Effect level:
0.02 mg/L air
Sex:
female
Basis for effect level:
other: irritation of the upper respiratory tract
Dose descriptor:
NOAEC
Remarks:
local effects
Effect level:
<= 0.02 mg/L air
Sex:
male
Basis for effect level:
other: irritation of the upper respiratory tract, minimal to moderate focal inflammatory change in the submucosa of the larynx

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion