Diethylamine

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Dec 2002 - Mar 2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2011

Reference 2

Reference Type:

publication

Title:

Assessment of chronic inhalation non-cancer toxicity for diethylamine

Author:

Grant, R.L, Taiwo, S.O., McCant, D.

Year:

2015

Bibliographic source:

Inhal. Toxicol. 27 (14), 778-786

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Version / remarks:

June 2018

Principles of method if other than guideline:

Study performed according to standard NTP protocols.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Diethylamine

EC Number:

203-716-3

EC Name:

Diethylamine

Cas Number:

109-89-7

Molecular formula:

C4H11N

IUPAC Name:

diethylamine

Specific details on test material used for the study:

- Physical state: colorless liquid with a strong ammonia odor
- Analytical purity: approximately 99.9%
- Lot/batch No.: BE/07/01
- Stability under test conditions: no degradation of the bulk chemical was detected
- Storage condition of test material: at controlled room temperature

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Farms, Inc. (Germantown, NY)
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: males: 23.3 g (mean), female: 19.8 g (mean)
- Housing: individually in stainless steel wire bottom (Lab Products, Inc., Seaford, DE), changed weekly and rotated daily
- Diet: NTP-2000 irradiated wafers (Zeigler Brothers, Inc., Gardners, PA), available ad libitum, except during exposure periods
- Water: Tap water (Richland municipal supply) via automatic watering system (Edstrom Industries, Waterford, WI), available ad libitum
- Acclimation period: 12 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3 °C (72°±3 °F)
- Humidity (%): 50% ± 15%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: no data

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation chamber (Harvord Systems Division of Lab Products, Inc. Aberdeen, MD)
- Method of conditioning air: glass beads in a heated glass coloum for vapourization
- Air flow rate: 15 air changes /h

Analytical verification of doses or concentrations:

yes

Remarks:

analysed with an on-line gas chromatograph

Details on analytical verification of doses or concentrations:

Samples were drawn from each exposure chamber approximately every 20 minutes during each 6-hour exposure period using stream-select and gas sampling valves in a separate heated valve oven.

Duration of treatment / exposure:

14 weeks (93 days exposure)

Frequency of treatment:

6 hours/day, 5 days/week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

8 ppm (nominal)

Remarks:

analytical concentration 8 ± 0.3 ppm

Doses / concentrations 2

Dose / conc.:

16 ppm (nominal)

Remarks:

analytical concentration 15.9 ± 0.6 ppm

Doses / concentrations 3

Dose / conc.:

32 ppm (nominal)

Remarks:

analytical concentration 32 ± 1.3 ppm

Doses / concentrations 4

Dose / conc.:

62 ppm (nominal)

Remarks:

analytical concentration 62.2 ± 2.3 ppm

Doses / concentrations 5

Dose / conc.:

125 ppm (nominal)

Remarks:

analytical concentration 126 ± 5 ppm

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

- Dose selection rationale:
Because exposure to 250 and 500 ppm of the test substance for 17 days caused mortality in mice and body weight losses exceeding 18%, a high concentration of 125 ppm was selected for both sexes of mice in the 3-month study. Although nasal lesions were present in mice exposed to 125 ppm for 17 days, these lesions were generally mild and were not likely to compromise the 3-month study.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: days 0, 7 and weekly afterwards

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: days 0, 23 and 93
- Anaesthetic used for blood collection: Yes
- How many animals: all
- Parameters examined: Erythrocyte count, Mean corpuscular volume, Hemoglobin, Packed cell volume, Mean corpuscular hemoglobin, Mean corpuscular hemoglobin concentration, Erythrocyte morphologic assessment, Leukocyte count, Leukocyte differential, Reticulocyte count, Platelet count and morphologic assessment

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: days 0, 23 and 93
- How many animals: all
- Parameters examined: Sorbitol dehydrogenase (SDH), Alkaline Phosphatase (ALP), Creatine Kinase (CK), Creatinine, Total Protein, Albumin, Urea Nitrogen (BUN), Total Bile Acids, Alanine Aminotransferase (ALT), Glucose

URINALYSIS: No data

NEUROBEHAVIOURAL EXAMINATION: No data

OTHER: Organs weighed were heart, right kidney, liver, lung, right testis, and thymus

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, a complete necropsy is performed on all treated and control animals that either die or are sacrificed

HISTOPATHOLOGY: Complete histopathology was performed on 0 and 125 ppm core study rats. In addition to gross lesions and tissue masses, the following tissues were examined to a no-effect level: adrenal gland, bone with marrow, brain, clitoral gland, esophagus, eyes, Harderian gland, heart, large intestine (cecum, colon, rectum), small intestine (duodenum, jejunum, ileum), kidney, larynx, liver, lungs, lymph nodes (bronchial, mandibular, mediastinal, and mesenteric), mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach (forestomach and glandular), testis with epididymis and seminal vesicle, thymus, thyroid gland, trachea, urinary bladder, and uterus.

Other examinations:

At the end of the study: samples for sperm motility, densitiy and count; vaginal cytology (controls, 32, 62, 125 ppm).
Sampling of vaginal fluid and cells was performed.

Statistics:

- The probability of survival was estimated by the product-limit procedure of Kaplan and Meier (1958). Dose related effects on survival were analysed using Cox´s method for testing 2 groups for equality and Taraone´s life table test to identify dose-realted trends.
- Organ and body weight data: multiple comparison procedure of Dunnett (1955) and Williams (1971)
- Non-parametric multiple comparison methods of Shirley (1977) for hematology, clinical chemistry, spermatid, and epididymal spermatozoal data
- Fisher exact test and chi-square statistics
- Polyk-test for neoplastic and nonneoplastic lesions prevalence assessment

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The final mean body weights and body weight gains of 125 ppm males and females were significantly less than those of the chamber controls (males: 78%, females: 84% of control).

Food efficiency:

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not specified

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The absolute weights of the liver, right kidney, and thymus of 125 ppm males; heart, liver, and right kidney of 125 ppm females; and thymus of 62 and 125 ppm females were significantly less than those of the chamber controls.
The relative weights of the heart, right kidney, lung, and right testis of 125 ppm males and the lung of 125 ppm females were significantly greater than those of the chamber controls.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic changes were noted primarily in the nasal cavity and involved both the respiratory and olfactory epithelium of males and females principally in the 62 or 125 ppm groups. These lesions included suppurative inflammation, squamous metaplasia of the respiratory epithelium, olfactory epithelial atrophy, and necrosis of the turbinates. Sigificant olfactory epithelial atrophy was already observed after treatment with 32 ppm.

Histopathological findings: neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

There was a dose-related decrease seen in the motility of sperm from male mice with values of those exposed to 32, 62, or 125 ppm being significantly lower (7-15%) than those of the chamber controls; except for a slight (0.5 day), but statistically significant increase in estrous cycle length, no significant differences were observed in the estrous cyclicity of female mice administered 32, 62, or 125 ppm of the vapourized test substance when compared to the chamber controls.

Effect levels

1

Dose descriptor:

NOAEC

Remarks:

local

Effect level:

16 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

2

Dose descriptor:

LOAEC

Remarks:

systemic

Effect level:

32 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

other: decreased sperm motility

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Tab. 1 Mortality and relative weights

Concentration (ppm)	Survival (male/female)	Final weight in % relative to control (male/female)
0	10/10	-
8	10/10	98/98
16	10/10	69/105
32	10/10	101/100
62	10/10	100/97
125	10/10	78/84

Tab. 2 Incidences of nonneoplastic lesions in male mice

	Control	8 ppm	16 ppm	32 ppm	62 ppm	125 ppm
Nose of males
Inflammation, Suppurative^a	0	0	0	0	0	8** (1.5)^b
Olfactory Epithelium, Atrophy	0	0	0	4* (1.0)	9** (2.2)	10** (2.9)
Respiratory Epithelium, Metaplasia, Squamous	0	0	0	3	1 (1.0)	9** (2.2)
Turbinate, Necrosis	0	0	0	0	0	7** (2.4)

* significantly different (p≤ 0.05) from the chamber control group by the Fisher exact test

** p≤ 0.01

^aNumber of animals with lesions

^bAverage severity grade of lesions in affected animals: 1= minimal, 2 = mild, 3 = moderate, 4 = marked

Tab. 3 Incidences of nonneoplastic lesions in female mice

	Control	8 ppm	16 ppm	32 ppm	62 ppm	125 ppm
Nose of females
Inflammation, Suppurative^a	0	0	0	0	3 (1.0)^b	8** (1.0)
Olfactory Epithelium, Atrophy	0	0	0	9**(1.1)	10** (2.4)	10** (2.8)
Respiratory Epithelium, Metaplasia, Squamous	0	0	0	3	1 (1.0)	9** (1.8)
Turbinate, Necrosis	0	0	0	0	0	6** (2.7)

** significantly different (p≤ 0.01) from the chamber control group by the Fisher exact test

^aNumber of animals with lesions

^bAverage severity grade of lesions in affected animals: 1= minimal, 2 = mild, 3 = moderate, 4 = marked

Applicant's summary and conclusion

Conclusions:

A NOAEC of 16 ppm for local effects was derived based on the observation of nonneoplastic lesions of the mouse nose.
The derived LOAEC for systemic effects was 32 ppm taking into account the decrease in sperm motility for male mouse exposed to vapour concentrations of 32 ppm and higher concentration levels.

Executive summary:

In the 14 week study, groups of 10 male and 10 female mice were exposed to the test substance as a vapour at concentrations of 0, 8, 16, 32, 62, or 125 ppm, 6 hours per day with a additional T90 value (time to achieve 90% of target concentration) of 12 min, 5 days per week. All animals survived to the end of the study. The final mean body weights and body weight gains of 125 ppm males and females were significantly less than those of the chamber controls (males: 78%, females: 84% of control). The absolute weights of the liver, right kidney, and thymus of 125 ppm males; heart, liver, and right kidney of 125 ppm females; and thymus of 62 and 125 ppm females were significantly less than those of the chamber controls. The relative weights of the heart, right kidney, lung, and right testis of 125 ppm males and the lung of 125 ppm females were significantly greater than those of the chamber controls. There was a dose-related decrease seen in the motility of sperm for male mice with values of those exposed to 32, 62, or 125 ppm diethylamine being significantly lower (7-15%) than those of the chamber controls (animals exposed to 8 and 16 ppm were not investigated for spem motility changes). Except for a slight (0.5 day), but statistically significant increase in estrous cycle length, no significant differences were observed in the estrous cyclicity of female mice administered 32, 62, or 125 ppm of the vapour when compared to the chamber controls.

Histopathologic changes were noted primarily in the nasal cavity and involved both the respiratory and olfactory epithelium of males and females principally in the 62 or 125 ppm groups. These lesions included suppurative inflammation, squamous metaplasia of the respiratory epithelium, olfactory epithelial atrophy, and necrosis of the turbinates. Significant olfactory epithelial atrophy was already observed after treatment with 32 ppm.

A NOAEC of 16 ppm for local effects was derived based on the observed nonneoplastic lesions of the mouse nose.

The derived LOAEC for systemic effects was 32 ppm taking into account the decrease in the sperm motility for male mouse exposed to vapour concentrations of 32 ppm and higher concentration levels.