Diethylammonium chloride

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Scientific study according to NTP standard protocol that fully meets documentation requirements.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

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:

N-ethylethanamine

Test material form:

other: free base liquid

Details on test material:

Diethylamine was obtained from Alkyl Amines Chemicals, Ltd. (Maharashtra, India) in one lot (BE/07/01) that was used in the 2-week, 3-month, and 2-year studies. Identity and purity analyses were conducted by the analytical chemistry laboratory at Research Triangle Institute (RTI) (Research Triangle Park, NC), the study laboratory at Battelle Toxicology Northwest (Richland, WA), Galbraith Laboratories, Inc. (Knoxville, TN), and Chemir/Polytech Laboratories, Inc. (Maryland Heights, MO) (Appendix I). Reports on analyses performed in support of the diethylamine studies are on file at the National Institute of Environmental Health Sciences.
The chemical, a colorless liquid with a strong ammonia odor, was identified as diethylamine using infrared and nuclear magnetic resonance spectroscopy and gas chromatography (GC) coupled with mass spectrometry.
Karl Fischer titration indicated 275 ppm water. Elemental analyses for carbon, hydrogen, and nitrogen were in agreement with the theoretical values for diethylamine. GC indicated one major peak and no impurities with areas greater than 0.1% of the total peak area. The overall purity of lot BE/07/01 was determined to be approximately 99.9%.
To ensure stability, the bulk chemical was stored at controlled room temperature in the original shipping containers (55-gallon metal drums). Periodic reanalyses of the bulk chemical were performed during the 2-week, 3-month, and 2-year studies using GC, and no degradation of the bulk chemical was detected.

Test animals

Species:

rat

Strain:

Fischer 344

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: 110 g (mean), female: 93 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

Remarks:

inhalation chamber

Vehicle:

other: unchanged

Details on inhalation exposure:

Diethylamine was pumped onto glass beads in a heated glass column where it was vaporized. Heated nitrogen flowed through the column and carried the vapor into a short vapor distribution manifold. Concentration in the manifold was determined by the chemical pump rate and nitrogen flow rate. The pressure in the distribution manifold was kept fixed to ensure constant flow through the manifold and into all chambers as the flow of vapor to each chamber was adjusted.
Individual Teflon® delivery lines carried the vapor from the manifold to three-way exposure valves at the chamber inlets. The exposure valves diverted vapor delivery to the exposure chamber exhaust until the generation system was stable and exposures were ready to proceed. A metering valve with a flow indicator at the manifold controlled the flow rate to each chamber. To initiate exposure, the chamber exposure valves were rotated to allow the vapor to flow to each exposure chamber inlet duct where it was further diluted with HEPA®-filtered, conditioned air to achieve the desired exposure concentration.
The study laboratory designed the inhalation exposure chamber (Harford Systems Division of Lab Products, Inc., Aberdeen, MD) so that uniform vapor concen-trations could be maintained throughout the chamber with the catch pans in place. The total active mixing volume of each chamber was 1.7 m3. A small particle detector was used with and without animals in the exposure chambers to ensure that diethylamine vapor, and not aerosol, was produced. No particle counts above the minimum resolvable level (approximately 200 particles/cm3) were detected.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The on-line gas chromatograph was checked throughout the day for instrument drift against an on-line standard of diethylamine in nitrogen supplied by a standard generator. The on-line gas chromatograph was calibrated by a comparison of chamber concentration data to data from grade samples that were collected with acrylic ester adsorbent gas sampling tubes, extracted with methylene chloride containing triethylamine as an internal standard, and analyzed using an off-line gas chromatograph. Known values of chamber atmosphere were sampled at a constant flow rate ensured by a calibrated orifice. The off-line gas chromatograph was calibrated with gravimetrically prepared standards of diethylamine and the internal standard (triethylamine) in methylene chloride.

Duration of treatment / exposure:

93 days

Frequency of treatment:

6 h/d, 5 d/w

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

8 ppm (analytical)

Remarks:

(corresponding to 24 mg/m3)

Doses / concentrations 2

Dose / conc.:

16 ppm (analytical)

Remarks:

(corresponding to 49 mg/m3)

Doses / concentrations 3

Dose / conc.:

32 ppm (analytical)

Remarks:

(corresponding to 97 mg/m3)

Doses / concentrations 4

Dose / conc.:

62 ppm (analytical)

Remarks:

(corresponding to 188 mg/m3)

Doses / concentrations 5

Dose / conc.:

125 ppm (analytical)

Remarks:

(corresponding to 379 mg/m3)

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

- Dose selection rationale: Because exposure to 250 or 500 ppm diethylamine for 16 days caused significantly decreased body weights in rats, a high concentration of 125 ppm was selected for both sexes in the 3-month study. Although nasal lesions were present in rats exposed to 125 ppm for 16 days, these lesions were generally mild and were not likely to compromise the 3-month study. Diethylamine exposure concentrations of 0, 8, 16, 32, 62, and 125 ppm were selected for both sexes of rats in 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 was performed on all treated and control animals that either died or were 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.

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
All rats survived to the end of the study. The only clinical finding was a single occurrence of a torso lateral ulcer/abscess in a 125 ppm male.

BODY WEIGHT AND WEIGHT GAIN
Final mean body weights and body weight gains of all exposed groups were similar to those of the chamber control groups.

HAEMATOLOGY
There were no exposure-related changes in hematology endpoints.

CLINICAL CHEMISTRY
There were no exposure-related changes in clinical chemistry endpoints.

ORGAN WEIGHTS
The relative kidney weights of all groups of exposed females were increased and were significantly greater than those of the chamber controls, except in the 32 ppm group. The relative liver weight of 125 ppm males was significantly increased.

HISTOPATHOLOGY: NON-NEOPLASTIC
Exposure-related histopathology findings in rats were limited to the nose and were seen primarily in rats exposed to 62 or 125 ppm. These lesions included turbinate necrosis, suppurative inflammation, respiratory epithelial hyperplasia, squamous metaplasia of the respiratory epithelium, and olfactory epithelial atrophy.

There were no inflammatory changes of the eye as had been observed in the 2-week study at higher concentrations.

OTHER FINDINGS
There was a dose-related decrease seen in the motility of sperm from male rats with the values of those exposed to 32, 62, or 125 ppm diethylamine being significantly lower (5-26%) than those of the chamber controls; no significant differences were observed in the estrous cyclicity of female rats administered 32, 62, or 125 ppm diethylamine when compared to the chamber controls.

Effect levels

1

Key result

Dose descriptor:

NOAEC

Remarks:

systemic

Effect level:

16 ppm

Based on:

test mat.

Remarks:

equivalent to 49 mg/m3 and 0.049 mg/L air

Sex:

male

Basis for effect level:

other: sperm motility

2

Key result

Dose descriptor:

NOAEC

Remarks:

systemic

Effect level:

125 ppm

Based on:

test mat.

Remarks:

equivalent to 379 mg/m3 and 0.379 mg/L air

Sex:

female

Basis for effect level:

other: no adverse systemic effcets observed up to the highest dose tested

3

Key result

Dose descriptor:

NOAEC

Remarks:

local

Effect level:

16 ppm

Based on:

test mat.

Remarks:

equivalent to 49 mg/m3 and 0.049 mg/L air

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Target system / organ toxicity

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

32 ppm

System:

respiratory system: upper respiratory tract

Organ:

nasal cavity

Treatment related:

yes

Dose response relationship:

yes

Applicant's summary and conclusion

Conclusions:

DEA was studied in a subchronic study in rats using the NTP standard protocol. From the data a NOAEC for systemic and local toxicity of 16 ppm (corresponding to 49 mg/m3) was established.

Executive summary:

Diethylamine (DEA) provides a suitable surrogate for diethylamine hydrochloride. DEA was studied in a subchronic study in rats using the NTP standard protocol. The report is publicly avaialable on the NTP website (TR 566).

In the study groups of 10 male and 10 female rats were exposed to diethylamine vapor at concentrations of 0, 8, 16, 32, 62, or 125 ppm (corresponding to 24, 49, 97, 188 and 379 mg/m³, respectively), 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. All rats survived to the end of the study. Mean body weights of all exposed groups were similar to those of the chamber control groups. There were significant exposure concentration-related decreases in sperm motility in 32, 62, and 125 ppm males; there were no significant differences in the lengths of estrous cycles between chamber control and exposed groups of females. Exposure-related nasal lesions were seen primarily in rats exposed to 62 or 125 ppm, but occurred already at 32 ppm, although not reaching the level of statistical significance. These lesions included turbinate necrosis, suppurative inflammation, respiratory epithelial hyper-plasia, squamous metaplasia of the respiratory epithelium, and olfactory epithelial atrophy.

From the data a NOAEC for systemic and local toxicity of 16 ppm (corresponding to 49 mg/m³) could be established.