Cyclohexyldimethylamine

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December 1987 to September 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Similar to guideline study; GLP. Exposure was only two weeks.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of 5 male and five female rats were exposed to 0, 5, 20 or 75 ppm nominal concentrations by whole body exposure in 1000 L inhalation chambers. The actual atmosphere concentrationswere determined analytically on three occasions and the mean exposures were calculated to be 0, 0.026, 0.104 and 0.389 mg/L. The rats were exposed to DMCHA for 6 hours per day, 5 days per week and had a total of 9 exposures on days 1-5 and 8-11.
Blood samples were collected, ophthalmic examinations completed after initial exposure, clinical signs recorded daily and bodyweights recorded regularly.
The study duration was shorter than normal for a guideline subacute study but the ocal effects of exposure to DMCHA were detectable in the study results

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Cyclohexyldimethylamine

EC Number:

202-715-5

EC Name:

Cyclohexyldimethylamine

Cas Number:

98-94-2

Molecular formula:

C8H17N

IUPAC Name:

N,N-dimethylcyclohexanamine

Details on test material:

- Name of test material (as cited in study report):cyclohexyldimethylamine
- Molecular formula (if other than submission substance): C6H11N(CH3)2
- Molecular weight (if other than submission substance): 127 daltons

- Physical state: colourless to straw coloured liquid
- Analytical purity: 99.67%
-Impurity: 2-methylcyclopentanol present at concentation of 0.12%
-Vapour pressure: 9.8 mm Hg at 38°C
- Lot/batch No.: 03230EM

- Stability under test conditions: No data
- Storage condition of test material: No data
- Other: CAS 98-94-2

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Species, strain: Fischer 344 rats
- Source: Charles River Breeding Laboratories, Inc., Kingston, NY
- Age at study initiation: 6 weeks
- Weight at study initiation: males 179±9 g, females 115±6 g
- Fasting period before study: Not applicable
- Housing:
- Diet (e.g. ad libitum): ad lib. Purina Certified Rodent Chow #5002
- Water (e.g. ad libitum): ad lib.
- Acclimation period: two weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): standard laboratory environmental conditions
- Humidity (%):standard laboratory environmental conditions
- Air changes (per hr):standard laboratory environmental conditions
- Photoperiod (hrs dark / hrs light):standard laboratory environmental conditions
- Air changes: 12/hour
IN-LIFE DATES: From: To: Not stated, study commenced in December 1987

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

clean air

Remarks on MMAD:

MMAD / GSD: Not applicable for vaporised liquid

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Animals were exposed in a 1000 L stainless steel and glass chamber by whole body exposure (dimensions 90x 90x 90 cm with pyrimidal top and bottom).
- Method of holding animals in test chamber:
- Source and rate of air: Compressed heated air was passed through the J-tube to volatilise the DMCHA awhich was also metered into the J-tube as a liquid. The dynamic airflow in the chamber was maintained at approximately 200L/min
- Method of conditioning air: Compressed air was heated with a flameless torch.

- Temperature, humidity, pressure in air chamber: Recorded after each 6 hour exposure and maintained to provide a chamber temperature of circa 22°C
- Air flow rate: 200L/min
- Air change rate: 12/hour
- Method of particle size determination: analytical concentration of DMCHA in the test atmosphere was determined at least 3x per exposure by gas chromatography

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography
- Samples taken from breathing zone: yes - also used to determine chamber distribution. Results indicated variation for concentration was within 16% of nominal reference values

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- Measurement of chamber concentrations by gas chromatography
- nominal concentrations were calculated based on the amount of test material used and the airflow through the chamber
- Sampling times: at least 3 times per exposure period

Duration of treatment / exposure:

9 days, Exposures were conducted on test days 1-5 and 8-11

Frequency of treatment:

6 hours/day, 5 days/week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/m³ air (analytical)

Doses / concentrations 2

Dose / conc.:

104 mg/m³ air (analytical)

Doses / concentrations 3

Dose / conc.:

389 mg/m³ air (analytical)

No. of animals per sex per dose:

5/sex/dose

Control animals:

yes

Details on study design:

Post-exposure period: Rats were subject tto necropsy on the day following the last exposure (Day 12)
- Dose selection rationale: The repeated adinistration dose concentrations were based on the results of acute investigations completed by the same investigators. Results f the acute study are also presented in the report
- Rationale for animal assignment (if not random): Random

Positive control:

Not applicable

Examinations

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS AND FREQUENCY: 
- Clinical signs and mortality: daily after exposure for overt signs of toxicity or changes in demeanor. 
- Body weight: at day 1, 3, 5, 8 and 11.
- Ophthalmoscopic examination: All eyes were examined prior to the initial exposure to DMCHA (the acute study resulted in irrreversible corneal opacity) but there are no recordeds of specific ocular examintions for the remainder of the study.
- Behavioural effects: daily assessments for signs of toxicity, behavioural change or CNS effects
-Food and water consumptions were visually assessed
Terminal blood samples were obtained for haematology and clinical pathology investigations (see pathology). Urinesamples were collected prior to the last exposure period and assessed for coour, appearance and standard urinary parameters (including bilirubin, glucose, ketones, blood, ph, protein and urobilinogen, specific gravity)

Sacrifice and pathology:

Terminal blood samples were obtained from the orbital sinus.

- Haematology: Haematocrit (HCT), haemoglobin (HGB), erythrocyte (RBC), total leukocyte (WBC) and platelet (PLAT) counts. 
- Biochemistry: nitrogen (UN), alanine aminotransferase activity (ALT), aspartate aminotransferase activity (AST), alkaline phosphatase activity (AP), glucose (GLUC), total protein (TP), albumin (ALB), globulin (GLOB), cholesterol (CHOL) and triglycerides (TRIG).
- Urinalysis: immediately prior to the last exposure; bilirubin, glucose, ketones, blood, pH, protein, urobilinogen and specific gravity 

ORGANS EXAMINED AT NECROPSY (MACROSCOPIC AND MICROSCOPIC): 
- Organ weights: brain, heart, lungs, liver, kidneys and testes 
- Macroscopic: adrenals, aorta, auditory sebaceous glands, bone (marrow), brain, cecum, cervix, coagulating glands, colon, duodenum, epididymis, oesophagus, eyes, gross lesions, heart, ileum, jejunum, kidneys, lacrimal glands, larynx, liver, lungs, mammary gland, mediastinal lymph node, mediastinal tissues, mesenteric tissues, nasal tissues, oral tissues, ovaries, oviducts, pancreas, parathyroid glands, peripheral nerve, pituitary, prostate, rectum, salivary glands, seminal vesicles, skeletal muscle, skin, spinal cord, spleen, stomach, testes, thymus, thyroid gland, tongue, trachea, urinary bladder, uterus, vagina
- Microscopic: same as macroscopic except auditory sebaceous glands

Other examinations:

No further information

Statistics:

Descripive statistics for chamber concentrations, temperature, relative humidity and white blood cell counts.
Bartlett's test (equality of variance); ANOVA; Dunnett's test

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

OBSERVATIONS
-no mortalities occurred 
- Clinical signs: no overt signs of toxicity or changes in demeanor were observed. 
- Body weight gain: body weights of male and female rats were statistically decreased from control values for all dose groups. Only the decreases in the 104 and 389 mg/m3 groups (males: 10% and 25% of control, respectively; females: 33% and 52% of control, respectively) were considered exposure-related. No effects on bodyweight were recorded forthe low dose concentration group

CLINICAL CHEMISTRY:
- Haematology: at 389 mg/m3 significantly decreased white blood cell counts in both sexes, but this was not considered toxicologically significant nor exposure related (due to the variability of this parameter in the historical controls and the similarity of historical control and the high concentration numbers); 
- Clinical chemistry: the following parameters were significantly deceased from control values, but were not considered to be toxicologically significant: total protein and alkaline phosphatase activity (at 26 and 389 mg/m3),  globulin (at 26 mg/m3) and albumin (389 mg/m3) 
- Urinalysis: no exposure-related effects were observed for anyof the urinary parameters evaluated 

NECROPSY FINDINGS:
- Organ weights:  at 26 mg/m3 significantly decreased absolute and relative heart weights in both sexes (not considered exposure-related, no dose response relationship);  at 389 mg/m3 increased relative kidney weights in both sexes: 2% in males and 7% in females (of questionable significance, not accompanied by changes in urinalysis, serum nitrogen or histopathologic changes in the kidney) 
- Gross pathology: no exposure related effects
- Histopathology: at 389 mg/m3 hyperplasia and hypertrophy of the nasal cavity in 3 males and 1 female

Effect levels

1

Key result

Dose descriptor:

NOAEC

Effect level:

104 mg/m³ air

Sex:

male/female

Basis for effect level:

other: based on effects on the nasal respiratory mucosa (local effect).

2

Dose descriptor:

NOEC

Effect level:

26 mg/m³ air

Sex:

male/female

Basis for effect level:

other: Absence of effects on body weight.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

ANALYSES:
- Actual dose level: The nominal and analytical concentrations were in close agreement at all exposure
levels.
- Stability: acceptable
- Homogeneity: The concentration from each sample point was
within 16% of the reference point. The average of the sample
point values was within 5% of the reference point values.

In an acute inhalation investigation rats were exposed to a single 6 -hour exposure to DMCHA at concentrations of 88, 320 or 1120 ppm. All rats in the high dose group died within 2.5 hours with antecedent signs of laboured respiration and tremors. In the lower dose groups the surviving rats had lower bodyweights initially but showed good recovery. The primary effect observed was aan ophthalmic lesion - although the iris and retina were overtly unaffected, the animals developed irreversible corneal opacities. Microscopically there effects on the cornea - slight to severe opacity, inflammation and some corneal neovascularisation. The lowest dose 88 ppm resulted in only slight transient eye irrition.

In the repeated administration study, concentrations of 2, 20 or 75 ppm were used. Although the eyes were examined prior to exposure, there are no indications that the high dose concentration, 75 ppm, elicited any of the corneal effcts observed in the acute study.

Applicant's summary and conclusion

Conclusions:

Local nasal epithelial irritation, evident microscopically as hyperplasia and hypertrophy, was the primary effect of toxicological significance following repeated exposure to a DMCHA atmosphere. No signs of systemic effects were noted in life at concentrations up to 104 mg/m3. Under the conditions of this study the test substance does not require classification according to Regulation EC No. 1272/20008 or Directive 67/548/EEC.

Executive summary:

In a study conducted by Nitschke and Johnson (1989), the test substance, DMCHA was tested for its ability to cause toxicity when administered via whole body inhalation. The test substance was administered to male and female Fischer 344 rats at concentrations of 0, 5, 20 or 75 ppm (equivalent to 0, 0.026, 0.104 or 0.389 mg/l) for 6 hours per day, 5 days a week for 9 exposures (test days 1 - 5 and 8 - 11). All test animals were observed daily after exposure for overt signs of toxicity or changes in demeanour. All animals were weighed on test days 1, 3, 5, 8 and 11. Animals were necropsied on the day following the last exposure and blood samples were obtained for haematologic and clinical chemistry determinations.

Slight decreases in mean body weights of male and female rats exposed to 75ppm and female rats exposed to 20ppm were observed. Slight hyperplasia and hypertrophy of the nasal respiratory mucosa was observed in four out of 10 rats exposed to 75ppm test concentration. Based on these results, the NOAEC was determined to be 104 mg/m³.

Under the conditions of this study the test substance does not require classification according to Regulation EC No. 1272/20008 or Directive 67/548/EEC.