Dihexyl adipate

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Basic data given. No details on analytical purity and environmental conditions in the exposure chamber. The particle count median diameters were only estimated. Weekly food consumption was not determined and only a limited number of parameters was examined at haematology and clinical chemistry analysis. Not all organs and tissues were preserved and examined at histopathology.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1979

Report date:

1979

Reference 2

Reference Type:

secondary source

Title:

ECB IUCLID set dihexyl adipate

Author:

ECB

Year:

2000

Bibliographic source:

EUROPEAN COMMISION – European Chemicals Bureau

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

yes

Remarks:

no analytical purity; particle count median diameters only estimated; food consumption not determined; not all parameters examined at blood analysis; not all organs and tissues preserved

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dihexyl adipate

EC Number:

203-757-7

EC Name:

Dihexyl adipate

Cas Number:

110-33-8

Molecular formula:

C18H34O4

IUPAC Name:

1,6-dihexyl hexanedioate

Details on test material:

- Name of test material (as cited in study report): Dihexyl Adipate
- Physical state: clear, colourless liquid
- Analytical purity: no data

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Wilmington, USA
- Age at study initiation: 6-7 weeks (males), 7 weeks (females)
- Weight at study initiation: 184-226 g (males), 137-180 g (females)
- Housing: Rats were housed individually in stainless steel wire mesh cages. During the inhalation study, rats were housed pairwise in the stainless steel and glass exposure chambers.
- Diet: Standard laboratory pellet diet (Purina Laboratory Chow®), ad libitum (out of chamber only)
- Water: ad libitum (out of chamber only)
- Acclimation period: approx. 3 weeks

IN-LIFE DATES: From: 13 Feb 1978 To: 10 Mar 1978

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Remarks on MMAD:

MMAD / GSD: The particle count median diameters had to be estimated due to excessive coincidence counting in the lower diameter channels. This prevented the graphing of a complete particle size distribution. Estimates of the particle count median diameters (were possible) were:
15 mg/m³: ≤ 2.9 µm (Day 1), ≤ 2.5 µm (Day 2), ≤ 2.65 µm (Day 3)
130 mg/m³: could not be estimated on Day 1-3 due to measurement limit of the instrument
1430 mg/m³: ≤ 3.5 µm (Day 3, after reduction of the aerosol concentration by dilution with air)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel and glass exposure chamber
- System of generating particulates/aerosols: The aerosol was generated by spray atomising the material against the walls of a one-litre glass baffle chamber using a stainless steel Laskin nebuliser.
- Temperature, humidity, pressure in air chamber: no data
- Air flow rate: 130 L/min
- Air change rate: every 5.8 min
- Method of particle size determination: The optical particle size distribution was estimated for each exposure chamber during 3 days of exposure using the Royco Model 218 Portable Particle Monitor.

TEST ATMOSPHERE
- Brief description of analytical method used: mass reading using a GCA dust monitor
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Three air samples were drawn from each exposure chamber on each exposure day using the GCA dust monitor to determine the mass of test substance in the aerosol. The analytical concentrations of each air sample were determined by employing the equation 500 (mg)/(t-0.33), whereby “mg” was the mass read-out value of the instrument and “t” was the length of time of sampling. The equation provided correction for sampled time which was not reported by the instrument, as well as the conversion from units of mass to milligram per cubic meter. The analytical concentrations of the test atmosphere were 15, 130 and 1430 mg/m³. In addition, on each of 5 exposure days an air sample was drawn from each chamber using the GCA dust monitor in conjunction with a cyclone precollector to determine the level of respirable aerosol present in the exposure chamber. The percentage of respirable aerosol was determined to be 25%, 37% and 58% for concentrations of 15, 130 and 1430 mg/m³, respectively.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

6 h/day, 5 days/week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
10, 100 amd 1000 mg/m³
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.01, 0.1 and 1 mg/mL
Basis:
nominal conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
15, 130 and 1430 mg/m³
Basis:
analytical conc.

Doses / concentrations 4

Remarks:

Doses / Concentrations:
0.015, 0.13 and 1.43 mg/L
Basis:
analytical conc.

No. of animals per sex per dose:

20 (control), 10 (dose groups), 5 (pre-tesz)

Control animals:

yes

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were observed daily for abnormal signs.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: A full, recorded, physical assessment was performed weekly.

BODY WEIGHT: Yes
- Time schedule for examinations: individual body weights were recorded weekly from 10 days prior to exposure through termination of the study (including the first day of exposure – Day 0).

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on Day 0 (pre-test animals) and at study termination after 4 weeks
- Anaesthetic used for blood collection: No
- Animals fasted: Yes, except for animals of the pre-test
- How many animals: 5/sex (pre-test animals); 10/sex from the control group and 5/sex from the treatment group at study termination
- Parameters examined: haemoglobin, haematocrit, erythrocyte count, clotting time and total and differential leukocytes

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on Day 0 (pre-test animals) and at study termination after 4 weeks
- Animals fasted: Yes, except for animals of the pre-test
- How many animals: 5/sex (pre-test animals); 10/sex from the control group and 5/sex from the treatment group at study termination
- Parameters examined: alanine aminotransferase, alkaline phosphatase, blood urea nitrogen and glucose

URINALYSIS: Yes
- Time schedule for collection of urine: 10/sex from the control group and 5/sex from the treatment group at study termination
- Parameters examined: appearance, specific gravity, pH, protein, bilirubin, ketones, glucose and occult blood

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (all animals of the pre-test and the main study), adrenals, bone marrow (sternal), brain, eye, gonad, heart (with coronary vessels), intestine, colon, duodenum, ileum, kidneys, liver, lung, lymph node (mesenteric), mammary gland, pancreas, pituitary, salivary gland, skeletal muscle, skin, spinal cord (cervical), spleen, stomach, thyroid, urinary bladder, uterus/prostate, gross lesions, tissue masses
HISTOPATHOLOGY: Yes (all animals of control and high dose group), adrenals, bone marrow (sternal), brain, eye, gonad, heart (with coronary vessels), intestine, colon, duodenum, ileum, kidneys, liver, lung, lymph node (mesenteric), mammary gland, pancreas, pituitary, salivary gland, skeletal muscle, skin, spinal cord (cervical), spleen, stomach, thyroid, urinary bladder, uterus/prostate
ORGAN WEIGHTS: Yes, adrenals, brain (sans pituitary), heart, kidneys, liver and lungs

Statistics:

Mean values of haematology and clinical chemistry analysis from compound-treated groups were compared to control using the F-test and Student’s t-test. When variance differed significantly (F-test), Student’s t-test was appropriately modified using Cochran’s approximation (t’). The mean values of body weights from compound-treated groups were compared to controls using the Dunnett’s test. Furthermore, mean values of organ weights, organ/body weight ratios and organ/brain weight from treated and control groups were statistically evaluated.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Not treatment-related: all groups: dry rales, mucoid nasal discharge; 15 mg/m³: nasal discharge in 1 animal; 130 mg/m³: reduced activity and excessive lacrimation in 1 animal; 1430 mg/m³: red stain around the mouth in 1 animal

Mortality:

mortality observed, treatment-related

Description (incidence):

Not treatment-related: all groups: dry rales, mucoid nasal discharge; 15 mg/m³: nasal discharge in 1 animal; 130 mg/m³: reduced activity and excessive lacrimation in 1 animal; 1430 mg/m³: red stain around the mouth in 1 animal

Body weight and weight changes:

no effects observed

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

Description (incidence and severity):

Stat. significant, non-adverse: 15 mg/m³ (m): slightly elevated clotting time; 130 mg/m³ (m): slightly increased haemoglobin; 15 mg/m³ (f): reduced haemoglobin; 15 and 130 mg/m³ (f): slightly reduced haematocrit

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

control and treated groups: mild proteinuria (non-adverse)

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

non-adverse, males: 15 mg/m³: slight increase in abs. lung and rel. adrenal weight; 130 mg/m³: increase in abs. and rel. adrenal weight, slight increase in abs. lung weight; 1430 mg/m³: increase in abs. and rel. weight of lungs and adrenals

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortalities were observed up to the end of the study. During the study, several animals in all groups exhibited rales, but this was not considered unusual for this type of exposure. Some animals also showed nasal discharge, while 1 animal exposed to 15 mg/cm³ exhibited red nasal discharge. Reduced activity and excessive lacrimation were observed in 1 animal treated with 130 mg/m³ and a red stain around the mouth was observed in 1 animal exposed to 1430 mg/m³. However, none of these clinical signs were considered to be treatment-related.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights and weight gains for all treated groups were similar compared to those of the control group.

HAEMATOLOGY
A slightly elevated clotting time was observed in males exposed to 15 mg/m³ and slightly increased haemoglobin value was observed in males treated with 130 mg/m³. In females, a slightly depressed haemoglobin value was observed at 15 mg/m³ as well as a reduction in haematocrit values at 15 and 130 mg/m³, respectively. Although these values were statistically significant (p ≤ 0.05) compared to controls, they were within the normal biological limits, and thus not considered to be treatment-related.

CLINICAL CHEMISTRY
All clinical chemistry parameters for treated and control groups were within the normal biological ranges and no statistically significant changes were observed.

URINALYSIS
Mild proteinuria was observed randomly throughout the control and treatment groups, and was thus not considered treatment-related. All other observations were considered normal or spontaneous, unremarkable and unrelated to treatment.

ORGAN WEIGHTS
Changes in organ weight were observed for adrenal and lungs of treated animals, while all other organ weights were considered to be within the normal biological ranges and not remarkably changed. Statistical analysis revealed a significant elevation (p ≤ 0.05) in mean absolute adrenal weights in males exposed to 130 mg/m³ when compared to controls. The adrenal/body weight ratio for this group was also elevated as did the adrenal weights and adrenal (body weight ratios for males exposed to 1430 mg/m³, but this change was not statistically significant compared to controls. The mean adrenal/brain weight ratios were also elevated in males of all dose groups, but statistically significant changes were only noted in males exposed to 130 mg/m³. Thus, a slight treatment-related response might be indicated, as these findings were similar to those observed for the mean adrenal weights and adrenal/body weight ratios. However, since no corresponding histopathological alterations were observed, changes in adrenal weights were considered to be non-adverse.
In animals of the high dose group (1430 mg/m³), a significant increase in mean lung/body weight ratio was observed compared to controls. Absolute lung weights of this group were also elevated, but did not reach statistical significance compared to controls. In the lower exposure groups (15 and 1430 mg/m³), slight increases in lung weight were also observed, but none being statistically significant. Since all values for lung weight were within normal biological limits, these findings were of doubtful toxicological significance.

GROSS PATHOLOGY
No gross pathology changes were observed in any of the treated animals that could be attributed to treatment with the test substance.

HISTOPATHOLOGY: NON-NEOPLASTIC
No histopathological changes were observed in any of the treated animals.

Effect levels

1

Dose descriptor:

NOAEC

Effect level:

>= 1.43 other: mg/mL (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects observed upt ot the highest dose

2

Dose descriptor:

NOAEC

Effect level:

>= 1 430 mg/m³ air (analytical)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects observed upt ot the highest dose

Target system / organ toxicity

Critical effects observed:

not specified