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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:
1988-03-30 to 1988-05-19
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report date:
1988

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Isophthalic acid
EC Number:
204-506-4
EC Name:
Isophthalic acid
Cas Number:
121-91-5
Molecular formula:
C8H6O4
IUPAC Name:
isophthalic acid
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): isophthalic acid
- Physical state: white powder
- Storage condition of test material: stored at room temperature
- Lot/batch No.: 10820-59-A
Specific details on test material used for the study:
- Name of test material (as cited in study report): isophthalic acid
- Physical state: white powder
- Storage condition of test material: stored at room temperature
- Lot/batch No.: 10820-59-A

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 Laboratoreies, Inc., Portage, Michigan, USA
- Age at study initiation: 6 weeks
- Weight at study initiation: ~ 277 ± 42 g
- Fasting period before study: No data
- Housing: The rats were housed individually in stainless steel cages measuring 15.5 x 17.0 x 15.8 com dueint the 3 week quarintine and recovery period.s. The rats were confined in inhalation cages measuring 13.0 x 20.0 x 27.5 cm during the exposure phase. The cages were suspended over excrement pans fitted with deotised cage boards except during exposures.
- Diet (e.g. ad libitum): Purina Rodent Chow 5001 ad libitum (except during inhalation exposures)
- Water (e.g. ad libitum): water supplied from a reverse osmosis purifier, ad libitum (except during inhalation exposures)
- Acclimation period: 3 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 °C
- Humidity (%): 40 %
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours darkness

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
whole body
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: Average particle size was 5.04, 5.59 and 5.74 microns for the low, medium and high exposure groups, respectively. The proportion of respirable size particles (10 microns or less) averaged 87.9% overall and 91.6%, 87.4% and 84.6% in the low, medium and high exposure chambers, respectively.
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The test article aerosol entered the exposure chamber through the top via a venturi tube and was discharged through a pipe located near the bottom of the chamber. Exposures were conducted in 2-m3 stainless steel and glass chambers.
- Method of holding animals in test chamber: No data
- Source and rate of air: a Transvector Jet blew the test article aerosol from the mixing chamber into the exposure chamber. The chamber airflw was between 305 and 315 l/min depending on the exposure concentration.
- Method of conditioning air: The chamber air was filtered by high efficieny particle absorbing filters and controlled for temperature and humidity.
- System of generating particulates/aerosols: The generator was a dry materials feeder. The feeder consisted of a reservoir into which the test article was placed. The tapered walls of the feeder were flexible and moved the test article to the bottom of the feeder by slow peristalic action. The test article was picked up by a rotating helix and carried to the generator exhaust. At the end of the line, a Transvector Jet blew the test article into mixing chamber. Another Transvector Jet drew the test article aerosol from the mixing chamber through a tygon line and blew it into the tubing leading to the exposure chamber.
- Temperature, humidity, pressure in air chamber: chamber temperatures, humidity and airflow were measured hourly during each exposure period: 22 °C, 40 % humidity
- Air flow rate: ranged between 305 and 315 l/min depending on the exposure concentration
- Air change rate: no data
- Method of particle size determination: The particle size of the aerosol in each expsoure chamber was determined weekly using an Anderson Cascade Impactor.
- Treatment of exhaust air: The chamber exhaust air was passed through a filtering system before being discharged to the outside environment.


TEST ATMOSPHERE
- Brief description of analytical method used: The test article aerosol concentrations were determined both gravimetrically and spectophotometrically. Samples were collected by drawing a given volume of test atmosphere (i.e. approximately 200, 300 and 1000 liters for the high, medium and low exposure chambers, respectively, and 1000 liters for the filtered air control chamber) across an open-faced filter. Test article concentration was determined gravimetrically by dividing the weight of the test article collected by the volume of the sample taken. During each exposure day, two samples were taken from the filtered air control and low exposure chambers and four samples were taken from each of the medium and high exposure chambers.
The exposure concentrations of the test article were also monitored using a UV/VIS Spectrophotometer operated at 287.3 nm. This filter was extracted with approximately 6 ml of HPLC/Spectro Grade Methanol and the optical density of the extract was determined.
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The exposure concentrations of the test article were also monitored using a UV/VIS Spectrophotometer operated at 287.3 nm. This filter was extracted with approximately 6 ml of HPLC/Spectro Grade Methanol and the optical density of the extract was determined. The absorbance of the extracted samples was compared to a previously prepared standard curve and the exposure concentration was determined from the amount of test article extracted.
Duration of treatment / exposure:
Three groups of 10 male and 10 female rats were exposed for 6 hours per day.
In addition, 5 rats/sex designated for pre-exposure, single exposure and weekly serum analysis for IPA were included in the control and high exposure groups. These rats were retained for 3 weeks after the last exposure to monitor diminishing serum levels of IPA and to evaluate recovery from IPA-induced effects.
Frequency of treatment:
5 days per week for four weeks
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
1.0, 5.0, 10.0 mg/m3
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.96, 4.59 and 9.59 mg/m3
Basis:
analytical conc.
Dose / conc.:
1 mg/m³ air (nominal)
Remarks:
0.96 mg/cubic metre air (analytical)
Dose / conc.:
5 mg/m³ air (nominal)
Remarks:
4.59 mg/cubic metre air (analytical)
Dose / conc.:
10 mg/m³ air (nominal)
Remarks:
9.59 mg/cubic metre air (analytical)
No. of animals per sex per dose:
Three groups of 10 male and 10 female rats per test concentration. A fourth group of equal size was exposed to filtered air only and served as a control group.
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: No data
- Rationale for animal assignment (if not random): random
- Rationale for selecting satellite groups: no data
- Post-exposure recovery period in satellite groups: 5 rats/sex designated for pre-exposure, sinlge exposure and weekly serum analysis for IPA were included in the control and high exposure groups.
Positive control:
A positive control was not included.

Examinations

Observations and examinations performed and frequency:
The rats were observed once daily for morbidity and mortality during the quarantine period. Following treatment initiation, all rats were observed at least once daily, 7 days/week. Recovery rats were continued to be observed daily after the final exposure. Bodyweights and food consumption were measured weekly.

Haematology
- Time schedule for collection of blood: blood samples were taken after the 18 hours of fasting
- Anaesthetic used for blood collection: Yes - sodium pentobarbital
- Animals fasted: Yes, for 18 hours following the last exposure
- How many animals: 30 rats

WBC, RBC, Hb, HCT, MCV, MCH, MCHC, differential count


CLINICAL CHEMISTRY:
- Time schedule for collection of blood: blood samples were taken after the 18 hours of fasting
- Animals fasted: Yes, for 18 hours following the last exposure
- How many animals: 30 rats

Glucose, BUN, ALT, AST, ALP, albumin, globulin, total protein, CK, Na+, Cl-, K+


URINALYSIS: No data


NEUROBEHAVIOURAL EXAMINATION: No data


ORGAN WEIGHTS: brain, heart, lung, liver, spleen, kidneys, adrenals. gonads, lungs

LUNG VOLUMES:



Sacrifice and pathology:
All animals were subjected to gross and microscopic investigation at necropsy
Other examinations:
Blood samples were investigated for the presence of the test material.
Statistics:
Mean and standard deviations were calculated for all quantitative parameters. The data were log-transformed and statistically analysed using both multivariate and univariate two-factor fixed effects analyses of variance (ANOVA). The body weights were evaluated using a multivariate repeated-measures analysis of variance to determine the shape of the dose-response relationship over time. These analytical methods were applied using SYSTAT software. A minimum significance level of P =< 0.05 was used in all comparsions.

There were no statistically significant effects of treatment on any body weight or organ weight parameter in the exposed rats. There were no significant differences between exposed and control rats with regards to haematology or clinical chemistry parameters.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
: redness round the nose
Mortality:
mortality observed, treatment-related
Description (incidence):
: redness round the nose
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:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
No deaths occurred during the study, other than four serum analysis rats which succumbed during anaesthesia or were sacrificed due to trauma of the eye. The incidence of redness around the nose was increased in all exposed groups compared to the filtered air controls.

BODY WEIGHT AND WEIGHT GAIN
There were no staristically significant effects od treatment on body weight or body weight gain.

FOOD CONSUMPTION
No data

FOOD EFFICIENCY
No data

WATER CONSUMPTION
no data

OPHTHALMOSCOPIC EXAMINATION
no data

HAEMATOLOGY
There were no statistically significant effects of treamtment on haematological parameters

CLINICAL CHEMISTRY
There were no statistically significant effects of treamtment on clinical chemistry parameters

URINALYSIS
no data

NEUROBEHAVIOUR
no data

ORGAN WEIGHTS
There were no statistically significant effects of treamtment on absolute or relative organ weights or lung volumes.

GROSS PATHOLOGY
Prominent lesions observed at necropsy included lung foci and enlargd, reddened mandibular lymph nods. However, there was no difference in incidence of these lesions between the exposed and the control groups so thye were not considered to be treatment related. Other lesions were of a minor, incidental nature, unrelated to the treatment.

HISTOPATHOLOGY: NON-NEOPLASTIC
No microscopic lesions were observed in the nasal turbinates, trachea or lungs of any of the rats exposed to the test article. The most common microscpoic lesions seen included lymphoid and plasma cell hyperplasia in the mandibular lymph nodes, but these were of similar incidence among the exposed and control rats, so that the lesions were not considered to be treatment-related. Other lesions were of a minor, incidental nature, unrelated to the treatment.



OTHER FINDINGS
SERUM IPA ANALYSIS :
Four rats died or were sacrificed in extremis as a result of the blood sampling procedure. Numbers of rats in the two groups were minimally 9 controls and 12 high exposure rats. IPA was detected in the serum of male and female high exposure rats immediately after the first exposure and level remained elevated for the duration of the exposure period. Mean male concentrations ranged from 1.44 to 3.99 ug/ml; mean female concentrations were consistently higher, ranging from 5.33 to 9.26 ug/ml. All traces of serum IPA were gone from all exposed rats one week following the last exposure. No IPA was detected in the serum of any control rat at any time.

Effect levels

Dose descriptor:
NOAEC
Effect level:
9.59 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Summary of mortality and clinical observations (10/sex/group)

Observation

Study Group

Filtered Air Control

Target Concentrations (mg/m3)

1.0

5.0

10.0

M

F

M

F

M

F

M

F

No signs observed

5

10

-

3

3

8

7

4

Salivation

2

-

2

1

-

-

1

1

Redness around eyes

-

-

2

-

1

-

1

1

Redness around nose

3

-

8

6

7

2

2

5

Dicsoloured Inguinal Fur

1

-

-

-

-

-

-

-

Discoloured paws

1

-

-

-

-

-

-

-

Hair loss:

Forepaws/shoulder/back

2

-

-

3

2

-

1

-

Miscellaneous lesions:

Neck/shoulder

Broken teeth

1

-

-

-

-

-

-

-

1

-

-

-

-

1

-

-

Mean combined male and female clinical chemistry values (mean and SD (10 rats/sex/group))

Parameter

Filtered air control

Isophthalic Acid

1.0 (mg/m3)

5.0 (mg/m3)

10.0 (mg/m3)

GLU

128.6 ± 17.4

120.2 ± 13.5

123.9 ± 12.0

127.3 ± 13.6

BUN

15.0 ± 1.9

15.6 ± 2.2

15.1 ± 2.5

15.9 ±2.0

ALT/SGPT

26 ± 6

28 ± 10

27 ± 6

26 ± 7

AST/SGOT

79 ± 16

81 ± 18

84 ± 18

79 ± 21

ALK P

87 ± 18

85 ± 30

88 ± 25

79 ± 31

ALB

3.5 ± 0.3

3.5 ± 0.2

3.4 ± 0.2

3.5 ± 0.3

T PRO

5.5 ± 0.3

5.5 ± 0.3

5.4 ± 0.4

5.4 ± 0.3

GLOB

2.0 ± 0.2

2.0± 0.2

1.9 ± 0.3

2.0 ± 0.2

ALB/GLOB

1.8 ± 0.3

1.8 ± 0.2

1.8 ± 0.2

1.8 ± 0.2

CK

379 ± 150

356 ± 176

477 ± 119

431 ± 228

K

3.9 ± 0.3

4.0 ± 0.4

4.0 ± 0.3

3.8± 0.3

Cl

108.1 ± 2.8

108.0 ± 3.1

108.5 ± 3.1

107.5 ± 2.6

Na

143 ± 2.6

143 ± 2.1

142 ± 2.1

142 ± 2.7

Mean combined male and female haematology values

Parameter

Filtered air control

Isophthalic Acid

1.0 (mg/m3)

5.0 (mg/m3)

10.0 (mg/m3)

WBC

7.2 ± 1.4

6.7 ± 2.6

6.6 ± 1.3

7.0 ± 1.8

RBC

7.96 ± 0.48

7.78 ± 0.43

7.96 ± 0.44

7.84 ± 0.58

HGB

15.5 ± 0.5

15.3 ± 0.6

15.3 ± 0.5

15.3 ± 0.7

HCT

42.9 ± 1.7

42.2 ± 1.6

42.4 ± 1.7

42.1 ± 2.3

MCV

54.0 ± 2.0

54.3 ± 1.7

53.4 ± 2.0

53.8 ± 1.9

MCH

19.6 ± 0.8

19.7 ± 0.6

19.3 ± 0.8

19.6 ± 0.8

MCHC

36.3 ± 0.6

36.3 ± 0.4

36.1 ± 0.4

36.4 ± 0.6

Mean combined differential white blood cells values

Parameter

Filtered air control

Isophthalic Acid

1.0 (mg/m3)

5.0 (mg/m3)

10.0 (mg/m3)

IM NEU

0 ± 0

0 ± 0

0 ± 0

0 ± 0

MAT NEU

15 ± 6

15 ± 5

15 ± 6

16± 7

LYM

80 ± 7

80 ± 5

80 ± 7

78 ± 8

MONO

4 ± 2

4 ± 1

4 ± 2

4 ± 3

EOS

1 ± 1

1 ± 1

1 ± 1

1 ± 1

BASO

0 ± 0

0 ± 0

0 ± 0

0 ± 0

NRBC

0 ± 0

0 ± 0

0 ± 0

0 ± 0

Mean combined absolute organ weights (g)

Parameter

Filtered air control

Isophthalic Acid

1.0 (mg/m3)

5.0 (mg/m3)

10.0 (mg/m3)

Brain

2.09 ± 0.11

2.06 ± 0..09

2.08 ± 0.11

2.12 ± 0.09

Heart

1.07 ± 0.16

1.06 ± 0.17

1.10 ± 0.16

1.04 ± 0.13

Liver

9.49 ± 1.68

9.52 ± 1.26

9.89 ± 1.41

9.63 ± 1.37

Spleen

0.66 ± 0.10

0.62 ± 0.08

0.68 ± 0.08

0.67 ± 0.08

Kidneys

2.47 ± 0.43

2.46 ± 0.37

2.56 ± 0.50

2.53 ± 0.46

Adrenals

0.066 ± 0.016

0.068 ± 0.015

0.070 ± 0.016

0.068 ± 0.014

Gonads

1.634 ± 1.587

1.606 ± 1.555

1.606 ± 1.563

1.578 ± 1.531

Lungs

1.25 ± 0.10

1.28 ± 0.09

1.30 ± 0.17

1.30 ± 0.10

Mean lung volumes (ml)

Parameter

Filtered air control

Isophthalic Acid

1.0 (mg/m3)

5.0 (mg/m3)

10.0 (mg/m3)

Males

1.7 ± 0.2

1.7 ± 0.2

1.9 ± 0.3

1.8 ± 0.2

Females

1.6 ± 0.1

1.7 ± 0.1

1.7 ± 0.2

1.7 ± 0.2

Combined

1.7 ± 0.1

1.7 ± 0.2

1.8 ± 0.2

1.7 ± 0.2

Summary of necropsy observations

Tissue and Observation

Study Group

Filtered Air

Control

Target Concentrations (mg/m³)

1.0

5.0

10.0

M

F

M

F

M

F

M

F

No. gross lesions

1

2

-

2

1

3

1

4

Lungs

  Foci

5

5

9

6

9

3

8

2

  Pale

1

-

1

-

1

-

1

-

  Puffy

-

-

-

-

2

-

1

-

  Total rats with lung lesions

6

5

9

6

9

3

8

2

Liver

  Lobular

-

-

-

-

-

1

1

-

  Pale

-

1

-

-

-

1

-

2

Mandibular Lymph Nodes

  Red

2

-

2

1

1

-

3

1

  Red Foci

1

-

-

-

1

2

-

1

  Enlarged

2

1

1

2

-

3

1

1

Mesenteric Lymph Nodes

  Red

-

-

1

-

-

-

-

-

  Enlarged

-

-

-

-

-

2

-

-

Kidneys

  Dilated Pelvis

-

1

1

-

-

1

-

-

  Unusual Fluid Present

-

-

-

-

-

1

-

-

Urinary Bladder

  Calculi

5

-

-

-

4

-

-

-

  Red, thickened, distended

-

-

-

-

-

-

-

1

Ovaries

  Enlarged

-

2

-

-

-

1

-

-

  Cyst

-

1

-

-

-

-

-

-

Uterus

  Enlarged

-

1

-

-

-

-

-

-

Summary of histopathological incidence data

Organ Lesion

Filtered Air Control

10 mg/m³ Isophthalic Acid

Males

Females

Males

Females

Respiratory Lymph Node

  Haemorrhage

0/10*

1/10

0/9

4/10

  Reticuloendothelial cell hyperplasia

0/10

0/10

1/9

1/10

Thymus

  Haemmorrhage

0/10

0/10

1/10

0/10

Liver

  Focus of cellular alteration, clear cell

0/10

0/10

0/10

1/10

Kidneys

  Cyst, medulla

1/10

0/10

0/10

0/10

  Hydropelvis, bilateral

0/10

1/10

0/10

0/10

Mandibular lymph node

  Lymphoid hyperplasia

2/10

6/10

4/10

8/10

  Plasma cell hyperplasia

4/10

4/10

3/10

6/10

  Haemorrhage

2/10

0/10

3/10

1/10

Jejunum

  Lymphoid hyperplasia

0/9

0/10

1/10

0/10

Cecum

  Lymphoid hyperplasia

1/10

0/10

2/10

2/10

Ileum

  Lymphoid hyperplasia

1/9

0/10

0/10

1/10

Colon

  Lymphoid hyperplasia

0/10

0/10

2/10

0/10

Mesenteric lymph node

  Lymphoid hyperplasia

2/10

2/10

0/10

1/10

  Reticuloendothelial cell hyperplasia

1/10

1/10

0/10

0/10

  Plasma cell hyperplasia

1/10

0/10

0/10

0/10

Uterus

  Luminal distension

--

3/10

--

3/10

Prostate

  Chronic inflammation, interstitial

2/10

--

3/10

--

  Acute inflammation, intraglandular

2/10

--

0/10

--

* incidence of lesion/total number of tissues examined

-- = tissue not examined

Mean concentrations of IPA in male and female (results combined) rat serum (µg/ml)

No. of Exposures

Filtered Air Control

IPA (10 mg/m3)

0

0 ± 0 (5)

0 ± 0 (15)

1

0 ± 0 (9)

4.32 ± 1.89 (15)

6

0 ± 0 (10)

4.22 ± 2.15 (13)

11

0 ± 0 (10)

6.55 ± 4.90 (13)

16

0 ± 0 (10)

5.09 ± 4.98 (12)

20

0 ± 0 (9)

4.38 ± 3.87 (12)

Recovered 1 week

0 ± 0 (9)

0 ± 0 (12)

Applicant's summary and conclusion

Conclusions:
No clearly treatment-related effects of toxicological significance were seen in this study.
Executive summary:

Isophthalic acid (IPA) was administered as a particulate aerosol by inhalation at target concentrations of 1.0, 5.0 and 10.0 mg/m³ to three groups of 10 male and 10 female rats each. A fourth group of an equal size, was exposed to filtered air only and served as a control. The rats were exposed for 6 hours/day, 5 days per week for four weeks. In addition, 5 rats/sex designated for pre-exposure, single exposure and weekly serum analysis for IPA were included in the control and high exposure groups. These rats were retained for 3 weeks after the last exposure to monitor diminishing levels of IPA and to evaluate recovery from IPA-induced effects. IPA was detected in the serum of high exposure rats immediately after the first exposure and remained elevated for the duration of the exposure. One week after the last exposure, no IPA was detected in the serum of any exposed rat. No clearly treatment-related effects of toxicological significance were seen in this study; a NOAEC of 9.59 mg/m³ is therefore derived.