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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study appears to be well conducted, however only the results and statistical analyses are presented in this report (no methodological information is available).
Cross-reference
Reason / purpose:
read-across: supporting information
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The justification of the read across is described in the document attached in the section 13.
Reason / purpose:
read-across source
Specific details on test material used for the study:
4-chloroformylphthalic anhydride
Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
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:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
no effects observed
Details on results:
Clinical observations noted included primarily wheezing and some slight emaciation. Incidences of wheezing were 6/20, 7/19, 7/19 and 4/19 in the control, 1000, 5000 and 10,000 ppm treated groups, respectively. Emaciation was not seen in the controls but was observed in one or two animals per sex in each of the treated groups.

Gross necropsy observations included lung lesions, consisting of congestion or caseous abscesses, and kidney lesions, usually dilated pelvis of one or both kidneys. Gross lung lesions were observed in 6/20, 2/19, 5/19 and 6/19 in the control, 1000, 5000 and 10,000 ppm treated groups, respectively. Kidney lesions were similarly evenly distributed among the groups at 5/20, 4/19, 3/19 and 2/19 respectively.

Microscopic examination of tissues was performed on 16 animals. Microscopic lung lesions consisted of bronchiectasis, bronchitis, peribronchitis and/or focal pneumonia. Incidences of microscopic lung lesions were 5/8 in the controls examined and 8/8 in the 10,000 ppm TMA-treated group.
Thus, there were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups.
Key result
Dose descriptor:
NOAEL
Effect level:
10 960 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No significant differences in the incidences of clinical observations, gross necropsy and histpathological findings between the treated and control groups.
Key result
Critical effects observed:
no

Table 1: Thirteen-week oral (diet) toxicity study of trimellitic anhydride (TMA) in rats

Study group

Parameter

Control

1000

5000

10000

 

M

F

T

M

F

T

M

F

T

M

F

T

Number of animals

10

10

20

9

10

19

10

9

19

9

10

19

Clinical Observations

 

 

 

 

 

 

 

 

 

 

 

 

Wheezing

4

2

6

4

3

7

5

2

7

3

2

5

Emaciation

0

0

0

1

2

3

1

1

2

1

1

2

Hypersensitivity

0

1

1

1

0

1

0

0

0

0

0

0

Miscellaneous Lesions

2

0

3

1

3

4

0

1

1

1

0

1

Gross Necropsy Findings

Lungs

 

 

 

 

 

 

 

 

 

 

 

 

Caseous Abscess

2

1

3

0

2

2

3

1

4

3

2

5

Congestion

5

0

5

0

1

1

0

0

0

0

0

0

Free Blood

0

0

0

0

0

0

0

1

1

0

1

1

Kidneys

 

 

 

 

 

 

 

 

 

 

 

 

Dilated Pelvis

2

3

4

2

2

4

2

1

3

2

0

2

Nodule

1

0

1

0

0

0

0

0

0

0

0

0

Liver

 

 

 

 

 

 

 

 

 

 

 

 

Abscess

0

0

0

1

0

1

0

0

0

0

0

0

Thymus

 

 

 

 

 

 

 

 

 

 

 

 

Haemorrhage

0

0

0

0

0

0

1

0

1

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

Histopathology

 

 

 

 

 

 

 

 

 

 

 

 

Number Examined

4

4

8

..

..

..

..

..

..

4

4

8

Lungs

 

 

 

 

 

 

 

 

 

 

 

 

Bronchitis

0

2

2

..

..

..

..

..

..

4

4

8

Peribronchitis

1

2

3

..

..

..

..

..

..

0

0

0

Pneumonia

1

2

3

..

..

..

..

..

..

1

1

2

Bronchiectasis

1

0

1

..

..

..

..

..

..

1

2

3

Free Blood

1

01

 

..

..

..

..

..

..

0

1

1

Table 2: Mean male body weights (g)

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

0

66± 9.8

73± 6.3

70± 9.7

72± 9.2

1

109± 17.5

110± 12.3

102± 20.2

98± 14.5

2

168± 29.6

160± 21.9

145± 42.1

148± 20.7

3

226± 28.7

212± 39.9

199± 38.6

203± 25.2

4

279± 28.1

272± 33.2

257±37.8

254± 25.7

5

328± 28.8

325± 27.4

310±38.7

300± 21.5

6

366± 29.6

368± 25.9

352± 43.4

341± 26.8

7

388± 29.5

394± 26.3

384± 46.7

373± 29.3

8

417± 31.6

426± 30.4

419±52.9

403± 30.2

9

443± 30.7

452± 30.9

447± 55.8

426± 30.5

10

461± 32.2

471± 33.1

467± 55.1

442±31.3

11

476 ± 34.8

489± 34.9

491± 60.8

464± 36.5

12

476 ± 32.1

503± 34.2

504± 66.9

477± 37.5

13

487± 31.8

506± 40.8

507± 70.3

487± 46.1

Table 3: Mean female body weights (g)

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

0

65± 9.2

66± 6.7

66± 11.7

68± 5.0

1

100± 9.5

93± 13.0

98± 16.2

94±16.6

2

144± 11.3

129± 20.9

138± 23.7

128± 19.4

3

179± 15.2

155± 30.2

168± 22.0

162±14.0

4

192± 17.8

178± 24.2

190± 20.9

185± 12.9

5

215± 17.6

199±23.9

211± 24.6

207± 12.5

6

233± 20.6

213± 24.3

229± 23.2

224± 14.3

7

243± 20.7

226± 21.4

242± 24.8

237± 15.3

8

255± 23.6

242±23.9

253± 27.7

246 ± 16.4

9

266± 28.0

249± 23.9

262± 29.7

255± 17.2

10

275± 25.0

260± 22.1

275± 34.2

261± 16.8

11

278±23.8

265± 19.8

279± 34.9

268± 16.3

12

281±26.7

271±22.7

280± 34.2

272±17.9

13

286±27.1

274± 25.6

281± 33.3

276± 19.8

Table 4: Mean male haematocrit and white blood cell differential values sampled at study initiation

 

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

HGB

11.0± 1.1

11.9± 0.3

10.7± 0.6

11.3 ± 0.8

HCT

43± 2.4

48± 2.2

43 ± 1.1

43 ± 1.6

WBC

5.9± 0.7

6.3± 2.1

3.6 ± 1.6

6.6±2.0

EOS

0± 0.5

0± 0.4

0± 0.0

0± 0.0

BASO

0± 0.0

0± 0.0

0± 0.0

0± 0.0

MYE

0± 0.0

0± 0.0

0± 0.0

0± 0.0

JUV

0± 0.0

0± 0.0

0± 0.0

0± 0.0

BAND

0± 0.0

0± 0.0

0± 0.0

0± 0.0

SEGS

30± 7.8

19± 14.6

30 ± 12.7

18± 3.5

LYM

70± 8.3

81± 15.0

70 ± 12.7

82± 3.5

MONO

0± 0.0

0± 0.0

0 ± 0.0

0± 0.0

Table 5: Mean female haematocrit and white blood cell differential values sampled at study initiation

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

HGB

11.6 ± 0.5

11.8± 1.0

11.2± 0.6

11.5± 1.7

HCT

44± 2.8

45± 3.5

43± 1.3

44±1.3

WBC

4.3± 1.3

4.7±1.0

2.3± 0.3

4.8± 1.1

EOS

0 ±0.5

0 ± 0.0

0 ± 0.0

0 ± 0.0

BASO

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

MYE

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

JUV

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

BAND

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

SEGS

23± 11.4

24± 10.1

16±7.6

18±12.7

LYM

76± 11.1

76± 10.1

83± 7.4

82± 12.7

MONO

0 ± 0.4

0± 0.0

0± 0.4

0± 0.0

Conclusions:
By analogy, the NOAEL of 4-chloroformylphthalic anhydride (TMAC) is estimated 10960 ppm, corresponding to 438.4 mg/kg bw in male rats and 548 mg/kg bw/day in female rats after conversion in mg/kg bw/day using the rat food intake provided in the Chapter R.8 (ECHA) and applying the correcting factor based on molecular weights. There were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups.
Executive summary:

This subchronic toxicity study was performed to assess the systemic toxicity of the test substance after oral administration. The study did not followed any guidelines and the GLP compliance was not specified. However, the study appears to be well conducted. In this study, the test substance was administered in the diet to groups of 10 male and 10 female rats at dose levels of 0, 1000, 5000 and 10000 ppm. Investigations included weekly body weights, weekly food consumption and haematology data (5 rats/sex/group) for three time points (i.e., initial or baseline, week 7 and week 13) consisting of haemoglobin, haematocrit, white blood cells and differential white cell counts consisting of EOS, BASO, MYE, JUV, BAND, SEG, LYMP and MONO. Cumulative body weight gains, daily food consumption and change in haematology parameters from baseline to study end were calculated from the data. Statistical analysis of the differential white cell count did not include BASO, MYE, JUV or BAND, as these were all zero in all groups. The data sheet for each animal also had nominations of clinical observations and gross necropsy findings.

Clinical observations noted included primarily wheezing and some slight emaciation. Incidences of wheezing were 6/20, 7/19, 7/19 and 4/19 in the control, 1000, 5000 and 10000 ppm treated groups, respectively. Emaciation was not seen in the controls but was observed in one or two animals per sex in each of the treated groups. Gross necropsy observations included lung lesions, consisting of congestion or caseous abscesses, and kidney lesions, usually dilated pelvis of one or both kidneys. Gross lung lesions were observed in 6/20, 2/19, 5/19 and 6/19 in the control, 1000, 5000 and 10000 ppm treated groups, respectively. Kidney lesions were similarly evenly distributed among the groups at 5/20, 4/19, 3/19 and 2/19 respectively. Microscopic examination of tissues was performed on 16 animals. Microscopic lung lesions consisted of bronchiectasis, bronchitis, peribronchitis and/or focal pneumonia. Incidences of microscopic lung lesions were 5/8 in the controls examined and 8/8 in the 10000 ppm-treated group. There were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups. Therefore, no systemic effects were observed.

By analogy, under the test conditions, the NOAELof 4 -chloroformylphthalic anhydride (TMAC) is estimated to be 10960 ppm, corresponding to 438.4 mg/kg bw in male rats and 548 mg/kg bw/day in female rats after conversion in mg/kg bw/day using the rat food intake provided in the Chapter R.8 (ECHA) and applying the correcting factor based on molecular weights. Therefore, TMAC is not considered to induce systemic toxicity and serious damage to health on repeated dose.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
13 week repeated dose toxicity study
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified
Details on test material:
No further details.
- Name of test material (as cited in study report): trimellitic anhydride
Specific details on test material used for the study:
Trimellitic anhydride

Test animals

Species:
rat
Strain:
not specified
Sex:
male/female
Details on test animals and environmental conditions:
The animals were male and female rats, no further information is available.

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
The test substance was mixed into the diet at three concentration levels and fed to the rats for 13 weeks.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
The duration of the treatment was thirteen weeks.
Frequency of treatment:
Daily in diet
Doses / concentrationsopen allclose all
Dose / conc.:
1 000 ppm
Remarks:
nominal in diet
Dose / conc.:
5 000 ppm
Remarks:
nominal in diet
Dose / conc.:
10 000 ppm
Remarks:
nominal in diet
No. of animals per sex per dose:
The study included data from rats in a control and three treatment groups consisting of 10 males and 10 females per group.
Control animals:
yes, concurrent no treatment
Details on study design:
No further information available.
Positive control:
A positive control was not included.

Examinations

Observations and examinations performed and frequency:
The rats were observed for clinical signs. Raw data consisted of weekly body weights, weekly food consumption and haematology data (half the animals or 5 rats/sex/group) for three time points (i.e., initial or baseline, week 7 and week 13) consisting of haemoglobin, haematocrit, white blood cells and differential white cell counts consisting of EOS, BASO, MYE, JUV, BAND, SEG, LYMP and MONO. Cumulative body weight gains, daily food consumption and change in haematology parameters from baseline to study end were calculated from the data. Statistical analysis of the differential white cell count did not include BASO, MYE, JUV or BAND, as these were all zero in all groups.
Sacrifice and pathology:
Gross necropsy was performed followed by histopathological examination in the control and high dose groups.
Other examinations:
No other examinations reported.
Statistics:
Quantitative data were log-transformed (except body weight gains and changes in haematology from baseline to study termination) and analysed by univariate and multivariate two-factor, fixed-effects analysis of variance (ANOVA) across time points.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Mortality:
mortality observed, treatment-related
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
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:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
no effects observed
Details on results:
Clinical observations noted included primarily wheezing and some slight emaciation. Incidences of wheezing were 6/20, 7/19, 7/19 and 4/19 in the control, 1000, 5000 and 10,000 ppm treated groups, respectively. Emaciation was not seen in the controls but was observed in one or two animals per sex in each of the groups treated with trimellitic anhydride (TMA).

Gross necropsy observations included lung lesions, consisting of congestion or caseous abscesses, and kidney lesions, usually dilated pelvis of one or both kidneys. Gross lung lesions were observed in 6/20, 2/19, 5/19 and 6/19 in the control, 1000, 5000 and 10,000 ppm treated groups, respectively. Kidney lesions were similarly evenly distributed among the groups at 5/20, 4/19, 3/19 and 2/19 respectively.

Microscopic examination of tissues was performed on 16 animals. Microscopic lung lesions consisted of bronchiectasis, bronchitis, peribronchitis and/or focal pneumonia. Incidences of microscopic lung lesions were 5/8 in the controls examined and 8/8 in the 10,000 ppm TMA-treated group.
Thus, there were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups.

Effect levels

Key result
Dose descriptor:
NOAEL
Effect level:
10 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No significant differences in the incidences of clinical observations, gross necropsy and histpathological findings between the treated and control groups.

Target system / organ toxicity

Key result
Critical effects observed:
no

Any other information on results incl. tables

Table 1: Thirteen-week oral (diet) toxicity study of trimellitic anhydride (TMA) in rats

Study group

Parameter

Control

1000

5000

10000

 

M

F

T

M

F

T

M

F

T

M

F

T

Number of animals

10

10

20

9

10

19

10

9

19

9

10

19

Clinical Observations

 

 

 

 

 

 

 

 

 

 

 

 

Wheezing

4

2

6

4

3

7

5

2

7

3

2

5

Emaciation

0

0

0

1

2

3

1

1

2

1

1

2

Hypersensitivity

0

1

1

1

0

1

0

0

0

0

0

0

Miscellaneous Lesions

2

0

3

1

3

4

0

1

1

1

0

1

Gross Necropsy Findings

Lungs

 

 

 

 

 

 

 

 

 

 

 

 

Caseous Abscess

2

1

3

0

2

2

3

1

4

3

2

5

Congestion

5

0

5

0

1

1

0

0

0

0

0

0

Free Blood

0

0

0

0

0

0

0

1

1

0

1

1

Kidneys

 

 

 

 

 

 

 

 

 

 

 

 

Dilated Pelvis

2

3

4

2

2

4

2

1

3

2

0

2

Nodule

1

0

1

0

0

0

0

0

0

0

0

0

Liver

 

 

 

 

 

 

 

 

 

 

 

 

Abscess

0

0

0

1

0

1

0

0

0

0

0

0

Thymus

 

 

 

 

 

 

 

 

 

 

 

 

Haemorrhage

0

0

0

0

0

0

1

0

1

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

Histopathology

 

 

 

 

 

 

 

 

 

 

 

 

Number Examined

4

4

8

..

..

..

..

..

..

4

4

8

Lungs

 

 

 

 

 

 

 

 

 

 

 

 

Bronchitis

0

2

2

..

..

..

..

..

..

4

4

8

Peribronchitis

1

2

3

..

..

..

..

..

..

0

0

0

Pneumonia

1

2

3

..

..

..

..

..

..

1

1

2

Bronchiectasis

1

0

1

..

..

..

..

..

..

1

2

3

Free Blood

1

01

 

..

..

..

..

..

..

0

1

1

Table 2: Mean male body weights (g)

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

0

66± 9.8

73± 6.3

70± 9.7

72± 9.2

1

109± 17.5

110± 12.3

102± 20.2

98± 14.5

2

168± 29.6

160± 21.9

145± 42.1

148± 20.7

3

226± 28.7

212± 39.9

199± 38.6

203± 25.2

4

279± 28.1

272± 33.2

257±37.8

254± 25.7

5

328± 28.8

325± 27.4

310±38.7

300± 21.5

6

366± 29.6

368± 25.9

352± 43.4

341± 26.8

7

388± 29.5

394± 26.3

384± 46.7

373± 29.3

8

417± 31.6

426± 30.4

419±52.9

403± 30.2

9

443± 30.7

452± 30.9

447± 55.8

426± 30.5

10

461± 32.2

471± 33.1

467± 55.1

442±31.3

11

476 ± 34.8

489± 34.9

491± 60.8

464± 36.5

12

476 ± 32.1

503± 34.2

504± 66.9

477± 37.5

13

487± 31.8

506± 40.8

507± 70.3

487± 46.1

Table 3: Mean female body weights (g)

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

0

65± 9.2

66± 6.7

66± 11.7

68± 5.0

1

100± 9.5

93± 13.0

98± 16.2

94±16.6

2

144± 11.3

129± 20.9

138± 23.7

128± 19.4

3

179± 15.2

155± 30.2

168± 22.0

162±14.0

4

192± 17.8

178± 24.2

190± 20.9

185± 12.9

5

215± 17.6

199±23.9

211± 24.6

207± 12.5

6

233± 20.6

213± 24.3

229± 23.2

224± 14.3

7

243± 20.7

226± 21.4

242± 24.8

237± 15.3

8

255± 23.6

242±23.9

253± 27.7

246 ± 16.4

9

266± 28.0

249± 23.9

262± 29.7

255± 17.2

10

275± 25.0

260± 22.1

275± 34.2

261± 16.8

11

278±23.8

265± 19.8

279± 34.9

268± 16.3

12

281±26.7

271±22.7

280± 34.2

272±17.9

13

286±27.1

274± 25.6

281± 33.3

276± 19.8

Table 4: Mean male haematocrit and white blood cell differential values sampled at study initiation

 

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

HGB

11.0± 1.1

11.9± 0.3

10.7± 0.6

11.3 ± 0.8

HCT

43± 2.4

48± 2.2

43 ± 1.1

43 ± 1.6

WBC

5.9± 0.7

6.3± 2.1

3.6 ± 1.6

6.6±2.0

EOS

0± 0.5

0± 0.4

0± 0.0

0± 0.0

BASO

0± 0.0

0± 0.0

0± 0.0

0± 0.0

MYE

0± 0.0

0± 0.0

0± 0.0

0± 0.0

JUV

0± 0.0

0± 0.0

0± 0.0

0± 0.0

BAND

0± 0.0

0± 0.0

0± 0.0

0± 0.0

SEGS

30± 7.8

19± 14.6

30 ± 12.7

18± 3.5

LYM

70± 8.3

81± 15.0

70 ± 12.7

82± 3.5

MONO

0± 0.0

0± 0.0

0 ± 0.0

0± 0.0

Table 5: Mean female haematocrit and white blood cell differential values sampled at study initiation

Study Group

 

 

TMA (ppm)

Week

Control

1000

5000

10000

HGB

11.6 ± 0.5

11.8± 1.0

11.2± 0.6

11.5± 1.7

HCT

44± 2.8

45± 3.5

43± 1.3

44±1.3

WBC

4.3± 1.3

4.7±1.0

2.3± 0.3

4.8± 1.1

EOS

0 ±0.5

0 ± 0.0

0 ± 0.0

0 ± 0.0

BASO

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

MYE

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

JUV

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

BAND

0 ± 0.0

0 ± 0.0

0 ± 0.0

0 ± 0.0

SEGS

23± 11.4

24± 10.1

16±7.6

18±12.7

LYM

76± 11.1

76± 10.1

83± 7.4

82± 12.7

MONO

0 ± 0.4

0± 0.0

0± 0.4

0± 0.0

Applicant's summary and conclusion

Conclusions:
There were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups, therefore the NOAEL was 10,000 ppm.
Executive summary:

Trimellitic anhydride (TMA) was administered in the diet to groups of 10 male and 10 female rats at dose levels of 0, 1000, 5000 and 10000 ppm. Investigations included weekly body weights, weekly food consumption and haematology data (5 rats/sex/group) for three time points (i.e., initial or baseline, week 7 and week 13) consisting of haemoglobin, haematocrit, white blood cells and differential white cell counts consisting of EOS, BASO, MYE, JUV, BAND, SEG, LYMP and MONO. Cumulative body weight gains, daily food consumption and change in haematology parameters from baseline to study end were calculated from the data. Statistical analysis of the differential white cell count did not include BASO, MYE, JUV or BAND, as these were all zero in all groups. The data sheet for each animal also had nominations of clinical observations and gross necropsy findings.

Clinical observations noted included primarily wheezing and some slight emaciation. Incidences of wheezing were 6/20, 7/19, 7/19 and 4/19 in the control, 1000, 5000 and 10000 ppm treated groups, respectively. Emaciation was not seen in the controls but was observed in one or two animals per sex in each of the treated groups. Gross necropsy observations included lung lesions, consisting of congestion or caseous abscesses, and kidney lesions, usually dilated pelvis of one or both kidneys. Gross lung lesions were observed in 6/20, 2/19, 5/19 and 6/19 in the control, 1000, 5000 and 10000 ppm treated groups, respectively. Kidney lesions were similarly evenly distributed among the groups at 5/20, 4/19, 3/19 and 2/19 respectively. Microscopic examination of tissues was performed on 16 animals. Microscopic lung lesions consisted of bronchiectasis, bronchitis, peribronchitis and/or focal pneumonia. Incidences of microscopic lung lesions were 5/8 in the controls examined and 8/8 in the 10000 ppm TMA-treated group. There were no significant differences in the incidences of clinical observations, gross necropsy and histopathological findings between the treated and control groups, therefore the NOAEL was 10000 ppm.