Benzene-1,2,4-tricarboxylic acid 1,2-anhydride

Endpoint summary

Description of key information

Trimellitic anhydride was found to be of low acute toxicity via the oral, dermal and inhalation routes.  LD50 values of 2730 mg/kg bw (oral) and >2000 mg/kg bw (dermal) are reported.  The acute inhalation LC50 was investigated in two studies and found to be >2.33 mg/L for the substance itself and >3.75 mg/L for the di-acid hydrolysis product, both of these being the maximum achievable respirable concentrations. The substance does not require classification for acute toxicity according to CLP.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991-09-16 to 1991-10-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant (self-certified) proprietary study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Remarks:

self-certified including GLP compliance statement

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female Sprague-Dawley rats (Crl:CDR BR), approximately 6 weeks of age, purchased from Charles River Breeding Laboratories Inc. (Portage, MI). The rats weighed 130-227 g on arrival. They were acclimatised for at least 1 week and examined to ensure their health and suitability as test subjects. Rats selected for the study were identified by ear tags and cage cards. Purina Rodent Chow 5001 and reverse-osmosis purified water were provided ad libitum. The rats were housed in stainless steel cages suspended over deotized animal cage boards. The animal room average temperature and relative humidity were 22°C and 39%, respectively. Fluorescent lighting was provided on a 12 hour light/dark cycle.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

The test material was prepared as a 50% (w/v) suspension in corn oil. The flakes were first ground using a pestle and mortar, then the test article and corn oil was homogenised with a Polytron. The dosage formulation was stirred continuously whilst being administered at dosing volumes of 4, 7 and 10 mL/kg bw. Formulations were prepared fresh for each group and administered by oral gavage using a glass syringe equipped with a ball-tipped stainless steel needle.

Doses:

2000 mg/kg bw, 3500 mg/kg bw and 5000 mg/kg bw as a 50% (w/v) suspension in corn oil.

No. of animals per sex per dose:

5 animals/sex/dose

Control animals:

no

Details on study design:

Animals were fasted for approximately 18 hours prior to dosing and for approximately 4 hours after dosing. Body weights were recorded prior to fasting and immediately prior to dosing, then at 7 and 14 days after dosing. Dosage calculations were based on fasted body weights. Rats were observed for clinical signs and mortality for 14 days after dosing. Necropsies were performed on all rats that died during the study, and those that survived to study termination.

Statistics:

The calculation method for the determination of the LD50 was based on Miller and Tainter (Proc. Soc. Exp. Bio. Med., 57:261-264, 1944)

Preliminary study:

No preliminary results

Sex:

male

Dose descriptor:

LD50

Effect level:

3 340 mg/kg bw

Based on:

test mat.

95% CL:

1 740 - 6 410

Remarks on result:

other: Mortality incidences were 2 males in the 3500 mg/kg bw group and all animals in the 5000 mg/kg bw group.

Sex:

female

Dose descriptor:

LD50

Effect level:

2 030 mg/kg bw

Based on:

test mat.

95% CL:

700 - 5 890

Remarks on result:

other: Mortality incidences were 2 females in the 2000 mg/kg bw group, 5 females in the 3500 mg/kg bw group and all animals in the 5000 mg/kg bw group.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

2 730 mg/kg bw

Based on:

test mat.

95% CL:

1 730 - 4 290

Remarks on result:

other: Mortality incidences were 2 females in the 2000 mg/kg bw group, 2 males and 5 females in the 3500 mg/kg bw group and all animals in the 5000 mg/kg bw group.

Mortality:

The deaths were observed between 1 and 48 hours after administration.

Clinical signs:

other: Prominent clinical signs observed included hypoactivity, hypothermia, ataxia, salivation, discolouration around the mouth, wet/coloured inguinal fur, lacrimation, redness around the nose-eyes and discoloured paws. Rales, loss of righting reflex, pale appe

Gross pathology:

Treatment related lesions observed at necropsy included thinning of the stomach walls in the 2000 mg/kg bw, stomach ulcerations in two, five and nine rats that died in the 2000 mg/kg bw, 3500 mg/kg bw and 5000 mg/kg bw, respectively, and discoloured areas in the stomach (indicative of haemorrhage and necrosis) seen in the majority of animals administered 3500 and 5000 mg/kg bw .
Distention of the gastrointestinal tract with gas and/or liquid was also present in several animals which died, however, these changes were considered autolytic in nature rather than treatment related.

Other findings:

No other findings reported.

Table 1: Summary of mortality data

Dose levels (mg/kg bw)	Number of deaths/group
	Male	Female	Total
2000	0/5	2/5	2/10
3500	2/5	5/5	7/10
5000	5/5	5/5	10/10
LD50combined sexes	2730 mg/kg bw with a 95% confidence limits of 1730 - 4290

 

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The LD50 of trimellitic anhydride (TMA) is estimated 3340 mg/kg bw in male rats, 2030 mg/kg bw in females and 2730 mg/kg bw in combined sexes. The LD50 is above 2000 mg/kg bw. On this basis, trimellitic acid does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No 1272/2008.

Executive summary:

Trimellitic anhydride was administered to three groups of 5 animals/sex at 2000 mg/kg bw, 3500 mg/kg bw and 5000 mg/kg bw. Clinical signs and body weights were recorded over a 14 day post exposure period. All animals that died during the course of the study and all surviving animals were necropsied.

Mortality incidences were 2 females in the 2000 mg/kg bw, 2 males and 5 females in the 3500 mg/kg bw and all animals in the 5000 mg/kg bw. The clinical signs reported included hypoactivity, ataxia, hypothermia, lacrimation, salivation, redness around the nose, discoloration around the mouth, wet/discoloured inguinal fur and discoloured paws. Treatment related lesions observed at necropsy included thinning of the stomach walls in the 2000 mg/kg bw, stomach ulcerations in two, five and nine rats that died in the 2000 mg/kg bw, 3500 mg/kg bw and 5000 mg/kg bw, respectively, and discoloured areas as a sign of haemorrhage and necrosis was also reported in the stomach of several animals in the 3500 and 5000 mg/kg bw dose levels.

Under the conditions of this test, the oral LD50 of trimellitic anhydride for male was 3340 mg/kg with 95% confidence limits of 1740 - 6410 mg/kg bw. The oral LD50 of trimellitic anhydride for female was 2030 mg/kg with 95% confidence limits of 700 - 5890 mg/kg bw. The oral LD50 of trimellitic anhydride for combined sexes was 2730 mg/kg with 95% confidence limits of 1730 - 4290 mg/kg bw. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

2 730 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1992-06-12 to 1992-06-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant regulatory study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes

Remarks:

self-certified including GLP compliance statement

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female Sprague-Dawley (Crl:CDR BR) rats, approximately 6 weeks of age, obtained from Charles River Laboratories Inc (Portage MI). The rats weighed 128-162 g two days after arrival. They were acclimatised for approximately 4 weeks, during which time they were examined to ensure their health and suitability as test subjects. Individuals were identified by ear tags and cage cards. The rats were acclimatised to the nose-only exposure tubes on three successive days during quarantine and prior to randomisation.
Purina Rodent Chow 5001 and reverse osmosis-purified water were available ad libitum. The rats were housed individually in suspended stainless steel cages with deotized animal cage boards underneath. The animal room average temperature and relative humidity were 23°C and 52%, respectively. Fluorescent lighting was provided on a 12 hour light/dark cycle.

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

The test material was ground in a ball mill for at least 2 hours using a 19 litre jar and stainless steel or porcelain balls. The material was placed in a sieve shaker and material passing through a No. 20 screen was collected and used for the exposure. The generation system consisted of an AccuRate dust feeding with a 0.5 inch helix. The ground test substance was delivered at a constant rate from the dust feeder through 3/4 inch stainless steel tubing into a transvector jet. The exposure was conducted in a 160 litre stainless steel nose-only chamber, airflow was maintained at 150 l/min during the exposure and the chamber was operated under slight negative pressure.
Upon determining output rates and particle sizes, a setting of 160 (approximately 7.2 g/min of output) gave the maximum obtainable chamber concentration while maintaining an acceptable particle size distribution; MMAD <5 µm with 90% or more ≤10 µm. Chamber temperature and airflow were monitored continuously and recorded every half-hour during the exposure. Particle size analysis was performed once using an Anderson 1ACFM Cascade Impactor.
Food and water were not available during the exposure period.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Concentration was measured gravimetrically by drawing a known volume of exposure atmosphere across a pre-weighed open-faced filter and dividing the sample weight gain by the volume of the sample. Four samples were collected during the exposure.

Duration of exposure:

4 h

Remarks on duration:

single exposure period

Concentrations:

The time weighted average aerosol concentration was 2.33 mg/L. This dose level was the maximum achievable concentration.

No. of animals per sex per dose:

One group with 5 females and 5 males.

Control animals:

no

Details on study design:

Rats were randomly selected for testing. Clinical signs were observed frequently after the exposure, then at least once per day for the remainder of the 14 day observation period. Body weights were recorded prior to exposure, one week later and immediately prior to necropsy. All animals that died during the course of the study and all surviving animals were necropsied.

Statistics:

Statistical analysis was not performed.

Preliminary study:

No preliminary results

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.33 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Nose-only exposure. Two males and one female died at this exposure level

Mortality:

Three animals died during the course of the study. Mortalities were reported in one female and two males in the 2.33 mg/L bw dose group. At 2.33 mg/L there was 20% mortality in females and 40% mortality in males. Deaths occurred near the end of the exposure, approximately 1.5 hour and one day after exposure.

Clinical signs:

other: Animals showed signs of laboured breathing in four males, rales in five males and two females, redness around the nose/eyes in four males and two females, discoloration around the mouth in two males and one female, discoloration of the paws in three males

Body weight:

All surviving animals gained weight during the course of the study.

Gross pathology:

At necropsy, all the surviving rats displayed red foci on their lungs. Two males that died during the course of the study showed dark red coloured lungs. Other findings noted included fluid filled, enlarged or mottled appearance of the lungs.

Other findings:

No other findings reported.

Table 1: Summary of mortality data

Dose levels (mg/L)	Number of deaths/group
	Male	Female	Total
2.33	1/5	2/5	3/10
LC50	>2.33 mg/L

The average exposure temperature was 24.2°C. Chamber relatively humidity could not be monitored.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute inhalation LC50 is estimated to be > 2.33 mg/L in both sexes.

Executive summary:

Trimellitic anhydride was administered to one group of 5 animals/sex at 2.33 mg/L. Clinical signs and body weights were recorded over a 14 day post exposure period. All animals that died during the course of the study and all surviving animals were necropsied.

Mortalities were reported in one female and two males. Clinical signs reported included laboured breathing, rales, redness around the nose/eyes, discoloration around the mouth and of the paws, clear nasal discharge, wet inguinal fur and lacrimation. All surviving animals gained weight during the course of the study. At termination, all the surviving rats displayed red foci on their lungs. Two males that died during the course of the study showed dark red coloured lungs. Other findings noted included fluid filled, enlarged or mottled appearance lungs.

Under the conditions of this test, the inhalation LC50 of trimellitic anhydride was greater than 2.33 mg/L, the maximum achievable concentration. However, the clinical and gross necropsy observations suggest that a single exposure to this concentration produced severe pulmonary irritation resulting in the death of 3/10 rats. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

discriminating conc.

Value:

2 330 mg/m³ air

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991-09-16 to 1991-10-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This guideline-comparable proprietary study was carried out according to GLP (self-certified).

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Principles of method if other than guideline:

The methods were broadly comparable to OECD 402 with the following exceptions: The test substance was not applied moistened, instead the shaved application site was moistened immediately prior to test article application. There was no information on the purity of the test article. There was no evidence that cage-side observations were carried out.

GLP compliance:

yes

Remarks:

self-certified including GLP compliance statement

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals were male and female New Zealand White rabbits, 2-4 months of age, purchased from Johnson Rabbit Ranch. The rabbits weighed 1.97-2.65 kg on arrival, and were held in quarantine for approximately 12 weeks, during which time they were examined to ensure their health and suitability as test subjects. Individuals were identified by metal ear tags and cage cards. Each rabbit was provided with approximately 150 g of Purina Lab Rabbit Chow HF #5326. Reverse-osmosis purified water was supplied ad libitum.
The rabbits were housed individually in stainless steel cages with Polyzorb cage liners underneath the grid floor. The animal room was maintained at an average temperature and relative humidity of 23°C and 39%, respectively. Fluorescent lighting was provided on a 12 hour light/dark cycle.

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

The test material was applied undiluted. Individual doses were dispensed onto aluminium foil prior to application.
Approximately 24 hours prior to treatment initiation the fur was clipped from an area of approximately 240 cm² on the back of each rabbit and the skin was examined for abnormalities. The shaved application site was moistened immediately prior to test article application, and the test article covered with a 12.8x11.5 cm surgical dressing. The dressing was then covered by plastic film and secured by lint-free cloth and an Elastoplast bandage.
The dressings were removed after 24 hours and the skin was wiped gently with a paper towel and light mineral oil, to remove residual test material.

Duration of exposure:

24 hours

Doses:

Single dose of 2000 mg/kg bw

No. of animals per sex per dose:

One group of five rabbits/sex

Control animals:

no

Details on study design:

Rabbits used in the study were selected at random. Clinical signs were recorded over a 14 day post exposure period. Body weights were recorded immediately prior to dosing (and used for dosing calculations), then at 7 and 14 days post-application.
A limited gross necropsy was performed at the end of the observation period.

Statistics:

Statistical analysis was not performed.

Preliminary study:

No preliminary results.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: No mortality at the limit dose

Mortality:

There were no mortalities.

Clinical signs:

other: All animals showed signs of irritation (erythema and oedema immediately following removal of the dressing). On day 2, none of the rabbits showed signs of oedema. Superficial flaking was noted in two animals during the course of the study. By day 10 -14, f

Gross pathology:

No abnormalities were detected at necropsy.

Other findings:

No other findings reported.

Summary of mortality data

Dose levels (mg/kg bw)	Number of deaths/group
	Male	Female	Total
2000	0/5	0/5	0/10
LD50	>2000 mg/kg bw

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute dermal LD50 is greater than 2000 mg/kg bw in both sexes. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.

Executive summary:

Trimellitic anhydride was administered to one group of 5 animals/sex at 2000 mg/kg bw. Clinical signs and body weights were recorded over a 14 day post exposure period. All animals survived during the course of the study. Clinical signs reported included signs of dermal irritation such as erythema and oedema immediately after removal of the dressing. All surviving animals had recovered at the end of the 14-day post exposure period. No adverse treatment-related effects were reported in any rabbit during the course of the study. All females gained weight during the study while two out five males lost weight. No lesions were noted at necropsy. Under the conditions of this test, the dermal LD50 of trimellitic anhydride was greater than 2000 mg/kg bw. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

Acute Oral Toxicity

Hatoum and Johnson (1991) investigated the potential acute toxic effects of trimellitic anhydride in Sprague-Dawley rats following dosing by oral gavage. Three groups consisting of five male and female rats were administered a single dose of 50% (w/v) suspension of the test substance in corn oil at three dose levels, specifically, 2.0, 3.5 and 5.0 g/kg bw. The rats were then observed for 14 days following test article administration. Two females died in the 2.0 g/kg dose level, two males and five females died in the 3.5 g/kg dose level and all test animals died in the highest dose level, 5.0 g/kg. All deaths occurred 1 to 48 hours following test article administration. Surviving animals appeared essentially normal 3 to 4 days after test article administration. The LD50 of trimellitic anhydride was calculated to be 3.34 g/kg body weight in male rats, 2.03 g/kg body weight in female rats and 2.73 g/kg body weight in male and female rats combined, under the conditions of this study.

Acute Dermal Toxicity

Hatoum and Johnson (1991) investigated the acute dermal toxicity of trimellitic anhydride to New Zealand White rabbits following a single application of the test substance to the skin. The test article was applied as a single dose of 2 g/kg of body weight to the shaved backs of five male and five female rabbits and left in contact with the skin for 24 hours before being removed. At termination of the study after 14 days, no deaths had occurred and test animals had recovered completely from the dermal irritation observed immediately following unwrapping of the dressing. The dermal LD50 was found to be greater than 2 g/kg body weight under the conditions of this study.

Acute Inhalation Toxicity

Hatoum & Garthwaite (1992) administered trimellitic anhydride by a single nose-only inhalation exposure to one group of five male and female Sprague-Dawley rats at the maximum obtainable chamber concentration of 2.33 mg/L. The exposure period was 4 hours. Three rats died during the study. The LC50 for trimellitic anhydride in male and female rats was estimated to be greater than 2.33 mg/L. Ledbetteret al(1988) investigated the effects of trimellitic acid, the hydrolysis product of the anhydride, on a single group of five male and female Sprague-Dawley rats. The rats were exposed to a respirable aerosol concentration of 3.75 mg/L. No rats died in the study, resulting in an estimated LC50 for trimellitic acid greater than 3.75 mg/L.

Justification for selection of acute toxicity – oral endpoint
Single study available

Justification for selection of acute toxicity – inhalation endpoint
Best documented of the available studies

Justification for selection of acute toxicity – dermal endpoint
Single study available

Justification for classification or non-classification

Acute Oral Toxicity Study

Under the conditions of this test (Hatoum and Johnson, 1991), the oral LD50 of trimellitic anhydride was greater than 2000 mg/kg bw. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No 1272/2008.

Acute Dermal Toxicity Study

Under the conditions of this test (Hatoum and Johnson, 1991), the dermal LD50 of trimellitic anhydride was greater than 2000 mg/kg bw. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.

Acute Inhalation Study

Under the conditions of this test (Hatoum and Garthwaite, 1992), the inhalation LC50 of trimellitic anhydride was greater than 2.33 mg/L, the maximum achievable concentration. On this basis, trimellitic anhydride does not warrant any classification according to Directive 67/548/EEC and Regulation (EC) No. 1272/2008.