Benzene-1,2:4,5-tetracarboxylic dianhydride

Endpoint summary

Description of key information

Repeat dose oral toxicity

PDMA was administered by gavage to three groups, each of three male and three female Wistar rats, for 14 consecutive days, at dose levels of 250, 750 and 1000 mg/kg bw/day. A control group of was dosed with vehicle alone. There were no unscheduled deaths. And no clinically observable signs of toxicity were detected. Reduced body weight gains/body weight losses were evident for males treated with 1000 and 750 mg/kg bw/day. Females were unaffected by treatment at any level tested. No adverse effects on food or water consumption were detected and there were no macroscopic changes were detected at terminal kill. A NOAEL of 250 mg/kg bw/day for males was derived and a NOAEL of greater than 1000 mg/kg bw/day for the females.

 

Sub-chronic studies in the rat and mouse

Phthalic anhydride (a close structural analogue of PDMA) was administered in the diet to either rats or mice for seven weeks. The dosages for rats were: 0, 410, 830, 1670 or 3300 mg/kg bw/day. And for mice were: 0, 890, 1790, 3570 or 7140 mg/kg bw/day.

In the rat, phthalic anhydride at dosages up to 3300 mg/kg bw/day (50,000 ppm) was well tolerated with no overt adverse toxicity evident. However, phthalic anhydride had a NOAEL of 1670 mg/kg bw/day (25000 ppm) based on body weight performance.

In the mouse, phthalic anhydride at dosages up to 7140 mg/kg bw/day (50,000 ppm) was well tolerated with no adverse toxicity evident which is considered at the NOAEL in this study.

Chronic studies in the rat and mouse

Phthalic anhydride (a close structural analogue of PDMA) was administered in the diet to either rats or mice for 104-105 weeks. The dosages for rats were: 0 (control), 7500 or 15000 ppm (approx. 0, 500, 1000 mg/kg bw/day); for mice were 0, 12500 or 25000 ppm (approx. 0, 1717or 3430 mg/kg bw/day).

In the rat, phthalic anhydride at dosages up to 1000 mg/kg bw/day was well tolerated with no overt adverse toxicity evident. However, phthalic anhydride had a NOAEL of 500 mg/kg bw/day based on body weight performance at 1000 mg/kg bw/day.

In the mouse, phthalic anhydride at dosages up to 3430 mg/kg bw/day was reasonably well tolerated. However, body weight deficits were evident at both dosages and so the LOAEL was 2340 mg/kg bw/day for the males and was 1717 mg/kg bw/day for the females.

 

Supporting study

1000 mg/kg of pyromellitic dianhydride as a 20 per cent suspension in peanut oil, was administered to each of six male albino rats, five times a week for two weeks. Other than a mild slowing of the growth rate, it was reported that no clinical signs of toxicity were observed. Three animals were sacrificed four hours after the tenth treatment, and the remaining three, ten days later. Microscopic examination of the tissues revealed chronic gastritis in the case of the first three rats, and no pathology in the last three.

 

Two-week inhalation study

Rats exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks (nominal: 0.01. 0.03 and 0.1mg/L; analysed: 0.021, 0.035 and 0.091 mg/L) exhibited symptoms directly related to the route of exposure, i.e. most effects were evident in the lungs.  The signs were indicative of local, direct effects in the lungs. PMDA is highly reactive and hydrolyses in contact with water or body fluids to the corresponding pyromellitic acid; PMDA is also a severe eye irritant. It is unsurprising that direct local effects in the lungs were observed. Other changes seen in this study were likely to be related to physiological stress because of the clinical signs induced via inhalation exposure to the dusts. Only the lungs showed any histopathological treatment related signs, importantly the signs seen were only slight to very slight.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05-12-2012 to 10-09-2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Remarks:

GLP and Quality Assured Study

Justification for type of information:

The study was designed to provide information for potential further repeat dose toxicity studies.

Qualifier:

no guideline required

Principles of method if other than guideline:

Study was a repeat-dose dose range finding study.

GLP compliance:

yes

Limit test:

yes

Specific details on test material used for the study:

PMDA, pyromellitic dianhydride 99.4%, batch NJC1207029

Species:

rat

Strain:

Wistar

Remarks:

Wistar Han™:RccHan™:WIST strain rat

Details on species / strain selection:

The rat was selected for this study as it is a readily available rodent species historically used in safety evaluation studies and is recommended by regulatory authorities.

Sex:

male/female

Details on test animals or test system and environmental conditions:

A sufficient number of male and female VVistar Han™:RccHan™:WIST strain rats were obtained from Harlan Laboratories U.K. Ltd., Oxon, UK. On receipt the animals were examined for signs of ill-health or injury. The animals were acclimatised for six days during which time their health status was assessed. A total of twenty-four animals (twelve males and twelve females) were allocated to the study. At the start of treatment, the males weighed 313 to 336g, the females weighed 206 to 221 g, and were approximately twelve weeks old.

The animals were housed in groups of three by sex in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK). The animals were allowed free access to food and water. A pelleted diet (Rodent 2018C Teklad Global Certified Diet, Harlan Laboratories U.K. Ltd., Oxon, UK) was used. A certificate of analysis of the batch of diet used is given in Addendum 1. Mains drinking water was supplied from polycarbonate bottles attached to the cage. The diet and drinking water were considered not to contain any contaminant at a level that might have affected the purpose or integrity of the study. Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK).
The animals were housed in a single air-conditioned room within the Harlan Laboratories Ltd., Shardlow, UK, Barrier Maintained Rodent Facility. The rate of air exchange was at least fifteen air changes per hour and the low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness. Environmental conditions were continuously monitored by a computerised system, and print-outs of hourly temperatures and humidities are included in the study records. The temperature and relative humidity controls were set to achieve target values of 22 ± 3°C and 50 - 60% respectively.

The animals were allocated to dose groups using a randomisation procedure based on stratified body weights and the group mean body weights were then determined to ensure similarity between the dose groups. The animals were uniquely identified within the study, by an ear punch system routinely used in these laboratories.

Route of administration:

oral: gavage

Details on route of administration:

The oral route was selected as the most appropriate route of exposure, based on the physical properties of the test item.

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1% CMA with 0.1% Tween 80

Details on oral exposure:

Oral gavage for 14 consecutive days.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

HPLC Methodology.
Homogeneity assessed and proven at 3 mg/ml and 100 mg/ml
Stability at least 21 days at 4oC.
Verification of concentrations: 100 mg/ml: 100% - 139%; 25 mg/ml: 75%-114%

Duration of treatment / exposure:

14 consecutive days.

Frequency of treatment:

Daily.

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Control

Dose / conc.:

250 mg/kg bw/day (actual dose received)

Dose / conc.:

750 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

3 males/females per dose group

Control animals:

yes, concurrent vehicle

Details on study design:

As a dose range finding study, the design had a defined number of endpoints to aid in the assessment of dosages for repeat oral toxicity studies.

Positive control:

No

Observations and examinations performed and frequency:

Daily clinical observations, before dosing, up to 30 minutes after dosing and one hour after dosing. Additionally 5 hours after dosing Monday to Friday.
Body weights recorded days 1, 4, 8, 11 and 15.
Food consumption recorded days 1-4, 4-8, 8-11 and 11-15.
Water consumption recorded daily.

Sacrifice and pathology:

Killed on completion of dosing by an iv overdose of a barbiturate followed by exsanguination. External and internal examinations performed.

Statistics:

Means and SD calculated. No tests of statistical significance were evident.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Reduced body weight gains and body weight losses for the male rats were recorded at 750 and 1000 mg/kg bw/day.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Key result

Dose descriptor:

LOAEL

Effect level:

>= 750 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

Key result

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

Key result

Dose descriptor:

NOEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: No adverse effects.

Critical effects observed:

no

Conclusions:

Based on the study evidence a NOAEL of 250 mg/kg bw/day for the males can be considered appropriate. And a NOAEL of greater than 1000 mg/kg bw/day would be appropriate for the females.

Executive summary:

The study was designed to provide information for further repeated dose toxicity studies.

The test item was administered by gavage to three groups, each of three male and three female Wistar Han™:RccHan™:WIST strain rats, for fourteen consecutive days, at dose levels of 250, 750 and 1000 mg/kg bw/day. A control group of three males and three females was dosed with vehicle alone (1% Carboxymethyl cellulose/0.1% Tween 80).

Clinical signs, body weight change, food consumption and water consumption were monitored during the study. All animals were subjected to gross necropsy examination.

There were no unscheduled deaths.

No clinically observable signs of toxicity were detected.

Reduced body weight gains and actual body weight losses were evident for males treated with 1000 and 750 mg/kg bw/day when compared to controls. Females were unaffected by treatment at any level tested.

 

No adverse effects on food consumption were detected.

No toxicologically significant differences in water intake were detected.

 

No macroscopic changes were detected at terminal kill.

 

A NOAEL of 250 mg/kg bw/day for males can be considered appropriate. A NOAEL of greater than 1000 mg/kg bw/day would be appropriate for the females.

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Remarks:

Brief synopsis of study only.

Adequacy of study:

supporting study

Study period:

Not specified

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Justification for type of information:

Medical research project of the then manufacturer. Gives succinct information on the toxicity of pyromellitic anhydride.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Not specified.

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

Pyromellitic dianhydride

Species:

rat

Strain:

not specified

Remarks:

Albino rats

Details on species / strain selection:

Not specified

Sex:

male

Details on test animals or test system and environmental conditions:

Not specified

Route of administration:

other: From the information reviewed it is likely that the route was oral gavage

Vehicle:

arachis oil

Details on oral exposure:

Five days a week for two weeks.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Five days a week for two weeks.

Frequency of treatment:

Five days a week for two weeks.

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

6

Control animals:

not specified

Details on study design:

Not specified

Positive control:

Not specified

Observations and examinations performed and frequency:

Not specified

Sacrifice and pathology:

Three animals were sacrificed four hours after the tenth treatment, and the remaining three, ten days later.

Other examinations:

Not specified

Statistics:

Not specified

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Slower growth rate

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

chronic gastritis

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Key result

Dose descriptor:

LOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

Remarks on result:

other: Mild slowing of growth rate

One-fifth of the ALD or 1,000 mg/kg of pyromellitic dianhydride as a 20 per cent suspension in peanut oil, was administered to each of six male albino rats, five times a week for two weeks.

Other than a mild slowing of the growth rate, clinical signs of toxicity were not observed. Three animals were sacrificed four hours after the tenth treatment, and the remaining three, ten days

later. Microscopic examination of the tissues revealed chronic gastritis in the case of the first three rats, and no pathology in the last three.

Conclusions:

Six male rats dosed by oral gavage at 1000 mg/kg bw/day showed a mild slowing of growth rate over two weeks but no other signs of toxicity were evident

Reference 3

Endpoint:

sub-chronic toxicity: oral

Remarks:

Bioassay of Phthalic Anhydride for possible carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

not specified

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

CAS No. 85-44-9; Registry name: Phthalic anhydride

Species:

mouse

Strain:

B6C3F1

Remarks:

B6C3F1 mice front the NCI Frederick Cancer Research Center animal farm, Frederick, Maryland; Mice used were 4-week old weanlings.

Details on species / strain selection:

B6C3F1 mice front the NCI Frederick Cancer Research Center animal farm, Frederick, Maryland; Mice used were 4-week old weanlings.

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal Maintenance
Polycarbonate cages; serializable lab meal ad libitum replenished at least 3 times per week; water acidified to pH=2.5 ad libitum; air in the animal room; 22-24°C, relatively humidity: 45-55%, I5 changes of room air per hour; fluorescent lighting oil n 12 hour-per day cycle.

Route of administration:

oral: feed

Details on route of administration:

Dietary, in feed.

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Daily via unrestricted access to feed.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Seven weeks.

Frequency of treatment:

Daily via unrestricted access to feed.

Dose / conc.:

0 ppm

Remarks:

Control

Dose / conc.:

6 200 ppm

Remarks:

890 mg/kg bw/day

Dose / conc.:

12 500 ppm

Remarks:

1790 mg/kg bw/day

Dose / conc.:

25 000 ppm

Remarks:

3570 mg/kg bw/day

Dose / conc.:

50 000 ppm

Remarks:

7140 mg/kg bw/day

No. of animals per sex per dose:

5

Control animals:

yes, concurrent no treatment

Details on study design:

See attached report

Positive control:

No

Observations and examinations performed and frequency:

Each mouse was weighed twice per week. Also see attached report.

Sacrifice and pathology:

At termination all animals were killed using carbon dioxide inhalation and necropsied.

Statistics:

Statistical methods used: Ten percent depression in body weight was taken as the major criterion for the estimation of MTD’s. The doses required to produce this response were determined by the following procedure: first, least squares regressions of mean body weights versus days on study were used to estimate mean body weights of each of the dosed groups at day 49. Next, probits of the percent weights of the dosed groups at day 49 relative to weights of corresponding control groups were plotted against the logarithms of the doses, and least squares regressions fitted to the data were used to estimate the doses required to induce 10% depression in weight.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

See attached report.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight at week 7 as percent of control (dose; m/f):
6200ppm= 114/100%; 12,500= 113/99%; 25,000 ppm= ll1/101%; 50,000ppm= 104/99%.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Details on results:

Histopathologic examination revealed that tissues were essentially normal in males and females at 50,000 ppm. No adverse effects were reported at any dose.

Key result

Dose descriptor:

NOAEL

Effect level:

7 140 mg/kg bw/day (nominal)

Sex:

male/female

Remarks on result:

other: No adverse effects were reported at any dose.

Key result

Critical effects observed:

no

Conclusions:

In a seven week dietary study in mice no adverse effects were evident up to and including the top dosage of 50,000 ppm ~= 7140 mg/kg bw/day.

Executive summary:

In a seven week dietary study in mice no adverse effects were evident up to and including the top dosage of 50,000 ppm ~= 7140 mg/kg bw/day.

Reference 4

Endpoint:

sub-chronic toxicity: oral

Remarks:

Bioassay of Phthalic Anhydride for possible carcinogenicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

not specified

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

CAS No. 85-44-9; Registry name: Phthalic anhydride

Species:

rat

Strain:

other: Fischer 344 rats from NCI Frederick Cancer Research Cenler animal farm, Frederick, Maryland; Rats used were 4-week old weanlings.

Details on species / strain selection:

See attached report

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal Maintenance
Polycarbonate cages; sterilized lab meal replenished at least 3 limes per week; water ad libitum; air in the animal room; 22-24°C, relatively humidity: 45-55%, 15 changes of room air per hour; fluorescent lighting on a 12 hour-per day cycle.

Route of administration:

oral: feed

Vehicle:

not specified

Remarks:

See attached report

Details on oral exposure:

7 weeks

Analytical verification of doses or concentrations:

not specified

Remarks:

See attached report

Duration of treatment / exposure:

7 weeks

Frequency of treatment:

Continuous in the diet.

Dose / conc.:

0 ppm

Remarks:

Control

Dose / conc.:

6 200 ppm

Remarks:

410 mg/kg bw/day

Dose / conc.:

12 500 ppm

Remarks:

830 mg/kg bw/day

Dose / conc.:

25 000 ppm

Remarks:

1670 mg/kg bw/day

Dose / conc.:

50 000 ppm

Remarks:

3300 mg/kg bw/day

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

See attached report.

Positive control:

No

Observations and examinations performed and frequency:

Each rat was weighed twice per week. Also see attached report.

Sacrifice and pathology:

At termination all animals were killed using carbon dioxide inhalation and necropsied.

Other examinations:

See attached report.

Statistics:

Statistical methods used: Ten percent depression in body weight was taken as the major criterion for the estimation of MTD’s. The doses required to produce this response were determined by the following procedure: first, least squares regressions of mean body weights versus days on study were used to estimate mean body weights of each of the dosed groups at day 49. Next, probits of the percent weights of the dosed groups at day 49 relative to weights of corresponding control groups were plotted against the logarithms of the doses, and least squares regressions fitted to the data were used to estimate the doses required to induce 10% depression in weight

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

See attached report.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Mean body weight at week 7 as percent of control dose: 6200 ppm= 90/95%, 12,500= 95/93%, 25,000 ppm= 92/91%, 50,000 ppm= 71/76%.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

no effects observed

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

See attached report.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, non-treatment-related

Histopathological findings: neoplastic:

effects observed, non-treatment-related

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Effect level:

1 670 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Critical effects observed:

no

Lowest dose at which histopathological findings were observed in males and females was 25,000 ppm, at this dose, trace amounts of centrilobular cytoplasmic vacuolation were seen in the livers of four males. Tissues were essentially normal in both males and females at 50,000 ppm.

Conclusions:

It is concluded that under the conditions of this bioassay that was phthalic anhydride had a NOAEL of 1670 mg/kg bw/day (25000 ppm) based on body weight performance. No other adverse toxicity was evident.
Phthalic anhydride not carcinogenic for F344 rats of either sex.

Executive summary:

In this sub-chronic study in rats, phthalic anhydride at dosages up to 50,000 ppm (in the diet) were well tolerated with no overt adverse toxicity evident. Phthalic anhydride had a NOAEL of 1670 mg/kg bw/day (25000 ppm) based on body weight performance.

Reference 5

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:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across hypothesis proposed is that the organism is not exposed to common compounds but rather, as a result of structural similarity, that different compounds have similar toxicological and fate properties. In this case the ECHA Read-Across Assessment Framework (RAAF) Scenario 2 is used

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source: Phthalic anhydride [EC 201-607-5; CAS 85-44-9]
Target: Pyromellitic dianhydride [EC 201-898-9; CAS 89-32-7]

3. ANALOGUE APPROACH JUSTIFICATION
Pyromellitic dianhydride and phthalic anhydride can be regarded as close structural analogues having both similar physical chemical and toxicological properties. It follows that where endpoints for pyromellitic dianhydride may not have experimental evidence, particularly those involving animal studies, that these can be addressed by read across grouping using an analogue approach. Indeed, this approach has already been successfully used by at least the US EPA. It is therefore proposed that, after careful assessment, experimental data from phthalic anhydride may be used as surrogate evidence for read across to pyromellitic dianhydride. Please refer to the attached document for information on the data available to support the read-across.

4. DATA MATRIX

Please refer to attached document

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

7 140 mg/kg bw/day (nominal)

Sex:

male/female

Remarks on result:

other: No adverse effects were reported at any dose.

Critical effects observed:

no

Reference 6

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:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across hypothesis proposed is that the organism is not exposed to common compounds but rather, as a result of structural similarity, that different compounds have similar toxicological and fate properties. In this case the ECHA Read-Across Assessment Framework (RAAF) Scenario 2 is used

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source: Phthalic anhydride [EC 201-607-5; CAS 85-44-9]
Target: Pyromellitic dianhydride [EC 201-898-9; CAS 89-32-7]

3. ANALOGUE APPROACH JUSTIFICATION
Pyromellitic dianhydride and phthalic anhydride can be regarded as close structural analogues having both similar physical chemical and toxicological properties. It follows that where endpoints for pyromellitic dianhydride may not have experimental evidence, particularly those involving animal studies, that these can be addressed by read across grouping using an analogue approach. Indeed, this approach has already been successfully used by at least the US EPA. It is therefore proposed that, after careful assessment, experimental data from phthalic anhydride may be used as surrogate evidence for read across to pyromellitic dianhydride. Please refer to the attached document for information on the data available to support the read-across.

4. DATA MATRIX

Please refer to attached document.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

1 670 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Critical effects observed:

no

Reference 7

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Qualifier:

equivalent or similar to guideline

Guideline:

other: EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

not specified

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

CAS No. 85-44-9; Registry name: Phthalic anhydride

Species:

mouse

Strain:

B6C3F1

Remarks:

.

Details on species / strain selection:

B6C3FI mice from the NCI Frederick Cancer Research Center animal farm, Frederick, Maryland; Mice used in this study weighed 18-22 g (males) and 80-95 g (females) and were 6 weeks old al initiation.

Sex:

male/female

Details on test animals or test system and environmental conditions:

B6C3FI mice

Polycarbonate cages; sterilisable lab meal replenished at least 3 limes per week; water acidified to pH-2.5 ad libitum; air in the animal room: 22-24°C, relatively humidity: 45-55%, 15 changes of room air per hour; fluorescent lighting on a 12 hour-per day cycle.

Route of administration:

oral: feed

Details on route of administration:

Continuously in diet.

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Continuously in diet.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical analyses indicated that when phthalic anhydride as mixed with Lab Meal at a concentration of 15,000 ppm and stored at room temperature for 2 weeks, the loss was 2.59% (372 ppm) per day.

Duration of treatment / exposure:

104 weeks

Test diets containing phthalic anhydride were prepared every I to 1.5 weeks at appropriate doses. The diets were routinely stored at 5 degrees Celsius until used.

Frequency of treatment:

Continuously in diet.

Dose / conc.:

0 ppm

Remarks:

Control

Dose / conc.:

12 500 ppm

Remarks:

1785 mg/kg bw/day

Dose / conc.:

25 000 ppm

Remarks:

3570 mg/kg bw/day

No. of animals per sex per dose:

50 per test group and 20 in the control group.

Control animals:

yes, plain diet

Details on study design:

Doses/concentrations tested: Dose levels for the first 32 weeks were 0 (control), 25,000 or 50,000 ppm (approx. 3570 or 7140 mg/kg-bw/day). Exposure levels were then reduced to 12,500 or 25,000 ppm (approx. 1785 or 3570 mg/kg-bw/day), respectively, and the (loses for the females were reduced to 6250 and 12,500 ppm (approx., 890 or 1780 mg/kg-bw/day), respectively, for the remainder of the study (72 weeks). The time-weighted average doses for the males were either 16,346 or 32692 ppm (approx. 2340 or 5670 mg/kg-bw/day), and those for the females were either 12,019 or 24,038 ppm (approx. 1717 or 3430 mg/kg-bw/day).

Positive control:

No

Observations and examinations performed and frequency:

Each mouse was weighed once per month, daily observations for sick, tumour bearing and moribund animals, twice daily cheeked for deaths. See attached report.

Sacrifice and pathology:

At the end all animals were killed using C02 inhalation and necropsied; gross and microscopic examination of:

Skin, lungs and bronchi, trachea, bone marrow (femur), spleen, lymph nodes (mesenteric and submandibular), thymus, heart, salivary glands (parotid, sublingual, and submaxillary), liver, pancreas, esophagus, stomach (glandular and non-glandular), small and large intestines, kidneys, urinary bladder, pituitary, adrenal, thyroid, parathyroid, pancreatic islets, epididymis, uterus, ovary, brain (cerebrum, and cerebellum), and all tissue masses. Peripheral blood smears were made for ail animals, whenever possible.

Statistics:

Statistical methods used: Probabilities of survival were estimated by the product-limit procedure of Kaplan and Meier (1958). Animals were statistically censored as of (he time that they died of other than natural causes or were found to be missing; animals dying from natural causes were not statistically censored. Statistical analyses for a possible dose-related effect on survival used the method of Cox (1972) for testing two groups of equality and Tarone’s (1975) extensions of Cox methods for testing for a dose-related trend. One-tailed P values have been reported for all tests except the departure from linearity test, winch is only reported when its two- tailed P value is less than 0.05.

Clinical signs:

effects observed, non-treatment-related

Mortality:

mortality observed, non-treatment-related

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

decreased mean body weights and body weight gain

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, non-treatment-related

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Increased incidences of lung and kidney lymphocytosis and adrenal atrophy and mineralization of the thalamus and increased incidences of lung and kidney lymphocytosis.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Increased incidences of lung and kidney lymphocytosis and adrenal atrophy and mineralization of the thalamus and increased incidences of lung and kidney lymphocytosis.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Key result

Dose descriptor:

LOAEL

Effect level:

2 340 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

histopathology: non-neoplastic

Key result

Dose descriptor:

LOAEL

Effect level:

1 717 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

histopathology: non-neoplastic

Key result

Critical effects observed:

no

Conclusions:

Endpoint value(s): LOAEL (males) - 16346 ppm (approx. 2340 mg/kg/day; lowest dose tested) based on decreased mean body weights aid body weight gain and increased incidences of lung and kidney lymphocytosis and adrenal atrophy and mineralization of the thalamus; NOAEL (males) = Not established. LOAEL (females) = 12019 ppm (approx. 1717 mg/kg/day; lowest dose tested) based on decreased mean body weights and body weight gain and increased incidences of lung and kidney lymphocytosis; NOAEL (females) - Not established.

Executive summary:

Males and female mice were treated with the test material in the diet at 0 (control), 25000 or 50000 ppm (approx. 3570 or 7140 mg/kg-bw/day). But after 32 weeks exposure levels were reduced to 12500 or 25000 ppm (approx. 1785 or 3570 mg/kg-bw/day) primarily because of body weight deficits. The overall duration of the study was 104 weeks, in general the test material was well tolerated, and no oncogenic lesions were evident.

The LOAEL for the males was 16346 ppm (approx. 2340 mg/kg/day; lowest dose tested) based on decreased mean body weights aid body weight gain and increased incidences of lung and kidney lymphocytosis and adrenal atrophy and mineralization of the thalamus; a NOAEL (males) was not established. The LOAEL for the females was 12019 ppm (approx. 1717 mg/kg/day; lowest dose tested) based on decreased mean body weights and body weight gain and increased incidences of lung and kidney lymphocytosis; a NOAEL (females) was not established

Reference 8

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

not specified

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

CAS No. 85-44-9; Registry name: Phthalic anhydride

Species:

rat

Strain:

Fischer 344

Details on species / strain selection:

Fischer 344 rats from the NCI Frederick Cancer Research Center animal farm, Frederick, Maryland; were used in this study and weighed 90-105 g (males) or 80-95 g (females) and were 6 weeks old at initiation.

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal Maintenance
Polycarbonate cages; sterilisable lab meal replenished at least 3 times per week; water acidified lo pH=2.5 ad libitum; air in the animal room: 22-24“C, relatively humidity: 45-55%, 15 changes of room air per hour; fluorescent lighting on a 12 hour-per day cycle.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

105 weeks continuously via the diet

Analytical verification of doses or concentrations:

yes

Remarks:

See attached report

Details on analytical verification of doses or concentrations:

Analytical analyses indicated that when phthalic anhydride as mixed with Lab Meal at a concentration of 15,000 ppm and stored at room temperature for 2 weeks, the loss was 2.59% (372 ppm) per day.

Duration of treatment / exposure:

105 weeks continuously via the diet
Test diets containing phthalic anhydride were prepared every 1 to 1.5 weeks at appropriate doses. The diets were routinely stored at 5 degrees Celsius until used.

Frequency of treatment:

105 weeks continuously via the diet

Dose / conc.:

0 ppm

Remarks:

Control

Dose / conc.:

7 500 ppm

Remarks:

500 mg/kg bw/day

Dose / conc.:

15 000 ppm

Remarks:

1000 mg/kg bw/day

No. of animals per sex per dose:

50 for tests; 20 for control

Control animals:

yes, plain diet

Details on study design:

See attached report.

Positive control:

No

Observations and examinations performed and frequency:

Each rat was weighed once per month, daily observations for sick, tumour bearing and moribund animals, twice daily checked for deaths. Also see attached report.

Sacrifice and pathology:

Necropsy and Histological Examination:

At the end all animals were killed using C02 inhalation and necropsied; gross and microscopic examination of:
Skin, lungs and bronchi, trachea, bone marrow (femur), spleen, lymph nodes (mesenteric and submandibular), thymus, heart, salivary glands (parotid, sublingual, and submaxillary), liver, pancreas, esophagus, stomach (glandular and non-glandular), small and large intestines, kidneys, urinary bladder, pituitary, adrenal, thyroid, parathyroid, pancreatic islets, testis, prostate, mammary gland, uterus, ovary, brain (cerebrum, and cerebellum), and all tissue masses.
Peripheral blood smears were made for all animals, whenever possible.

Statistics:

Statistical methods used: Probabilities of survival were estimated by the product-limit procedure of Kaplan and Meier (1958). Animals were statistically censored as of the time that they died of oilier than natural causes or were found to be missing; animals dying from natural causes were not statistically censored. Statistical analyses for a possible dose-related effect on survival used the method of Cox (1972) for testing two groups of equality and Tarone’s (1975) extensions of Cox methods for testing for a dose-related trend. One-tailed P values have been reported for all tests except the departure from linearity test, which is only reported when its two- tailed P value is less than 0.05.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Arched back, rough hair coat, ulceration, and corneal opacity occurred only in dosed groups, but at low incidences. Wasting and tissue masses were common to the dosed and control groups indicative of aging rats..

Mortality:

mortality observed, non-treatment-related

Description (incidence):

The result of the Tarone’s test for dose-related (rend in mortality was not significant in either sex. In male rats, an indicated departure from linear trend (P ~ 0.037) was observed, due to the earlier mortality of the control group when compared with that of either the high- or low-dose group. The results of the Cox test applied to any two of the tree groups show no statistically significant difference between groups of any pair.

In male rats, 36/50 (72%) of the high-dose group, 44/50 (88%) of the low-dose group, and 14/20 (70%) of the control group lived to the end of the bioassay. In females, 41/50 (82%) of the high- dose group, 42/50 (84%) of the low-dose group, and 17/20 (85%) of the control group lived to the end of the bioassay.

Sufficient numbers of rats of each sex were at risk for the development of late-appearing tumors.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The mean body weights of the high-dose male rats were lower than those of the corresponding controls from week 13 to the end of the bioassay; mean body weights of the low-dose males and both the low-and high-dose females were essentially unaffected by administration of the test chemical. Fluctuation in the growth curves may be due lo mortality; as the size of a group diminished, the mean body weight may be subject to variation.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Arched back only in dosed groups, but at low incidences.

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, non-treatment-related

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

Severe chronic inflammatory, degenerative, or proliferative lesions frequently seen in aged rats occurred with approximately equal frequency and severity in the dosed and control groups of animals.
There were no treatment-related adverse effects in the reproductive organs examined at necropsy (seminal vesicle, epididymis, mammary gland, preputial gland) and the reproductive organs examined microscopically (prostate, testis, uterus, uterus/endometrium, endometrial gland, ovary).

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Key result

Dose descriptor:

LOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Key result

Critical effects observed:

no

Conclusions:

The LOAEL was 15,000 ppm (1000 mg/kg/day) and the NOAEL was 7500 ppm (500 mg/kg/day).

Executive summary:

Males and female rats treated continuously in the diet with 15000 ppm (1000 mg/kg/day) or 7500 ppm (500 mg/kg/day) for 105 weeks tolerated the test material very well. There was no evidence of adverse treatment related pathology or tumorigenicity. The LOAEL was 15,000 ppm (1000 mg/kg/day) and the NOAEL was 7500 ppm (500 mg/kg/day) based on body weight performance.

Reference 9

Endpoint:

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:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across hypothesis proposed is that the organism is not exposed to common compounds but rather, as a result of structural similarity, that different compounds have similar toxicological and fate properties. In this case the ECHA Read-Across Assessment Framework (RAAF) Scenario 2 is used

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source: Phthalic anhydride [EC 201-607-5; CAS 85-44-9]
Target: Pyromellitic dianhydride [EC 201-898-9; CAS 89-32-7]

3. ANALOGUE APPROACH JUSTIFICATION
Pyromellitic dianhydride and phthalic anhydride can be regarded as close structural analogues having both similar physical chemical and toxicological properties. It follows that where endpoints for pyromellitic dianhydride may not have experimental evidence, particularly those involving animal studies, that these can be addressed by read across grouping using an analogue approach. Indeed, this approach has already been successfully used by at least the US EPA. It is therefore proposed that, after careful assessment, experimental data from phthalic anhydride may be used as surrogate evidence for read across to pyromellitic dianhydride. Please refer to the attached document for information on the data available to support the read-across.

4. DATA MATRIX

Please refer to attached document

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

LOAEL

Effect level:

2 340 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

histopathology: non-neoplastic

Key result

Dose descriptor:

LOAEL

Effect level:

1 717 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

histopathology: non-neoplastic

Critical effects observed:

no

Reference 10

Endpoint:

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:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across hypothesis proposed is that the organism is not exposed to common compounds but rather, as a result of structural similarity, that different compounds have similar toxicological and fate properties. In this case the ECHA Read-Across Assessment Framework (RAAF) Scenario 2 is used

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source: Phthalic anhydride [EC 201-607-5; CAS 85-44-9]
Target: Pyromellitic dianhydride [EC 201-898-9; CAS 89-32-7]

3. ANALOGUE APPROACH JUSTIFICATION
Pyromellitic dianhydride and phthalic anhydride can be regarded as close structural analogues having both similar physical chemical and toxicological properties. It follows that where endpoints for pyromellitic dianhydride may not have experimental evidence, particularly those involving animal studies, that these can be addressed by read across grouping using an analogue approach. Indeed, this approach has already been successfully used by at least the US EPA. It is therefore proposed that, after careful assessment, experimental data from phthalic anhydride may be used as surrogate evidence for read across to pyromellitic dianhydride. Please refer to the attached document for information on the data available to support the read-across.

4. DATA MATRIX

Please refer to attached document

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Key result

Dose descriptor:

LOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

500 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

Key study: Reliability 1

System:

other: body weight

Organ:

not specified

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03-03-1978 to 30-11-1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

no guideline followed

Principles of method if other than guideline:

A scientifically acceptable short-term inhalation toxicity study in which rats were exposed to airborne dusts of the test material for 10 days. Appropriate study parameters were assessed and adequately reported.

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

PMDA
pyromellitic dianhydride
IC-4054 3-72
Lot No. RI-18

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

Charles River CD rats, 6-8 weeks old

Sex:

male

Details on test animals or test system and environmental conditions:

Forty male (weighing from 196 to 228 grams) Charles River CD rats, 6-8 weeks of age were used in the study. The 40 males were randomized into 4 groups of 10 rats each. in accordance with a random table of 40. After the randomization process, the rats were individually identified with ear punches in numerical order from l to 40. Each rat was housed individually in compartmented stainless-steel holding cages and kept in a temperature and humidity-controlled room throughout the 1-week quarantine, the 2-veek experimental, and the 2-week post exposure observation periods. The rats were supplied with water and Purina rat Chow ad libitum except during exposure.

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

>= 3 - <= 3.7 µm

Remarks on MMAD:

GSD given as 2.32 to 2.43 in the study report.

Details on inhalation exposure:

All exposures were conducted in a 1 cubic meter cubical stainless steel and glass chamber, with pyramidal top and bottom. Chamber airflow was maintained by means of a rotary centrifugal air pump located at the exhaust side of the chamber. The chamber exhaust was filtered through an activated charcoal filter and a Cambridge Absolute filter before being discharged outside of the laboratory. The dust atmosphere of the compound was generated by dispersing the powder at a calculated rate with an IRAD Dust Gun located near the chamber air inlet at the top of the exposure chamber. This dust generator consisted of a revolving plate with calibrated cups for transporting a known quantity of powder per unit time from a. reservoir to a "blowhole.”. At the “blowhole" the powder in a "cup" was dispersed into the chamber by a jet of desiccated air flowing at a rate of 10 litres/minute.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The actual quantity of powder disseminated was determined by weighing the quantity of powder in the reservoir before and after the exposure. The concentration of the dust in the chamber atmosphere was calculated from the ratio of the quantity of powder used to the total chamber airflow per unit time.
The concentration of the airborne dusts in the chamber atmosphere was determined gravimetrically using a fiberglass Millipore filter sampling technique. The chamber atmosphere was drawn through a 37 mm 0.8 µ pore size filter at a rate of 2 litres/minute. A critical orifice was used to regulate the flow race. Samples were taken from each exposure chamber once every 30 minutes during the exposure period. The weight of pyromellitic dianhydride collected on the filter was determined and the concentration of the duet was calculated in milligrams/litre of air.
The particle size distribution of the pyromellitic dianhydride in a sample of the chamber atmosphere was determined using an Andersen 8-stage Fractionating Sampler. The chamber atmosphere was drawn through the sampler at a rate of 28.3 1/min for a suitable duration. The weight of the particles collected on each stage is determined gravimetrically and the weight percent of each size category was calculated. The cumulative weight percent of particles smaller that each size range was plotted on a logarithmic probability graph paper. The aerodynamic mass median diameter and the percent of respirable particles in the sample was determined graphically by interpolation.

Duration of treatment / exposure:

Two weeks, 10 exposures, 6 hours per day.

Frequency of treatment:

10 exposures in 2 weeks.

Dose / conc.:

0 mg/L air

Remarks:

Control

Dose / conc.:

0.01 mg/L air (nominal)

Remarks:

0.021 mg/L air analytical

Dose / conc.:

0.03 mg/L air (nominal)

Remarks:

0.035 mg/L air analytical

Dose / conc.:

0.1 mg/L air (nominal)

Remarks:

0.091 mg/L air analytical

No. of animals per sex per dose:

10 males

Control animals:

yes

Details on study design:

These are given in the previous sections.

Positive control:

No

Observations and examinations performed and frequency:

The rats were observed daily before and after exposure for respiratory distress, nasal irritation and discharge, and any other observable toxic signs.

The rats were weighed daily on exposure days and periodically during the quarantine and post exposure observation period. Five rats from each group were sacrificed and necropsied following the 10th exposure. The remaining rats were observed for an additional 14 days and then sacrificed.

Sacrifice and pathology:

Five rats/group sacrificed after 10th exposure and the reamining rats after another 14 days.

Other examinations:

Clinical laboratory tests were conducted on 5 rats from each group at the termination of the exposure period, the remaining rats from each group were kept and observed for 14 days. At the end of the 14-day observation period, clinical laboratory tests were conducted on the remaining, 20 rats. For the collection of urine samples, the rats were placed in metabolism cages and fasted overnight. Blood was then collected by the orbital sinus puncture technique. The rats were then sacrificed for gross and histopathological examinations.
Haematological studies included erythrocyte count, total and differential leucocyte count, haemoglobin and haematocrit. Mean corpuscular volume and mean corpuscular haemoglobin were calculated.
Biochemical studies included serum glutamyl transpeptidase, alkaline phosphatase, bilirubin, lactic dehydrogenase, serum glutamic oxaloacetate and pyruvic transaminase activities, blood urea nitrogen and total protein.
Urinalyses included measurement of volume, osmolality, pH, sugar, proteins , blood, urobilinogen, bilirubin and microscopic examination of sediment.

Statistics:

All statistical analyses compared the treatment groups with the control group.
Erythrocytes, haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin, MCRC, LDH (post 10 exposure and 13 day post exposure) aid absolute and relative organ weights withdrawal sacrifice and terminal sacrifice) were compared by analysis of variance (one-way classification), Bartlett's test for homogeneity of variances and the appropriate t-test (for equal or unequal variances) using Dunnett’s multiple comparison tables to judge significance of differences.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The most notable observable changes in the rats after exposure to the compound were respiratory difficulties and the appearance of nasal irritation and discharge. There was an observable gradient in the severity and onset of these effects from the low to high exposure levels. By the end of the third day the rats exposed to 0.01 mg/1experienced slight breathing difficulties and nasal irritation. The rats exposed to 0.03 mg/1 of the dust exhibited nasal irritation with a few intermittent cases of red nasal discharge. By the end of the third exposure day the rats experienced markedly laboured respiration. The rats in the 0.1 mg/1 exposure group had nasal and respiratory involvement from the first day of exposure. Nasal irritation had progressed to a red nasal discharge in 50-80% of these rats. By the second exposure day all rats in this group had marked difficulty in breathing, about half to the point of gasping.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weights recorded before, during and after the exposure period showed a direct relationship between body weight loss and exposure concentrations. The control rats, which were exposed to filtered air, gained weight throughout the experimental period. The rats at 0.01 and 0.03 mg/1 maintained weight during exposure and gained weight on weekends when they were not exposed. The rats exposed to 0.1 mg/1 lost weight during the exposure periods but showed weight gains on the weekends. At the termination of the 10 exposures, the mean body weights of the rats of the 0.01 and the 0.03 mg/1 groups were below that of the control group but were above the pre-exposure mean weights. The mean body weight of the rats in the 0.1 mg/l group at the end of the exposure period was below the pre-exposure mean weight.

All the exposed rats, which were kept for post exposure observations, showed body weight gain. At the end of the observation period, the mean body weights of all the exposed rats were still below that of the control group in a concentration related manner.

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):

Examination of the hematological parameters of rats which were sacrificed shortly after the 10th exposure revealed a significant (p<0.05) increase in the number of erythrocytes per unit volume of blood in the 0.03 and 0.1 mg/l concentration groups and a significant (p<0.05 and 0.01) increase in haemoglobin concentration in all the exposed groups. A significant (p<0.01) increase in neutrophils also was seen for rats at the 0.1 mg/1 dosage level. Similar examinations of the rats which were sacrificed 2 weeks after the exposures revealed no significant differences between the groups.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Examination of the data revealed a significant (p<0.01) depression of the level of lactate dehydrogenase in the rats which were sacrificed immediately after the exposure. to 0.1 mg/1 of the compound. However, similar examinations of the rats, which were sacrificed after 14 days of observation revealed no depression of LDH in all groups. There were no other detectable changes seen in the studies of serum alkaline phosphatase, glutamic pyruvic transaminase and gamma glutamyl transpeptidase activities and the levels of blood urea nitrogen and total protein at all time intervals.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Some variations were noted but were of unknown biologic significance.
There was an increase in lung weight noted at the 0.01 mg/1 - 0.1 mg/l level, but this was unaccompanied by morphologic alterations.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No gross lesions considered compound-related were seen in rats sacrificed at tile end of exposure and those sacrificed after a compound withdrawal period of 14 days.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

No microscopic lesions considered compound-related were observed in tissues other than lungs of rats from the test groups at either sacrifice.

All rats in the 0.01, 0.03 and 0.1 mg/1 exposure groups sacrificed at the end of the exposure period or after 14 days of compound withdrawal had very slight to slight multifocal hypertrophy and hyperplasia of type 2 alveolar cells with occasional formation of alveolar giant cells (foreign body type). Most rats had very slight to slight focal to multifocal interstitial pneumonia characterized by very slight to slight interstitial fibrosis and very slight to slight interstitial mononuclear inflammatory cell infiltrates. All rats in the 3 test groups sacrificed after 10 exposures had very slight to slight aggregates of foamy macrophages in bronchiolar lumens; two rats, one from the 0.01 mg/1 group and one from the 0.03 mg/1 group, at 14th day post exposure had very slight aggregates of foamy macrophages in bronchiolar lumens. All rats in the 3 test groups at 14th day post exposure had slight to very slight aggregates of dark-brown pigment in cytoplasm of hypertrophic and hyperplastic type 2 alveolar cells; no similar pigment was observed in rats from these groups sacrificed immediately after 10 exposures. No microscopic changes which were considered treatment related were seen in the lungs of rats from the control group of either sacrifice.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Key result

Dose descriptor:

LOAEL

Remarks:

local effects

Effect level:

>= 0.021 - <= 0.091 mg/L air

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

organ weights and organ / body weight ratios

Remarks on result:

other: Slight/very slight changes seen only in the lungs

Critical effects observed:

no

Conclusions:

Rats exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks (nominal: 0.01. 0.03 and 0.1mg/L; analysed: 0.021, 0.035 and 0.091 mg/L) exhibited symptoms directly related to the route of exposure, i.e. most effects were evident in the lungs. The signs were indicative of local, direct effects in the lungs. PMDA is highly reactive and hydrolyses in contact with water or body fluids to the corresponding pyromellitic acid; PMDA is also a severe eye irritant. It is unsurprising that direct local effects in the lungs were observed. Other changes seen in this study were likely to be related to physiological stress because of the clinical signs induced via inhalation exposure to the dusts. Only the lungs showed any histopathological treatment related signs, importantly the signs seen were only slight to very slight.

Executive summary:

Male rats were exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks. Ten rats were used at nominal dosage levels of 0.01. 0.03 and 0.1mg/l and in a control group. Rats exposed to a concentration of 0.1 mg/1 exhibited a red nasal discharge and breathing difficulties to the point of gasping. The group exposed to 0.03 mg/1 had laboured breathing and nasal irritation with a few incidences of red nasal discharge. At an exposure level of 0.01 mg/1 the rats had slight breathing difficulties and nasal irritation. The severity of the laboured breathing and nasal effects decreased with decreasing concentration. All exposed groups had decreased weight gains. Examination of the hematological parameters of rats which were sacrificed shortly after the 10th exposure revealed an increase in the number of erythrocytes per unit volume of blood in the 0.03 and 0.1 mg/1 concentration groups and an increase in haemoglobin concentration in all the exposed groups. An increase in neutrophils also was seen for rats at the 0.1 mg/1 dosage level. Lactate dehydrogenase activity was reduced in the rats which were sacrificed immediately after the exposures to 0.1 mg/1 of the compound. No gross lesions or organ weight variations considered compound related were seen in rats sacrificed after 10 exposures and those sacrificed after a compound withdrawal period of 14 days. No microscopic pathological lesions which were considered compound related were seen in tissues other than the lungs of rats at the 0.01, 0.03 and 0.1 mg/1 exposure levels sacrificed after 10 exposures and after 14 days withdrawal. microscopically, the lung lesions considered compound related were very slight to slight, focal to multifocal interstitial pneumonia, very slight to slight aggregates of foamy macrophages in bronchiolar lumens, and very slight to slight multifocal hypertrophy and hyperplasia of type 2 alveolar cell, with occasional formation of alveolar giant cells (foreign body type).

In conclusion, rats exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks (nominal: 0.01. 0.03 and 0.1mg/L; analysed: 0.021, 0.035 and 0.091 mg/L) exhibited symptoms directly related to the route of exposure, i.e. most effects were evident in the lungs.  The signs were indicative of local, direct effects in the lungs. PMDA is highly reactive and hydrolyses in contact with water or body fluids to the corresponding pyromellitic acid; PMDA is also a severe eye irritant. It is unsurprising that direct local effects in the lungs were observed. Other changes seen in this study were likely to be related to physiological stress because of the clinical signs induced via inhalation exposure to the dusts. Only the lungs showed any histopathological treatment related signs, importantly the signs seen were only slight to very slight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

91 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliability 2

System:

other: respiratory system: upper respiratory tract, local/direct effects

Organ:

lungs

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03-03-1978 to 30-11-1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

no guideline followed

Principles of method if other than guideline:

A scientifically acceptable short-term inhalation toxicity study in which rats were exposed to airborne dusts of the test material for 10 days. Appropriate study parameters were assessed and adequately reported.

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

PMDA
pyromellitic dianhydride
IC-4054 3-72
Lot No. RI-18

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

Charles River CD rats, 6-8 weeks old

Sex:

male

Details on test animals or test system and environmental conditions:

Forty male (weighing from 196 to 228 grams) Charles River CD rats, 6-8 weeks of age were used in the study. The 40 males were randomized into 4 groups of 10 rats each. in accordance with a random table of 40. After the randomization process, the rats were individually identified with ear punches in numerical order from l to 40. Each rat was housed individually in compartmented stainless-steel holding cages and kept in a temperature and humidity-controlled room throughout the 1-week quarantine, the 2-veek experimental, and the 2-week post exposure observation periods. The rats were supplied with water and Purina rat Chow ad libitum except during exposure.

Route of administration:

inhalation: dust

Type of inhalation exposure:

whole body

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

>= 3 - <= 3.7 µm

Remarks on MMAD:

GSD given as 2.32 to 2.43 in the study report.

Details on inhalation exposure:

All exposures were conducted in a 1 cubic meter cubical stainless steel and glass chamber, with pyramidal top and bottom. Chamber airflow was maintained by means of a rotary centrifugal air pump located at the exhaust side of the chamber. The chamber exhaust was filtered through an activated charcoal filter and a Cambridge Absolute filter before being discharged outside of the laboratory. The dust atmosphere of the compound was generated by dispersing the powder at a calculated rate with an IRAD Dust Gun located near the chamber air inlet at the top of the exposure chamber. This dust generator consisted of a revolving plate with calibrated cups for transporting a known quantity of powder per unit time from a. reservoir to a "blowhole.”. At the “blowhole" the powder in a "cup" was dispersed into the chamber by a jet of desiccated air flowing at a rate of 10 litres/minute.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The actual quantity of powder disseminated was determined by weighing the quantity of powder in the reservoir before and after the exposure. The concentration of the dust in the chamber atmosphere was calculated from the ratio of the quantity of powder used to the total chamber airflow per unit time.
The concentration of the airborne dusts in the chamber atmosphere was determined gravimetrically using a fiberglass Millipore filter sampling technique. The chamber atmosphere was drawn through a 37 mm 0.8 µ pore size filter at a rate of 2 litres/minute. A critical orifice was used to regulate the flow race. Samples were taken from each exposure chamber once every 30 minutes during the exposure period. The weight of pyromellitic dianhydride collected on the filter was determined and the concentration of the duet was calculated in milligrams/litre of air.
The particle size distribution of the pyromellitic dianhydride in a sample of the chamber atmosphere was determined using an Andersen 8-stage Fractionating Sampler. The chamber atmosphere was drawn through the sampler at a rate of 28.3 1/min for a suitable duration. The weight of the particles collected on each stage is determined gravimetrically and the weight percent of each size category was calculated. The cumulative weight percent of particles smaller that each size range was plotted on a logarithmic probability graph paper. The aerodynamic mass median diameter and the percent of respirable particles in the sample was determined graphically by interpolation.

Duration of treatment / exposure:

Two weeks, 10 exposures, 6 hours per day.

Frequency of treatment:

10 exposures in 2 weeks.

Dose / conc.:

0 mg/L air

Remarks:

Control

Dose / conc.:

0.01 mg/L air (nominal)

Remarks:

0.021 mg/L air analytical

Dose / conc.:

0.03 mg/L air (nominal)

Remarks:

0.035 mg/L air analytical

Dose / conc.:

0.1 mg/L air (nominal)

Remarks:

0.091 mg/L air analytical

No. of animals per sex per dose:

10 males

Control animals:

yes

Details on study design:

These are given in the previous sections.

Positive control:

No

Observations and examinations performed and frequency:

The rats were observed daily before and after exposure for respiratory distress, nasal irritation and discharge, and any other observable toxic signs.

The rats were weighed daily on exposure days and periodically during the quarantine and post exposure observation period. Five rats from each group were sacrificed and necropsied following the 10th exposure. The remaining rats were observed for an additional 14 days and then sacrificed.

Sacrifice and pathology:

Five rats/group sacrificed after 10th exposure and the reamining rats after another 14 days.

Other examinations:

Clinical laboratory tests were conducted on 5 rats from each group at the termination of the exposure period, the remaining rats from each group were kept and observed for 14 days. At the end of the 14-day observation period, clinical laboratory tests were conducted on the remaining, 20 rats. For the collection of urine samples, the rats were placed in metabolism cages and fasted overnight. Blood was then collected by the orbital sinus puncture technique. The rats were then sacrificed for gross and histopathological examinations.
Haematological studies included erythrocyte count, total and differential leucocyte count, haemoglobin and haematocrit. Mean corpuscular volume and mean corpuscular haemoglobin were calculated.
Biochemical studies included serum glutamyl transpeptidase, alkaline phosphatase, bilirubin, lactic dehydrogenase, serum glutamic oxaloacetate and pyruvic transaminase activities, blood urea nitrogen and total protein.
Urinalyses included measurement of volume, osmolality, pH, sugar, proteins , blood, urobilinogen, bilirubin and microscopic examination of sediment.

Statistics:

All statistical analyses compared the treatment groups with the control group.
Erythrocytes, haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin, MCRC, LDH (post 10 exposure and 13 day post exposure) aid absolute and relative organ weights withdrawal sacrifice and terminal sacrifice) were compared by analysis of variance (one-way classification), Bartlett's test for homogeneity of variances and the appropriate t-test (for equal or unequal variances) using Dunnett’s multiple comparison tables to judge significance of differences.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The most notable observable changes in the rats after exposure to the compound were respiratory difficulties and the appearance of nasal irritation and discharge. There was an observable gradient in the severity and onset of these effects from the low to high exposure levels. By the end of the third day the rats exposed to 0.01 mg/1experienced slight breathing difficulties and nasal irritation. The rats exposed to 0.03 mg/1 of the dust exhibited nasal irritation with a few intermittent cases of red nasal discharge. By the end of the third exposure day the rats experienced markedly laboured respiration. The rats in the 0.1 mg/1 exposure group had nasal and respiratory involvement from the first day of exposure. Nasal irritation had progressed to a red nasal discharge in 50-80% of these rats. By the second exposure day all rats in this group had marked difficulty in breathing, about half to the point of gasping.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weights recorded before, during and after the exposure period showed a direct relationship between body weight loss and exposure concentrations. The control rats, which were exposed to filtered air, gained weight throughout the experimental period. The rats at 0.01 and 0.03 mg/1 maintained weight during exposure and gained weight on weekends when they were not exposed. The rats exposed to 0.1 mg/1 lost weight during the exposure periods but showed weight gains on the weekends. At the termination of the 10 exposures, the mean body weights of the rats of the 0.01 and the 0.03 mg/1 groups were below that of the control group but were above the pre-exposure mean weights. The mean body weight of the rats in the 0.1 mg/l group at the end of the exposure period was below the pre-exposure mean weight.

All the exposed rats, which were kept for post exposure observations, showed body weight gain. At the end of the observation period, the mean body weights of all the exposed rats were still below that of the control group in a concentration related manner.

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):

Examination of the hematological parameters of rats which were sacrificed shortly after the 10th exposure revealed a significant (p<0.05) increase in the number of erythrocytes per unit volume of blood in the 0.03 and 0.1 mg/l concentration groups and a significant (p<0.05 and 0.01) increase in haemoglobin concentration in all the exposed groups. A significant (p<0.01) increase in neutrophils also was seen for rats at the 0.1 mg/1 dosage level. Similar examinations of the rats which were sacrificed 2 weeks after the exposures revealed no significant differences between the groups.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Examination of the data revealed a significant (p<0.01) depression of the level of lactate dehydrogenase in the rats which were sacrificed immediately after the exposure. to 0.1 mg/1 of the compound. However, similar examinations of the rats, which were sacrificed after 14 days of observation revealed no depression of LDH in all groups. There were no other detectable changes seen in the studies of serum alkaline phosphatase, glutamic pyruvic transaminase and gamma glutamyl transpeptidase activities and the levels of blood urea nitrogen and total protein at all time intervals.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Some variations were noted but were of unknown biologic significance.
There was an increase in lung weight noted at the 0.01 mg/1 - 0.1 mg/l level, but this was unaccompanied by morphologic alterations.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No gross lesions considered compound-related were seen in rats sacrificed at tile end of exposure and those sacrificed after a compound withdrawal period of 14 days.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

No microscopic lesions considered compound-related were observed in tissues other than lungs of rats from the test groups at either sacrifice.

All rats in the 0.01, 0.03 and 0.1 mg/1 exposure groups sacrificed at the end of the exposure period or after 14 days of compound withdrawal had very slight to slight multifocal hypertrophy and hyperplasia of type 2 alveolar cells with occasional formation of alveolar giant cells (foreign body type). Most rats had very slight to slight focal to multifocal interstitial pneumonia characterized by very slight to slight interstitial fibrosis and very slight to slight interstitial mononuclear inflammatory cell infiltrates. All rats in the 3 test groups sacrificed after 10 exposures had very slight to slight aggregates of foamy macrophages in bronchiolar lumens; two rats, one from the 0.01 mg/1 group and one from the 0.03 mg/1 group, at 14th day post exposure had very slight aggregates of foamy macrophages in bronchiolar lumens. All rats in the 3 test groups at 14th day post exposure had slight to very slight aggregates of dark-brown pigment in cytoplasm of hypertrophic and hyperplastic type 2 alveolar cells; no similar pigment was observed in rats from these groups sacrificed immediately after 10 exposures. No microscopic changes which were considered treatment related were seen in the lungs of rats from the control group of either sacrifice.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Key result

Dose descriptor:

LOAEL

Remarks:

local effects

Effect level:

>= 0.021 - <= 0.091 mg/L air

Based on:

test mat.

Sex:

male

Basis for effect level:

clinical signs

organ weights and organ / body weight ratios

Remarks on result:

other: Slight/very slight changes seen only in the lungs

Critical effects observed:

no

Conclusions:

Rats exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks (nominal: 0.01. 0.03 and 0.1mg/L; analysed: 0.021, 0.035 and 0.091 mg/L) exhibited symptoms directly related to the route of exposure, i.e. most effects were evident in the lungs. The signs were indicative of local, direct effects in the lungs. PMDA is highly reactive and hydrolyses in contact with water or body fluids to the corresponding pyromellitic acid; PMDA is also a severe eye irritant. It is unsurprising that direct local effects in the lungs were observed. Other changes seen in this study were likely to be related to physiological stress because of the clinical signs induced via inhalation exposure to the dusts. Only the lungs showed any histopathological treatment related signs, importantly the signs seen were only slight to very slight.

Executive summary:

Male rats were exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks. Ten rats were used at nominal dosage levels of 0.01. 0.03 and 0.1mg/l and in a control group. Rats exposed to a concentration of 0.1 mg/1 exhibited a red nasal discharge and breathing difficulties to the point of gasping. The group exposed to 0.03 mg/1 had laboured breathing and nasal irritation with a few incidences of red nasal discharge. At an exposure level of 0.01 mg/1 the rats had slight breathing difficulties and nasal irritation. The severity of the laboured breathing and nasal effects decreased with decreasing concentration. All exposed groups had decreased weight gains. Examination of the hematological parameters of rats which were sacrificed shortly after the 10th exposure revealed an increase in the number of erythrocytes per unit volume of blood in the 0.03 and 0.1 mg/1 concentration groups and an increase in haemoglobin concentration in all the exposed groups. An increase in neutrophils also was seen for rats at the 0.1 mg/1 dosage level. Lactate dehydrogenase activity was reduced in the rats which were sacrificed immediately after the exposures to 0.1 mg/1 of the compound. No gross lesions or organ weight variations considered compound related were seen in rats sacrificed after 10 exposures and those sacrificed after a compound withdrawal period of 14 days. No microscopic pathological lesions which were considered compound related were seen in tissues other than the lungs of rats at the 0.01, 0.03 and 0.1 mg/1 exposure levels sacrificed after 10 exposures and after 14 days withdrawal. microscopically, the lung lesions considered compound related were very slight to slight, focal to multifocal interstitial pneumonia, very slight to slight aggregates of foamy macrophages in bronchiolar lumens, and very slight to slight multifocal hypertrophy and hyperplasia of type 2 alveolar cell, with occasional formation of alveolar giant cells (foreign body type).

In conclusion, rats exposed to dust atmospheres of pyromellitic dianhydride for 6 hours per day for a total of 10 exposures in 2 weeks (nominal: 0.01. 0.03 and 0.1mg/L; analysed: 0.021, 0.035 and 0.091 mg/L) exhibited symptoms directly related to the route of exposure, i.e. most effects were evident in the lungs.  The signs were indicative of local, direct effects in the lungs. PMDA is highly reactive and hydrolyses in contact with water or body fluids to the corresponding pyromellitic acid; PMDA is also a severe eye irritant. It is unsurprising that direct local effects in the lungs were observed. Other changes seen in this study were likely to be related to physiological stress because of the clinical signs induced via inhalation exposure to the dusts. Only the lungs showed any histopathological treatment related signs, importantly the signs seen were only slight to very slight.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

21 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliability 2

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the data available the substance is not classified or labelled according to Regulation 1272/2008/EC (CLP).

Regarding the inhalation study, the content of inhalable particles in the registered substance is very low. The particle size distribution of the test item was found to be [125μm; 1000μm]. Less than 10% of the test item is larger than 1 mm and more than 90% is larger than 125μm. The effects seen in the repeat dose inhalation study are suggestive local/direct upper respiratory tract irritation with no clear evidence of systemic effects. There is therefore no proposal to classify according to Regulation 1272/2008/EC (CLP).