Benzophenone-3,3':4,4'-tetracarboxylic dianhydride

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: experimental result in a reliable toxicology laboratory, preceding establishment of guideline and GLP. Documentation is limited.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

no notation of adjuvant; challenge exposure was administered via intradermal injection.

GLP compliance:

no

Remarks:

precedes establishment of GLP

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The described guinea pig sensitisation test similar to OECD 406 was conducted in 1977 before the guidance for the LLNA (OECD429, first adopted in 2002) was available, and before the method was fully established and validated. And since the result of the non-LLNA test is considered to be scientifically valid, the test was not repeated also taking into account exposure and animal welfare considerations.

Species:

guinea pig

Strain:

not specified

Sex:

not specified

Details on test animals and environmental conditions:

no data

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.4 mg over 8 administrations, 0.1% solution (w/v) of BTDA crystalline powder in normal saline.

Day(s)/duration:

every other day

Adequacy of induction:

not specified

No.:

#1

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.4 mg over 8 administrations, 0.1% solution (w/v) of BTDA crystalline powder in normal saline.

Adequacy of challenge:

not specified

No. of animals per dose:

36

Details on study design:

The study was undertaken with unwashed, commercial grade BTDA, and also with BTDA washed with acetone. Eighteen guinea pigs received intradermal injections (0.05 ml of 0.1% BTDA unwashed w/v in saline, without adjuvant) every other day for 8 injections. They were allowed a rest period of 3 weeks, after which they received a single challenge dose by intradermal injection. The experiment was repeated with BTDA purified by washing in acetone.

Positive control substance(s):

not specified

Key result

Reading:

1st reading

Group:

other: unwashed BTDA

Dose level:

0.1%

No. with + reactions:

15

Total no. in group:

18

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Group:

other: acetone-washed BTDA

Dose level:

0.1%

No. with + reactions:

17

Total no. in group:

18

Remarks on result:

positive indication of skin sensitisation

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

1,3-Isobenzofurandione, 5,5'-carbonylbis- (BTDA) was purified by washing in acetone, and commercial-grade (unwashed) and purified BTDA was tested in a non-LLNA skin sensitisation test in guinea pigs. Both the unwashed and washed substance were found to be sensitising in the guinea pig.

Reference 2

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: experimental study, precedes establishment of guideline and GLP. Documentation is limited.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

no notation of adjuvant; challenge exposure was administered via intradermal injection.

GLP compliance:

no

Remarks:

preceeds establishment of guideline and GLP

Type of study:

guinea pig maximisation test

Species:

guinea pig

Strain:

not specified

Sex:

not specified

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.95 mg administered in 0.05 ml (first injection)/ 0.1ml (following injections) of 0.1% BTDA in buffered saline

Day(s)/duration:

any other day

Adequacy of induction:

not specified

No.:

#1

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.05 mg administered in 0.05 ml of 0.1% BTDA in buffered saline.

Adequacy of challenge:

not specified

No. of animals per dose:

8

Details on study design:

Eight guinea pigs received intradermal injections (0.05 ml of 0.1% BTDA on the first and 0.1 ml on following days, without adjuvant) every other day for 10 injections. They were allowed a rest period of 2 weeks, after which they received a single challenge dose by intradermal injection. Reactions were assessed at 24 and 48 hours after the challenge dose.

Positive control substance(s):

not specified

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.1%

No. with + reactions:

6

Total no. in group:

7

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.1%

No. with + reactions:

6

Total no. in group:

7

Remarks on result:

positive indication of skin sensitisation

As study progressed, skin reaction (wheal and flare) to sensitizing dose as well as control occurred.

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

1,3-Isobenzofurandione, 5,5'-carbonylbis- (BTDA) was solubilized in saline and tested for dermal sensitisation in a non-LLNA protocol in guinea pigs. After repeated intradermal injections, the animals were challenged with an intradermal injection. Six of seven animals displayed signs of sensitisation.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The substance was tested in several in vivo assays (non-LLNA protocol in guinea pigs) and found to be sensitising when given as an intradermal injection during the induction and challenging phases.

Respiratory sensitisation

Link to relevant study records

Reference

Endpoint:

respiratory sensitisation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable study with restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

One of three groups of rats was exposed (whole body) to aerosol containing the test material for 6 hours/day for 5 days. Following a 3-week rest period, the exposed rats and the 2 other groups were challenged with aerosol containing the test material for one period of 6 hours. The animals were sacrificed and lungs were examined. Specific IgG was measured in serum.

GLP compliance:

not specified

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, MI.
- Age at study initiation: 7 weeks
- Weight at study initiation:
- Housing: stainless steel cages 15.8 x 15.5 x 17.0 cm, suspended over excrement pans fitted with deodorizing cage boards.
- Diet (e.g. ad libitum): Purina Rodent Chow 5001 (Ralston Purina Co., St. Louis, MO) ad libitum
- Water (e.g. ad libitum): reverse-osmosis purified, ad libitum
- Acclimation period: 6 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 40
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: July 20, 1988 To: Sept. 29, 1988

Route of induction exposure:

inhalation

Remarks:

whole body

Route of challenge exposure:

inhalation

Vehicle:

other: Air filtered through HEPA filters

Concentration:

50 µg/m3

No. of animals per dose:

20; 10 males and 10 females

Details on study design:

MAIN STUDY
A. INDUCTION EXPOSURE: whole body exposure
- No. of exposures: 5
- Exposure period: 6 hours
- Test groups: 1
- Control group: 2
- Frequency of applications: once daily
- Duration: 6 hours
- Concentrations: 50 microgram/m3

B. CHALLENGE EXPOSURE: whole body exposure
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: 6 hours
- Test groups: 2
- Control group: 1
- Concentrations: 50 microgram/m3
- Evaluation (hr after challenge): 18

Rats were observed for morbidity and mortality twice daily on weekdays (once daily on weekends and holidays). Physical examinations were performed once prior to study initiation. Clinical observations were performed daily on weekdays during the exposure phase of the study and weekly thereafter. Body weights were measured at the initiation of the study, weekly thereafter and at the termination of the study immediately prior to sacrifice.
Test rats were fasted for appoximately 18 h following the challenge exposure and anesthetized with sodium pentobarbital. Blood samples were obtained from the femoral artery of each rat just prior to the scheduled necropsy.
Gross necropsies were performed on all rats. The lungs were removed, trimmed of excess adherent tissue, weighed and examined for external hemorrhagic foci. Lung volume was determined by liquid displacement. The lungs were perfused with 10% neutral buffered formalin and collected.

Challenge controls:

1 group of 10 animals which did not receive exposure to the test material in the induction test or the challenge test.

Positive control substance(s):

none

Negative control substance(s):

none

Results:

The analytical concentrations of BTDA ranged from 20.4 to 73.5 µg/m3 during the 5 exposures and from 33.2 to 52.5 µg/m3 during the challenge exposure. The time-weighted average was 47.0 and 53.2 µg/m3 for the two scenarios. The average particle size was 2.01 microns with 99.8% of the particles being equal to or less than 10 microns in size. No test article was detected in the filtered air control chamber at any time during the study.
No deaths of animals occurred in any group. No significant clinical signs were noted in any rat during the study. There were no statistically significant effects of treatment on body weight during the study.
Small numbers of lung foci (< 10) were noted in rats of all groups and were more prevalent in males than females. Statistically, there was no significant difference in the number of lung foci between the BTDA-exposed and control rats. There were no statistically significant effects of treatment on either absolute or relative lung weights and volume.
Serum BTDA-specific IgG antibody levels were statistically significantly increased in the BTDA-exposed males and combined males/females. However, antibody levels in three of the FAC/nonchallenged females were also elevated, for unknown reasons.

Table 1: Summary of Chamber Concentrations

	5 Exposures		Challenge
	Filtered Air Control (FAC)	BTDA	Filtered Air Control (FAC)	BTDA
Target concentration (µg/m^3)	0	50	0	50
Analytical concentration (µg/m^3)
Mean ± SD	-	47.8 ± 5.7	-	43.8 ± 9.8
Min/Max	-	20.4/73.5	-	33.2/52.5
TWA	-	47.0	-	43.2

Means and standard deviations were calculated. Data were log-transformed and analyzed using multivariate and univariate two-factor ANOVA. If significant main effects were seen, Dunnett's Test (1955) was conducted. Body weights were evaluated using multivariate repeated-measures ANOVA to determine the shape of the dose-response relationship over time (Bock, 1975). All analyses were performed on a PC using SYSTAT Software (1986). A minimum significance level of p < 0.05 was used in all comparisons. Table 2: Respiratory Screen of BTDA in Rats

Group	Lung Foci	IgG Antibody
Males
BTDA	5 ± 5.1	0.313 ± 0.21*
Filtered Air control/challenged	1 ± 0.8	0.085 ± 0.05
Filtered Air control/unchallenged	1 ± 1.6	0.080 ± 0.04
Females
BTDA	1 ± 2.1	0.352 ± 0.41
Filtered Air control/challenged	2 ± 2.3	0.108 ± 0.05
Filtered Air control/unchallenged	1 ± 0.7	0.186 ± 0.17
Combined Male and Female
BTDA	3 ± 4.3	0.333 ± 0.32*
Filtered Air control/challenged	1 ± 1.8	0.096 ± 0.05
Filtered Air control/unchallenged	1 ± 1.3	0.133 ± 0.13

Interpretation of results:

other: Inconclusive, not sufficient for classification

Conclusions:

1,3-Isobenzofurandione, 5,5'-carbonylbis- (BTDA) was tested in an in vivo respiratory sensitisation experiment with male and female CD rats at aerosol concentrations (whole body) of 50 µg/m3, 6 hours/day for 5 days. No deaths occurred and there were no statistically significant clinical or histopathological findings. While elevated levels of serum IgG, specific to BTDA, were found in exposed rats compared with filtered air-exposed control, this was also found in several control animals. There was no difference in the number of lung foci between exposed and control rats, nor between antibody levels and lung foci. BTDA cannot conclusively be considered as sensitising under the conditions of this study.

Executive summary:

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

1,3-Isobenzofurandione, 5,5'-carbonylbis- (BTDA) is a skin sensitiser according to established animal models.

Several older studies with BTDA have been conducted to investigate the hazard of respiratory sensitisation. In a 1989 study by Andresen, rats were exposed (whole body) to 5 days of airborne BTDA (55 µg/m3, 2.0 µmeters diameter particles). There were no adverse effects of treatment in the number of lung foci, body weight or lung weight or volume.  There was a statistically significant increase in BTDA-specific IgG in males only; antibody levels in three of the nonchallenged female controls were also elevated for unknown reasons.  Immediate-response antibodies (IgE) were not measured. As whole body exposure was performed, skin sensitization cannot be excluded as the reason for increased IgG levels. There was no correlation between antibody levels and lung foci; animals exhibiting the highest number of lung foci did not, in most cases, have the highest levels of serum antibody. There were no other associated changes which would be indicative of an immunologic response due to respiratory sensitization (i.e. Increases in absolute and relative lung weight and volume). There is insufficient evidence to conclude that BTDA results in respiratory sensitisation.

BTDA was tested in guinea pigs in a sensitisation protocol involving intradermal injections (0.4 mg total) followed by a single intratracheal challenge dose (1.0 ml of 0.4% suspension in normal saline) of BTDA. Animals showed an immediate lacrimation reaction and redness of scleral vessels of the eyes, and jumping and jerky movements.  When tissue was examined, there was evidence of granulomatous reaction in the lung and skin. 

Guinea pigs were exposed to BTDA dust (135 to 251 mg/m³, 6 hours per day for 14 days, whole body), and after a two-week rest period, were challenged with an additional chamber exposure. Treatment resulted in moderate chronic pneumonitis with one animal showing hyperplasia of mediastinal lymph nodes and severe granulomatous pneumonia. 

These studies are confounded by old study design including the potential for dermal sensitisation as the protocol was as whole body exposure. Pneumonitis and granulomatous reactions can be the result of particle exposure to the lung, and are not of themselves immunological events. Statistical evaluation of selected parameters (specific Ig G levels) does not support the conclusion that BTDA is a respiratory sensitiser. 

There is insufficient evidence to classify BTDA is a respiratory sensitiser. Current labeling as a STOT-SE for respiratory irritation will inform workers of hazard, and risk management measures are designed to minimize exposure of workers to BTDA dust exposure.

Migrated from Short description of key information:
In a 1989 study, rats were exposed (whole body) to 5 days of airborne BTDA (55 µg/m3) with the result of no significant adverse effects in lungs. There was no increase in BTDA-specific IgG. Guinea pigs which were sensitised with repeated intradermal injections of BTDA demonstrated a granulomatous reaction in lungs after a challenge insufflation administration of BTDA. In another older experiment, guinea pigs repeatedly exposed to BTDA dust showed lung granulomatous reactions and lymph node hyperplasia.

Justification for selection of respiratory sensitisation endpoint:
Experimental results

Justification for classification or non-classification

1 -3,-Isobenzofurandione, 5,5 -carbonylbis- (BTDA) has been shown experimentally to result in dermal sensitisation. There is insufficient evidence to classify BTDA is a respiratory sensitiser. The substance is classified as a dermal sensitiser according to Regulation EC No. 1272/2008.