Tetrahydromethylphthalic anhydride

Endpoint summary

Description of key information

Oral:
Oral LD50 values were >2000 mg/kg for rat. The major toxicity was squamous hyperplasia of the forestomach.

Dermal:
The acute dermal median lethal dose (LD50) of the test material, tetrahydromethylphthalic anhydride, in the Sprague-Dawley strain rat was found to be greater than 2000 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995-11-28 to 1997-06-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles river Japan
- Age at study initiation: purchase at 5 weeks old. Study is initiate at 6 weeks old
- Weight at study initiation: male 172.1-193.1g, female 125.4-139.9g
- Fasting period before study: from 17:00 on before day to after 3hr on dosing
- Housing:2-3 animals in polycarbonate cage with wood tip
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period:1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-26°C
- Humidity (%): 45-65%
- Air changes (per hr): 13 times/hr
- Photoperiod (hrs dark / hrs light): 12/12 AM07:00-PM07:00

Route of administration:

oral: gavage

Vehicle:

other: corn oil (10ml/kg)

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 5, 10 and 20 w/v% in vehicle
- Amount of vehicle: 10mL/kg
- Justification for choice of vehicle: Corn oil is generally used
- Lot/batch no.: V5P5523 Nakalai Tesque

MAXIMUM DOSE VOLUME APPLIED: 10mL/kg

CLASS METHOD
- Rationale for the selection of the starting dose: From results of prestudy (500, 1000 and 2000mg/kg p.o.). All animals did not die. at 2000mg/kg the body weight is decreased.

Doses:

0 (Vehicle), 500, 1000 and 2000 mg/kg/day (in corn oil)

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observation: more than one time/day. weighing: day 0, 2, 4, 6, 8, 11 and 15.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, organ weights, histopathology, other: histopathology: In representative case, histopathology observation was performed on stomach.

Statistics:

average and standard deviation (weight, per group)

Preliminary study:

From results of prestudy (500, 1000 and 2000 mg/kg bw p.o.). No mortality occured at 2000mg/kg, the body weights were decreased.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

No deaths prior to schedule termination.

Clinical signs:

other: Hypoactivity, bradypnea and prone position were observed in males and females of the 2000 mg/kg group on the day of administration.

Gross pathology:

At necropsy, thickening of the forestomach mucosa was observed in males and females of the 1000 and 2000 mg/kg group.
Adhesion of forestomach and liver was noted in one female of the 2000 mg/kg group.

Other findings:

Histopathology:
Squamous hyperplasia and granulomatous inflammation in submucosa of the forestomach were observed, and a squamous hyperplasia was also noted.
Squamous hyperplasia of the forestomach
1000mg/kg : male (2/5), female (1/5)
2000mg/kg : male (5/5), female (5/5)
(Squamous hyperplasia and granulomatous inflammation was observed in representative case of in males and females of the 1000 and 2000mg/kg group)
Adhesion of forestomach and liver and a foreign body granuloma in the adhesion area
2000mg/kg : female (1/5)

Interpretation of results:

GHS criteria not met

Conclusions:

Oral LD50 values were >2000 mg/kg for rat. The major toxicity was squamous hyperplasia of the forestomach.

Executive summary:

In this study, tetrahydromethylphthalic anhydride (MTHPA) was studied for oral toxicity in rats in a single dose toxicity test at doses of 0, 500, 1000 and 2000 mg/kg for both sexes. No deaths occurred of either males or females. Clinical signs of hypoactivity, bradypnea and prone position were observed in males and females of the 2000 mg/kg group on the day of administration. Decrease of body weights was observed in males of the 2000mg/kg group and suppression of body weight gain was observed in females of the 2000mg/kg group on the day of administration. At necropsy, thickening of the forestomach mucosa was observed in males and females of the 1000 and 2000 mg/kg groups most likely caused by the irritative properties of the test substance. Adhesion of forestomach and liver was noted in one female of the 2000 mg/kg group. Histopathologically, squamous hyperplasia and granulomatous inflammation in submucosa of the forestomach were observed in the 1000 and 2000 mg/kg groups. A foreign body granuloma in the adhesion area was also noted in the female of the 2000 mg/kg group. As the result, LD50 value was decided as >2000 mg/kg.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

GLP and guideline study

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 1993-08-04 to 1993-08-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

1981

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Version / remarks:

84/449/EEC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Five male and five female Sprague-Dawley strain rats were supplied by Charles River (UK) Ltd., Manston, Kent, U.K. At the start of the study the males weighed 234-255 g and the females 207-237 g, and were ten to fourteen weeks of age. After a minimal acclimatisation period of at least five days the animals were selected at random and given a unique number within the study by indelible ink marking on the tail and a number written on a cage card.
The animals were housed in suspended polypropylene cages furnished with softwood sawdust. The animals were housed individually during the 24-hour exposure period and in groups of up to five, by sex, for the remainder of the study. Free access to mains drinking water and food (Rat and Mouse Expanded Diet No. 1, Special Diet Services Limited, Witham, Essex, U.K.) was allowed throughout the study. The animal room was maintained at a temperature of 19-22°C and relative humidity of 50-56 %. The rate of air exchange was approximately 15 changes per hour and the lightening was controlled by a time switch to give 12 hours continuous light and 12 hours darkness.

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

On the day before treatment the back and flanks of each animal were clipped free of hair using veterinary clippers to expose a skin area of approximately 5 cm x 4 cm. The calculated volume (1.68 mL/kg) of the undiluted test material, as received, was applied uniformly to an area of shorn skin (approximately to 10 % of the total body surface area) using a graduated syringe. A piece of surgical gauze measuring 7 cm x 4 cm was placed over the treatment area and semioccluded with a piece of self-adhesive bandage (HYPERTIE). The bandage was further secured with a piece of BLENDERM wrapped around each end. The animals were caged individually for the 24-hour exposure period. Shortly after dosing the dressings were examined to ensure that they were securely in place. After the 24-hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with distilled water to remove any residual test material. The animals were returned to group housing for the remainder of the study period.

Duration of exposure:

24 h

Doses:

2000 mg/kg bw (1.68 mL/kg bw)

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

The animals were observed for deaths or overt signs of toxicity 0.5, 1, 2 and 4 hours after dosing and subsequently once daily for 14 days. The animals were also observed for any dermal reactions after removal of the dressings and subsequently once daily for the remainder of the study. Individual bodyweights were recorded prior to application of the test material on Day 0 and on Days 7 and 14.
At the end of the study the animals were killed by cervical dislocation and subjected to gross pathological examination. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Statistics:

Data evaluations included the relationship, if any, between the animals' exposure to the test material and the incidence and severity of all abnormalities including behavioural and clinical observations, gross lesions, bodyweight changes, mortality and any other toxicological effects.
Using the mortality data obtained, an estimate of the acute dermal median lethal dose (LD50) of the test material was made.

Preliminary study:

no preliminary study

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

There were no deaths.

Clinical signs:

other:

Gross pathology:

No abnormalities were noted at necropsy.

Other findings:

none

Interpretation of results:

GHS criteria not met

Conclusions:

The acute dermal median lethal dose (LD50) of the test material, tetrahydromethylphthalic anhydride, in the Sprague-Dawley strain rat was found to be greater than 2000 mg/kg bw.

Executive summary:

The study was performed to assess the acute dermal toxicity of the test material in the Sprague-Dawley strain rat. The method used followed that described in the OECD Guidelines for Testing of Chemicals (1981) No. 402 "Acute Dermal Toxicity" referenced as Method B.3 in Commission Directive 84/449/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

A group of ten animals (five males and five females) was given a single 24-hour, semi-occluded dermal application to intact skin at a dose level of 2000 mg/kg bw. The animals were observed for fourteen days after the day of treatment and were then killed for gross pathological examination.

There were no deaths. No signs of systemic toxicity were noted during the study. Very slight to well-defined erythema was noted at the treatment sites of all animals. Other skin reactions noted were haemorrhage of the dermal capillaries and crust formation. Treatment sites appeared normal two to five days after dosing. All animals showed expected gain in bodyweight during the study. No abnormalities were noted at necropsy.

The acute dermal median lethal dose (LD50) of the test material in the Sprague-Dawley strain rat was found to be greater than 2000 mg/kg bodyweight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

2 000 mg/kg bw

Quality of whole database:

GLP and guideline study

Additional information

Oral:

Different studies were available investigating acute oral toxicity of tetrahydromethylphthalic anhydride (MTHPA). The study by Furukawa (1997) was chosen as key study, as this is the only study which was conducted according to a Guideline (OECD 401) and GLP. LD50 values of the supporting studies are in the same concentration range as the key study (some slightly below) but are regarded as less reliable than the key study.

 

In the key study (Furukawa, 1997), MTHPA was studied for oral toxicity in rats in a single dose toxicity test at doses of 0, 500, 1000 and 2000 mg/kg for both sexes. No deaths occurred of either males or females. Clinical signs of hypoactivity, bradypnea and prone position were observed in males and females of the 2000 mg/kg group on the day of administration. Decrease of body weights was observed in males of the 2000mg/kg group and suppression of body weight gain was observed in females of the 2000mg/kg group on the day of administration. At necropsy, thickening of the forestomach mucosal was observed in males and females of the 1000 and 2000 mg/kg groups. Adhesion of forestomach and liver was noted in one female of the 2000 mg/kg group. Histopathologically, squamous hyperplasia and granulomatous inflammation in submucosal of the forestomach were observed in the 1000 and 2000 mg/kg groups. A foreign body granuloma in the adhesion area was also noted in the female of the 2000 mg/kg group. As the result, LD50 value was decided as >2000 mg/kg.

 

In a supporting acute oral toxicity study (Irie, 1969a), groups of T23-48:Donryu rats (6/sex) were given a single oral dose of MTHPA in olive oil at doses of 1160, 1390, 1660, 2000 and 2400 mg/kg bw and observed for 7 days.

Oral LD50 = 2102 mg/kg bw

 

In a supporting acute oral toxicity study (Irie, 1969b), groups of dd mice (10/sex) were given a single oral dose of MTHPA in olive oil at doses of 920, 1100, 1330, 1590, 1900, 2280, 2720 mg/kg bw and observed for 7 days.

Oral LD50 = 1707 mg/kg bw

 

In a supporting acute oral toxicity study (Sheena, 1980), groups of Crj: CD(SD) rats (105/sex) were given a single oral dose of MTHPA in olive oil at doses of 1000, 1600, 2000, 3200, 5000 and 6400 mg/kg bw and observed for 14 days.

Oral LD50 = 1900 mg/kg bw (1600-2900 mg/kg bw)

 

In a supporting acute oral toxicity study, groups of rats were given a single oral dose of MTHPA.

Oral LD50 = 25894 mg/kg bw

 

Dermal:

In the key study (Allen (1993), the acute dermal toxicity of the test material in the Sprague-Dawley strain rat was assessed. The method used followed that described in the OECD Guidelines for Testing of Chemicals (1981) No. 402 "Acute Dermal Toxicity" referenced as Method B.3 in Commission Directive 84/449/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

A group of ten animals (five males and five females) was given a single 24-hour, semi-occluded dermal application to intact skin at a dose level of 2000 mg/kg bw. The animals were observed for fourteen days after the day of treatment and were then killed for gross pathological examination.

There were no deaths. No signs of systemic toxicity were noted during the study. Very slight to well-defined erythema was noted at the

treatment sites of all animals. Other skin reactions noted were haemorrhage of the dermal capillaries and crust formation. Treatment sites appeared normal two to five days after dosing. All animals showed expected gain in bodyweight during the study. No abnormalities were noted at necropsy.

The acute dermal median lethal dose (LD50) of the test material in the Sprague-Dawley strain rat was found to be greater than 2000 mg/kg bodyweight.

 

In a supporting acute dermal toxicity study (Irie, 1969), Belgian Hare rabbits (1/dose) were dermally exposed to MTHPA either to a single dose of 242 and 1210 mg/kg bw (0.4 and 2 mL application volume) or daily for 3 days to a dose of 242 mg/kg bw/day (0.4 mL application volume). Animals then were observed for 14 days.

No mortality was observed. Incrustation was observed after 3 days when applied continuously.

Dermal LD50 > 1210 mg/kg bw (single dose)

Dermal LD50 > 242 mg/kg bw (continuous dosing over 3 days)

 

In a second, poorly documented supporting study by Smyth (1969), the LD50 in rabbits after dermal administration of MTHPA was determined to be 1706 mg/kg bw (single dose).

Justification for selection of acute toxicity – oral endpoint
GLP and guideline study

Justification for selection of acute toxicity – dermal endpoint
GLP and guideline study

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008
The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008.

 

Oral toxicity

Based on available data on acute toxicity, the test item does not need to be classified for acute oral toxicity according to Regulation (EC) No 1272/2008 (CLP), as amended for the eighteenth time in Regulation (EU) 2022/692.

 

Dermal toxicity

Based on available data on acute toxicity, the test item does not need to be classified for acute dermal toxicity as Acute Tox. 2 (H310) according to Regulation (EC) No 1272/2008 (CLP), as amended for the eighteenth time in Regulation (EU) 2022/692.