Isophthaloyl dichloride

Endpoint summary

Description of key information

Oral: NOAEL; OECD 408; 90-day rat; feed; small increases in the incidence of crystalluria and renal pathology (mild hydronephrosis and pelvic calcification) were observed in the two higher dose groups (≥ 1405 mg/kg bw/day); reliability = 2. [CAS# 121-91-5]

Dermal: Testing has been waived due to exposure considerations.

Inhalation: Testing has been waived due to exposure considerations.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

The test substance rapidly hydrolyses to isophthalic acid (IPA). Therefore, the study with IPA is being used to fulfil this data requirement. Additional documentation, provided within the IUCLID Assessment Reports section, supports the read-across approach.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

GLP compliance:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:
- Age at study initiation: 28 days
- Weight at study initiation:
- Fasting period before study:
- Housing:
- Diet (e.g. ad libitum):
- Water (e.g. ad libitum):
- Acclimation period:


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

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): diets were prepared biweekly
- Mixing appropriate amounts with (Type of food): normal diet (Purina Laboratory Chow)

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

daily

Dose / conc.:

0.5 other: %

Remarks:

nominal in diet

Dose / conc.:

1.6 other: %

Remarks:

nominal in diet

Dose / conc.:

5 other: %

Remarks:

nominal in diet (changed to 3% after first week into study)

No. of animals per sex per dose:

450 rats total, 25 males and 25 females in both control groups, the remainder equally distributed across test groups.

Control animals:

yes, concurrent vehicle

Details on study design:

Following the first week of the study the weight gains of the rats were examined. It was concluded that the 5% dose level would not permit growth. Therefore the high dose was reduced to 3%.

Animals were housed individually in mesh-bottom cages and supplied with food and fresh tap water ad libitum.

Positive control:

Terephthalic acid (5% in diet through week 1, and 3% in diet from week 2 to termination)

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- All animals were observed for any deviations from normal appearance or behavior which would indicate an adverse effect of the treatments.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes / No / No data
- Time schedule for examinations:

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to administration of the test substance on days 30, 60, and 90
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 5 males and 5 females
- Determinations: total erythrocytes, hemoglobin, hematocrit, total and differential leukocyte counts (see Table 1)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to administration of the test substance on days 30, 60, and 90
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 5 males and 5 females
- Determinations: blood urea nitrogen, blood glucose, serum alkaline phosphatase, serum glutamic pyruvic transaminase (SGPT)

URINALYSIS: Yes
- Time schedule for collection of urine: prior to administration of the test substance on days 30, 60, and 90
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- How many animals: 5 males and 5 females
- Determinations: pH, specific gravity, qualitative tests for albumin, glucose, ketones, occult blood, microscopic examination of the centrifuged sediment

NEUROBEHAVIOURAL EXAMINATION: No

OTHER:
DETERMINATION OF PHTHALATES: Yes
- Time schedule for collection of blood and urine: after administration of the test substance on days 7, 30, 60, and 90
- Metabolism cages used for collection of urine: Yes, for 24 hours prior to sacrifice
- Blood collection: blood was obtained by cardiac puncture at autopsy
- How many animals: 5 rats per sex per group (7th and 90th days); 3 rats per sex per group (30th and 60th days)
- Blood preparation: Prior to analysis, blood samples were diluted with twice the volume of distilled water and the pH adjusted to 9.5 with NaOH. After complete hemolysis of the cells, the sample was dehydrated from the frozen state to provide a stable storage form until analysis could be completed.
- Urine preparation: Urine samples were also adjusted to pH 9.5 and freeze-dried.
- Determinations: Total phthalate content of the blood and urine
- Method of determination: gas chromatographic method

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

After 30 and 60 days on test, 3 animals per sex per group were terminated and gross pathological examinations were performed. At 90 days of the study, all surviving animals were euthanized and submitted to detailed necropsies. The following organs were weighed: liver, spleen, kidneys, heart, brain, gonads, adrenals, thyroid, and pituitary. Subsequently, the organ to body weight and organ to brain weight ratios were calculated. Microscopic examinations were performed on the liver, spleen, stomach, small intestine, large intestine, pancreas, kidneys, ureters, urinary bladder, adrenals, gonads, thyroids, pituitary, thymus, salivary gland, lymph nodes, heart, lungs, bone marrow, skin, skeletal muscle, and brain from 3 animals per sex per group at 30 and 60 days of the study and from 5 animals per sex per group after the 90-day examination. For the 60 and 90-day examinationsm thymus, salivary gland, and lymph nodes were deleted from the histopathological studies. In addition, histopathological examinations were made of the bladders of all animals sacrificed terminally as well as any tissues which appeared to be grossly abnormal at time of autopsy.

Statistics:

descriptive

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Examination of the weight gains of all rats at the end of the first week made it appear unlikely that the 5% level would permit growth or even survival of rats fed the test substance. Therefore, the highest administered dietary level was changed to 3% starting at the begin ning of the second week of the study. The 1.6% dietary level represented a "no-effect" level in terms of growth.

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):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Microscopic sediment showed evidence of red blood cells in the urine. The incidence appeared to be somewhat higher among the male animals tham among the female animals. In addition, crystals apparently similar to the test substance was found in all groups of animals. On the basis of these data, it is evident that the only clinical observations which may be correlated with the occurrence of the reported pathology was that of hematuria or crystalluria.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Increased incidence of renal and urinary bladder calculi only after 90 days on study. Grossly, the stones occurred almost exclusively in the bladder. They ranged in color from off-white to dark brown and in size from fine sand to stones several millimeters in diameter. It appeared that the calculus formation was a relatively slow process and that it increased in frequency as the dose level increased.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Mild to moderate hyperplasia in kidneys in highest dosage level.

Histopathological findings: neoplastic:

no effects observed

Details on results:

BLOOD LEVELS OF TEST SUBSTANCE: There was a correlation with the dose level and blood concentration. At the low and middle dose levels, blood values of the test substance remained fairly constant or tended to decrease. At the highest dosage level, the test substance tended to decrease in blood (with a concurrent increase in urine output). At the moderate levels of intake, the test substance achieved a steady state or equilibrium condition with respect to metabolism and/or excretion.

URINE LEVELS OF TEST SUBSTANCE: There was a correlation with the dose level and urine concentration. At the low and middle dose levels, urinary values of the test substance remained constant or tended to increase. At the highest dosage level, the test substance tended to increase in urine output (with a concurrent decrease in blood). At the moderate levels of intake, the test substance achieved a steady state or equilibrium condition with respect to metabolism and/or excretion.

Dose descriptor:

NOAEL

Effect level:

447 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Dose descriptor:

NOAEL

Effect level:

474 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Critical effects observed:

no

System:

urinary

Organ:

kidney

Table 1: Toxic Response/Effects by Dose Level

	Incidence
Approximate Dose (% in diet)	Renal Pathology		Crystalluria*
	Male	Female	Male	Female
0	1/25	4/25	0/5	0/5
0.5	1/25	5/25	0/5	0/5
1.6	5/25	4/25	1/5	2/5
5 (wk 1); 3 (remainder of study)	4/25	7/25	3/5	3/5

* Only five animals per test group were evaluated for crystalluria.

Conclusions:

No adverse responses associated with the ingestion of the test substance on total or differential leukocyte counts, total erythrocyte counts, hemoglobin, or hematocrit levels were noted. In addition, no adverse effects were noted on blood urea nitrogen, fasting blood glucose, serum glutamic pyrumic transaminase, or serum alkaline phophatase levels. Examination of organs at necropsy revealed no effect of treatment. This study identifies a NOAEL of 0.5% (calculated as 447 mg/kg-day in males and 474 mg/kg-day in females) and a LOAEL of 1.6% (calculated as 1405 mg/kg-day for males and 1598 mg/kg-day for females) based on a small increase in the incidence of kidney effects and crystalluria.

Executive summary:

Male and female rats were fed daily for 13 weeks at levels of 0.5, 1.6, and 5% of the test substance in the diet. Following the first week of the study the weight gains of the rats were examined. It was concluded that the 5% dose level would not permit growth. Therefore the high dose was reduced to 3%. No adverse responses associated with the ingestion of test substance on total or differential leukocyte counts, total erythrocyte counts, hemoglobin, or hematocrit levels were noted. In addition, no adverse effects were noted on blood urea nitrogen, fasting blood glucose, serum glutamic pyrumic transaminase, or serum alkaline phophatase levels. Examination of organs at necropsy revealed mild to moderate hyperplasia in kidneys in the highest dosage level. This study identifies a NOAEL of 0.5% (calculated as 447 mg/kg-day for males and 474 mg/kg-day for females) and a LOAEL of 1.6% (calculated as 1405 mg/kg-day for males and 1598 mg/kg-day for females) based on a small increase in the incidence of kidney effects and crystalluria.

Endpoint conclusion

Dose descriptor:

NOAEL

447 mg/kg bw/day

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

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

Additional information

This study was used for derivation of the long term systemic DNEL.

Male and female rats were fed daily for 13 weeks at levels of 0.5, 1.6, and 5% of the test substance in the diet. Following the first week of the study the weight gains of the rats were examined. It was concluded that the 5% dose level would not permit growth. Therefore the high dose was reduced to 3%. No adverse responses associated with the ingestion of test substance on total or differential leukocyte counts, total erythrocyte counts, haemoglobin, or haematocrit levels were noted. In addition, no adverse effects were noted on blood urea nitrogen, fasting blood glucose, serum glutamic pyrumic transaminase, or serum alkaline phophatase levels. An increase in crystalluria was observed. Examination of organs at necropsy revealed mild to moderate hyperplasia in kidneys in the highest dosage level. Based on this information, the 90 -day rat oral NOAEL was identified as 447 mg/kg-day for males and 474 mg/kg-day for females.

Repeated dose toxicity: via oral route - systemic effects (target organ) urogenital: kidneys

Justification for classification or non-classification

Based on results of repeated oral studies, the substance does not need to be classified for repeated dose toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.