Diallyl isophthalate

Endpoint summary

Description of key information

Information is only available for repeated oral dose toxicity. No data is available for dermal toxicity or toxicity through inhalation.

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:

experimental study

Adequacy of study:

key study

Study period:

21 July- 17 October 1977

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

ANALOGUE APPROACH JUSTIFICATION
Please refer to attached document.]

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

Diallylphthalate was administered by gavage to groups of rats for 13 weeks to evaluate the cumulative toxicity of diallylphthalate, characterize lesions and to determine the doses to be used in a 2-year study.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Center
- Age at study initiation: 8 wk old
- Housing: 5 animals per cage; cages Polycarbonate (Lab Products. Garfield, NJ. and Hazleton Systems, Aberdeen, MD)
- Diet:Purina Lab Chow@ (ground); provided ad libitum except for night before dosing when feed was removed from cages (Ralston Purina Co., St. Louis, MO)
- Water (e.g. ad libitum):Tap water in bottles, acidified to pH 2.5 with HCl; provided ad libitum
- Acclimation period: 4 wk

ANIMAL DISTRIBUTION
Randomized so that the average cage weights for each sex and species were approximately equal

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23
- Humidity (%): 30-70
- Air changes (per hr): 12-15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: necropsy date: 18 October 1977

Route of administration:

oral: gavage

Vehicle:

corn oil

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses for diallylphthalate in the dosing solutions were performed periodically to confirm that the correct doses were administered. The analyses involved extraction of the test chemical from corn oil using carbon disulfide followed by gas chromatography. One set of dose mixtures prepared for the 13-week studies was analyzed and found to be within 10% of their target concentrations.

Duration of treatment / exposure:

13 wk

Frequency of treatment:

5 times/wk

Remarks:

Doses / Concentrations:
0, 25, 50, 100, 200 & 400 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

Dose volume: 3.33 ml/kg

Positive control:

Not applicable

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice a day on working days and once a day on weekends

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

Sacrifice and pathology:

SACRIFICE:
Moribund animals and survivors (fasted overnight) at the end of the 13-week studies were killed by carbon dioxide asphyxiation.

GROSS PATHOLOGY: Yes, necropsies on all animals

HISTOPATHOLOGY:

all groups except 25 mg/kg bw:
kidneys, liver and colon

vehicle control group + 400 mg/kg bw group:
mandibular lymph node, salivary gland, sternebrae (including marrow), thyroid gland, parathyroids, colon, small intestine, prostate/testes or ovarieduterus, lungs and bronchi, heart, esophagus, stomach, brain, thymus, trachea, pancreas, spleen, pituitary gland, eyes (if grossly abnormal), mammary gland, gross lesions, urinary bladder, and adrenal glands

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY
400 mg/kg and less frequently at 200 mg/kg.: diarrhea, rough hair coat or alopecia around the head, hunched posture, general emaciation
No clinical signs were observed in lower dose groups.
400 mg/kg male: 6/10 dead + 2 in a moribund condition

BODY WEIGHT AND WEIGHT GAIN
400 mg/kg male: mean body weight gain depressed

FEED CONSUMPTION
Feed consumption was lower in the 400 mg/kg groups of both sexes than in other groups for weeks 1-3 of study but matched or exceeded the feed consumption for vehicle control groups thereafter.

GROSS PATHOLOGY
400 mg/kg for all males: gross abnormalities of the liver in the 8 dead male rats: enlarged, mottled and pale livers, with rough, granular or pitted surface texture; darkened or bright red lungs.
200 mg/kg for 5/10 males:similar liver lesions as at 400 mg/kg with dose related severity
400 mg/kg for most but not all females: similar liver lesions as for males + abnormal coloration of the kidneys

HISTOPATHOLOGY:
400 mg/kg for males that died during the study: acute, necrotizing colitis characterized by the loss of surface and glandular epithelium, mucosal and submucosal edema, acute inflammatory cell infiltration, three males exhibited multifocal renal cortical tubular necrosis ;
200 & 400 mg/kg for both sexes: periportal hepatocellular necrosis and fibrosis, bile duct hyperplasia, hepatocellular nodular hyperplasia;
Hepatocellular alterations in the periportal region were observed with decreasing frequency and severity at doses as low as 50 mg/kg (males) or 100 mg/kg (females): hepatocellular basophilia, cellular and nuclear hypertrophy, nuclear hyperchromatism.

Dose descriptor:

LOEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: clinical signs; gross pathology; histopathology: periportal hepatocellular necrosis and fibrosis, bile duct hyperplasia, hepatocellular nodular hyperplasia

Dose descriptor:

LOEL

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: histopathology: hepatocellular basophilia, cellular and nuclear hypertrophy, nuclear hyperchromatism

Dose descriptor:

LOAEL

Effect level:

50 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: histopathology: hepatocellular basophilia, cellular and nuclear hypertrophy, nuclear hyperchromatism

Dose descriptor:

NOAEL

Effect level:

25 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: histopathology: hepatocellular basophilia, cellular and nuclear hypertrophy, nuclear hyperchromatism

Critical effects observed:

not specified

TABLE: Survival and mean body weights of rats in the thirteen-week repeated-administration gavage studies of diallylphthalate

Dose	Survival	Mean body weights (grams)
		Initial	Final	Change
MALE
0	10/10	186	311	125
25	10/10	185	321	136
50	10/10	189	322	133
100	10/10	188	312	124
200	10/10	186	303	117
400	2/10	184	273	89
FEMALE
0	10/10	134	192	58
25	10/10	133	202	69
50	10/10	134	197	63
100	10/10	135	199	64
200	10/10	133	197	64
400	10/10	134	191	57

 

 

Conclusions:

More than 50% mortality was observed at 400 mg/kg bw in males (LD50 between 200 and 400 mg/kg bw), whereas no mortality occurred among females (LD50 > 400 mg/kg bw). Comparing these results with the acute (LD50=656-891 mg/kg bw) and 14-day study (LD50=350 mg/kg bw), sub-chronic exposure did not decrease the LD50 significantly.
The liver was the primary target organ in this study with dose related histopathological effects at and above 50 mg/kg bw for males and 100 mg/kg bw for females.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

subchronic

Species:

rat

System:

hepatobiliary

Organ:

liver

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

Evaluation of the key value for repeated oral dose toxicity is based on a series of studies in rats. Studies with mice have also been added, but these show a higher tolerance for oral DAP exposure compared to rats. In rats, the liver appeared to be the primary target organ with changes observed at and above 50 mg/kg/day for males and 100 mg/kg/day for females in the 90-day study. However, the features identified in the subchronic oral rat study at 50 mg/kg/day were termed "hepatocellular alterations characterised by hepatocellular basophillia, cellular and nuclear hypertrophy and nuclear hyperchromatism". There were only mild alterations at 100 mg/kg/day and the 25 mg/kg/day histopathological examination was not performed because of the "absence (or presence of only minimal) hepatic changes at 50 mg/kg/day". The description in the study report of a low incidence of minimal (or absent) hepatic changes confirms the identification of the NOAEL at 50 mg/kg/day.

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver

Justification for classification or non-classification

Specific Target Organ Toxicity: Repeated. STOT-RE is assigned on the basis of findings of ‘significant’ or ‘severe’ toxicity. In this context ‘significant’ (Category 2) means changes which clearly indicate functional disturbance or morphological changes which are toxicologically relevant. ‘Severe’ (Category 1) effects are generally more profound or serious than ‘significant’ effects and are of a considerably adverse nature which significantly impact on health. Both factors have to be evaluated by weight of evidence and expert judgement. Classification in Category 2 is applicable when significant toxic effects observed in a 90-day repeated-dose study conducted in experimental animals are seen to occur within guidance value ranges which are presented in the "Guidance on the Application of the CLP Criteria" Page 482 (noting that these are guidance values intended for guidance purposes). For a 90 day study significant effects are seen at dose levels between 10 and 100 mg/kg/day. In the results of the key study, described above, an NOAEL of 50 mg/kg/day has been selected (on the basis of the absence of or minimal hepatic changes) and the alterations at 100 mg/kg/day are described as mild. Consequently, the changes described are not considered to be significant (changes which clearly indicate functional disturbance or morphological changes which are toxicologically relevant) and therefore a classification of STOT Repeated Exposure Category 1 or 2 is not justified.