Diisononyl adipate

Carcinogenicity

Description of key information

No data were available on DINA. Therefore, data on the structural analogue diethylhexyl adipate (DEHA) were used.

In a carcinogenicity study (103 weeks), DEHA was administered to F344 rats and B6C3F1 mice in the diet at levels of 12 000 or 25 000 ppm, equivalent to a daily intake of 600 or 1250 mg/kg bw/day in rats and 1715 and 3570 mg/kg bw/day in mice. DEHA is considered not to cause an increase in tumors in rats or mice.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records

Reference

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 1977- May 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

yes

Remarks:

Urinalysis, haematological and clinical biochemistry measurements were not reported

Principles of method if other than guideline:

Study was performed to detect any carcinogenic potential of DEHA; additionally clinical signs, body weights, survival, gross pathology also detecting in detail nonneoplastic effects in the tissue, and histopathology were determined.

GLP compliance:

no

Specific details on test material used for the study:

Supplier: W.R. Grace Co.(Fords, NJ)
- Name of test material (as cited in study report): di(2-ethylhexyl)adipate
- Substance type: a clear colourless liquid
- Analytical purity: 101.4 % for Lot No. GC-2-27-76 and 100.5 % for Lot No. 0-62-494 (ester titration, Thin-layer chromatography results: one component for both lots.)
- Lot/batch No.: GC-2-27-76. Lot no. 0-62-494 was used for the final 46 weeks of the chronic studies.
- Storage condition of test material: at 4 degrees Celcius

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: NCI Frederick cancer Research Center, Maryland
- Age at study initiation: 3 weeks
- Housing: 5 per cage
- Diet :e.g. ad libitum
- Water :e.g. ad libitum
- Acclimatisation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-31
- Humidity (%): 10-88
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on exposure:

Dietary preparation:
Test diets were prepared by mixing the chemical with an aliquot of powdered Wayne® Lab Blox animal feed (Allied Mills, Chicago, IL), placing the mixture in a Patterson-Kelly twin-shell intensifier bar V-blender with the remainder of the feed, and mixing for 10 minutes . Test diets were sealed in labelled plastic bags and stored at 4°C for no longer than 14 days.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The amounts of di(2-ethylhexyl)adipate in selected batches of feed were measured by vapor-phase chromatography of 50-ml methanol extracts of 2-g samples. At each dietaryconcentration, the mean of the analytical concentration was usually within +/-10% of the theoretical.

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

Diet was available ad libitum for 103 weeks

Post exposure period:

Week 104-107

Dose / conc.:

12 000 ppm (nominal)

Remarks:

600 mg/kg bw

Dose / conc.:

25 000 ppm (nominal)

Remarks:

1250 mg/kg bw

No. of animals per sex per dose:

50 rats

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: based on performed subchronic pre-study (14-week study)

Positive control:

No positive control used.

Observations and examinations performed and frequency:

Body weight: yes, recorded every 4 weeks.
Clinical observations: twice daily.
In addition, survival was recorded.

Sacrifice and pathology:

Necropsy: CO2 inhalation.

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Gross and microscopic examinations were performed on major tissues, major organs, and all gross lesions from killed animals and from animals found dead. Tissues were preserved in 10% neutral buffered formalin, embedded in paraffin, sectioned, and stained with hematoxylin and eosin . The following tissues were examined microscopically : skin, lungs and bronchi, trachea , bone and bone marrow, spleen, lymph nodes, heart, salivary gland, liver, pancreas, stomach, small intestine, large intestine, kidneys, urinary bladder, pituitary, adrenal, thyroid, parathyroid, mammary gland, prostate and seminal vesicles or uterus, testis or ovary, brain, thymus, larynx, and esophagus. Necropsies were performed on all animals found dead unless precluded in whole or in part by autolysis or cannibalization . Thus, the number of animals from which particular organs or tissues were examined microscopically varies and does not necessarily represent the number of animals that were placed on study in each group.

Other examinations:

No other examinations were performed.

Statistics:

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 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 for equality and Tarone's (1975) extension of Cox's 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 reported only when its two-tailed P value is less than 0.05
The incidence of neoplastic or non-neoplastic lesions has been given as the ratio of the number of animals bearing such lesions at a specific anatomic site (numerator) to the number of animals in which that site is examined (denominator).
The one-tailed Fisher exact test (Cox, 1970) was used to compare the tumor incidence of a control group with that of a group of dosed animals at each dose level.
The Cochran-Armitage test for linear trend in proportions, with continuity correction (Armitage, 1971), was also used. Life table methods were used to analyze the incidence of tumors. Curves of the proportions surviving without an observed tumor were computed as in Saffiotti et al . (1972).

Details on results:

CLINICAL SIGNS AND MORTALITY: No compound- related clinical signs were observed.

BODY WEIGHT AND WEIGHT GAIN: Mean body weights of high-dose rats of either sex were lower than those of the controls throughout the study.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): no data

FOOD EFFICIENCY: no data

HAEMATOLOGY: not examined

CLINICAL CHEMISTRY: not examined

URINALYSIS: not examined

NEUROBEHAVIOUR: not examined

ORGAN WEIGHTS: not examined

GROSS PATHOLOGY: no compound-related effects occurred.

HISTOPATHOLOGY: NON-NEOPLASTIC: No compound-related lesions were observed.

HISTOPATHOLOGY: NEOPLASTIC (if applicable): Tumors that were noted were those seen routinely in this strain of rat, and they occurred in comparable numbers in control and dosed rats. There were no compound-related effects.

HISTORICAL CONTROL DATA (if applicable): no data

OTHER FINDINGS
Under the conditions of this bioassay, di(2-ethylhexyl)adipate was not carcinogenic for F344 rats.

Dose descriptor:

NOAEL

Effect level:

> 25 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: At all dose levels there was no significant increase in tumor incidence at any site.

Remarks on result:

other: 25000 ppm was considered to be equivalent to 1250 mg/kg bw

Conclusions:

No increased tumor incidences were found in the rat.

Executive summary:

In a 103-week carcinogenicity study, DEHA was administered to F344 rats in the diet at levels of 12 000 or 25 000 ppm, equivalent to a daily intake of 600 or 1250 mg/kg of body weight in rats (conversion based on data form the WHO report (2004)).

All in all, no substance related increase in tumor incidences were observed, and the NOAEL for carcinogenicity was 25000ppm (equal to 1250 mg/kg in rats).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

3 150 mg/kg bw/day

Justification for classification or non-classification

Based on the available data of the structural analogue diethylhexyl adipate (DEHA) in both mice and rats it is concluded that DINA is not considered carcinogenic to man. According to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 classification is not warranted.

Additional information

As no data on diisononyl adipate (DINA) were available, the data on diethylhexyl adipate (DEHA, structural analogue of DINA) were used. In a 103-week carcinogenicity study, DEHA was administered to F344 rats and B6C3F1 mice in the diet at levels of 12 000 or 25 000 ppm, equivalent to a daily intake of 600 or 1250 mg/kg of body weight in rats and 1715 or 3570 mg/kg of body weight in mice (conversion based on data form the WHO report (2004)).

No increased tumor incidences were found in the rat. In female mice a non-dose-dependent increase of hepatocellular carcinomas was observed. An increase in hepatocellular adenomas, but not carcinomas in high-dose male mice. These types of tumors are frequently observed in these mice, and incidences were well within historical control values. All in all, no substance related increase in tumor incidences were observed, and the NOAEL for carcinogenicity was 25000ppm in both species (equal to 1250 mg/kg in rats and 3570 mg/kg in mice).