Undecan-4-olide

Carcinogenicity

Description of key information

Not carcinogenic by oral route in mice and rats (NTP, 1992, Key, rel.1)

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 03, 1981 to November 04, 1983

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

GLP study conducted similarly to OECD Guideline 451 without deviation.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: GAF Corporation (New York, NY) / Lot 600-BLO
- Physical state: Clear, colorless liquid
- Analytical purity: > 97%
- Impurities (identity and concentrations): 11 impurities were identified by GC method, there is no data on chemical identity of these impuries.

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored in the dark at 5 °C at the study laboratory.
- Stability under test conditions: Stability studies performed by the analytical chemistry laboratory using gas chromatography indicated that y-butyrolactone was stable as a bulk chemical for at least 2 weeks at temperatures to 60 °C. The stability of the bulk chemical was monitored by the study laboratory using gas chromatography and infrared absorption periodically during all phases of the studies. No change in the study material was detected.

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Facility (Frederick, MD)
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: Males -55 days; Females -62 days
- Weight at study initiation: At week 1, approx. 23.7 g (males) / 18.5 g (females)
- Fasting period before study: No
- Housing: Animals were housed 5/cage (male mice were housed individually from February 9, 1983 and female mice were housed individually from July 1, 1983) in solid-bottom polycarbonate cages (Lab Products, Inc., Garfield, NJ)
- Diet: NIH-07 Rat and Mouse Ration, Open formula, pellets (Zeigler Bros., Inc., Gardners, PA), available ad libitum
- Water: Tap water (Birmingham Water Works) via outside-the-cage automatic watering system (Edstrom Industries, Inc., Waterford, WI), available, ad libitum
- Acclimation period: 19 days

ENVIRONMENTAL CONDITIONS
- Temperature: 16-29 °C
- Humidity: 25-79 %
- Air changes: Minimum of 15 per hour
- Photoperiod: 12 h dark / 12 h light

IN-LIFE DATES: November 03, 1981 to November 04, 1983

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The dose formulations were prepared by mixing appropriate amounts of test item and corn oil to give the required concentrations. Dose formulations were prepared weekly and discarded 2 weeks after the date of preparation. During the studies, the dose formulations were stored in sealed amber serum vials in the dark at 5 °C for no longer than 2 weeks.

VEHICLE
- Amount of vehicle (if gavage): 10 mL/kg bw

STABILITY
Gas chromatography confirmed the stability of the dose formulations when stored 14 days in the dark at temperatures to 25 °C.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of the test item dose formulations were performed using gas chromatography. The dose formulations were analyzed at approximately 8-week intervals; 96% (27/28) of the dose formulations for mice were within 10% of the target concentrations.

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

5 days/week

Post exposure period:

1 week

Dose / conc.:

262 mg/kg bw/day (actual dose received)

Dose / conc.:

525 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

50

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses selected for 2 year study for mice were 262 and 525 mg/kg bw/day, which were based on the chemical related mortality observed in male mice (3/10) and in female mice (1/10) at 1050 mg/kg bw/day in a 13 week study.
Rationale for animal assignment (if not random): Animals were grouped by weight intervals, then groups were assigned to cages. A table of random numbers was used to assign cages to treatment groups.

Positive control:

None

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were observed twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Animals were observed at study initiation, weekly for 13 weeks, and monthly thereafter.

BODY WEIGHT: Yes
- Time schedule for examinations: Animals were weighed at study initiation, weekly for 13 weeks, and monthly thereafter.

FOOD CONSUMPTION: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

NECROPSY: Animals found moribund or surviving to the end of the 2-year studies were killed. Necropsy was performed on all animals.

GROSS PATHOLOGY: Yes; At necropsy, all organs and tissues were examined for gross lesions.

HISTOPATHOLOGY: Yes; all major tissues were fixed and preserved in 10% neutral buffered formalin, processed and trimmed, embedded in paraffin, sectioned, and stained with haematoxylin and eosin for microscopic examination. Complete histopathlogical examinations were performed on all control, all high-dose and low dose male mice. Selected tissues were examined from low-dose female mice. Histopathology examinations were performed on all grossly visible lesions in all dose groups.

Other examinations:

None

Statistics:

The probability of survival was estimated by the product-limit procedure of Kaplan and Meier (1958). Animals found dead of other than natural causes or found missing were censored from the survival analyses; animals dying from natural causes were not censored. Statistical analyses for possible dose-related effects on survival used Cox’s (1972) method for testing two groups for equality and Tarone’s (1975) life table test to identify dose-related trends. All reported P values for the survival analyses are two sided. The incidences of neoplasms or non-neoplastic lesions were given as the numbers of animals bearing such lesions at a specific anatomic site to the numbers of animals with that site examined microscopically. Analysis of tumor incidence was performed using logistics regression analysis. Other tests used were life table test (Cox; 1972; Tarone, 1975), Fisher exact test and the Chochran-Armitage trend test (Armitage, 1971; Gart et. al., 1979). For analysis of continuous variables tests performed include Dunnett (1955) and Williams (1971, 1972), and Jonckheere’s test (Jonckheere, 1954).

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

High dose (525 mg/kg bw/day) males and females were slightly lethargic after dosing.

Mortality:

mortality observed, treatment-related

Description (incidence):

High dose (525 mg/kg bw/day) males and females were slightly lethargic after dosing.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

High dose (525 mg/kg bw/day) females had reduced final mean body weights at the end of the study.

Food consumption and compound intake (if feeding study):

not examined

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):

effects observed, treatment-related

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Low dose (262 mg/kg bw/day) males had statistically significant increased incidence of proliferative lesions, primarily hyperplasia, of the adrenal medulla.

Other effects:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
High-dose male mice were partially sedated or lethargic and inactive shortly after dosing; There was a significantly lower survival of high-dose male mice. This was attributed partially to fighting during the first year of the study, when the animals were housed in groups of five (males were housed individually after approximately 66 weeks on study). Survival of low- and high-dose female mice was similar to controls.
Survival rate for male mice: 35/50 (control), 30/50 (262 mg/kg bw/day) and 12/50 (525 mg/kg bw/day)
Survival rate for female mice: 38/50 (control), 34/50 (262 mg/kg bw/day) and 38/50 (525 mg/kg bw/day)

BODY WEIGHT AND WEIGHT GAIN
Mean body weights of low- and high-dose male mice followed a similar pattern throughout the study and were consistently lower than the mean body weights of the controls. The decrement in bodyweight gain was evident as early as week 3 and continued to increase until approximately week 66. Mean body weights of low- and high-dose males were within 10% of the mean body weight of the controls through week 27; from week 32 to week 66 the decrement increased to a maximum of 17%. During week 67, all male mice were housed individually; thereafter, the difference between the mean body weights of dosed males and control mice decreased. By the end of the study, the final mean body weights of low- and high-dose male mice were only 6% less than that of the controls.
In female mice, the mean body weights of both dose groups were within 10% of those of the controls through week 27. Thereafter, weight gains of low-and high-dose females steadily declined relative to controls, and the differences did not diminish after the females were housed individually at week 87. At the end of the study, the final mean body weights of low-and high-dose female groups were 17% and 14% lower than that of the controls.

HISTOPATHOLOGY: NON-NEOPLASTIC
There were no non-neoplastic degenerative lesions associated with the administration of test item. Decreases in a number of miscellaneous spontaneous legions in low- and high dose male mice were attributed to decreased survival and were not considered related to test item. The observed dose-related increases in several non-neoplastic lesions in male mice were considered to be associated with fighting or bite wounds.

HISTOPATHOLOGY: NEOPLASTIC
Adrenal Medulla: There was a statistically significant increase in the incidence of focal hyperplasia in low-dose male mice. Moreover, there was a marginal increase in the incidence of pheochromocytomas (benign or malignant combined) in low-dose male mice compared to controls, although neither the trend test nor the pairwise comparison was statistically significant. Because focal hyperplasia and pheochromocytomas constitute a morphological and biological continuum, the increased incidence of these lesions, principally hyperplasia, may be related to test item administration. The lack of a dose response may be related to the reduced survival in the high-dose group. In female mice, there was no apparent increase in the incidence of adrenal medulla proliferative lesions associated with the administration of test item (hyperplasia: control, 3/50; high-dose, 1/49; pheochromocytoma, benign or malignant: 0/50, 2/49).

Liver: Hepatocellular adenomas or carcinomas (combined) occurred with a statistically significant negative trend in male mice, and the incidences in low- and high dose groups were significantly lower than the incidence in the controls by survival-adjusted analyses (24/50, 8/50, 9/50). The overall incidence of hepatocellular neoplasms in NTP historical control males receiving corn oil by gavage is 210/599 (35.1%, range 14%-52%).

Harderian Gland: Adenomas in male mice occurred with a statistically significant negative trend, and the incidences in low-and high-dose groups were significantly less than controls by survival-adjusted analyses (8/50, 1/50, 0/50). The overall historical control incidence of this tumor in males is 38/600 (6.3%) with a range of 0% to 16%. Thus, the significance of the decrease may be due to the rather high incidence in controls in this study, rather than to the administration of test item. The incidence of harderian gland neoplasms in low- and high-dose female mice was not decreased (2/50, 2/50, 4/50).

Miscellaneous Non-neoplastic Lesions: Decreases in a number of miscellaneous spontaneous non-neoplastic lesions in low- and high-dose male mice were attributed to decreased survival and were not considered related to test item administration. The observed dose-related increases in several non-neoplastic lesions in male mice were considered to be associated with fighting or bite wounds. The skin lesions were primarily located around the genitalia and backs, and the lymphoid hyperplasia of the inguinal lymph node was considered to be an immunological response to superficial bacterial infections of the bite wounds. Prostatitis is frequently seen in group-housed male mice and is believed to be the result of ascending bacterial infections resulting from bite wounds on and around the genitalia. Depletion of lymphocytes from the thymus (also called thymic atrophy) often accompanies debilitation and stress and was usually seen in mice dying early from fight wounds. The leukocytosis, hemorrhage, and congestion of the lung were also seen principally in males dying early from fight wounds.

Key result

Dose descriptor:

NOAEL

Effect level:

525 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: carcinogenicity

Key result

Dose descriptor:

LOAEL

Effect level:

262 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical signs

mortality

Remarks on result:

other: toxicity

Key result

Critical effects observed:

no

Table 7.7/1: Mean body weights and survival of male mice

Weeks on Study	Vehicle Control		262 mg/kg bw/day			525 mg/kg bw/day
	Av. Wt. (g)	Number of Survivors	Av. Wt. (g)	Wt. (% of controls)	Number of Survivors	Av. Wt. (g)	Wt. (% of controls)	Number of Survivors
1	23.6	50	24.1	102	50	23.7	100	50
2	25.8	50	25.9	100	50	26.3	102	50
3	28.8	50	27.4	95	50	27.0	94	50
4	29.1	50	28.5	98	50	27.9	96	50
5	30.1	50	29.8	99	50	28.8	96	50
6	31.3	50	29.0	93	50	30.0	96	50
7	32.4	50	31.7	98	50	30.9	95	50
8	33.1	50	31.9	96	50	31.5	95	50
9	33.9	50	32.4	96	50	32.2	95	50
10	34.6	50	33.5	97	50	32.8	95	50
11	35.1	50	34.2	97	50	34.0	97	49
12	35.7	50	34.7	97	50	34.4	96	49
13	36.1	50	34.6	96	50	33.6	93	49
15	36.7	50	35.4	97	50	35.2	96	48
18	37.5	50	35.3	94	50	36.0	96	44
22	39.9	50	37.2	93	48	37.5	94	44
27	41.9	49	38.0	91	47	38.7	92	38
32	44.3	49	39.8	90	46	39.0	88	36
35	44.4	49	39.2	88	46	39.6	89	36
40	46.0	49	40.8	89	45	40.2	87	36
44	45.8	49	40.7	89	45	38.6	84	36
48	46.1	49	40.6	88	45	40.9	89	35
52	48.1	49	41.4	86	44	41.7	87	35
56	48.9	48	42.1	86	43	41.0	84	33
58	48.7	48	40.6	83	40	41.4	85	33
62	49.9	48	41.4	83	39	41.7	84	32
66	50.0	47	42.7	85	38	41.3	83	30
70	48.1	45	42.5	88	38	41.3	86	30^a
74	46.9	45	41.9	89	38	40.2	86	28
78	47.5	44	42.6	90	36	41.2	87	28
82	46.5	44	43.2	93	36	42.9	92	24
86	47.4	41	43.0	91	34	40.9	86	20
90	47.4	39	43.8	92	32	41.8	88	19
94	45.3	38	42.4	94	32	41.8	92	17
98	43.9	38	42.4	97	30	42.0	96	14
102	44.2	36	41.6	94	30	41.7	94	12
Terminal sacrifice		35	-	-	30	-	-	12
Mean for weeks
1-13	31.5	-	30.6	97	-	30.2	96	-
14-52	43.1	-	38.8	90	-	38.7	90	-
53-102	47.3	-	42.3	89	-	42	88	-

^a The number of animals weighed for this week is fewer than the number of animals surviving.

Table 7.7/2: Mean body weights and survival of female mice

Weeks on Study	Vehicle Control		262 mg/kg bw/day			525 mg/kg bw/day
	Av. Wt. (g)	Number of Survivors	Av. Wt. (g)	Wt. (% of controls)	Number of Survivors	Av. Wt. (g)	Wt. (% of controls)	Number of Survivors
1	18.5	50	18.7	101	50	18.4	100	50
2	19.8	50	19.8	100	50	20.1	102	50
3	21.3	50	20.9	98	50	21.0	99	50
4	22.0	50	21.5	98	50	21.0	96	50
5	23.2	50	22.5	97	50	22.4	97	50
6	23.0	50	23.3	101	50	22.4	97	50
7	23.8	50	23.8	100	50	23.1	97	50
8	24.3	50	23.4	96	50	22.8	94	50
9	24.6	50	24.0	98	50	23.9	97	50
10	25.8	50	24.8	96	50	25.0	97	50
11	26.5	50	26.0	98	50	25.6	97	50
12	26.6	50	25.3	95	50	25.5	96	50
13	27.1	50	25.0	92	50	24.8	92	50
15	26.9	50	25.7	96	50	26.0	97	50
18	27.6	50	26.1	95	50	26.2	95	50
22	29.2	50	28.2	97	50	27.8	95	50
27	31.7	50	29.2	92	50	28.9	91	50
32	34.6	50	29.2	84	50	30.6	88	50
35	33.1	50	30.9	93	50	30.8	93	50
40	35.9	50	31.5	88	50	30.7	86	50
44	36.6	50	32.6	89	50	32.5	89	50
48	37.4	50	33.4	89	50	33.0	88	50
52	39.2	50	34.6	88	50	34.8	89	50
56	39.8	50	34.5	87	50	35.5	89	50
58	40.1	50	34.9	87	50	36.0	90	50
62	40.2	50	35.6	89	50	36.6	91	50
66	43.3	50	38.5	89	50	39.7	92	50
70	44.8	50	38.4	86	48	39.8	89	49
74	44.9	50	38.4	86	48	39.1	87	48
78	47.1	50	38.8	82	47	39.4	84	48
82	46.0	50	39.2	85	45	40.3	88	48
86	48.2	46	40.2	83	41	40.5	84	46
90	45.9	42	38.7	84	39	39.0	85	46
94	47.1	41	38.3	81	35	40.3	86	44
98	44.1	39	36.9	84	35	39.5	90	41
102	44.4	38	36.7	83	34	38.3	86	39
Terminal sacrifice		38	-	-	34	-	-	38
Mean for weeks
1-13	23.6	-	23.0	97	-	22.8	97	-
14-52	33.2	-	30.1	91	-	30.1	91	-
53-102	44.3	-	37.6	85	-	38.8	88	-

 

Table 7.7/3: Lesions of the adrenal medulla in male mice

 

Lesions	Vehicle Control	262 mg/kg	525 mg/kg
Hyperplasia
Overall rates^a	2/48 (4%)	9/50 (18%)	4/50 (8%)
Logistic regression tests^b	P=0.071	P=0.011	P=0.191
Benign Pheochromocytoma
Overall rates	1/48 (2%)	5/50 (10%)	1/50 (2%)
Adjusted rates^c	2.3%	16.7%	5.3%
Terminal rates^d	0/34 (0%)	5/30 (17%)	0/12 (0%)
First incidence (days)	582	729 (T)	640
Logistic regression tests	P =0.352	P =0.073	P =0.760
Malignant Pheochromocytoma
Overall rates	1/48 (2%)	1/50 (2%)	0/50 (0%)
Benign or Malignant Pheochromocytoma^e
Overall rates	2/48 (4%)	6/50 (12%)	1/50 (2%)
Adjusted rates	4.90%	20.0%	5.3%
Terminal rates	0/34 (0%)	6/30 (20%)	0/12 (0%)
First incidence (days)	582	729 (T)	640
Logistic regression tests	P=0.472	P =0.092	P=0.592N

(T) Terminal sacrifice

^aNumber of lesion-bearing animals/number of animals necropsied or examined microscopically for this lesion

^bBeneath the control incidence are the P values associated with the trend test. Beneath the dosed group incidence are the P values corresponding to pairwise comparisons between the controls and that dosed group. The logistic regression tests regard tumors in animals dying prior to terminal kill as nonfatal. A lower incidence in a dose group is indicated by N.

^cNumber of lesion-bearing animals/effective number of animals, i.e., number of animals alive at first occurrence of this tumor type in any of the groups

^dObserved incidence at terminal kill

^eHistorical incidence for 2-year NTP corn-oil gavage studies with vehicle control groups (mean ± standard deviation): 18/582 (3.1% ± 1.8%), range 0%-6%

Table 7.7/4: Selected non-neoplastic lesions in male mice

Lesions	Vehicle Control	262 mg/kg	525 mg/kg
Inguinal Lymph Node
Lymphoid hyperplasia	0/50	5/50*	5/49*
Lung
Congestion	1/50	1/50	4/50
Hemorrhage	0/50	1/50	7/50**
Leukocytosis	1/50	2/50	5/50
Prostate Gland
Inflammation, suppurative	1/49	5/48	8/48*
Skin
Acanthosis	12/50	36/50**	39/50**
Inflammation, chronic	4/50	17/50**	19/50**
Pigmentation	3/50	12/50**	19/50**
Ulcer	4/50	15/50**	17/50**
Hair follicle, atrophy	1/50	11/50**	16/50**
Thymus
Depletion	0/42	5/39*	6/38**
Epithelial hyperplasia	0/42	4/39*	4/38*

* Significantly different (P<0.05) from the control group by the logistic regression tests

** P<0.01

^aNumber of lesion-bearing animals/number of tissues examined

Conclusions:

Under the conditions of this study, there was no evidence of carcinogenic activity of test item in female B6C3F1 mice. There was equivocal evidence of carcinogenicity of test item in male B6C3F1 mice at 262 mg/kg bw/day based on the marginally increased incidences of adrenal medulla pheochromocytomas and hyperplasia. Sensitivity of the study in male mice to detect a carcinogenic effect was reduced by the low survival of the high-dose group associated with fighting.

Executive summary:

In a carcinogenicity study performed similarly to OECD Guideline 451 and in compliance with GLP, B6C3F1 mice (50/sex/dose) were administered γ-butyrolactone at 0, 262 and 525 mg/kg bw/day, 5 days/week for 103 weeks. The following parameters were performed: clinical signs, mortality, body weight, gross pathology, histopathologic – neoplastic and non-neoplastic lesions.

High-dose mice were partially sedated or lethargic and inactive shortly after dosing. There was a significantly lower survival of high-dose male mice.  This was attributed partially to fighting during the first year of the study, when the animals were housed in groups of five. Survival of low- and high-dose female mice was similar to controls.

Survival rate for male mice: 35/50 (control), 30/50 (262 mg/kg bw/day) and 12/50 (525 mg/kg bw/day)

Survival rate for female mice: 38/50 (control), 34/50 (262 mg/kg bw/day) and 38/50 (525 mg/kg bw/day)

The mean body weights of dosed male mice were lower than those of the controls throughout the study, but the differences in mean bodyweights decreased when male mice were housed individually at week 67. The final mean body weights of dosed male mice were 6% lower than that of the controls. Mean body weights of dosed female mice were also lower than those of the controls throughout the study, and the final mean bodyweights were from14% to17% lower than that of the controls.

There were no non-neoplastic degenerative lesions associated with the administration of test item. Increased incidences of proliferative lesions, primarily hyperplasia, of the adrenal medulla in low-dose male mice were associated with test item administration (pheochromocytoma, benign or malignant: 2/48, 6/50, 1/50; hyperplasia: 2/48, 9/50, 4/50). The incidence of hepatocellular neoplasms in both dose groups of male mice was lower than the incidence in the controls (hepatocellular adenoma or carcinoma: 24/50, 8/50, 9/50). The incidences of harderian gland adenoma in the dosed groups of male mice were also significantly lower than the incidence in the controls.

Under the conditions of this study, there was no evidence of carcinogenic activity of test item in female B6C3F1 mice at 262 or 525 mg/kg bw/day. There was equivocal evidence of carcinogenicity of test item in male B6C3F1 mice at 262 mg/kg bw/day based on the marginally increased incidences of adrenal medulla pheochromocytoma and hyperplasia. Sensitivity of the study in male mice to detect a carcinogenic effect was reduced by the low survival of the high-dose group associated with fighting.

Reference 2

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

November 10, 1981 to November 14, 1983

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

GLP study conducted similarly to OECD Guideline 451 without deviation.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: GAF Corporation (New York, NY) / Lot 600-BLO
- Physical state: Clear, colorless liquid
- Analytical purity: > 97%
- Impurities (identity and concentrations): 11 impurities were identified by GC method, there is no data on chemical identity of these impuries.

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored in the dark at 5 °C at the study laboratory.
- Stability under test conditions: Stability studies performed by the analytical chemistry laboratory using gas chromatography indicated that y-butyrolactone was stable as a bulk chemical for at least 2 weeks at temperatures to 60 °C. The stability of the bulk chemical was monitored by the study laboratory using gas chromatography and infrared absorption periodically during all phases of the studies. No change in the study material was detected.

Species:

rat

Strain:

Fischer 344

Remarks:

F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Facility (Frederick, MD)
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: 61 days
- Weight at study initiation: At week 1, approx. 190 g (males) / 138 g (females)
- Fasting period before study: No
- Housing: Animals were housed 5/cage throughout the study in solid-bottom polycarbonate cages (Lab Products, Inc., Garfield, NJ)
- Diet: NIH-07 Rat and Mouse Ration, Open formula, pellets (Zeigler Bros., Inc., Gardners, PA), available ad libitum
- Water: Tap water (Birmingham Water Works) via outside-the-cage automatic watering system (Edstrom Industries, Inc., Waterford, WI), available, ad libitum
- Acclimation period: 18 days

ENVIRONMENTAL CONDITIONS
- Temperature: 16-29 °C
- Humidity: 31-79 %
- Air changes: Minimum of 15 per hour
- Photoperiod: 12 h dark / 12 h light

IN-LIFE DATES: November 10, 1981 to November 14, 1983

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The dose formulations were prepared by mixing appropriate amounts of test item and corn oil to give the required concentrations. Dose formulations were prepared weekly and discarded 2 weeks after the date of preparation.
During the studies, the dose formulations were stored in sealed amber serum vials in the dark at 5 °C for no longer than 2 weeks.

VEHICLE
- Amount of vehicle (if gavage): 5 mL/kg bw

STABILITY
Gas chromatography confirmed the stability of the dose formulations when stored 14 days in the dark at temperatures to 25 °C.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of the test item dose formulations were performed using gas chromatography. The dose formulations were analyzed at approximately 8-week intervals; 98% (41/42) of the dose formulations were within 10% of the target concentrations.

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

5 days/week

Post exposure period:

1 week

Dose / conc.:

112 mg/kg bw/day (actual dose received)

Remarks:

males

Dose / conc.:

225 mg/kg bw/day (actual dose received)

Remarks:

males and females

Dose / conc.:

450 mg/kg bw/day (actual dose received)

Remarks:

females

No. of animals per sex per dose:

50

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The doses selected for the 2-year study in male rats were 0, 112, and 225 mg/kg bw/day. These doses were based on the mortality in males at 900 mg/kg bw/day and the depressed body gain in males at 450 mg/kg bw/day in the 13-week study. Because of the lower mortality in females at 900 mg/kg bw/day, the doses selected for the 2-year study in female rats were 0, 225, and 450 mg/kg bw/day.
- Rationale for animal assignment (if not random): Animals were grouped by weight intervals, then groups were assigned to cages. A table of random numbers was used to assign cages to treatment groups.

Positive control:

No

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were observed twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Animals were observed at study initiation, weekly for 13 weeks, and monthly thereafter.

BODY WEIGHT: Yes
- Time schedule for examinations: Animals were weighed at study initiation, weekly for 13 weeks, and monthly thereafter.

FOOD CONSUMPTION: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

NECROPSY: Animals found moribund or surviving to the end of the 2-year studies were killed. Necropsy was performed on all animals.

GROSS PATHOLOGY: Yes; At necropsy, all organs and tissues were examined for gross lesions.

HISTOPATHOLOGY: Yes; all major tissues were fixed and preserved in 10% neutral buffered formalin, processed and trimmed, embedded in paraffin, sectioned, and stained with haematoxylin and eosin for microscopic examination. Complete histopathologic examinations were performed on rats that died or were killed moribund prior to day 637. Selected tissues were examined from all low-dose rats. Histopathology examinations were performed on all grossly visible lesions in all dose groups.

Other examinations:

None

Statistics:

The probability of survival was estimated by the product-limit procedure of Kaplan and Meier (1958). Animals found dead of other than natural causes or found missing were censored from the survival analyses; animals dying from natural causes were not censored. Statistical analyses for possible dose-related effects on survival used Cox’s (1972) method for testing two groups for equality and Tarone’s (1975) life table test to identify dose-related trends. All reported P values for the survival analyses are two sided. The incidences of neoplasms or non-neoplastic lesions were given as the numbers of animals bearing such lesions at a specific anatomic site to the numbers of animals with that site examined microscopically. Analysis of tumor incidence was performed using logistics regression analysis. Other tests used were life table test (Cox; 1972; Tarone, 1975), Fisher exact test and the Chochran-Armitage trend test (Armitage, 1971; Gart et. al., 1979). For analysis of continuous variables tests performed include Dunnett (1955) and Williams (1971, 1972), and Jonckheere’s test (Jonckheere, 1954).

Clinical signs:

no effects observed

Description (incidence and severity):

There were no clinical findings attributed to test item administration.

Mortality:

mortality observed, treatment-related

Description (incidence):

There was no adverse effect of the test substance on survival in male or female.
There was a marginally significant increased survival of dosed males compared to controls; however, pairwise comparisons of survival between controls and low- or high dose groups showed no significant difference. The higher survival rates in the 225 mg/kg bw/day male dose group are due in part to the marginally decreased incidence of mononuclear cell leukemia (control, 16/50; low dose, 15/50; high dose, 9/50). Survival was similar in all female groups.
Survival rate for male rats: 24/50 (control), 27/50 (112 mg/kg bw/day) and 32/50 (225 mg/kg bw/day)
Survival rate for female rats: 28/50 (control), 27/50 (225 mg/kg bw/day) and 28/50 (450 mg/kg bw/day)

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

In male rats there was no body weight change associated with administration of 112 or 225 mg/kg bw/day test material. In female rats there was no body weight change associated with administration of the low dose (225 mg/kg bw/day). In female rats there was a reduction in body-weight gain associated with administration of the high-dose (450 mg/kg bw/day) from week 6 to end of the study. The mean body weight of high dose females was within 10% of the mean body weight of the controls until week 58; by the end of 2-year studies the mean body weight was 20% lower than that of the controls.

Food consumption and compound intake (if feeding study):

not examined

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

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no significant gross pathological effects reported.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There were no significant non-neoplastic lesions reported.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

Skin: Several morphological types of epithelial neoplasms, principally benign neoplasms, occurred more frequently in dosed male rats than in controls. The incidence of keratoacanthoma was marginally increased in low- and high-dose males, but pairwise comparisons were not significant (control, 1/50; low-dose, 4/50; high-dose, 6/50). The overall historical control incidence of keratoacanthomas in NTP corn oil gavage studies with F344/N male rats is 26/770 (3.4%) with a range of 0% to 12%. Because the incidences of keratoacanthoma in low-and high-dose male rats are not significantly greater than the incidence in the controls and because the incidences are within the range for historical controls, the marginally increased incidence of keratoacanthoma is not considered related to test item administration. Further, all keratoacanthomas occurred in animals killed at 2 years, and it is likely that the apparent increase in this neoplasm reflects in part the increased survival in the high-dose group relative to controls.
Basal cell adenomas occurred in four low-dose males; none were observed in high-dose or control males. One basal cell carcinoma occurred in a high-dose male rat. Although the incidence in the low-dose group was not significantly greater than the incidence in the control group, basal cell adenomas occur infrequently in male rats. The overall historical incidence of basal cell and related neoplasms in corn oil gavage controls is 13/770 (1.7%) with a range of 0% to 5%. The basal cell adenomas were not considered related to test item administration, because they did not occur at a significantly increased incidence in the low dose group and did not occur with an increased incidence in the high-dose group.

Mesothelium: Mesotheliomas occurred in four high-dose males and one low-dose male rat, but were not present in controls. The historical incidence of mesotheliomas in corn oil control male rats is 26/770 (3.4%) with a range of 0% to 10%. Thus, the apparent increased incidence reflects the low incidence in control males and is not considered to be related to test item administration.

Mammary Gland: The incidence of fibroadenomas in female rats occurred with a statistically significant (P<0.01) negative trend, and the incidence in the high-dose group was significantly lower than that of the controls (22/50, 14/50, 6/50). The overall historical control incidence for fibroadenomas in female rats is 298/770 (38.7%) with a range of 18% to 56%. The decreased incidence of fibro-adenomas in low-and high-dose female rats was considered related to test item administration. The incidence of mammary gland cysts (markedly dilated ducts or glands lined by a single layer of epithelium) also showed a statistically significant (P<0.01) negative trend (42/50, 35/50, 23/50).

Pituitary Gland: There was a statistically significant (P<0.01) decrease in the incidence of cysts in the pars distalis of high-dose female rats (25/49, 13/37, 11/48). Cysts of the pars distalis are cavities filled with serum proteins displacing the parenchyma and often occur within focal hyperplasia or adenoma. A decreased incidence of adenomas in high-dose females was not statistically significant (22/49, 24/37, 16/48).

Hematopoietic System: The incidence of mononuclear cell leukemia in male rats occurred with a significant negative trend, and the incidence in the high-dose males was significantly less than controls (16/50, 15/50, 9/50). Mononuclear cell leukemia is a common neoplasm in male F344/N rats with a overall historical control incidence of 164/770 (21.3%) and a range of 4% to 38%.

Other effects:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

225 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Remarks on result:

other: carcinogenicity

Key result

Dose descriptor:

NOAEL

Effect level:

450 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Remarks on result:

other: carcinogenicity

Key result

Dose descriptor:

NOAEL

Effect level:

225 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical signs

gross pathology

histopathology: non-neoplastic

mortality

organ weights and organ / body weight ratios

Remarks on result:

other: toxicity

Key result

Critical effects observed:

no

Table 7.7/1: Mean body weights and survival of male rats

Weeks on study	Vehicle control		112 mg/kg bw/day			225 mg/kg bw/day
	Av. Wt. (g)	Number of survivors	Av. Wt. (g)	Wt. (% of controls)	Number of survivors	Av. Wt. (g)	Wt. (% of controls)	Number of survivors
1	191	50	191	100	50	187	98	50
2	225	50	222	99	50	221	98	50
3	243	50	240	99	50	238	98	50
4	265	50	264	100	50	262	99	50
5	284	50	280	99	50	278	98	50
6	298	50	295	99	50	293	98	50
7	308	50	305	99	50	301	98	50
8	316	50	315	100	50	310	98	50
9	330	50	327	99	50	323	98	50
10	339	50	337	99	50	331	98	50
11	343	50	340	99	50	334	98	50
12	354	50	349	99	50	346	98	50
13	360	50	359	100	50	354	98	50
17	380	50	380	100	50	376	99	50
21	402	50	406	101	50	403	100	50
26	425	50	430	101	50	425	100	50
31	443	50	446	101	50	444	100	50
34	453	50	451	100	50	449	99	50
40	465	50	467	100	50	465	100	50
43	473	50	470	99	50	468	99	50
47	482	50	482	100	50	478	99	50
51	487	50	487	100	50	480	99	50
53	489	50	490	100	50	482	99	49
58	498	50	497	100	47	487	98	49
62	500	50	497	99	47	490	98	48
66	502	50	502	100	47	496	99	48
70	501	46	499	100	47	490	98	48
74	499	45	499	100	46	491	98	48
78	498	43	497	100	44	484	97	47
82	494	42	496	100	42	489	99	45
86	493	37	494	100	39	489	99	43
90	484	35	489	101	37	487	101	42
94	480	33	479	100	35	475	99	42
98	476	27	472	99	33	462	97	37
102	466	25	467	100	30	461	99	34
Terminal sacrifice		24	-	-	27	-	-	32
Mean for weeks
1-13	297	-	294	99	-	291	98	-
14-52	446	-	447	100	-	443	99	-
53-102	491	-	491	100	-	483	98	-

 

Table 7.7/2: Mean body weights and survival of female rats

Weeks on study	Vehicle Control		225 mg/kg bw/day			450 mg/kg bw/day
	Av. Wt. (g)	Number of survivors	Av. Wt. (g)	Wt. (% of controls)	Number of survivors	Av. Wt. (g)	Wt. (% of controls)	Number of survivors
1	139	50	139	100	50	137	98	50
2	155	50	155	101	50	151	98	50
3	162	50	162	100	50	156	96	50
4	173	50	171	99	50	166	96	50
5	180	50	181	100	50	173	96	50
6	187	50	185	99	50	177	95	50
7	190	50	187	99	50	180	95	50
8	194	50	192	99	50	182	94	50
9	196	50	195	100	50	184	94	50
10	199	50	199	100	50	189	95	50
11	202	50	199	99	50	189	94	50
12	203	50	200	99	50	189	93	50
13	206	50	204	99	50	192	93	50
17	214	50	209	98	50	200	93	50
21	220	50	216	98	50	206	94	49
26	230	50	226	98	50	215	93	48
31	238	50	235	99	50	222	93	48
34	243	50	237	98	50	223	92	46
40	252	50	245	97	50	234	93	46
43	255	50	252	99	49	236	92	46
47	268	49	260	97	49	241	90	45
51	271	49	268	99	48	246	91	45
53	276	49	274	99	47	248	90	45
58	289	49	283	98	46	254	88	45
62	300	49	294	98	45	261	87	45
66	306	49	301	98	45	268	87	44
70	313	49	305	98	45	270	86	44
74	323	46	313	97	43	275	85	44
78	326	45	316	97	43	276	85	44
82	328	42	322	98	42	277	85	43
86	331	41	319	96	42	272	82	37^a
90	334	41	323	97	42	278	83	37
94	331	40	325	98	40	277	84	36
98	333	34	321	96	37	273	82	31
102	339	30	323	95	28	272	80	30
Terminal sacrifice	-	28	-	-	27	-	-	28
Mean for weeks
1-13	184	-	182	99	-	174	95	-
14-52	243	-	239	98	-	225	93	-
53-102	318	-	309	97	-	269	85	-

a The number of animals weighed for this week is fewer than the number of animals surviving.

Conclusions:

Under the test conditions, there was no evidence of carcinogenic activity of test item in male or female rats. There was a decreased incidence of mammary gland fibroadenomas and cysts and pituitary cysts in female rats which were associated with the administration of test item.

Executive summary:

In a carcinogenicity study performed similarly to OECD Guideline 451 and in compliance with GLP, Fischer 344 rats (50/sex/dose) were administered γ-butyrolactone at 0, 112 and 225 mg/kg bw/day to male rats and 0, 225 and 450 mg/kg bw/day to female rats, 5 days/week for 103 weeks. The following parameters were performed: clinical signs, mortality, body weight, gross pathology, histopathologic – neoplastic and non-neoplastic lesions.

 

There were no clinical findings or adverse effect on survival in male or female rats attributed to test item. The mean body weights of male rats administered test item were similar to those of the controls throughout the study. The mean body weight of high-dose females was lower than that of the controls after week 5 and was 10% to 20% lower than that of the controls throughout the second year. The survival of high-dose male rats was slightly higher than that of the controls (control, 24/50; low-dose, 27/50, high-dose, 32/50) due primarily to a lower incidence of mononuclear cell leukemia in the high-dose group (16/50, 15/50, 9/50). The survival of dosed females was similar to that of the controls (28/50, 27/50, 28/50). No increased incidences of neoplasms or non-neoplastic lesions in male rats were related to the administration of test item for 2 years. In female rats, negative trends were observed in the incidences of cysts (42/50, 35/50, 23/50) and fibroadenomas of the mammary gland (22/50, 14/50, 6/50) and in cysts of the pituitary pars distalis (25/49, 13/37, 11/48). These decreases were considered to be related to test item administration. There was no evidence of carcinogenic activity of test item in male and female rats.

 

Under the test conditions, there was no evidence of carcinogenic activity of test item in male or female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

225 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

GLP study of high quality (Klim. 1)

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Harmonized classification

γ-Undecalactone has no harmonized classification according to the Regulation (EC) No. 1272/2008.

Self classification

Based on the available data, no additional self-classification is proposed regarding carcinogenicity according to the Annex I of the Regulation (EC) No. 1272/2008 (CLP) and the GHS.

Additional information

Only an old subcutaneous study with γ-undecalactone was available.

In this carcinogenic study (Swern, 1970), γ-undecalactone was administered via subcutaneous injections to a group of 16 female Swiss-Webster mice at a dose level of 25 mg/injection; 3 times a week for 4 weeks. Untreated and vehicle (tricaprylin) controls were also included in the study. All mice were weighed at the start of the experiments and at regular intervals throughout the ensuing period of observation of 18 to 24 months.

Total alive mice at 6 months were recorded to be 97/100, 171/203 and 4/16 in vehicle control, untreated and treatment groups, respectively. No excessive weight losses or gains were found as compared with untreated control groups. Subcutaneous sarcomas, breast cancers pulmonary and other tumors were identified in control groups. No tumor was observed in any of the mice in treatment group. 

Under the test conditions, there was no evidence of carcinogenic activity of γ-undecalactone in female Swiss-Webster mice.

More recent studies were performed by oral route on the read-across substance γ-butyrolactone, a lactone considered adequate for read-across purpose (see § "Toxicokinetics").

In these carcinogenicity studies performed similarly to OECD Guideline 451 and in compliance with GLP, B6C3F1 mice (50/sex/dose) were administered γ-butyrolactone at 0, 262 and 525 mg/kg bw/day, 5 days/week for 103 weeks and Fischer 344 rats (50/sex/dose) were administered γ-butyrolactone at 0, 112 and 225 mg/kg bw/day to male rats and 0, 225 and 450 mg/kg bw/day to female rats, 5 days/week for 103 weeks (NTP, 1992). The following parameters were performed: clinical signs, mortality, body weight, gross pathology, histopathologic – neoplastic and non-neoplastic lesions.

Survival rate for male mice: 35/50 (control), 30/50 (262 mg/kg bw/day) and 12/50 (525 mg/kg bw/day)

Survival rate for female mice: 38/50 (control), 34/50 (262 mg/kg bw/day) and 38/50 (525 mg/kg bw/day)

There was no evidence of carcinogenic activity of test item in female B6C3F1 mice at 262 or 525 mg/kg bw/day. There was equivocal evidence of carcinogenicity of the source substance in male B6C3F1 mice at 262 mg/kg bw/day based on the marginally increased incidences of adrenal medulla pheochromocytoma and hyperplasia. Sensitivity of the study in male mice to detect a carcinogenic effect was reduced by the low survival of the high-dose group associated with fighting.

  

The survival of high-dose male rats was slightly higher than that of the controls (control, 24/50; low-dose, 27/50, high-dose, 32/50) due primarily to a lower incidence of mononuclear cell leukemia in the high-dose group (16/50, 15/50, 9/50). The survival of dosed females was similar to that of the controls (28/50, 27/50, 28/50). No increased incidences of neoplasms or non-neoplastic lesions in male rats were related to the administration of test item for 2 years. In female rats, negative trends were observed in the incidences of cysts (42/50, 35/50, 23/50) and fibroadenomas of the mammary gland (22/50, 14/50, 6/50) and in cysts of the pituitary pars distalis (25/49, 13/37, 11/48). These decreases were considered to be related to test item administration. There was no evidence of carcinogenic activity of the source substance in male and female rats.

 

Under the test conditions, there was no evidence of carcinogenic activity of γ-butyrolactone in B6C3F1 mice and Fischer 344 rats.

There is evidence suggesting lack of carcinogenicity of γ-butyrolactone in experimental animals (IARC, 1999).

γ-butyrolactone is not classifiable as to its carcinogenicity to humans (group 3) in the overall evaluation of IARC (1999)

IARC (1999) IARC Monograph on the Evaluation of carcinogenic Risks to humans.Vol. 71, Re-evaluation of Some Organic Chemicals, hydrazine and hydrogen peroxide.

Finally, γ-Undecalactone is not classifiable as to its carcinogenicity to human based on the read-across approach with γ-Butyrolactone