spirodiclofen (ISO);3-(2,4-dichlorophenyl)-2-oxo-1-oxaspiro[4.5]dec-3-en-4-yl 2,2-dimethylbutyrate

Carcinogenicity

Description of key information

A combined chronic toxicity/carcinogenicity study in the rat is available for spirodiclofen (M-026284-02-1).

A carcinogenicity study in the mouse is available for spirodiclofen (M-044116-01-1).

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:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Remarks:

This study in the rat was performed at dietary concentrations of 0, 50, 100, 350 and 2500 ppm; the chronic toxicity phase is relevant for this endpoint.

Qualifier:

according to guideline

Guideline:

other: 88/302/EEC

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.4300 (Combined Chronic Toxicity / Carcinogenicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: B.67/548/EEC

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

no

Principles of method if other than guideline:

Deviations from GLP:
Deviations: 1) One out of ten analytical contents check that was reevaluated after the end of the in-life phase was found to be invalid due to insufficient documentation.
2) Determination of test substance concentration in plasma samples as well as experiments for method development (telomere measurements in different tissues) were not conducted according to GLP.

GLP compliance:

yes (incl. QA statement)

Remarks:

There were two deviations that were not conducted according to GLP. They are found in box above 'Principles of method if other than guideline'.

Species:

rat

Strain:

Wistar

Sex:

male/female

Route of administration:

oral: feed

Vehicle:

other: food

Details on exposure:

Exposed to test material via diet in relevant doses over a period of up to 108 weeks. Some rats that were treated with same doses were sacrificed after a treatment period of about 1 year.

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

Up to 108 weeks.

Frequency of treatment:

Daily/continuous

Dose / conc.:

0 ppm

Dose / conc.:

50 ppm

Dose / conc.:

100 ppm

Dose / conc.:

350 ppm

Dose / conc.:

2 500 ppm

No. of animals per sex per dose:

60; 10/sex sacrificed after 12 months

Control animals:

yes, plain diet

Details on study design:

Spirodiclofen was administered via the diet to Wistar rats (50 males and 50 females per dose), in doses of 0, 50, 100, 350 and 2500 ppm over a period of up to 108 weeks. In addition, 10 rats per dose and sex, respectively, were treated with the same doses of Spirodiclofen and sacrificed after a treatment period of about 1 year. Average daily test substance intake was - in ascending order of doses 2.04, 4.11, 14.72, and 110.14 mg/kg bw per day in male rats, and 2.87, 5.93, 19.88, and 152.90 mg/kg bw per day in females, respectively.

Observations and examinations performed and frequency:

Detailed clinical observations, body weight, food and water consumption, ophthalmoscopic examination, hematology, urinalysis, clinical chemistry and neurobehavioral examination.

Sacrifice and pathology:

Gross pathology, organ weights, histopathology

Clinical signs:

no effects observed

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Mortality was increased in 2500 ppm females, but with no statistical significance. Mortality of 2500 ppm males was decreased.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At the highest dose the body weight-related food consumption was slightly increased in both sexes. The body weight development was slightly retarded in both sexes at 2500 ppm.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

The clinical chemical investigations revealed an increase in alkaline phosphatase activity levels at 2500 ppm, whereas the activities of ALT and AST were not affected. The cholesterol and triglyceride levels in the plasma were reduced at 2500 ppm in both sexes at most time-points. Slight changes of thyroid parameters were seen in this study at some time-points (increased thyroxine level in 2500 ppm males in week 105; increased TSH levels in 2500 ppm females in weeks 79 and 105), but there was no clear dose-response relationship and consistency over the time so that a treatment-relationship is not assumed.

Endocrine findings:

not examined

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

No treatment-related differences in the organ weights were seen at interim or final necropsy, although some deviations occurred but these were related to the body weight retardation. Isolated kidney weight changes were regarded as incidental and unrelated to treatment.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

At interim necropsy no changes were seen. At final necropsy an increased incidence of liver discoloration (females), dilation of renal pelvis (females), consistency changes of pancreas (females, only intercurrent deaths), and of uterine nodules was seen at the highest dose of 2500 ppm.
Decreased incidences of kidney findings (discoloration, surface changes in 2500 ppm males), liver findings (distinct lobulation in 2500 ppm males), and of pituitary findings (nodules in 50 and 2500 ppm females) were detected at final necropsy.

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

At 2500 ppm in animals scheduled for interim necropsy after one year an increased incidence and/or higher severity of minimal to moderate cytoplasmic vacuolation (microvesicular and/or large vacuoles) of the adrenal zona fasciculata cells, minimal to slight diffuse adrenocorticocellular hypertrophy in three males, a minimally to moderately increased portion of ovarian stroma, and slight and perhaps spurious changes in the estrus were seen.

At final necropsy the incidences of vacuolated enterocytes in the jejunum (both sexes), diffuse
hypertrophy/vacuolation of adrenal zona fasciculata cells (males), atrophy/degeneration of the olfactory epithelium in the nasal cavity (males), and of colloidal alteration in the thyroid gland (males) were increased at 2500 ppm. At 2500 ppm the incidences of several age-dependent, non-neoplastic findings were decreased in males and/or females. Reduced incidences of arteritis/periarteritis incidences were seen in the blood vessels of various organs (males), of chronic progressive nephropathy in the kidneys (reduced severity in males; reduced incidence in females), diffuse transitional cell hyperplasia in the renal pelvis of both sexes, mineralization in the kidneys
(females), squamous cell hyperplasia of the uterine cervix (at 100 ppm and above), peliosis in the adrenal cortex (females), focal hyperplasia in the adrenal medulla (females), pigment deposits in spleen and mesenteric lymph node (both sexes), and of epithelial hyperplasia in the thymus (both sexes).

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The incidences of Leydig cell adenomas and focal Leydig cell hyperplasia were increased in rats treated with 2500
ppm. In addition, the number of (metastasizing) uterine adenocarcinoma, correlating with the gross pathological
finding of uterine nodules, was increased in female intercurrent deaths at 2500 ppm. This results in an increased
number of females (2500 ppm) with malignant tumors and slightly more females with both benign and malignant
neoplasms among intercurrent deaths. The number of female intercurrent deaths with neoplasms and only benign
neoplasms was comparable between the female groups. In male intercurrent deaths the number of animals with
neoplasms, malignant tumors, benign tumors and with both benign and malignant tumors was comparable in treated
and control rats. Considering all animals intended for terminal necropsy together, the number of rats with neoplasms (both sexes),
with only benign (both sexes), with both benign and malignant (both sexes) or with only malignant neoplasms
(males) was evenly distributed among the groups. Due to the high incidence of metastasising uterine
adenocarcinoma, the number of females with malignant tumors was increased at 2500 ppm.
The pancreatic consistency changes (females, several intercurrent deaths) correlated histopathologically with
metastasis of carcinoma.
A decrease was seen with regard to pituitary gland adenomas (pars distalis, both sexes) and to fibroadenomas of the
mammary gland (females) at 2500 ppm.

Details on results:

General observations: No treatment-related clinical signs were detected by daily observation of the animals. Mortality was increased in 2500 ppm females, but with no statistical significance. Mortality of 2500 ppm males was decreased. Spirodiclofen had no effect on water consumption. At the highest dose the body weight-related food consumption was slightly increased in both sexes. The body weight development was slightly retarded in both sexes at 2500 ppm. No oculotoxic effects of the test compound were observed. The functional observational battery test performed in study week 77 and the home cage observations and observations during handling did not reveal evidence of a neurotoxic potential.
Hematology, clinical chemistry, urinalysis: The results of the hematological examinations did not provide evidence of damage to the blood, the coagulation and the blood-forming tissues. The clinical chemical investigations revealed an increase in alkaline phosphatase activity levels at 2500 ppm, whereas the activities of ALT and AST were not affected. The cholesterol and triglyceride levels in the plasma were reduced at 2500 ppm in both sexes at most time-points. Slight changes of thyroid parameters were seen in this study at some time-points (increased
thyroxine level in 2500 ppm males in week 105; increased TSH levels in 2500 ppm females in weeks 79 and 105), but there was no clear dose-response relationship and consistency over the time so that a treatment-relationship is not assumed. Urinalysis did not reveal any compound-related effect.

Gross pathology, organ weights, histopathology: At interim necropsy no changes were seen. At final necropsy an increased incidence of liver discoloration (females), dilation of renal pelvis (females), consistency changes ofpancreas (females, only intercurrent deaths), and of uterine nodules was seen at the highest dose of 2500 ppm.
Decreased incidences of kidney findings (discoloration, surface changes in 2500 ppm males), liver findings (distinct lobulation in 2500 ppm males), and of pituitary findings (nodules in 50 and 2500 ppm females) were detected at final necropsy. No treatment-related differences in the organ weights were seen at interim or final necropsy, although some deviations occurred but these were related to the body weight retardation. Isolated kidney weight changes were
regarded as incidental and unrelated to treatment.

Non-neoplastic findings:
Histopathological examination after one year of dietary exposure to Spirodiclofen did not reveal treatment-related findings in both sexes up to and including 350 ppm. At 2500 ppm in animals scheduled for interim necropsy after one year an increased incidence and/or higher severity of minimal to moderate cytoplasmic vacuolation (microvesicular and/or large vacuoles) of the adrenal zona fasciculata cells, minimal to slight diffuse adrenocorticocellular hypertrophy in three males, a minimally to moderately increased portion of ovarian stroma, and
slight and perhaps spurious changes in the estrus were seen.
Other degenerative and inflammatory changes typical for this strain and age when kept under conventional conditions were also observed, but were not regarded as treatment-related due the type, number and distribution of the findings in the individual treatment groups.
At final necropsy the incidences of vacuolated enterocytes in the jejunum (both sexes), diffuse
hypertrophy/vacuolation of adrenal zona fasciculata cells (males), atrophy/degeneration of the olfactory epithelium in the nasal cavity (males), and of colloidal alteration in the thyroid gland (males) were increased at 2500 ppm.
At 2500 ppm the incidences of several age-dependent, non-neoplastic findings were decreased in males and/or females. Reduced incidences of arteritis/periarteritis incidences were seen in the blood vessels of various organs (males), of chronic progressive nephropathy in the kidneys (reduced severity in males; reduced incidence in females), diffuse transitional cell hyperplasia in the renal pelvis of both sexes, mineralization in the kidneys (females), squamous cell hyperplasia of the uterine cervix (at 100 ppm and above), peliosis in the adrenal cortex (females), focal hyperplasia in the adrenal medulla (females), pigment deposits in spleen and mesenteric lymph node
(both sexes), and of epithelial hyperplasia in the thymus (both sexes).
Degenerative and inflammatory changes not related to the treatment were also observed in control and treatment
groups.

Neoplastic findings:
No substance-related neoplastic changes were observed in animals scheduled for interim necropsy.
The incidences of Leydig cell adenomas and focal Leydig cell hyperplasia were increased in rats treated with 2500
ppm. In addition, the number of (metastasizing) uterine adenocarcinoma, correlating with the gross pathological
finding of uterine nodules, was increased in female intercurrent deaths at 2500 ppm. This results in an increased
number of females (2500 ppm) with malignant tumors and slightly more females with both benign and malignant
neoplasms among intercurrent deaths. The number of female intercurrent deaths with neoplasms and only benign
neoplasms was comparable between the female groups. In male intercurrent deaths the number of animals with
neoplasms, malignant tumors, benign tumors and with both benign and malignant tumors was comparable in treated
and control rats.
At terminal necropsy no difference between treated and control rats (both sexes) was seen with regard to the number
of animals with neoplasms, with only malignant or with both malignant and benign tumors. At 350 ppm the number
of females with only benign neoplasms was increased as compared to the other female groups (terminal necropsy).
Since this was not dose-related (26 females at 350 ppm versus 13 at 2500 ppm) or based on the increase of a specific
tumor type, this is considered to be incidental. The number of males with only benign tumors was similar in treated
and control rats.
Considering all animals intended for terminal necropsy together, the number of rats with neoplasms (both sexes),
with only benign (both sexes), with both benign and malignant (both sexes) or with only malignant neoplasms
(males) was evenly distributed among the groups. Due to the high incidence of metastasising uterine
adenocarcinoma, the number of females with malignant tumors was increased at 2500 ppm.
The pancreatic consistency changes (females, several intercurrent deaths) correlated histopathologically with
metastasis of carcinoma.
A decrease was seen with regard to pituitary gland adenomas (pars distalis, both sexes) and to fibroadenomas of the
mammary gland (females) at 2500 ppm. With the exception of the tumors discussed in the text above all neoplasms listed in the Table 5.5.1g were evenly
distributed among the groups and were found at incidences known from previous studies with this strain. Considering the time-dependent occurrence of tumor bearing animals no dose correlated effect is obvious (see Tables 5.5.1j and 5.5.1k).

Key result

Dose descriptor:

NOAEL

Effect level:

350 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: neoplastic

histopathology: non-neoplastic

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

2 500 ppm

System:

male reproductive system

Organ:

testes

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

2 500 ppm

System:

female reproductive system

Organ:

uterus

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Chronic toxicity and carcinogenicity study in rats: Clinical chemistry (males)

Dose (ppm)	APh (U/L)	CHOL [MMOL/L]	Trigl [mmol/L]
Week 27
0	175	4.44	4.31
50	196	2.72	1.91
100	186	2.20	2.18
350	201	2.57	1.75
2500	305**	1.90	1.36
Week 53
0	203	3.15	1.73
50	199	3.90	2.13
100	180	2.91	2.10
350	213	3.81	2.09
2500	279**	2.78	1.81
Week 79
0	171	3.59	2.70
50	178	4.25	2.45
100	163	3.07	2.39
350	192	4.44	2.42
2500	277**	2.89	1.84
Week 105
0	176	4.11	2.39
50	167	4.41	2.16
100	212	3.88	2.42
350	197	3.77	2.15
2500	265**	3.29	1.57

* p  0.05, ** p  0.01

 

Chronic toxicity and carcinogenicity study in rats: Clinical chemistry (females)

Dose (ppm)	APh (U/L)	CHOL [MMOL/L]	Trigl [mmol/L]
Week 27
0	122	2.17	2.00
50	128	2.46	2.13
100	134	2.04	1.82
350	150	2.21	1.66
2500	226**	2.07	1.16*
Week 53
0	123	2.32	1.69
50	112	2.79	2.38
100	115	2.54	1.89
350	135	2.11	1.82
2500	183	2.06	1.31
Week 79
0	122	2.25	2.12
50	100	3.71	6.30
100	105	2.47	2.73
350	120	2.24	2.06
2500	226**	2.06	1.91
Week 105
0	117	2.25	2.26
50	110	3.71	2.66
100	112	2.47	2.70
350	135	2.24	2.43
2500	188**	2.06	2.06

* p  0.05, ** p  0.01

 

 

Treatment-Related Necropsy Findings - Terminal Necropsy

Dose (ppm)	0		50		100		350		2500		0		50		100		350		2500
Sex	m		m		m		m		m		f		f		f		f		f
No. investigated	50		50		50		50		50		50		50		50		50		50
UTERUS
Nodules	-		-		-		-		-		8		7		9		9		17
PANCREAS
Consistency Change/s	1*		2*		0		0		0		1*		1*		0		0		5*
KIDNEYS
Surfac Change/s PITUITARY GLAND Nodules	12   4		11   5		11   0		13   2		1   3		1*   11		4   6		6   13		4   13		0   4*

Non-Neoplastic Changes in Animals Scheduled for Interim Sacrifice  

Dose (ppm)	0	50	100	350	2500
Sex	m	m	m	m	m
No. of animals	10	10	10	10	10
Adrenal glands	10	10	10	10	10
Cytoplasmic vacuoles/small	6	7	5	3	9
Average Grading	1.3	1.0	1.0	1.0	2.2
Cytoplasmic vacuoles/large	6	5	4	5	10
Average Grading	1.5	1.4	1.3	1.2	1.5
Cortical Hypertrophy/diffuse	-	-	-	-	3
Average Grading	0	0	0	0	1.7

Non-Neoplastic Changes in Animals Scheduled for Interim Sacrifice

Dose (ppm)		50	100	350	2500
Sex		f	f	f	f
	10	10	10	10	10
OVARIES	10	10	10	10	10
- Portion/Ovarian Stroma	6	7	6	9	9
Average Grading	1.8	1.6	1.5	1.7	2.3
ESTRUS CYCLE	10	10	10	10	10
- Metestrus/ Diestrus	3	2	2	2	0

 

Non-Neoplastic Changes in animals scheduled for terminal necropsy

Sex Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	50	Females 100	350	2500
NASAL CAVITY	No.Examined	50	50	50	50	50	50	50	50	50	50
Atrophy/degeneration olfactory epithelium		13	19	15	16	25	13	19	14	13	17
TONGUE	No.Examined	50	50	50	50	50	50	50	50	50	50
Arteritis/Periarteritis		3	2	2	1	0	0	3	2	1	3
GLANDULAR STOMACH No.Examined		50	50	50	50	50	50	50	50	50	50
Arteritis/Periarteritis		3	4	4	2	0	0	0	1	1	0
JEJUNUM	No.Examined	50	50	50	50	50	50	49	50	50	50
Vacuoles enterocytes		3	0	4	3	18	5	0	0	1	17
PANCREAS	No.Examined	50	50	50	50	50	50	50	50	50	50
Arteritis/Periarteritis		6	9	3	3	0	2	2	4	4	1
KIDNEYS	No.Examined	50	50	50	50	50	50	50	50	50	50
Diffuse transitional cell hyperplasia		3	2	3	3	0	7	10	5	4	4
Chronic progressive nephropathy		46	47	46	48	45	44	44	40	41	37
Grading		2.8	2.7	2.9	2.8	2.2	2.4	2.2	2.4	2.2	2.3
Mineralization		1	1	1	1	1	13	15	19	13	3
URINARY BLADDER	No.Examined	50	50	50	50	50	50	50	49	50	50
Diffuse transitional cell hyperplasia		2	0	1	1	0	0	0	1	1	0
TESTES	No.Examined	50	50	50	50	50	-	-	-	-	-
Arteritis/Periarteritis		13	16	17	17	8
UTERINE CERVIX	No.Examined	-	-	-	-	-	50	50	50	50	50
Squamous cell hyperplasia							8	9	2	3	2
THYROID GLAND	No.Examined	50	50	50	50	50	50	50	50	50	50
Colloidal alteration		23	23	28	28	35	2	5	2	5	3
ADRENAL CORTICES	No.Examined	50	50	50	50	50	50	50	50	50	50
Diffuse hypertrophy and vacuolization		3	1	5	5	25	0	0	0	0	0
Peliosis		2	1	0	0	1	35	38	39	34	28
ADRENAL MEDULLAS	No.Examined	50	50	50	50	50	50	49	50	50	50
Focal hyperplasia		13	16	16	17	6	6	6	9	7	2
SPLEEN	No.Examined	50	50	50	50	50	50	50	50	50	50
Pigment deposits		7	9	8	9	0	21	24	26	23	6
THYMUS	No.Examined	48	50	48	50	50	49	50	49	50	48
Epithelial glandular hyperplasia		8	6	3	4	2	26	24	26	27	18
MESENT. LYMPH NODE	No.Examined	50	50	50	49	49	49	50	50	50	50
Pigment deposits		33	30	24	24	9	32	31	33	36	13

- = not available

 

 

Incidence of Neoplasms (including Intercurrent Deaths)

Sex Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	Females 50 100		350	2500
BRAIN	No. Examined	50	50	50	50	50	50	50	50	50	50
- Astrocytoma (b)		1	0	0	0	0	0	0	0	0	0
- Malignant astrocytoma (m)		0	0	0	1	1	0	0	0	0	0
- Oligodendroglioma (m)		0	0	1	0	0	0	0	0	0	0
- Granular cell tumor (b)		2	0	0	0	0	1	0	0	2	0
SPINAL CORD	No. Examined	50	50	50	50	49	50	50	50	50	50
- Astrocytoma Benign (b)		0	0	1	0	0	0	0	0	0	0
- Neurilemmoma (b)		0	0	1	0	0	0	0	0	0	0
HEART	No. Examined	50	50	50	50	50	50	50	50	50	50
- Malignant atriocaval mesothelioma (m)		0	0	0	0	0	0	0	0	1	0
- Malignant endocardial schwannoma (m)		0	1	0	0	0	0	0	0	1	0
PHARYNX	No. Examined	50	50	50	50	50	50	50	50	50	50
- Malignant Schwannoma (m)							0	1	0	0	0
GLANDULAR STOMACH No. Examined		50	50	50	50	50	50	50	50	50	50
- Leiomyosarcoma (m)		0	0	0	0	0	0	0	0	1	0
JEJUNUM	No. Examined	50	50	50	50	50	50	49	50	50	50
- Leiomyoma (b)		0	1	0	0	0	0	0	0	0	0
- Leiomyosarcoma (m)		0	0	0	0	0	0	1	0	0	1
ILEUM	No. Examined	50	50	50	50	49	50	50	50	50	50
- Adenoma (b)		0	0	1	0	0
LIVER	No. Examined	50	50	50	50	50	50	50	50	50	50
- Cholangioma (b)		0	0	1	0	0	0	0	1	0	0
- Hepatocellular carcinoma (m)		0	0	0	0	1	0	0	0	0	0
- Hepatocellular adenoma (b)		2	1	0	0	0	0	0	0	0	0
PANCREAS	No. Examined	50	50	50	50	50	50	50	50	50	50
- Mixed acinar-islet cell adenoma (b)		0	0	0	1	0	0	0	0	0	0
- Islet cell carcinoma (m)		0	0	1	0	0	0	0	0	0	0
- Islet cell adenoma (b)		0	0	2	0	0	0	0	0	0	0
KIDNEYS	No. Examined	50	50	50	50	50	50	50	50	50	50
- Liposarcoma (m)		0	0	1	0	0	0	0	1	0	0
TESTES	No. Examined	50	50	50	50	50	-	-	-	-	-
- Benign Leydig cell tumor (b)		2	1	0	4	10
OVARIES	No. Examined	-	-	-	-	-	50	50	50	50	50
- Benign luteoma (b)							1	0	0	0	0
- Benign sex cord stromal tumor (b)							0	0	2	0	0
- Benign thecoma (b)							1	2	1	0	0
- Malignant thecoma (m)							1	0	0	0	0

 

 

Incidence of Neoplasms (including Intercurrent Deaths) (continued)

Sex Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	Females 50 100		350	2500
UTERUS	No. Examined	-	-	-	-	-	50	50	50	50	50
- Adenocarcinoma (m)							4	5	3	2	14
- Adenoma (b)							0	0	0	1	0
- Adenosquamous carcinoma (m)							0	0	0	0	1
- Glandular polyp (b)							1	2	0	0	2
- Granular cell tumor (b)							0	2	1	0	0
- Malignant mixed Muellerian tumor (m)							0	0	1	0	0
- Malignant Schwannoma (m)							1	0	0	1	0
- Squamous cell carcinoma (m)							1	0	0	0	1
- Stromal cell sarcoma (m)							1	0	0	0	0
- Stromal polyp (b)							9	8	7	11	10
CERVIX	No. Examined	-	-	-	-	-	50	50	50	50	50
- Granular cell tumor (b)							0	2	0	0	0
VAGINA	No. Examined	-	-	-	-	-	49	50	50	50	49
- Squamous cell carcinoma (m)							0	1	0	0	0
PITUITARY GLAND	No. Examined	50	50	50	50	50	50	50	50	50	50
- Adenoma of pars distalis (b)		11	13	13	12	5	19	21	25	25	16
THYROID GLAND	No. Examined	50	50	50	50	50	50	50	50	50	50
- C-cell adenoma (b)		4	6	5	4	7	2	2	3	5	6
- C-cell carcinoma (m)		1	0	0	0	0	0	0	1	0	0
- Follicular cell adenoma (b)		1	1	2	2	1	0	0	0	0	1
ADRENAL CORTICES	No. Examined	50	50	50	50	50	50	50	50	50	50
- Adenoma (b)		0	1	0	0	0	0	1	0	0	0
ADRENAL MEDULLAS	No. Examined	50	50	50	50	50	50	49	50	50	50
- Benign medullary tumor (b)		6	10	6	9	5	2	0	0	0	2
- Malignant medullary tumor (m)		0	0	2	1	1	0	0	0	0	0
- Tumor/NOS (b)		0	0	0	0	0	0	0	0	0	1
HEMOLYMPHORETICULAR SYSTEM		50	50	50	50	50	50	50	50	50	50
No. Examined
- Granulocytic leukemia (m)		0	0	0	1	0	0	0	0	0	2
- Histiocytic sarcoma (m)		0	2	0	3	1	0	0	0	0	1
- Malignant fibrous histiocytoma (m)		0	1	1	1	0	0	0	0	0	0
- Malignant lymphoma (m)		0	1	0	0	1	1	1	1	1	0
SPLEEN	No. Examined	50	50	50	50	50	50	50	50	50	50
- Hemangiosarcoma (m)		1	0	0	0	0	0	0	0	0	0
THYMUS	No. Examined	48	50	48	50	50	49	50	49	50	48
- Hibernoma (m)		0	0	0	0	0	1	0	0	0	0
- Malignant thymoma (m)		1	0	0	1	0	0	0	0	0	0
- Benign thymoma (b)		0	0	3	2	0	4	1	1	2	3

 

 

Incidence of Neoplasms (including Intercurrent Deaths) (continued)

Sex Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	Females 50 100		350	2500
MESENTERIC LYMPH NODE No. Examined		50	50	50	49	49	49	50	50	50	50
- Hemangioma (b)		0	0	0	1	0	0	0	0	0	0
MAMMARY GLAND	No. Examined	50	50	50	49	50	50	50	50	50	50
- Adenocarcinoma arising in fibroadenoma (m)							1	0	0	0	0
- Adenocarcinoma (m)							1	1	2	0	2
- Adenoma (b)							0	0	1	0	0
- Fibroadenoma (b)							9	6	9	7	4
SKIN/OTHER	No. Examined	7	4	6	4	2	2	3	5	2	2
- Basal cell carcinoma (m)		1	1	0	0	0	1	0	0	0	0
- Fibrosarcoma (m)		1	0	0	0	0	0	1	0	0	0
- Hair follicle tumor (b)		0	0	1	0	1	0	0	0	0	0
- Keratoacanthoma (b)		1	0	1	0	0	0	0	0	0	0
- Maligant schwannoma (m)		1	0	0	0	1	0	0	0	0	0
- Fibroma (b)		0	0	0	0	0	0	0	0	1	1
BODY CAVITIES	No. Examined	1	1	1	1	1	5	1	3	2	5
- Malignant mesothelioma (m)		1	0	0	0	1	0	0	0	0	0
ORAL CAVITY	No. Examined	0	1	0	0	0	0	0	1	0	0
- Squamous carcinoma (m)		0	1	0	0	0	0	0	1	0	0

- = not available                              (m) = malignant             (b) = benign              NOS = not otherwise specified

Incidence of Neoplasms (Intercurrent Deaths)

Sex Males Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	Females 50 100		350	2500
BRAIN	No. Examined	19	20	14	19	9	21	18	19	15	24
- Malignant astrocytoma (m)		0	0	0	1	1	0	0	0	0	0
- Granular cell tumor (b)		0	0	0	0	0	1	0	0	1	0
HEART	No. Examined	19	20	14	19	9	21	18	19	15	24
- Malignant endocardial schwannoma (m)		0	1	0	0	0	0	0	0	0	0
- Malignant atriocaval mesothelioma (m)		0	0	0	0	0	0	0	0	1	0
PHARYNX	No. Examined	19	20	14	19	9	21	18	19	15	24
- Malignant Schwannoma (m)		0	0	0	0	0	0	1	0	0	0
JEJUNUM	No. Examined	19	20	14	19	9	21	17	19	15	24
- Leiomyosarcoma (m)		0	0	0	0	0	0	1	0	0	0
LIVER	No. Examined	19	20	14	19	9	21	18	19	15	24
- Cholangioma (b)		0	0	1	0	0	0	0	1	0	0
- Hepatocellular adenoma (b)		1	0	0	0	0	0	0	0	0	0
PANCREAS	No. Examined	19	20	14	19	9	21	18	19	15	24
- Mixed acinar-islet cell adenoma (b)		0	0	0	1	0	0	0	0	0	0
- Islet cell carcinoma (m)		0	0	1	0	0	0	0	0	0	0
KIDNEYS	No. Examined	19	20	14	19	9	21	18	19	15	24
- Liposarcoma (m)		0	0	0	0	0	0	0	1	0	0
TESTES	No. Examined	19	20	14	19	9	-	-	-	-	-
- Benign Leydig cell tumor (b)		0	0	0	0	1
OVARIES	No. Examined	-	-	-	-	-	21	18	19	15	24
- Benign luteoma (b)							1	0	0	0	0
- Benign sex cord stromal tumor (b)							0	0	1	0	0
- Benign thecoma (b)							0	0	1	0	0
UTERUS	No. Examined	-	-	-	-	-	21	18	19	15	24
- Adenocarcinoma (m)							2	2	1	2	11
- Adenosquamous carcinoma (m)							0	0	0	0	1
- Glandular polyp (b)							1	1	0	0	0
- Granular cell tumor (b)							0	1	1	0	0
- Malignant Schwannoma (m)							1	0	0	1	0
- Squamous cell carcinoma (m)							1	0	0	0	1
- Stromal cell sarcoma (m)							1	0	0	0	0
- Stromal polyp (b)							5	3	2	4	3
CERVIX	No. Examined	-	-	-	-	-	21	18	19	15	24
- Granular cell tumor (b)							0	1	0	0	0
VAGINA	No. Examined	-	-	-	-	-	20	18	19	15	23
- Squamous cell carcinoma (m)							0	1	0	0	0
PITUITARY GLAND	No. Examined	19	20	14	19	9	21	18	19	15	24
- Adenoma of pars distalis (b)		4	4	2	2	2	10	9	9	7	7

 

 

Incidence of Neoplasms (Intercurrent Deaths) (continued)

Sex Males Dose (ppm) Organ/ Findings		0	50	Males 100	350	2500	0	Females 50 100		350	2500
THYROID GLAND	No. Examined	19	20	14	19	9	21	18	19	15	24
- C-cell adenoma (b)		0	2	1	0	0	1	0	0	1	2
- C-cell carcinoma (m)		1	0	0	0	0	0	0	1	0	0
- Follicular cell adenoma (b)		0	0	0	0	0	0	0	0	0	1
ADRENAL CORTICES	No. Examined	19	20	14	19	9	21	18	19	15	24
- Adenoma (b)		0	0	0	0	0	0	1	0	0	0
ADRENAL MEDULLAS	No. Examined	19	20	14	19	9	21	18	19	15	24
- Benign medullary tumor (b)		1	3	3	5	1	0	0	0	0	2
- Malignant medullary tumor (m)		0	0	1	0	0	0	0	0	0	0
- Tumor/N0S (b)		0	0	0	0	0	0	0	0	0	1
HEMOLYMPHORETICULAR SYSTEM		19	20	14	19	9	21	18	19	15	24
No. Examined
- Granulocytic leukemia (m)		0	0	0	1	0	0	0	0	0	2
- Histiocytic sarcoma (m)		0	1	0	2	1	0	0	0	0	1
- Malignant fibrous histiocytoma (m)		0	1	1	1	0	0	0	0	0	0
- Malignant lymphoma (m)		0	1	0	0	1	1	1	1	1	0
THYMUS	No. Examined	18	20	13	19	9	21	18	18	15	22
- Hibernoma (m)		0	0	0	0	0	1	0	0	0	0
- Benign thymoma (b)		0	0	1	1	0	3	0	0	0	2
MESENTERIC LYMPH NODE No. Examined		19	20	14	19	9	21	18	19	15	24
- Hemangioma (b)		0	0	0	1	0	0	0	0	0	0
MAMMARY GLAND	No. Examined	19	20	14	18	9	21	18	19	15	24
- Adenocarcinoma (m)		0	0	0	0	0	0	1	0	0	2
- Fibroadenoma (b)		0	0	0	0	0	3	3	7	1	2
SKIN/OTHER	No. Examined	4	3	3	2	1	2	1	4	0	1
- Basal cell carcinoma (m)		1	1	0	0	0	1	0	0	0	0
- Fibrosarcoma (m)		1	0	0	0	0	0	1	0	0	0
- Fibroma (b)		0	0	0	0	0	0	0	0	0	1
- Maligant schwannoma (m)		1	0	0	0	1	0	0	0	0	0
BODY CAVITIES	No. Examined	1	0	1	1	0	5	1	1	2	5
- Malignant mesothelioma (m)		1	0	0	0	0	0	0	0	0	0
ORAL CAVITY	No. Examined	0	1	0	0	0	0	0	1	0	0
- Squamous carcinoma (m)		0	1	0	0	0	0	0	1	0	0

ne = not examined                  (m) = malignant(b) = benign NOS = not otherwise specified ot available

 

 

Table 5.5.1i: Rats Intended for Terminal Necropsy with Benign and/or Malignant Tumors

Sex	Males	Females
Dose (ppm)	0    50   100 350 2500	0    50   100 350 2500
n	50   50   50   50   50	50   50   50   50   50
	Animals Deceased During Treatment
Number of Animals Examined	19   20   14   19    9	21   18   19   15    24
Animals with Neoplasms	8   11    9   12    6	19   16   14   14    22
Animals with only Benign Neoplasms	3    5    6    7    2	11    9    9    9     6
Animals with only Malignant Neoplasms	2    3    2    5    3	2    1    1    2     7
Animals with both Neoplasms	3    3    1    0    1	6    6    4    3     9
	Terminal Necropsy
Number of Animals Examined	31   30   36   31   41	29   32   31   35    26
Animals with Neoplasms	17   16   24   18   21	17   20   22   28    17
Animals with only Benign Neoplasms	15   15   21   15   19	12   17   17   26    13
Animals with only Malignant Neoplasms	1    0    2    1    1	0    1    2    1     1
Animals with both Neoplasms	1    1    1    2    1	5    2    3    1     3
	All Animals Intended for Terminal Necropsy
Number of Animals Examined	50   50   50   50   50	50   50   50   50    50
Animals with Neoplasms	25   27   33   30   27	36   36   36   42    39
Animals with only Benign Neoplasms	18   20   27   22   21	23   26   26   35    19
Animals with only Malignant Neoplasms	3    3    4    6    4	2    2    3    3     8
Animals with both Neoplasms	4    4    2    2    2	11    8    7    4    12

 

 

Table 5.5.1j: Tumor Bearing Animals Scheduled for Interim Necropsy

Dose (ppm)		0	50	100	350	2500	0	50	100	350	2500
Sex		m	m	m	m	m	f	f	f	f	f
n		10	10	10	10	10	10	10	10	10	10
Weeks
1 - 13		0	0	0	0	0	0	0	0	0	0
14 - 26		0	0	0	0	0	0	0	0	0	0
27 - 39		0	0	0	0	0	0	0	0	0	0
40 - 52		0	0	0	0	1	0	0	0	0	0
53 - 54		0	0	0	0	0	2	1	0	1	1
1 -	54	0	0	0	0	1	2	1	0	1	1

 

 

Table 5.5.1k: Tumor Bearing Animals Scheduled for Terminal Necropsy

Dose (ppm)		0	50	100	350	2500	0	50	100	350	2500
Sex		m	m	m	m	m	f	f	f	f	f
n		50	50	50	50	50	50	50	50	50	50
Weeks
1 - 13		0	0	0	0	0	0	0	0	0	0
14 - 26		0	0	0	0	0	0	0	0	0	0
27 - 39		1	1	0	0	0	0	0	0	0	0
40 - 52		1	0	0	0	1	1	0	0	1	0
53 - 65		2	0	0	0	0	0	0	0	2	2
66 - 78		1	1	0	1	2	1	1	3	1	3
79 - 91		1	1	2	5	2	4	9	3	3	7
92 - 104		2	6	6	3	1	12	5	8	7	9
105 - 109		17	18	25	21	21	18	21	22	28	18
1	- 109	25	27	33	30	27	36	36	36	42	39

 

Conclusions:

There was some evidence of carcinogenicity in this study; the incidences of uterine adenocarcinoma in females and Leydig cell adenoma in males were increased at the highest dietary concentration of 2500 ppm.

Executive summary:

In this combined chronic toxicity/carcinogenicity study performed to OECD 453, spirodiclofen was administered in the diet to groups of Wistar rats (50/sex) at concentrations of 0 (controls), 50, 100, 350 and 2500 ppm over a period of up to 108 weeks.  In addition, 10 rats/se/group were treated with the same dietary concentrations and sacrificed after a treatment period of about 1 year.  Mean achieved intakes over the entire study period were 0, 2.04, 4.11, 14.72 and 110.14 mg/kg bw/d in males; 0, 2.87, 5.93, 19.88 and 152.90 mg/kg bw/d in females, respectively.  No treatment-related clinical signs were detected by daily observation of the animals.  Mortality was increased in 2500 ppm females, but with no statistical significance; mortality of 2500 ppm males was decreased.  There was no effect of treatment on water consumption.  At the highest dose level, food consumption was slightly increased in both sexes.  Body weight development was slightly retarded in both sexes at 2500 ppm.  Ophthalmoscopy did not reveal any treatment-related findings.  FOB did not reveal evidence of neurotoxic potential.  The results of the haematological examinations did not provide evidence of adverse effects.  Clinical chemistry revealed an increase in alkaline phosphatase activity at 2500 ppm; ALT and AST activities were not affected.  Cholesterol and triglyceride levels were reduced at 2500 ppm in both sexes at most timepoints.  Slight changes in thyroid parameters were seen in this study at some time-points (increased thyroxine level in 2500 ppm males at Week 105; increased TSH levels in 2500 ppm females at Weeks 79 and 105), but there was no clear dose-response relationship and consistency over the time so that a treatment-relationship is not assumed. Urinalysis did not reveal any treatment-related effect.  At interim necropsy no changes were seen.  At terminal necropsy, an increased incidence of liver discoloration (females), dilation of renal pelvis (females), consistency changes of pancreas (females, only intercurrent deaths), and of uterine nodules was seen at the highest dose of 2500 ppm.  Decreased incidences of kidney findings (discoloration, surface changes in 2500 ppm males), liver findings (distinct lobulation in 2500 ppm males), and of pituitary findings (nodules in 50 and 2500 ppm females) were detected at final necropsy. No treatment-related differences in the organ weights were seen at interim or final necropsy; some deviations occurred but these were related to the body weight retardation. Isolated kidney weight changes were regarded as incidental and unrelated to treatment.  Histopathological examination after one year did not reveal treatment-related findings in either sex up to and including 350 ppm. At 2500 ppm in animals scheduled for interim necropsy after one year an increased incidence and/or higher severity of minimal to moderate cytoplasmic vacuolation (microvesicular and/or large vacuoles) of the adrenal zona fasciculata cells, minimal to slight diffuse adrenocorticocellular hypertrophy in three males, a minimally to moderately increased portion of ovarian stroma, and slight and perhaps spurious changes in the estrus were seen.  Other degenerative and inflammatory changes typical for this strain and age when kept under conventional conditions were also observed, but were not regarded as treatment-related due the type, number and distribution of the findings in the individual treatment groups.  At final necropsy the incidences of vacuolated enterocytes in the jejunum (both sexes), diffuse hypertrophy/ vacuolation of adrenal zona fasciculata cells (males), atrophy/ degeneration of the olfactory epithelium in the nasal cavity (males), and of colloidal alteration in the thyroid gland (males) were increased at 2500 ppm.  At 2500 ppm the incidences of several age-dependent, non-neoplastic findings were decreased in males and/or females. Reduced incidences of arteritis/periarteritis incidences were seen in the blood vessels of various organs (males), of chronic progressive nephropathy in the kidneys (reduced severity in males; reduced incidence in females), diffuse transitional cell hyperplasia in the renal pelvis of both sexes, mineralization in the kidneys (females), squamous cell hyperplasia of the uterine cervix (at 100 ppm and above), peliosis in the adrenal cortex

(females), focal hyperplasia in the adrenal medulla (females), pigment deposits in spleen and mesenteric lymph node (both sexes), and of epithelial hyperplasia in the thymus (both sexes).  Degenerative and inflammatory changes not related to the treatment were also observed in control and treatment groups. No substance-related neoplastic changes were observed in animals scheduled for interim necropsy. The incidences of Leydig cell adenomas and focal Leydig cell hyperplasia were increased in rats treated with 2500 ppm. In addition, the number of (metastasizing) uterine adenocarcinoma, correlating with the gross pathological finding of uterine nodules, was increased in female intercurrent deaths at 2500 ppm. This results in an increased number of females (2500 ppm) with malignant tumours and slightly more females with both benign and malignant neoplasms among intercurrent deaths. The number of female intercurrent deaths with neoplasms and only benign neoplasms was comparable between the female groups. In male intercurrent deaths the number of animals with neoplasms, malignant tumours, benign tumours and with both benign and malignant tumours was comparable in treated and control rats.  At terminal necropsy no difference between treated and control rats (both sexes) was seen with regard to the number of animals with neoplasms, with only malignant or with both malignant and benign tumours. At 350 ppm the number of females with only benign neoplasms was increased as compared to the other female groups (terminal necropsy). Since this was not dose-related (26 females at 350 ppm versus 13 at 2500 ppm) or based on the increase of a specific tumour type, this is considered to be incidental. The number of males with only benign tumours was similar in treated and control rats. Considering all animals intended for terminal necropsy together, the number of rats with neoplasms (both sexes), with only benign (both sexes), with both benign and malignant (both sexes) or with only malignant neoplasms (males) was evenly distributed among the groups. Due to the high incidence of metastasising uterine adenocarcinoma, the number of females with malignant tumours was increased at 2500 ppm.  The pancreatic consistency changes (females, several intercurrent deaths) correlated histopathologically with metastasis of carcinoma. A decrease was seen with regard to pituitary gland adenomas (pars distalis, both sexes) and to fibroadenomas of the mammary gland (females) at 2500 ppm. With the exception of the tumours discussed above, all neoplasms were evenly distributed among the groups and were found at incidences known from previous studies with this strain. Considering the time-dependent occurrence of tumour bearing animals no dose correlated effect is obvious. The NOAEL of this study was 350 ppm (equivalent to 14.72 mg/kg bw/d in males; 19.88 mg/kg bw/d) in females. This was based on effects on the adrenals (vacuolation) and on some neoplastic (uterine adenocarcinomas, Leydig cell adenomas) and non-neoplastic findings at the highest dose of 2500 ppm. Due to these findings, the body weight effects and the changes of clinical chemistry parameters, the highest dose of 2500 ppm has to be regarded as an MTD.

Reference 2

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPP 83-2 (Carcinogenicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: TSCA 798.3300

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japan MAFF: Oncogenicity Study.

Deviations:

no

GLP compliance:

yes

Remarks:

Deviations: The INSTEM Computer Systems version C8 does not retain old and new feeder weights used to calculate food consumption during the feeder top-up procedure (FILLUP).

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

spirodiclofen was administered to CD-1 mice (50 males and 50 females per dose), at dose levels of 0, 25, 3500 and 7000 ppm in the diet over a period of approximately 18 months. The mean daily test compound intake was 0, 4.1, 610, and 1216 mg/kg bw in males and 0, 5.1, 722, and 1495 mg/kg bw in females, respectively. The dose levels for this study were established based on a range-finding study in which CD-1 mice were administered doses of spirodiclofen of 25, 50, 500, 2500 and 7000 ppm for 6 weeks via the diet.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

18 months

Frequency of treatment:

Test substance was administered within the diet, which was available ad libitum. The frequency of treatment is not applicable as food was replenished as the test animals consumed it. Due to this, the frequency of treatment can be considered daily as the test subjects were exposed to the test substance at every meal.

Dose / conc.:

0 ppm

Remarks:

No test substance - diet only

Dose / conc.:

25 ppm

Dose / conc.:

3 500 ppm

Dose / conc.:

7 000 ppm

No. of animals per sex per dose:

50 males and 50 females per dose. 100 total at each dose level.

Control animals:

yes, plain diet

Clinical signs:

no effects observed

Description (incidence and severity):

No clinical signs or a treatment-related increase in mortality were noted. Food intake and
body weight gain were also not affected at any dose.

Haematological findings:

no effects observed

Description (incidence and severity):

No treatment-related changes were detected at 12 and 18 months.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The adrenal and liver weights were increased and the kidney weights decreased at 3500 and 7000 ppm in both sexes. The testes weights were increased in males at 3500 and 7000 ppm. Histopathological examination revealed pigmentation and vacuolation in the adrenals at 3500 and 7000 ppm. Interstitial cell hypertrophy and hyperplasia was seen in the testes of 3500 and 7000 ppm males. Hepatocytomegaly was observed in 3500 and 7000 ppm males, and liver adenoma and liver carcinoma incidences were increased in 3500 ppm males and females and in 7000 ppm males.

Gross pathological findings:

no effects observed

Description (incidence and severity):

Final necropsy did not reveal any treatment-related findings.

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

The total rate of the animals with benign tumors was slightly increased in the 7000 ppm males, which is due to the increased incidence of liver adenomas in this group. However, the total tumor incidence was not affected by the treatment. In the animals, which were found dead or were sacrificed in moribund, no increased tumor incidences were seen so that the time of tumor occurrence was not increased.

Key result

Dose descriptor:

NOAEL

Effect level:

25 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

histopathology: non-neoplastic

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

3 500 ppm

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Critical effects observed:

yes

Lowest effective dose / conc.:

3 500 ppm

System:

endocrine system

Organ:

adrenal glands

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Table 1 - Oncogenicity study in male mice: Absolute Organ Weights (mg)

Dose (ppm)	0	25	3500	7000
Liver	2303	2421	2593*	2720*
Adrenals	8	8	12*	15*
Kidneys	937	960	787*	711*
Testes	203	204	225	242*

* p ≤ 0.05, ** p ≤ 0.01

 

Table 2 - Oncogenicity study in female mice: Absolute Organ Weights (mg)

Dose (ppm)	0	25	3500	7000
Liver	2254	2149	2315	2566*
Adrenals	13	13	19*	23*
Kidneys	679	658	558*	530*

* p ≤ 0.05, ** p ≤ 0.01

 

Table 3 - Oncogenicity study in male mice: Relative Organ Weights (mg/100 g)

Dose (ppm)	0	25	3500	7000
Liver	5797	6051	6818*	7108*
Adrenals	22	21	31*	40*
Kidneys	2365	2402	2062*	1861*
Testes	515	513	593*	636*

* p ≤ 0.05, ** p ≤ 0.01

 

Table 4 - Oncogenicity study in female mice: Relative Organ Weights (mg/100 g)

Dose (ppm)	0	25	3500	7000
Liver	6179	6063	6704	7454*
Adrenals	36	38	54*	66*
Kidneys	1864	1858	1627*	1542*

* p ≤ 0.05, ** p ≤ 0.01

 

Table 5 - Oncogenicity study in mice: Non-neoplastic changes in animals scheduled for final necropsy

Dose (ppm)	0	25	3500	7000	0	25	3500	7000
Gender	M	M	M	M	F	F	F	F
LIVER (n)	50	50	50	50	50	50	50	50
Hepatocytomegaly	2	6	17*	21*	0	0	0	1
ADRENALS (n)	50	49	50	49	50	49	50	50
Vacuolization	0	0	31*	37*	1	6	49*	48*
Pigmentation	7	5	11	27*	11	20*	45*	42*

* p ≤ 0.05, ** p ≤ 0.01

 

Table 6 - Oncogenicity study in mice: Neoplastic changes in animals scheduled for final necropsy

Dose (ppm)	0	25	3500	7000	0	25	3500	7000
Gender	M	M	M	M	F	F	F	F
LIVER (n)	50	50	50	50	50	50	50	50
hepatocell. adenoma (b)	0	0	5	6	0	0	3	1
hepatocell. carcinoma (m)	1	1	3	5	0	0	2	2

m = malign, b = benign

 

Table 7 - Oncogenicity study in mice: Number of animals (unscheduled sacrifice + found dead) with tumors

Dose (ppm)	0	25	3500	7000	0	25	3500	7000
Gender	M	M	M	M	F	F	F	F
n	12	11	10	14	12	12	12	14
benign tumour	3	0	0	2	2	0	0	4
malignant tumour	2	5	1	2	9	7	6	5
total no. any type	5	5	1	4	9	7	6	9

 

Table 8 - Oncogenicity study in mice: Number of animals (unscheduled + terminal) with tumors

Dose (ppm)	0	25	3500	7000	0	25	3500	7000
Gender	M	M	M	M	F	F	F	F
n	50	50	50	50	50	50	50	50
benign tumour	11	16	9	10	12	13	10	13
malignant tumour	10	12	5	9	21	20	17	17
total no. any type	19	25	13	17	27	30	27	26

 

Table 9 - Oncogenicity study in mice: Number of tumors

Dose (ppm)	0	25	3500	7000	0	25	3500	7000
Gender	M	M	M	M	F	F	F	F
n	50	50	50	50	50	50	50	50
benign tumour	11	17	11	10	16	15	12	15
malignant tumour	11	13	5	9	21	23	19	18

Conclusions:

A NOAEL was established at 25 ppm for both sexes which is equivalent to 4.1 and 5.1 mg/kg bw
in males and females, respectively. This was based on liver (hepatocytomegaly, hepatocellular
adenomas and carcinomas) and adrenal effects (vacuolization) at 3500 ppm. The total tumour
incidence and the time of occurrence and type of tumours observed in this study do not indicate a
primary oncogenic potential of spirodiclofen.

Executive summary:

In a carcinogenicity study performed to OECD 451, spirodiclofen was administered to groups of CD-1 mice (50/sex) at dietary concentrations of 0, 25, 3500 and 7000 ppm for up to 18 months. The mean achieved intake was 0, 4.1, 610 and 1216 mg/kg bw in males; 0, 5.1, 722, and 1495 mg/kg bw/d in females, respectively. No clinical signs or a treatment-related increase in mortality were noted. Food intake and body weight gain were not affected at any dose.  No treatment-related haematological changes were detected at 12 and 18 months.  Final necropsy did not reveal any treatment-related findings.  The adrenal and liver weights were increased and the kidney weights decreased at 3500 and 7000 ppm in both sexes. The testes weights were increased in males at 3500 and 7000 ppm. Histopathological examination revealed pigmentation and vacuolation in the adrenals at 3500 and 7000 ppm. Interstitial cell hypertrophy and hyperplasia was seen in the testes of 3500 and 7000 ppm males. Hepatocytomegaly was observed in 3500 and 7000 ppm males, and liver adenoma and liver carcinoma incidences were increased in 3500 ppm males and females and in 7000 ppm males.  The total rate of the animals with benign tumours was slightly increased in the 7000 ppm  males, which is due to the increased incidence of liver adenomas in this group. However, the total tumour incidence was not affected by the treatment. In the animals, which were found dead or had to be sacrificed moribundly, no increased tumour incidences were seen so that the time of tumour occurrence was not increased.  A NOAEL was established at 25 ppm for both sexes which is equivalent to 4.1 and 5.1 mg/kg bw/d in males and females, respectively. This was based on liver (hepatocytomegaly, hepatocellular adenomas and carcinomas) and adrenal effects (vacuolization) at 3500 ppm.  The total tumour incidence and the time of occurrence and type of tumours observed in this study do not indicate a primary oncogenic potential.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEL

Study duration:

chronic

Species:

mouse

Quality of whole database:

GLP- and guideline-compliant studies of chronic toxicity/carcinogenicity in the rat and mouse are available for spirodiclofen.

System:

endocrine system

Organ:

liver

testes

uterus

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

Spirodiclofen has a harmonised classification for carcinogenicity in Category 1B.  Based on the available mutagenicity tests, RAC concluded that the mechanism(s) for the carcinogenic effect of spirodiclofen was probably non-genotoxic.  In the mouse study, RAC concluded that the combined frequency of hepatocellular tumours (hepatocellular adenoma and carcinoma) was significantly increased over controls in 3500 and 7000 ppm males and in 3500 ppm females.  In the rat study, RAC concluded that the frequency of benign Leydig cell tumours was markedly increased at 2500 ppm.  In the uterus of female rats, adenocarcinomas were increased at 2500 ppm.  RAC concluded that classification for carcinogenicity in Cat 1B was appropriate on the basis of a combination of benign and malignant metastatic neoplasms in two or more species.