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Key value for chemical safety assessment

Effects on fertility

Description of key information

NOAEL = 830 mg/kg bw/day; no adverse effects on reproductive performance in rats, two-generation study (OECD 416, Osterburg 1991)

Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
26 September 1989 - 5 October 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Version / remarks:
1983 (current guideline adopted 2001)
Deviations:
yes
Remarks:
(does not meet current guideline specification)
Qualifier:
according to guideline
Guideline:
EPA OPP 83-4 (Reproduction and Fertility Effects)
Version / remarks:
1982 (current guideline adopted 1998)
Deviations:
yes
Remarks:
(does not meet current guideline specification)
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source of animals: Charles River, 8741 Sulzfeld, Germany
- Strain: Spraque-Dawley rats, strain Crl:CD (SD)BR
- Age at study initiation: P generation - approx. 6 weeks old
- Weight at study initiation: P generation - males 162-226 g, females 134-181 g
- Housing: individual in solid floor macrolone cages with stainless steel lids except during mating (one male with one female) and during lactation (one female with litter). Autoclaved sawdust bedding.
- Diet: powdered Ssniff R 10 ad libitum
- Source of feed: Ssniff Spezialdiäten GmbH, 4770 Soest, Germany
- Water: tap water in plastic bottles ad libitum
- Acclimation period: P generation 18 days

ENVIRONMENTAL CONDITIONS
- Temperature: 19-25°C
- Humidity: 30-70%
- Photoperiod: 12 hrs dark / 12 hrs light

Route of administration:
oral: feed
Vehicle:
other: diet
Details on exposure:
DIET PREPARATION
- The test substance was milled to a standardised particle size and admixed to the powdered diet. Fresh preparations were made monthly


Details on mating procedure:
One male was housed with one female from the same group for up to three weeks. After 2 weeks, females with no evidence of mating were paired with a proven male from the same group. Mating was confirmed by the presence of sperm in a vaginal smear or a vaginal plug and designated day 0 of gestation. After successful mating, females and males were caged individually. Sibling pairing was avoided.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
All batches of test diet made were analysed for achieved concentration and homogeneity. Stability was confirmed for the period of use and storage conditions. Satisfactory results were obtained. Analysis was by HPLC.
Duration of treatment / exposure:
From the start of the P generation through to necropsy of individual animals - F1 and F2a.
Frequency of treatment:
Continuous
Details on study schedule:
- Pre-mating period P Generation: 100 days
- Selection of F parents from F1 generation at 21 days of age
- F1 parental animals not mated until 100 days after weaning
Dose / conc.:
0 ppm
Remarks:
Negative control
Dose / conc.:
50 ppm
Dose / conc.:
500 ppm
Dose / conc.:
5 000 ppm
Dose / conc.:
10 000 ppm
No. of animals per sex per dose:
25
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: on basis of preliminary study
- Rationale for animal assignment: P generation by stratified randomisation based on body weight and the use randomisation tables; F1 generation selected by stratified use of randomly drawn cards
Positive control:
No
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: once weekly for males and females during the pre-mating and mating periods; for females on days 0, 7, 14 and 20 post coitum and days 1, 4, 7, 14 and 21 post partum

FOOD CONSUMPTION:
- Time schedule for examinations: twice weekly for males and females during the pre-mating period; for females on days 0-3, 3-7, 7-10, 10-14, 14-20 post coitum and days 1-4, 4-7, 7-10, 10-12, 14-15, 15-16, 16-17, 17-18, 18-19, 19-20, 20-21 post partum. Food consumption was calculated as mean daily food consumption per measuring period
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

OTHER:
- Date of mating
- Date of parturition
- Duration of gestation
- Abnormalities of nesting or nursing behaviour

Oestrous cyclicity (parental animals):
Not recorded
Sperm parameters (parental animals):
Not recorded
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes to 8 pups (4 males and 4 females where possible)

PARAMETERS EXAMINED
- F1 and F2 offspring: number and sex of pups, live births, postnatal mortality, clinical condition, body weight, pinna unfolding, tooth eruption, eye opening, pupillary reflex and auditory response

GROSS EXAMINATION OF DEAD PUPS:
- yes, for external and visceral abnormalities
Postmortem examinations (parental animals):
Parental males were necropsied after mating, females after weaning. Successfully mated females which failed to produce a litter were necropsied on day 26 post coitum. All parental animals were examined for gross pathological changes. Uteri were immersed in 10% ammonium sulfide to reveal evidence of implantation. The number of implantations was recorded.
The following tissues were sampled and fixed from all F0 and F1 adult animals: bladder, cervix, coagulating gland, epididymides, kidneys, liver, ovaries, pituitary, prostate, seminal vesicles, testes, uterus, vagina and macroscopically altered organs. Histopathology was conducted in controls and top dose group animals. Epididymides, kidneys, liver and testes were weighed before fixation. In addition, the kidneys of group 4 animals were examined histologically.
Postmortem examinations (offspring):
Non-selected pups from F1 and F2 litters were necropsied after weaning.
Statistics:
Statistical analyses used the SAS software package release 6.03.
Analysis of variance with one factor treatment followed by the Student-Newman-Keuls test for multiple group comparisons: body weight, body weight gain, litter weight, organ weights, food consumption.
Analysis of variance with one factor treatment based on taking the ranks of the variables and followed by the Student-Newman-Keuls test for multiple group comparisons: mating performance, duration of gestation, mean pup weight, pup number, live birth index, viability indices, weaning index, pinna unfolding, hair growth, incisor eruption, eye opening.
Reproductive indices:
For both generations the parental reproductive performance was assessed and the following calculated: mating performance, insemination index, fecundity index, fertility index, gestation index
Offspring viability indices:
Live birth index, pup viability index, weaning index and sex ratio
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Five P females with fur staining
Mortality:
no mortality observed
Description (incidence):
No effects in P animals
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The males and females of the P and F1 generations given 10000 ppm had slightly lower body weights during the premating period.
Food consumption and compound intake (if feeding study):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
10 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reproductive performance
Remarks on result:
not determinable due to absence of adverse toxic effects
Remarks:
highest dose tested equivalent to 830 mg/kg bw/day
Key result
Dose descriptor:
NOAEL
Remarks:
toxicity
Effect level:
5 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
Remarks on result:
other: Equivalent to 420 mg/kg bw/day.
Clinical signs:
no effects observed
Mortality:
mortality observed, treatment-related
Description (incidence):
Four P1 males given 10000 ppm were found dead
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The males and females of the P1 generation given 10000 ppm had slightly lower body weights during the premating period.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Slightly lower food consumption in P1 generation males and females.
Food efficiency:
not examined
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Changes in the kidneys and urinary bladder in particular were considered to be related to treatment with 10000 ppm in P1 males and females. Groups given 50, 500 or 5000 ppm were unaffected.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Changes in the kidneys and urinary bladder were considered to be related to treatment with 10000 ppm in P1 males and females. There were a variety of inflammatory changes, namely moderate to marked subacute to chronic interstitial pyelonephritis associated with changes such as hyaline casts, tubular and pelvis dilatation associated with parenchymal atrophy, pelvis lithiasis and signs of hyperplastic response such as proliferation and metaplasia of the urothelium. Groups given 50, 500 or 5000 ppm were unaffected.

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
10 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reproductive performance
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Dose descriptor:
NOAEL
Effect level:
5 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
gross pathology
histopathology: non-neoplastic
Clinical signs:
no effects observed
Mortality / viability:
mortality observed, non-treatment-related
Description (incidence and severity):
During the lactation period, pup losses were observed in all groups and no treatment-related effect was detected.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean pup weight of the F1a pups was significantly reduced at weaning on day 21 post partum.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
no effects observed
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Macroscopic examination revealed a high incidence of changes in the kidneys, particularly dilatation of the renal pelvis, in the F1a pups; groups treated at 50, 500 and 5000 ppm remained unaffected.
Histopathological findings:
not examined
Other effects:
no effects observed
Description (incidence and severity):
Treatment with cloquintocet-mexyl had no effect on the nature or incidence of malformations observed in the F1a pups.
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
There were no treatment-related effects on the physical development (incisor eruption, pinna unfolding, eye opening) of the F1a pups or on the outcome of the functional tests (pupillary reflex, auditory response) on either generation.
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
10 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
viability
sexual maturation
mortality
other: Nature and incidence of malformations
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
5 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
gross pathology
histopathology: non-neoplastic
Key result
Critical effects observed:
no
Clinical signs:
no effects observed
Mortality / viability:
mortality observed, non-treatment-related
Description (incidence and severity):
During the lactation period, pup losses were observed in all groups and no treatment-related effect was detected.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean pup weight of the F2a pups was significantly reduced at weaning on day 21 post partum.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
A low incidence of F2a pups had dilatation of the renal pelvis not clearly treatment-related.
Other effects:
no effects observed
Description (incidence and severity):
Treatment with cloquintocet-mexyl had no effect on the nature or incidence of malformations observed in the F2a pups.
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
There were no treatment-related effects on the physical development (incisor eruption, pinna unfolding, eye opening) of the F2a pups or on the outcome of the functional tests (pupillary reflex, auditory response) on either generation.
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F2a
Effect level:
5 000 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
Key result
Critical effects observed:
no
Key result
Reproductive effects observed:
no

Table 1 Test Substance Intake During The Pre-Mating Period (corrected means – mg/kg/day)

 

Males

Dietary concentration (ppm)

Females

Dietary concentration (ppm)

P Generation

50

500

5000

10000

P Generation

50

500

5000

10000

Week 1

5.2

51.2

555.4

1066.9

Week 1

5.1

49.7

548.8

1086.0

Week 14

2.8

28.0

277.9

565.9

Week 14

3.7

35.9

369.9

732.4

Mean intake

3.5

35.3

370.7

721.6

Mean intake

4.2

40.7

422.8

846.9

Overall mean intake for males and females

3.9

38.0

396.8

784.3

F1 Generation

F1 Generation

Week 1

6.2

66.6

627.1

1212.1

Week 1

6.6

69.1

673.0

1274.9

Week 14

2.9

30.7

300.9

613.3

Week 14

3.7

38.4

372.2

735.4

Mean intake

4.0

41.1

408.7

819.5

Mean intake

4.6

48.3

487.3

945.6

Overall mean intake for males and females

4.3

44.7

448.0

882.6

Overall mean intake for males and females

P + F1 generations

4.1

41

422

833

 

Table 2 Group Mean Pup Body Weight (g)

 

F1a pup

Weight (g)

Dietary concentration (ppm)

F2a pup

Weight (g)

Dietary concentration (ppm)

0

50

500

5000

10000

0

50

500

5000

10000

Day 1

6.1

5.9

6.1

6.1

6.2

Day 1

6.2

6.0

5.9

6.1

6.3

Day 4

7.5

7.1

7.3

7.6

7.6

Day 4

8.0

7.6

7.3

7.6

7.9

Day 7

11.4

10.3

10.8

11.4

10.9

Day 7

11.6

11.4

10.3

10.6

11.2

Day 14

24.5

21.6

22.9

25.2

21.8

Day 14

24.3

24.6

22.9

24.7

23.8

Day 21

41.0

36.6

38.3

39.6

34.9*

Day 21

41.8

41.0

40.3

40.0

37.7*

 P<0.05 * statistically significant difference from control

Table 3 Incidence of pups with renal pelvic dilatation

 

F1a pups

Dietary concentration (ppm)

F2a pups

Dietary concentration (ppm)

0

50

500

5000

10000

0

50

500

5000

10000

No. Examined

228

253

232

237

206

No. Examined

197

217

185

231

213

Unilateral

1

0

2

0

10

Unilateral

1

1

1

2

1

Bilateral

1

1

3

0

20

Bilateral

0

0

1

3

2

 

Conclusions:
Administration of cloquintocet-mexyl to rats at up to 10000 ppm in the diet over two generations resulted in no effects on the fertility or reproductive performance in either generation and no effect on the number and viability of the pups born.
Executive summary:

The reproductive toxicity of cloquintocet-mexyl to rats was studied under GLP in a two-generation study conducted to OECD TG 416. Groups of 25 male and 25 female Sprague-Dawley rats were given the substance in the diet at nominal concentrations of 0, 50, 500, 5000 and 10000 ppm continuously from the start of treatment until necropsy.

After a pre-mating period, the P0 parental animals were mated and allowed to litter and to rear the P1 pups to weaning. After a 100 day post weaning maturation period the selected P1 parental animals were mated and allowed to litter and to rear the F1 pups to weaning.

At 10000 ppm, effects in the P0 and P1 parental animals included reduced body weight and food consumption, the death of four P1 males and histological changes in the kidney and urinary bladder of the P1 animals. For pups, mean body weight was significantly reduced on day 21 for both P1 and F1 pups and the incidence of renal pelvic dilatation was increased in P1 pups. There were no adverse effects of 50, 500 or 5000 ppm.

There was no effect on fertility or general reproductive performance in either of the two generations at any dietary concentration of cloquintocet-mexyl in this study. There was also no effect on the nature or incidence of malformations observed in the pups of the P1 and F1 generations.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
830 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
A fully reliable two-generation reproductive toxicity feeding study in the rat conducted to GLP is available.
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

The reproductive toxicity of cloquintocet-mexyl has been evaluated in a two-generation (one litter per generation) study in the rat in a key guideline study (OECD TG 416) conducted to GLP. 


For the two-generation study, groups of 25 male and 25 female rats were fed cloquintocet-mexyl continuously in the diet at nominal concentrations of 0, 50, 500, 5000 or 10000 ppm. After a 14-week pre-mating period, the P0 parental animals were mated and allowed to litter and to rear the F1a pups to weaning. After a 14-week post weaning maturation period the P1 parental animals (selected from the F1 generation) were mated and allowed to litter and to rear the F2a pups to weaning.


 


At 10000 ppm, the P and P1 parental animals showed reduced body weight and food consumption. Four P1 males were found dead and an increased occurrence of histological changes in the kidney and urinary bladder of the P1 animals was seen. For pups, mean body weight was significantly reduced on day 21 for both F1a and F2a pups and the incidence of renal pelvic dilatation was increased in F1a pups but not in F2a pups. There were no adverse effects of 50, 500 or 5000 ppm cloquintocet-mexyl. The NOAEL for general toxicity was 5000 ppm, corresponding to a mean daily intake of 420 mg/kg bw/day.


There was no effect on fertility or general reproductive performance in either of the two generations at any dietary concentration of cloquintocet-mexyl in this study and thus the NOAEL for fertility was 10000 ppm corresponding to a mean daily intake of 830 mg/kg bw/day.


The study was not conducted to current guidelines which require evaluation of oestrous cyclicity and sperm together with extended histopathology and organ weight information for both parents and offspring. It is nevertheless considered to be robust and reliable, demonstrating that no adverse effects on reproduction and fertility occurred at high doses causing general toxicity.

Effects on developmental toxicity

Description of key information

NOAEL (maternal) = 100 mg/kg bw/day, rat (OECD 414, Thouin 1989)


NOAEL (foetal) = 100 mg/kg bw/day, rat (OECD 414, Thouin 1989)


NOAEL (maternal) = 60 mg/kg bw/day, rabbit (OECD 414, Thouin 1989)


NOAEL (foetal) = 300 mg/kg bw/day, rabbit (OECD 414, Thouin 1989)

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 September 1987 – 31 January 1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
1981 (current guideline adopted 2001)
Deviations:
yes
Remarks:
does not meet current guideline specification
Qualifier:
according to guideline
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Version / remarks:
1982 (current guideline adopted 1998)
Deviations:
yes
Remarks:
does not meet current guideline specification
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
other: strain Tif:RAIf (SPF), hybrids of RII/1 x RII/2
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Age at study initiation: about 2 months
- Weight at study initiation: 200-203 g
- Source of animals: Animal Production, Ciba-Geigy Ltd. CH-4332 Stein, Switzerland
- Housing: Individually in standard macrolon cages with wire mesh tops and granulated soft wood bedding material
- Diet: pelleted, certified standard diet (Nafag No. 890 Tox) ad libitum
- Source of diet: Naehr- und Futtermittel AG, Gossau, Switzerland
- Water: tap water in plastic bottles ad libitum
- Acclimatisation: between mating and start of dosing

ENVIRONMENTAL CONDITIONS
- Temperature: 21±2°C
- Humidity: 55±10%
- Air changes (per hr): 16
- Photoperiod: 12 hrs dark / 12 hrs light
Route of administration:
oral: gavage
Vehicle:
peanut oil
Remarks:
arachidis oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Made on 2 occasions (for dosing September 21-October 6 and for October 7 & 8). The test substance was mixed with the vehicle in a grinder using glass beads and a low speed rotor, portioned for each dosing day and refrigerated until use. Homogeneity was maintained using a magnetic stirrer. Doses were adjusted daily for body weight. Dose volume was 5 mL/kg body weight. The dosing solutions contained 0, 2, 20 or 80 mg/mL CGA185072 tech.
VEHICLE
- arachidis oil, PHHVI (Siegfried AG, Zofingen, Switzerland)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Achieved concentration was determined for both batches. Homogeneity and chemical stability were confirmed.
The achieved concentrations varied: 67.9-80% low dose; 90.7-95.9% mid dose and 83.1-99.6% high dose. Values were considered to be within acceptable limits.
Details on mating procedure:
Nulliparous females were mated overnight with males of the same strain and of proven fertility; 3 females were housed with 1 male. Successful mating was confirmed by a vaginal plug or by spermatozoa in a vaginal smear and was defined as day 0 of pregnancy.
Duration of treatment / exposure:
Pregnancy days 6 - 15 inclusive
Frequency of treatment:
Once daily
Duration of test:
Pregnancy days 0 - 21; termination on day 21
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Negative control
Dose / conc.:
10 mg/kg bw/day (nominal)
Dose / conc.:
100 mg/kg bw/day (nominal)
Dose / conc.:
400 mg/kg bw/day (nominal)
No. of animals per sex per dose:
24 mated females
Control animals:
yes, concurrent vehicle
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: daily

FOOD CONSUMPTION: Yes
- Time schedule: days 6, 11, 16 and 21

WATER CONSUMPTION: Not measured, visually assessed

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Macroscopic examination: main organs of the thoracic and abdominal cavities

Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: abortion sites and dead foetuses. Uteri without visible signs of implantation were stained with ammonium sulphide to confirm pregnancy status.
Fetal examinations:
- Body weight and sex: Yes: all per litter
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: one third of each litter. Examination of fixed foetus by slicing technique of Wilson - head and body.
- Skeletal examinations: Yes: two thirds of each litter. Examination following staining of the skeleton with Alizarin red S
- Classification of foetal observations: Yes
Statistics:
Standard methods were applied for statistical analysis. Continuous data were analysed using student’s t-test, foetal observations were analysed using the Chi square test.
Indices:
Pre- and post-implantation losses
Historical control data:
Yes
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
At 400 mg/kg: reduced body weight gain (3-7% from day 9-21)
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
At 400 mg/kg: reduced food consumption days 6-11 and 11-16
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
400 mg/kg bw/day: increased water consumption
Other effects:
effects observed, treatment-related
Description (incidence and severity):
At 400 mg/kg: increased wet bedding, odorous urine;
Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
body weight and weight gain
clinical signs
food consumption and compound intake
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
A 7% decrease of the foetal bodyweight for the sexes combined was observed at 400 mg/kg bw.
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
no effects observed
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
fetal/pup body weight changes
Key result
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no

Table 1 Group Mean Maternal Body Weight Change (g) During Gestation

Days

Dose level (mg/kg bw/day)

0

10

100

400

0-6

33

32

32

31

6-11

30

30

28

22**

11-16

42

45

43

31**

16-21

70

70

73

67

0-21

176

176

176

150**

6-21

142

144

144

119**

6-16

72

74

71

52**

P<0.01 ** statistically significant difference from control

 

Table 2 Group Mean Litter data

 

Dose level (mg/kg bw/day)

0

10

100

400

No. pregnant females

24

24

22

24

No. corpora lutea

17.0

18.2

18.0

18.7

No. implantations

15.1

15.2

15.4

15.4

% pre-implantation loss

11.7

17.0

14.5

16.9

% post-implantation loss

3.8

3.3

3.9

7.1

No. live foetuses

14.5

14.7

14.8

14.4

% males

48.0

48.3

49.8

47.0

Foetal weight (g)

5.6

5.6

5.6

5.1**

P<0.01 ** statistically significant difference from control

 

Table 3 Group Mean Foetal Observations

 

Dose level (mg/kg bw/day)

0

10

100

400

No. litters examined

24

24

22

24

No. foetuses examined – external malformations

348

352

325

345

No. foetuses with external malformations

7

0

0

1*

No. foetuses examined – visceral malformations

110

119

110

115

No. foetuses with visceral malformations

0

0

0

1

No. foetuses with visceral anomalies

0

0

0

1

No. foetuses examined – skeletal malformations

238

233

215

230

No. foetuses with skeletal anomalies

12

10

4

6

P<0.05 * statistically significant difference from control

Conclusions:
Oral administration of cloquintocet-mexyl to pregnant rats at doses of 10, 100 and 400 mg/kg bw produced some maternal toxicity and resulted in reduced foetal bodyweight at the highest dose. There was no increase in incidence of external, visceral or skeletal malformations or anomalies due to the test substance and no evidence of teratogenicity.
Executive summary:

The developmental toxicity of the substance was studied under GLP to OECD TG 414. The substance was administered in peanut oil by oral gavage to pregnant rats at doses of 10, 100 or 400 mg/kg bw/day from day 6 through to day 15 of gestation. A dose level of 400 mg/kg bw was toxic to pregnant rat resulting in increased water consumption, increased wet bedding and odorous urine, reduced body weight and reduced food consumption. Lower mean foetal weight was seen in the presence of this maternal toxicity but there was no increase in incidence of external, visceral or skeletal malformations or anomalies. There was no evidence of teratogenicity at any dose level.

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10 August 1987 - 31 December 1987
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
1981 (current guideline adopted 2001)
Deviations:
yes
Remarks:
(does not meet current guideline specification)
Qualifier:
according to guideline
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Version / remarks:
1982 (current guideline adopted 1998)
Deviations:
yes
Remarks:
(does not meet current guideline specification)
GLP compliance:
yes
Limit test:
no
Species:
rabbit
Strain:
Chinchilla
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source of animals: Ivanovas, Kisslegg, Germany
- Age at study initiation: 16 weeks old
- Weight at study initiation: 2.9 - 3.1 kg
- Housing: Individually in Heinkel batteries with wire mesh bottom
- Diet: pelleted, certified standard diet ad libitum (Nafag No. 814)
- Source of diet: Nafag, Naehr- und Futtermittel AG, Gossau, Switzerland
- Water: tap water ad libitum
- Acclimatisation: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature: 18±2°C
- Humidity: 55±10%
- Air changes: 16-20 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

Route of administration:
oral: gavage
Vehicle:
peanut oil
Remarks:
arachidis oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Made weekly by mixing the test substance with the vehicle in a grinder using glass beads and a low speed rotor, portioned for each dosing day and refrigerated until use. Doses were adjusted daily for body weight. Dose volume was 4 mL/kg body weight. The dosing solutions contained 0, 2.5, 15 or 75 mg/mL CGA185072 tech.
VEHICLE
- arachidis oil, PHHVI (Siegfried AG, Zofingen, Switzerland)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Achieved concentration was determined and homogeneity and chemical stability were confirmed. The achieved concentrations ranged from 93.6-94.5%. Stability was confirmed for at least one week.
Details on mating procedure:
Each nulliparous female was mated with one male of proven fertility from the same strain of rabbit. Coitus was observed. The rabbits then remained together for at least one additional hour.
Duration of treatment / exposure:
Pregnancy days 7 - 19 inclusive
Frequency of treatment:
Once daily
Duration of test:
Pregnancy days 0 - 29, termination on day 29
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Negative control
Dose / conc.:
10 mg/kg bw/day (nominal)
Dose / conc.:
60 mg/kg bw/day (nominal)
Dose / conc.:
300 mg/kg bw/day (nominal)
No. of animals per sex per dose:
20 mated females
Control animals:
yes, concurrent vehicle
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: daily

FOOD CONSUMPTION: Yes
- Time schedule: days 4, 8, 12, 16, 20, 24 and 29

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Macroscopic examination: main organs of the thoracic and abdominal cavities



Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: abortion sites and dead foetuses. Uteri without visible signs of implantation were stained with ammonium sulphide to confirm pregnancy status.

Fetal examinations:
- Body weight and sex: Yes: all per litter
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter. Examination of viscera by fresh dissection. Examination of head by slicing technique of Wilson following fixation.
- Skeletal examinations: Yes: all per litter. Examination following staining of the skeleton with Alizarin red S
- Classification of foetal observations: Yes
Statistics:
Standard methods were applied for statistical analysis. Continuous data were analysed using student’s t-test, foetal observations were analysed using the Chi square test.
Indices:
Pre- and post-implantation losses

Historical control data:
Yes
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
tremor and reduced locomotor activity for three animals receiving 300 mg/kg bw/day; one animal had hemorrhagic discharge in the perineal area due to abortion
Mortality:
mortality observed, treatment-related
Description (incidence):
300 mg/kg bw/day: 5 animals found dead between days 12 and 18 (treatment-related on basis of pathological findings).
60 mg/kg/day: no deaths related to test substance (one rabbit found dead day 27 considered to be incidental)
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
in the group receiving 300 mg/kg bw/day, gastrointestinal changes were seen in the animals found dead; one surviving animal had a liver with a rough, nodular surface. One animal in the group receiving 60 mg/kg bw/day that was found dead had a hemorrhagic perineal area due to dead and resorbed foetuses
Number of abortions:
effects observed, treatment-related
Description (incidence and severity):
300 mg/kg: one rabbit aborted on day 21 possibly test article related
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
no effects observed
Key result
Dose descriptor:
NOAEL
Effect level:
60 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
mortality
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
no effects observed
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Description (incidence and severity):
Two foetuses from the same litter of a dam receiving 300 mg/kg bw/day had multiple malformations, including generalised oedema, shortened shaws, skeletal changes in the should area, ribs and fore legs.
Visceral malformations:
no effects observed
Description (incidence and severity):
there was one foetus with agenesis of kidney and ureter (unilaterally). One foetus in the group receiving 10 mg/kg bw/day had a cleft palate, one foetus had agenesis of kidney and ureter (unilaterally) and one foetus had enlarged kidneys
Details on embryotoxic / teratogenic effects:
A slight delay in skeletal ossification was noted in the group receiving 300 mg/kg bw/day, which was considered to be due to maternal toxicity.
Key result
Dose descriptor:
NOAEL
Effect level:
300 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no

Table 1 Group Mean Maternal Body Weight Change (g) During Gestation

Days

Dose level (mg/kg bw/day)

0

10

60

300

0-7

261

280

300

235

7-10

-121

-52*

-81

-61

10-14

95

55

87

42

14-19

63

63

85

63

19-24

189

143*

142

171

24-29

124

129

133

149

0-29

613

618

667

598

7-29

352

338

367

363

7-19

38

66

92

43

P<0.05 * Statistically significant difference from control

 

Table 2 Group Mean Litter data

 

Dose level (mg/kg bw/day)

0

10

60

300

No. pregnant females

17

19

14

12

No. corpora lutea

10.1

10.9

10.9

11.0

No. implantations

8.7

8.5

8.8

8.6

% pre-implantation loss

14.7

20.9

18.5

22.1

% post-implantation loss

4.4

5.0

16.2**

10.0

No. live foetuses

8.3

8.2

7.7

7.6

% males

46.8

52.3

47.6

41.8

Foetal weight (g)

34.8

35.6

34.7

35.1

P<0.01 ** Statistically significant difference from control

 

Table 3 Group Mean Foetal Observations

 

Dose level (mg/kg bw/day)

0

10

60

300

No. litters examined

17

19

14

12

No. foetuses examined – external malformations

141

155

105

91

No. foetuses with external malformations

0

0

0

2

No. foetuses examined – visceral malformations

141

153

105

91

No. foetuses with visceral malformations

0

2

0

3

No. foetuses with visceral anomalies

0

1

0

0

No. foetuses examined – skeletal malformations

141

155

104

91

No. foetuses with skeletal malformations

0

0

0

2

No. foetuses with skeletal anomalies

3

3

2

3

No statistically significant differences from control

Conclusions:
A dose of 300 mg/kg bw/day administered by oral gavage produced significant maternal toxicity, but did not result in significant foetal toxicity.
Executive summary:

The developmental toxicity of the substance to rabbits was studied under GLP to OECD TG 414. The substance was administered to pregnant Chincilla rabbits at doses of 0 (negative control with solvent peanut oil), 10, 60 and 300 mg/kg bw/day from day 7 through to day 19 of gestation. The dose level of 300 mg/kg bw was toxic to the pregnant rabbits resulting in the premature death of 5 rabbits (found dead between days 12 and 18). There was no effect of this dose on the body weight or food consumption of the surviving rabbits. There was no adverse effect on the number of abortions, with the exception of one abortion in the dose group receiving 300 mg/kg bw/day, which possibly was treatment related. No adverse effect on pre- and postimplantation losses, total litter losses by resorption, early or late resorptions, number of dead foetuses, duration of pregnancy, or the number of pregnant rabbits. There was no adverse effect on foetal body weight. No adverse effect on the number of live offspring, the sex ratio in litters or the litter size and weight. There was no increase in incidence of external, visceral or skeletal malformations or significant anomalies. A slight delay in skeletal ossification was described for the group receiving 300 mg/kg bw/day, which was considered to be due to the significant maternal toxicity at this dose. There was no evidence of teratogenicity at any dose level.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
60 mg/kg bw/day
Study duration:
subacute
Species:
rabbit
Quality of whole database:
Two reliable developmental toxicity studies in rats and rabbits conducted under GLP are available.
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

The developmental toxicity of cloquintocet-mexyl has been evaluated in the rat and rabbit, in two key guideline studies (OECD TG 414) conducted to GLP.


Groups of 24 time-mated female rats were administered cloquintocet-mexyl by oral gavage on days 6 -15 of pregnancy at dose levels of 0, 10, 100 or 400 mg/kg bw/day. Foetuses were obtained by caesarean section on day 21 of pregnancy and examined for external, visceral and skeletal malformations and anomalies. 


The dose level of 400 mg/kg bw/day was toxic to the pregnant rats resulting in increased water consumption, increased wet bedding and odorous urine, reduced body weight and reduced food consumption. Lower mean foetal weight was seen in the presence of this maternal toxicity but there was no increase in incidence of external, visceral or skeletal malformations or anomalies. The NOAEL for maternal and developmental toxicity was 100 mg/kg bw/day. There was no evidence of teratogenicity at any dose level of cloquintocet-mexyl.


Groups of 20 mated rabbits were administered cloquintocet-mexyl by oral gavage on days 7 -19 of pregnancy at dose levels of 0, 10, 60 or 300 mg/kg bw/day. Foetuses were obtained by caesarean section on day 29 of pregnancy and examined for external, visceral and skeletal malformations and anomalies. 


The dose level of 300 mg/kg bw/day was toxic to the pregnant rabbits resulting in the premature death of 5 animals (between days 12 and 18 of pregnancy). No effect on body weight or food consumption was observed in the surviving rabbits. There was no effect of 300 mg/kg bw/day on mean foetal weight. There was no increase in incidence of external, visceral or skeletal malformations or anomalies although a slight delay in skeletal ossification was described for the 300 mg/kg bw/day dose group, which was related to the significant maternal toxicity. There was no evidence of teratogenicity at any dose level of cloquintocet-mexyl.


On the basis of these studies, it is concluded that cloquintocet-mexyl is not teratogenic to either rats or rabbits at dose levels that induce maternal toxicity. Foetal toxicity, described as a reduction in mean foetal weight or a slight delay in skeletal ossification, was observed only in the presence of maternal toxicity i.e. at dose levels of 400 and 300 mg/kg bw/day, in rats and rabbits respectively. The NOAEL for maternal and developmental toxicity is 100 mg/kg bw/day in the rat, and 60 mg/kg bw/day and 300 mg/kg bw/day in the rabbit.


The studies were not conducted to current guidelines which require an extended dosing period to cover the period from implantation through to the day before termination. However, the studies are considered to be robust and no further testing is warranted.

Justification for classification or non-classification

There is adequate information available from which to assess the potential of cloquintocet-mexyl to induce reproductive or developmental effects and to conclude that classification under the Regulation (EC) 1272/2008, Annex I, Part 3, 3.7.2. is not warranted.

Additional information