Methyl (R)-2-(4-(3-chloro-5-trifluoromethyl-2-pyridyloxy)phenoxy)propionate

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Description of key information

2-Generation Rat Diet: Not a reproductive toxin. OECD 416; Reliability = 1

Link to relevant study records

Reference

Reference 1

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Male and female Sprague-Dawley rats ingested 0, 0.01. 0.065 or 1.0 mg/kg/day of the test substance for 8 weeks. Male and female rats ingesting the same concentration of the test substance on a mg/kg basis were mated twice to produce the f1a and f1b litters. Selected f1b rats ingested the same concentration of test material as their parents for 11 weeks at which point they were mated twice to produce the f2a and f2b litters.

GLP compliance:

yes

Specific details on test material used for the study:

DOWCO 453
Lot # AGR 187381
Purity: 99.4%

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

This strain of rat was selected in order to assess the reproductive effects of the test substance in an outbred strain which has an extensive data base in the literature.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratory, Kingston, NewYork
- Age at study initiation: 6 wks
- Housing: Housed in wire-mesh bottomed, stainless steel cages
- Diet: Purina's Certified Rodent Chow #5002, ad libitum
- Water: Tap water, ad libitum
- Acclimation period: One week

ENVIRONMENTAL CONDITIONS
- Temperature: Approximately 22°C
- Humidity: 40-60%
- Photoperiod: 12hrs dark /12 hrs light

Route of administration:

oral: feed

Vehicle:

other: diet

Details on exposure:

DIET PREPARATION
- A 0.1% premix of the test substance in Purina Laboratory Chow was shown to be stable for up to 1 year. The premix diets were prepared bi-weekly throughout the study. Test diets were prepared from the working premix to provide the selected dose levels of the test substance on a mg/kg/day basis. The concentration of the test substance in the diets was adjusted weekly during the pre-mating period based on group mean body weight and food consumption to maintain the appropriate dose levels.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: two 7-day cohabitation periods
- After the first 7-day mating, the males were rotated and allowed to mate with a different female from the respective treatment group.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of control and test diets were analyzed 4 times per generation to determine the concentration of the test substance in the diet. Reference diet samples (working premix and one/sex/dose level) were retained weekly. weekly samples of Certified ground chow used to prepare the diet mixes were retained also.

Duration of treatment / exposure:

Test animals were maintained on diets containing sufficient test substance to provide dose levels of 0, 0.01, 0.065 and 1.0 mg/kg/day during the first 8 weeks and 11 weeks of the treatment period of f0 and f1 generations, respectively. During mating, gestation, and the first week of lactation, females from each treatment group were provided with the appropriate diet containing the respective concentration of the test substance given during the week immediately prior to mating. During the second and third weeks of lactation, females received 1/2 and 1/3, respectively, of the dietary concentration given during breeding and gestation in order to avoid overdosing of the neonates. To avoid potential overdosing of females during the mating period, males received the same concentration in the diet as their female cage mate. Following completion of the breeding period, males from each treatment group continued to receive the appropriate fixed concentration of the test substance equivalent to the dietary concentration administered to males during the week prior to mating. Until all f1 litters had been weaned, weanlings chosen for the f1 generation received the same concentration of the test substance in the diet as was given to the f0 rats during their first week of treatment.

Details on study schedule:

After 8 weeks of administration of the test material, f0 animals were mated using one male to one female of the respective treatment group to produce the f1a litters. After the last f1a litter was weaned, the f0 animals were allowed to mate a second time to produce the f1b litters. At the time of weaning, thirty animals/sex/dose level were randomly chosen from the f1b litters as parents for the next generation and placed on the respective test diets. After 11 weeks of ingesting the test material, these f1 animals were allowed to mate for the f2 generation. The first breeding of these f1 adults resulted in the f2a litters. After the last f2a litter was weaned, the f1 adults were allowed to mate a second time to produce the f2b litters.

Dose / conc.:

0.01 mg/kg bw/day

Dose / conc.:

0.065 mg/kg bw/day

Dose / conc.:

1 mg/kg bw/day

No. of animals per sex per dose:

30

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: The highest dose selected in this study (1 mg/kg/day) was identical to the original three-generation reproduction study in Fischer 344 rats. The lower two levels, 0.01 and 0.065 mg/kg/day, are similar to middle and low levels employed in the two-year chronic toxicity and oncogenicity study in Fischer 344 rats.
- Fasting period before blood sampling for clinical biochemistry: Yes (overnight)

Parental animals: Observations and examinations:

PHYSICAL OBSERVATIONS
- Each animal on study was observed for signs of toxicity and changes in demeanor at least once a day.

BODY WEIGHT AND FOOD CONSUMPTION
- Body weights and food consumption for all f0 and f1 adult animals were recorded weekly prior to mating. Since the male and female rats were still gaining weight prior to mating, the males were weighed weekly after the mating period for the f1a and f2a litters and the females were weighed once after weaning the f1a and
f2a litters.

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes
- If yes, maximum of 8 pups/litter (4/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in all offspring:
the date of parturition, the number of live and dead pups on the day of parturition (day zero), the number of live pups on day 1, 4, 7, 14 and 21 after delivery, the weight of the litter and lactating female on days 1, 4 (post-culling), 7, 14 and 21 of lactation, and individual body weights for each male and female pup on day 21. Any visible physical abnormalities in the neonates were recorded during the lactation period.

Postmortem examinations (parental animals):

After weaning the last litter from the f1b and f2b generations. all surviving adult f0 and f1 males and females were fasted overnight, weighed and anesthetized with methoxyflurane. The trachea was clamped and they were sacrificed by decapitation. The adults were subjected to a complete gross pathologic examination. The eyes were examined in situ by gently pressing a glass slide against the cornea and observing the eyes under fluorescent light illumination. Tissues were saved from these animals and preserved in neutral phosphate buffered 10% formalin with the exception of the testes and epididymides which were fixed in Bouin's solution. No histologic examination of these tissues was made. Adult rats that were moribund or died spontaneously were necropsied in a similar manner; however, a detailed eye examination was not performed and their testes and epididymides were fixed in formalin with the other tissues.
The following tissues are collected during the gross necropsy examination:
Liver, pancreas, peripheral nerve, adrenal, small intestine, mesenteric lymph node, epididymis, prostate, oviduct, urinary bladder, salivary gland, mediastinal lymph node, thyroid gland, larynx, eye, lacrimal gland, oral cavity, heart, brain, spinal cord, kidney, cecum, mesenteric tissue, seminal vesicle, uterus, cervix, lungs, thymus, aorta, parathyroid gland, skin, tongue, zymbal gland, spleen, pituitary, bone marrow, stomach, large intestine, testicle, coagulating gland, ovary, vagina, skeletal muscle, mediastinal tissue, esophagus, trachea, mammary gland, nasal turbinates, bone

Postmortem examinations (offspring):

Weanling Rats: The f1a and f2a weanlings were discarded at weaning on day 21 of lactation; no gross or histopathological examination was conducted. For f1b and f2b weanlings, 10 randomly selected animals/sex/dose level were sacrificed and subjected to a complete gross pathologic examination as described for the adults. Tissues were saved as indicated, for adults and no histologic examination was performed.

Statistics:

Body weights were evaluated by Bartlett's test for equality of variances (α=0.01). Based upon the outcome of Bartlett's test, either a parametric or nonparametric analysis of variance (ANOVA) was performed. If the ANOVA was significant, a Dunnett's test or the Wilcoxon Rank-Sum test with Bonferroni's correction was performed.
Statistical outliers (p <0.02) of food consumption data were identified by the method described by Grubbs (1969) and excluded from analysis. Descriptive statistics of food consumption data were subsequently determined. The fertility index was analyzed by the Fisher exact probability. Evaluation of the neonatal sex ratio was performed by the binomial distribution test. Survival indices and other incidence data among neonates were analyzed using the litter as the experimental unit by the Wilcoxon test as modified by Haseman and Hoel (1974).

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Several f1a pups from dams ingesting 0.065 mg/kg/day of the test substance were hypothermic or jaundice-appearing at some point during the lactation period. However, all of these pups survived and appeared normal at weaning. In addition, pups from dams ingesting higher concentrations of the test material did not exhibit symptoms of hypothermia or jaundice.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

The spontaneous deaths of the female rats occurred primarily during delivery and did not appear to be treatment related.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

The body weights of 14 and 21-day old f1a neonates from dams ingesting 1.0 mg/kg body weight/day of the test substance were statistically significantly decreased from control animals.
The f1a pups from dams ingesting 0.065 mg/kg/day of the test substance weighed significantly less than control animals on days 14 and 21 postpartum. Similarly, the female pups from dams ingesting 0.01 mg/kg/day weighed significantly less than controls on day 21 post-partum.

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Reproductive performance:

no effects observed

Description (incidence and severity):

the reproduction indices were comparable between experimental groups

Mortality:

mortality observed, non-treatment-related

Description (incidence):

The spontaneous deaths of the female rats occurred primarily during delivery and did not appear to be treatment related.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The body weights of 14 and 21-day old f1b neonates from dams ingesting 1.0 mg/kg body weight/day of the test substance were statistically significantly decreased from control animals. The pups from the f1b litters ingesting 1.0 mg/kg/day which were raised to adulthood always weighed less than control animals. This was due in part to an age difference. Two litters born from dams ingesting 1.0 mg/kg/day were 7 days younger than litters from other dose levels.

Food consumption and compound intake (if feeding study):

no effects observed

Gross pathological findings:

no effects observed

Description (incidence and severity):

The gross lesions observed at necropsy of the f1b litters were considered to be spontaneous in nature and not treatment related.

Reproductive performance:

no effects observed

Description (incidence and severity):

the reproduction indices were comparable between experimental groups

The size of the f1b litters were comparable between experimental groups

Key result

Dose descriptor:

NOEL

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

As with the f0 animals, several of the spontaneous deaths of the f1 rats occurred during delivery and did not appear to be treatment related.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

A slight decrease in day 21 weights of the f2a neonates was observed.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Food consumption of male f1 rats and female f1 rats was comparable between experimental groups.

Gross pathological findings:

no effects observed

Description (incidence and severity):

The gross pathologic observations of the f1 adults and the f2b weanlings were considered to be spontaneous in nature and not treatment related.

Other effects:

no effects observed

Description (incidence and severity):

No effects were observed between controls and treated animals in the reproduction indices, and the size of the f2a litters

Key result

Dose descriptor:

NOEL

Generation:

F1

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest concentration

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

As with the f0 animals, several of the spontaneous deaths of the f1 rats occurred during delivery and did not appear to be treatment related.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

The body weights of the f1 dams during the lactation period for the f2b litters were comparable between experimental groups.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Food consumption of male f1 rats and female f1 rats was comparable between experimental groups.

Gross pathological findings:

no effects observed

Description (incidence and severity):

The gross pathologic observations of the f1 adults and the f2b weanlings were considered to be spontaneous in nature and not treatment related.

The reproduction indices and the size of the f2b litters were comparable between experimental groups.

Key result

Dose descriptor:

NOEL

Generation:

F2

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest concentration

Key result

Reproductive effects observed:

no

Table 1: Body weight data (significant observations)

Day (post-partum)	0 mg/kg/day	0.01 mg/kg/day	0.065 mg/kg/day	1.0 mg/kg/day
Body weights of f1a litter
14	33.4±2.1	31.8±2.8	31.3±3.4*	31.5±2.9*
21 (male)	55.7±4.0	52.9±4.1	51.5±4.9*	50.6±5.3*
21 (male)	53.5±4.0	50.2±3.6*	49.4±4.9*	48.7±5.0*
Body weights of f1a litter
14	33.7±2.8	32.6±3.2	32.5±2.6	31.7±2.9*
21 (male)	56.1±5.1	53.5±6.4	52.9±5.1	51.9±5.3*
21 (male)	53.8±4.2	51.0±5.7	50.6±4.5	49.8±5.1*
Body Weights of f1 Dams During the Lactation Period for f2a Litters
14 (male)	357±17	337±29*	349±32	342±26
Body Weights of f2a Litters
21 (male)	55.3±4.3	53.6±5.3	55.1±5.3	51.8±4.1*

Conclusions:

Rat NOEL (Reproductive parameters): 1.0 mg/kg/day

Executive summary:

Male and female Sprague-Dawley rats ingested 0, 0.01, 0.065 or 1.0 mg/kg/day of the test substance for 8 weeks. Male and female rats ingesting the same concentration of the test substance on a mg/kg basis were mated twice to produce the f1a and f1b litters. Selected f1b rats ingested the same concentration of test material as their parents for 11 weeks at which point they were mated twice to produce the f2a and f2b litters.

Ingestion of 1.0 mg/kg/day of the test substance did result in a slight decrease in flat f1a, f1b and f2a weanling body weights and f1 adult body weights. However, concentrations as high as 1.0 mg/kg/day did not affect the ability of the parental animals to mate, produce a litter of normal size and number and raise a litter. Thus the no-observable-effect level (NOEL) for reproductive parameters in Sprague-Dawley rats is 1.0 mg/kg/day for the test substance.

Reference 2

Endpoint:

two-generation reproductive toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOEL

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Key result

Dose descriptor:

NOEL

Generation:

F1

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest concentration

Key result

Dose descriptor:

NOEL

Generation:

F2

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest concentration

Key result

Reproductive effects observed:

no

Conclusions:

Rat NOEL (Reproductive parameters): 1.0 mg/kg/day

Executive summary:

Male and female Sprague-Dawley rats ingested 0, 0.01, 0.065 or 1.0 mg/kg/day of the test substance for 8 weeks. Male and female rats ingesting the same concentration of the test substance on a mg/kg basis were mated twice to produce the f1a and f1b litters. Selected f1b rats ingested the same concentration of test material as their parents for 11 weeks at which point they were mated twice to produce the f2a and f2b litters.

Ingestion of 1.0 mg/kg/day of the test substance did result in a slight decrease in flat f1a, f1b and f2a weanling body weights and f1 adult body weights. However, concentrations as high as 1.0 mg/kg/day did not affect the ability of the parental animals to mate, produce a litter of normal size and number and raise a litter. Thus the no-observable-effect level (NOEL) for reproductive parameters in Sprague-Dawley rats is 1.0 mg/kg/day for the test substance.

Effect on fertility: via oral route

Dose descriptor:

NOAEL

1 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Only one study was 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

Groups of 30 male and 30 female Sprague-Dawley rats, approximately 6 weeks of age, were fed diets that provided 0, 5, 20 or 100 mg/kg/day, 7 days/week, for two generations. Dietary exposure of adult male and female rats to 100 mg/kg/day test substance resulted in parental and developmental effects. Parental effects consisted of centrilobular hepatocellular enlargement in high dose P1 and P2 male rats only. This effect was noted previously in a 13-week study with Fischer 344 rats. Slight decreases in female feed consumption were noted only during the final week of the P1 and P2 lactation periods, but were not associated with body weight effects in maternal animals. No significant effects were observed for P1 or P2 females given 100 mg/kg/day or male or female rats given 5 or 20 mg/kg/day in either parental generation. Additionally, no treatment-related effects were observed on any reproductive parameters or gross/histopathology of the reproductive organs for P1 or P2 adult animals at any dose level tested. Minimal neonatal effects were also observed at 100 mg/kg/day test substance in the F1a, F1b, and F2 litters. Decreases, both statistically identified and otherwise, were noted on Day 21 of lactation in the mean body weights of male and female pups in this dose group. These transient decreases were attributed, in part, to the decreased feed consumption noted during the final week of the P1 and P2 lactation periods. Although pup feed consumption was slightly decreased, the higher concentration of test material in the maternal diet they consumed would have resulted in a dose on a mg/kg/day basis greater than that targeted for the adults. No adverse effects were observed on pup body weights at doses of 5 or 20 mg/kg/day in either generation. Neonatal survival was not adversely affected at any dose level in either generation. Under the conditions of this study, the parental no-observed-effect level (NOEL) for systemic effects was 20 mg/kg/day for males and 100 mg/kg/day for females. The NOEL for reproductive effects was 100 mg/kg/day, the highest dose level tested. Based upon the transient effects observed on pup body weights, the NOEL for neonatal effects was conservatively determined to be 20 mg/kg/day.

Effects on developmental toxicity

Description of key information

Rat Developmental Oral gavage: Not a unique developmental toxin. OECD 414; Reliability = 1

Rabbit Developmental Oral gavage: Not a unique developmental toxin. OECD 414; Reliability = 1

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of at least 30 bred rats were given the test substance by gavage on days 6 through 15 of gestation at a level of 0.1, 1.0 and 7.5 mg/kg of test substance/day. Test animals were sacrificed by carbon dioxide inhalation on gestation day 21 and observed for alterations.

GLP compliance:

yes

Specific details on test material used for the study:

DOWCO 453 acid
Lot # AGR 192975
Purity: 99.7%

Species:

rat

Strain:

Fischer 344

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, Michigan
- Weight at breeding: Approximately 175-220 g
- Diet: Certified Laboratory animal Chow, ad libitum
- Water: Muncipal tap water, ad libitum
- Acclimation period: At least 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: Approximately 22°C
- Humidity: Approximately 50%
- Photoperiod: 12 hrs dark /12 hrs light

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionized distilled

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
- The sodium salt of test substance was prepared in deionized-distilled water by adding 1.0 N sodium hydroxide solution to dissolve the acid. The sample was back titrated with hydrochloric acid solution to a pH between 6 and 7. Solutions of test substance-sodium salt were prepared such that a dose volume of 4 mL/kg of body weight/day yielded the appropriate acid equivalent for each dose level. Fresh solutions of test substance-sodium salt were prepared as required based upon the previously reported 14 day stability data.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The mean analytical concentration of the dosing solutions used was 93-95% of the target concentration.

Details on mating procedure:

- Impregnation procedure: Adult virgin female rats were bred to adult males (one female to one male) from the same strain. The day sperm were found in a vaginal smear was considered day zero of gestation.

Duration of treatment / exposure:

GD6-GD15

Frequency of treatment:

Daily

Dose / conc.:

0.1 mg/kg bw/day

Dose / conc.:

1 mg/kg bw/day

Dose / conc.:

7.5 mg/kg bw/day

No. of animals per sex per dose:

30, 31, 31 and 30 dams in the control, 0.1, 1.0 and 7.5 mg/kg/day groups, respectively

Control animals:

yes, concurrent vehicle

Maternal examinations:

OBSERVATIONS
- Time schedule: Daily

BODY WEIGHT
- Time schedule for examinations: Body weights were recorded on gestation days 6 through 16 and on day 21 of gestation

POST-MORTEM EXAMINATIONS
- Sacrifice on gestation day # 21

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number and position of fetuses: Yes
- Number of live and dead fetus: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Sex, body weight and crown-rump length of each fetus: Yes

Fetal examinations:

- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [all per litter]

Statistics:

Maternal body weights, food and water consumption, absolute and relative organ weights, and fetal weight and length were evaluated by Bartlett's test for equality of variances. Based upon the outcome of Bartlett's test, a parametric or nonparametric analysis of variance (ANOVA) was performed. If the ANOVA was significant, a Dunnett's test or the Wilcoxon Rank-Sum test with Bonferroni's correction was performed. Corpora lutea, implantations, and litter size were analyzed by the Wilcoxon Rank-Sum test with Bonferroni's correction. For food consumption, statistical outliers were identified by a sequential method and excluded from analysis. Pregnancy rate was analyzed by the Fisher Exact Probability test. Evaluation of the neonatal sex ratio was done using the binomial distribution test. The frequency of alterations, resorptions, and other incidence data were analyzed by the Wilcoxon test, using the litter as the experimental unit.

Clinical signs:

no effects observed

Description (incidence and severity):

no treatment-related effects on general appearance or demeanor were observed among bred rats given 0, 0.1, 1.0, or 7.5 mg/kg/day on days 6 through 15 of gestation.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Decreases in body weight gain during days 6 through 8 of gestation, was observed in the 7.5 mg/kg/day group

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Decreases in food consumption during days 6 through 8 of gestation, was observed in the 7.5 mg/kg/day group

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

effects observed, treatment-related

Description (incidence and severity):

Water consumption in the top dose group was increased on days 12 through 20 of gestation.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Only liver weights were observed; Absolute and relative liver weights among the treated groups were comparable to controls

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

The incidence of implantations undergoing resorption among the treatment groups was comparable to the control group indicating that the test substance was not embryolethal in rats.

Key result

Dose descriptor:

NOEL

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

body weight and weight gain

food consumption and compound intake

maternal abnormalities

Fetal body weight changes:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidence of individual malformations was not significantly increased for any of the treated groups compared to controls

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No skeletal malformations were observed in any group including controls. A significant increase in the incidence of delayed ossification of the centra of the thoracic vertebrae was observed in the 7.5 mg/kg/day group. A slight increase in the incidence of unfused thoracic centra was also observed in this group. The deffects may be indicative of a slight fetotoxic effect which is probably secondary to the slight maternal toxicity observed in this group.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidence of individual malformations was not significantly increased for any of the treated groups compared to controls

Key result

Remarks on result:

other: Oral administration of the test substance was not teratogenic to rats at doses up to 7.5 mg/kg bw/day.

Key result

Developmental effects observed:

no

Table 1: Body weights and weight changes (g) of pregnant rats (significant observations)

Gestation day	0 mg/kg/day	0.1 mg/kg/day	1.0 mg/kg/day	7.5 mg/kg/day
16	236±13	231±12	232±10	228±14*
21	274±19	261 ±20	267±19	260±23*
6-8	6±3	5±4	6±3	4±3*

*Statistically different from the control value by Dunnett's test,α=0.05.

 

Table 2: Food consumption (g/rat/day) of pregnant rats (significant observations)

Gestation day	0 mg/kg/day	0.1 mg/kg/day	1.0 mg/kg/day	7.5 mg/kg/day
6-8	14±1	14±1	14±1	13±1*

*Statistically different from the control value by Dunnett's test,α=0.05.

 

Table 3: Water consumption (g/rat/day) of pregnant rats (significant observations)

Gestation day	0 mg/kg/day	0.1 mg/kg/day	1.0 mg/kg/day	7.5 mg/kg/day
12-14	27±5	28±4	28±3	32±10*
15-17	34±4	33±4	33±4	40±14*
18-20	28±3	29±4	30±3	33±5*

*Statistically different from the control value by Dunnett's test,α=0.05.

 

Table 4: Incidence of Fetal Alterations Among Litters of Pregnant Rats (significant observations)

Skeletal observations		0 mg/kg/day	0.1 mg/kg/day	1.0 mg/kg/day	7.5 mg/kg/day
Delayed ossification of thoracic centra	F	1(2)	2(4)	1(2)	6 (11)*
	L	8(2)	12(3)	4(1)	33 (8)*

Number Fetuses (Number Litters) Examined

*Statistically different from the control value by a modified Wilcoxon test,α=0.05.

 

Conclusions:

Rat NOEL: 1.0 mg/kg/day (maternal effects)
Oral administration of the test substance was not teratogenic to rats at doses up to 7.5 mg/kg bw/day.

Executive summary:

The objective of this study was to evaluate the embryotoxic and teratogenic potential of repeated oral administration of the test substance during organogenesis in rats. Bred rats were given 0, 0.1, 1.0, or 7.5 mg test substance/kg/day by gavage on days 6 through 15 of gestation.

Slight maternal toxicity was observed in the 7.5 mg/kg group as evidenced by decreased weight gain and food consumption early in gestation. No evidence of embryotoxicity or teratogenicity was observed in rats.

In conclusion, oral administration of the test substance during organogenesis was not teratogenic in rats at dose levels as high as 7.5 mg/kg/day.

Reference 2

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOEL

Effect level:

1 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

body weight and weight gain

food consumption and compound intake

maternal abnormalities

Key result

Remarks on result:

other: Oral administration of the test substance was not teratogenic to rats at doses up to 7.5 mg/kg bw/day.

Key result

Developmental effects observed:

no

Conclusions:

Rat NOEL: 1.0 mg/kg/day (maternal effects)
Oral administration of the test substance was not teratogenic to rats at doses up to 7.5 mg/kg bw/day.

Executive summary:

The objective of this study was to evaluate the embryotoxic and teratogenic potential of repeated oral administration of the test substance during organogenesis in rats. Bred rats were given 0, 0.1, 1.0, or 7.5 mg test substance /kg/day by gavage on days 6 through 15 of gestation.

Slight maternal toxicity was observed in the 7.5 mg/kg group as evidenced by decreased weight gain and food consumption early in gestation. No evidence of embryotoxicity or teratogenicity was observed in rats.

In conclusion, oral administration of the test substance during organogenesis was not teratogenic in rats at dose levels as high as 7.5 mg/kg/day.

Reference 3

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

EPA OPP 83-3 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Haloxyfop sodium salt
Lot # AGR 192975
Purity: 99.6%

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton-Dutehland, Inc., Denver, Pennsylvania
- Weight at study initiation: Approximately 3.5-4.5 kg
- Diet: Certified Laboratory Rabbit Chow, ad libitum
- Water: Muncipal tap water, ad libitum
- Acclimation period: At least 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: Approximately 22°C
- Humidity: Approximately 50%
- Photoperiod: 12 hrs dark/12 hrs light

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionized distilled

Details on exposure:

PREPARATION OF DOSING SOLUTIONS
- The sodium salt of test substance was prepared in deionized-distilled water by adding 1.0 N sodium hydroxide solution to dissolve the acid. The sample was back titrated with hydrochloric acid solution to a pH between 6 and 7. Solutions of test substance-sodium salt were prepared such that a dose volume of 1 mL/kg of body weight/day yielded the appropriate acid equivalent for each dose level. Fresh solutions of test substance-sodium salt were prepared as required based upon the previously reported 14 day stability data.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The solution prepared for each dose level was analyzed to determine the concentration of the test material at least once during the conduct of the study. The mean analytical concentration of the dosing solutions used throughout the study was 98.1±4.8% of the target concentration.

Details on mating procedure:

- Impregnation procedure: Artificial insemination (the day of artificial insemination is considered as day 0 of pregnancy)

Duration of treatment / exposure:

GD6-GD18

Frequency of treatment:

Daily

Dose / conc.:

3 mg/kg bw/day

Dose / conc.:

7.5 mg/kg bw/day

Dose / conc.:

15 mg/kg bw/day

No. of animals per sex per dose:

27, 28, 30 and 25 dams in the control, 3, 7.5 and 15 mg/kg/day groups, respectively

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The high dose level of 15 mg/kg/day was selected in order to minimize the possibility of maternal lethality as seen in a previous study at 20 mg/kg/day. The middle dose level of 7.5 mg/kg/day was selected to match the middle level of a previous study at which microphthalmia was seen. In as much as 1.0 mg/kg/day had not produced any adverse effects, the low dose level selected for the present study was set at 3.0 mg/kg/day in an effort to gain additional information at a previously untested dose level.

Maternal examinations:

OBSERVATIONS
- Time schedule: Daily

BODY WEIGHT
- Time schedule for examinations: Body weights were recorded on gestation days 6 through 19 and on day 29 of gestation

POST-MORTEM EXAMINATIONS
- Sacrifice on gestation day # 29

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number and position of fetuses: Yes
- Number of live and dead fetus: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Sex, body weight and crown-rump length of each fetus: Yes

Fetal examinations:

- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [all per litter]

Statistics:

Maternal body weights, body weight gains, and absolute and relative liver weights and fetal weights and lengths were evaluated by Bartlett's test for equality of variance. Based on the outcome of Bartlett's test, a parametric or nonparametric analysis of variance (ANOVA) was performed. If the ANOVA was significant, analysis by Dunnett's test or the Wilcoxon Rank Sum test with Bonferroni's correction was performed. Corpora lutea, implantations and litter size were analyzed by the Wilcoxon Rank-Sum test with Bonferroni's correction.
Statistical evaluation of the frequency of alterations, pre-implantation loss, and resorptions among litters and the fetal population was performed using a censored Wilcoxon test with Bonforroni's correction. The pregnancy rate was analyzed by the Fisher exact probability test. Evaluation of the neonatal sex ratio was performed using the binomial distribution test.

Clinical signs:

no effects observed

Description (incidence and severity):

No significant effects observed at any of the dose levels tested

Mortality:

mortality observed, treatment-related

Description (incidence):

Five maternal deaths were recorded during the conduct of this study. One animal in the 3.0 mg/kg/day dose group died on day 29 of gestation. Four deaths occurred among animals given 15 mg/kg/day. Two deaths occurred within 1.25 hours of dosing, with acute pulmonary edema and congestion diagnosed at necropsy, indicating an intubation error. Two other animals were found dead on days 25 and 28 of gestation, respectively. A definitive cause of death could not be determined in any of the deaths which occurred.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No significant effects observed at any of the dose levels tested

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Only liver weights were observed; however, no significant effects observed at any of the dose levels tested

Total litter losses by resorption:

effects observed, non-treatment-related

Description (incidence and severity):

A statistically identified increased resorption rate was observed among rabbits given 3.0 mg/kg/day; however the resorption rate among animals given the high dose (15 mg/kg/day) was comparable to controls and therefore this increase was not considered treatment-related.

Key result

Dose descriptor:

NOEL

Effect level:

7.5 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

mortality

Fetal body weight changes:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

no effects observed

Description (incidence and severity):

There were no indications of ocular alterations in any of the fetuses examined

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Statistical evaluation of the fetal alterations observed revealed significant decreases in the incidence of delayed ossification of the hyoid bones of the skull among fetuses in the 3.0 and 7.5 mg/kg/day dose groups when compared to controls, which were not considered to be an indication of a treatment-related effect. There were no alterations which occurred at a statistically increased incidence when compared to controls.

Key result

Dose descriptor:

NOEL

Effect level:

15 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No embryo-foetal effects

Key result

Developmental effects observed:

no

Conclusions:

Rabbit NOEL: 7.5 mg/kg/day (maternal effects)
Rabbit NOEL: 15 mg/kg/day (embryo-foetal effects)

Executive summary:

The objective of this study was to test whether the low incidence of malformations, and in particular, microphthalmia, observed in a previous teratology study in which New Zealand White rabbits were administered 1, 7.5 or 20 mg/kg/day of the test substance was a spontaneous occurrence or a treatment-related effect according to the guideline EPA OPP 83-3. Inseminated rabbits were therefore administered 0, 3.0, 7.5 or 15 mg/kg/day of the test substance by gavage on days 6 through 18 of gestation and the fetuses examined for developmental alterations.

There were no indications of maternal toxicity in any of the dose groups; however, four deaths occurred in the 15 mg/kg/day dose group, two of which may have been treatment-related. Examination of the fetuses revealed a low incidence of malformations in all groups, including the controls. There were no indications of ocular alterations in any of the fetuses examined. Therefore, the results of the present study support the conclusion of the previous study regarding the spontaneous nature of microphthalmia observed. Evaluation of the various alterations observed in this study did not reveal any treatment-related increases in any parameter.

In conclusion, oral administration of the test substance during organogenesis at dose levels up to 15 mg/kg/day was not teratogenic or fetotoxic in New Zealand White rabbits.

Reference 4

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOEL

Effect level:

7.5 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

mortality

Key result

Dose descriptor:

NOEL

Effect level:

15 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No embryo-foetal effects

Key result

Developmental effects observed:

no

Conclusions:

Rabbit NOEL: 7.5 mg/kg/day (maternal effects)
Rabbit NOEL: 15 mg/kg/day (embryo-foetal effects)

Executive summary:

The objective of this study was to test whether the low incidence of malformations, and in particular, microphthalmia, observed in a previous teratology study in which New Zealand White rabbits were administered 1, 7.5 or 20 mg/kg/day of the test substance was a spontaneous occurrence or a treatment-related effect according to the guideline EPA OPP 83-3. Inseminated rabbits were therefore administered 0, 3.0, 7.5 or 15 mg/kg/day of the test substance by gavage on days 6 through 18 of gestation and the fetuses examined for developmental alterations.

There were no indications of maternal toxicity in any of the dose groups; however, four deaths occurred in the 15 mg/kg/day dose group, two of which may have been treatment-related. Examination of the fetuses revealed a low incidence of malformations in all groups, including the controls. There were no indications of ocular alterations in any of the fetuses examined. Therefore, the results of the present study support the conclusion of the previous study regarding the spontaneous nature of microphthalmia observed. Evaluation of the various alterations observed in this study did not reveal any treatment-related increases in any parameter.

In conclusion, oral administration of the test substance during organogenesis at dose levels up to 15 mg/kg/day was not teratogenic or fetotoxic in New Zealand White rabbits.

Reference 5

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of at least 29 inseminated rabbits were given the test substance by gavage on days 6 through 18 of gestation at a level of 0, 1.0, 7.5, or 20.0 mg/kg of test substance/day. Test animals were sacrificed by carbon dioxide inhalation on gestation day 29 and observed for alterations.

GLP compliance:

yes

Specific details on test material used for the study:

DOWCO 453 acid
Lot # AGR 192975
Purity: 99.7%

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Langshaw Farms, Augusta, Michigan
- Weight at study initiation: Approximately 3.5-4.5 kg
- Diet: Certified Laboratory Rabbit Chow, ad libitum
- Water: Muncipal tap water, ad libitum
- Acclimation period: At least 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: Approximately 22°C
- Humidity: Approximately 50%
- Photoperiod: 12 hrs dark/12 hrs light

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionized distilled

Details on exposure:

PREPARATION OF DOSING SOLUTIONS
- The sodium salt of test substance was prepared in deionized-distilled water by adding 1.0 N sodium hydroxide solution to dissolve the acid. The sample was back titrated with hydrochloric acid solution to a pH between 6 and 7. Solutions of test substance-sodium salt were prepared such that a dose volume of 1 mL/kg of body weight/day yielded the appropriate acid equivalent for each dose level. Fresh solutions of test substance-sodium salt were prepared as required based upon the previously reported 14 day stability data.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The mean analytical concentration of the dosing solutions used was 99-106% of the target concentration.

Details on mating procedure:

- Impregnation procedure: Artificial insemination (the day of artificial insemination is considered as day 0 of pregnancy)

Duration of treatment / exposure:

GD6-GD18

Frequency of treatment:

Daily

Dose / conc.:

1 mg/kg bw/day

Dose / conc.:

7.5 mg/kg bw/day

Dose / conc.:

20 mg/kg bw/day

No. of animals per sex per dose:

29, 30, 30 and 31 dams in the control, 1, 7.5 and 20 mg/kg/day groups, respectively

Control animals:

yes, concurrent vehicle

Maternal examinations:

OBSERVATIONS
- Time schedule: Daily

BODY WEIGHT
- Time schedule for examinations: Body weights were recorded on gestation days 6 through 19 and on day 29 of gestation

POST-MORTEM EXAMINATIONS
- Sacrifice on gestation day # 29

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number and position of fetuses: Yes
- Number of live and dead fetus: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Sex, body weight and crown-rump length of each fetus: Yes

Fetal examinations:

- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [all per litter]

Statistics:

Maternal body weights, food and water consumption, absolute and relative organ weights, and fetal weight and length were evaluated by Bartlett's test for equality of variances. Based upon the outcome of Bartlett's test, a parametric or nonparametric analysis of variance (ANOVA) was performed. If the ANOVA was significant, a Dunnett's test or the Wilcoxon Rank-Sum test with Bonferroni's correction was performed. Corpora lutea, implantations, and litter size were analyzed by the Wilcoxon Rank-Sum test with Bonferroni's correction. For food consumption, statistical outliers were identified by a sequential method and excluded from analysis. Pregnancy rate was analyzed by the Fisher Exact Probability test. Evaluation of the neonatal sex ratio was done using the binomial distribution test. The frequency of alterations, resorptions, and other incidence data were analyzed by the Wilcoxon test, using the litter as the experimental unit.

Clinical signs:

no effects observed

Description (incidence and severity):

No significant effects observed at any of the dose levels tested

Mortality:

mortality observed, treatment-related

Description (incidence):

5 animals in the 20.0 mg/kg/day group died during the study. The cause of death for one animal was attributed to pneumonia, whereas in the other four rabbits the cause could not be determined upon gross pathologic examination. These deaths may be treatment-related.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No significant effects observed at any of the dose levels tested

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Only liver weights were observed; however, no significant effects observed at any of the dose levels tested

Total litter losses by resorption:

effects observed, treatment-related

Description (incidence and severity):

Evidence of embryolethality was observed in the 20.0 mg/kg dose group where a significant increase in the incidence of implantations undergoing resorption was observed. No other reproductive parameters among the treated groups were significantly altered when compared to controls.

Key result

Dose descriptor:

NOEL

Effect level:

7.5 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

mortality

total litter losses by resorption

Fetal body weight changes:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidences of individual malformations among the treated groups were not significantly increased compared to controls.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidences of individual malformations among the treated groups were not significantly increased compared to controls. A significant increase in the incidence of a crooked hyoid bone was observed in the 20.0 mg/kg/day group. This alteration is considered to be a minor skeletal variant.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidences of individual malformations among the treated groups were not significantly increased compared to controls.

Key result

Dose descriptor:

NOEL

Effect level:

20 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No foetal effects

Key result

Developmental effects observed:

no

Table 1: Maternal observations (significant changes)

	0 mg/kg/day	1 mg/kg/day	7.5 mg/kg/day	20 mg/kg/day
Number of bred females	29	30	30	31
Number of maternal deaths	0	1	1	5
% Implantations resorbed	9 (20/219)	6 (10/171)	9 (20/218)	22 (44/201)*
% Litters with resorptions	30 (8/27)	32 (8/25)	39 (10/26)	79 (19/24)*

Statistically different from the control value by a modified Wilcoxon test, α=0.05.

Conclusions:

Rabbit NOEL: 7.5 mg/kg/day (maternal effects)
Rabbit NOEL: 20.0 mg/kg/day (foetal effects)

Executive summary:

The objective of this study was to evaluate the embryotoxic and teratogenic potential of repeated oral administration of the test substance during organogenesis in rabbits. Rabbits were given 0, 1.0, 7.5, or 20.0 mg/kg of test substance/day on days 6 through 18 of gestation.

5 animals in the 20.0 mg/kg/day group died during the study. The cause of death for one animal was attributed to pneumonia, whereas in the other four rabbits the cause could not be determined upon gross pathologic examination. These deaths may be treatment-related. Maternal weight gain and liver weights among the treated rabbits were comparable to controls. Evidence of embryolethality was observed in the 20.0 mg/kg group, where the incidence of implantations undergoing resorption was significantly increased. Low incidences of malformations were observed in the treated groups. Atypically no malformations were observed in the concurrent control group. The incidence of litters with malformations in the treated groups was within the historical control range for this strain in this laboratory. Therefore, oral administration of the test substance at a dose level as high as 20.0 mg/kg/day was not considered to be teratogenic in rabbits.

In conclusion, oral administration of the test substance during organogenesis was not teratogenic in rabbits at dose levels as high as 20.0 mg/kg/day.

Reference 6

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOEL

Effect level:

7.5 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

mortality

total litter losses by resorption

Key result

Dose descriptor:

NOEL

Effect level:

20 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No foetal effects

Key result

Developmental effects observed:

no

Conclusions:

Rabbit NOEL: 7.5 mg/kg/day (maternal effects)
Rabbit NOEL: 20.0 mg/kg/day (foetal effects)

Executive summary:

The objective of this study was to evaluate the embryotoxic and teratogenic potential of repeated oral administration of the test substance during organogenesis in rabbits. Rabbits were given 0, 1.0, 7.5, or 20.0 mg/kg of test substance/day on days 6 through 18 of gestation.

5 animals in the 20.0 mg/kg/day group died during the study. The cause of death for one animal was attributed to pneumonia, whereas in the other four rabbits the cause could not be determined upon gross pathologic examination. These deaths may be treatment-related. Maternal weight gain and liver weights among the treated rabbits were comparable to controls. Evidence of embryolethality was observed in the 20.0 mg/kg group, where the incidence of implantations undergoing resorption was significantly increased. Low incidences of malformations were observed in the treated groups. Atypically no malformations were observed in the concurrent control group. The incidence of litters with malformations in the treated groups was within the historical control range for this strain in this laboratory. Therefore, oral administration of the test substance at a dose level as high as 20.0 mg/kg/day was not considered to be teratogenic in rabbits.

In conclusion, oral administration of the test substance during organogenesis was not teratogenic in rabbits at dose levels as high as 20.0 mg/kg/day.

Reference 7

Endpoint:

developmental toxicity

Remarks:

probe study

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of 10 bred rats were given the test substance orally on days 6 through 15 of gestation at a level of 1, 10 and 25 mg/kg of test substance/day. Test animals were sacrificed on gestation day 16 and observed for gross pathological changes.

GLP compliance:

yes

Specific details on test material used for the study:

DOWCO 453 acid
Lot # AGR 192975
Purity: 99.7%

Species:

rat

Strain:

Fischer 344

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionized distilled

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

GD6-GD15

Frequency of treatment:

Daily

Dose / conc.:

1 mg/kg bw/day

Dose / conc.:

10 mg/kg bw/day

Dose / conc.:

25 mg/kg bw/day

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Statistics:

Statistical evaluation of the frequency of preimplantation loss and of resorptions among litters and the fetal population were made by the Wilcoxon test. Other incidence data were analyzed by the Fisher exact probability test. Analysis of other data were done by parametric or nonparametric analysis of variance followed by either Dunnett's test or distribution free multiple comparisons as appropriate. For food and water consumption data, statistical outliers were identified by a sequential outlier test and deleted from the calculation of means.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Description (incidence):

No maternal deaths occurred during the conduct of the study

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Pregnant rats in the 10 and 25 mg/kg group gained significantly less weight than controls during gestation days 6 through 15.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

Pregnant rats in the 10 and 25 mg/kg group consumed less food than controls during gestation days 6 through 15.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

A significant increase in liver weight (absolute and relative) was observed in 25 mg/kg group. In 10 mg/kg group, the weight of the liver relative to body weight was significantly increased.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Hepatic enlargement, considered to be treatment-related, occurred in a significant number of rats given either 10 or 25 mg/kg/day

Total litter losses by resorption:

effects observed, non-treatment-related

Description (incidence and severity):

Embryolethality, as evidenced by a significant increase in the incidence of resorptions, was observed in the 10 and 25 mg/kg/day dose groups

Key result

Remarks on result:

other: maternal toxicity was observed in the 10 and 25 mg/kg bw/day dose groups

Conclusions:

Based on the results of this probe study, dose levels of 0.1, 1, and 7.5 mg/kg/day have been chosen for the definitive teratology study.

Executive summary:

The objective of this study was to establish the maximum tolerated dose level of the test substance administered orally to pregnant rats during the period of major organogenesis. Bred Fischer 344 rats were given 0, 1, 10, or 25 mg/kg/day of the test substance by gavage on days 6 through 15 of gestation.

Significant maternal effects were observed among pregnant rats in the 10 and 25 mg/kg groups as evidenced by dose-dependent decreases in body weight gain and food consumption, and increased liver weight. In addition, significant increases in the incidence of resorptions were observed in these groups indicating that the test material was embryolethal at these dose levels. No effects considered to be treatment-related were observed in rats given 1 mg/kg/day.

Based on the results of this probe study, dose levels of 0.1, 1, and 7.5 mg/kg/day have been chosen for the definitive teratology study.

Reference 8

Endpoint:

developmental toxicity

Remarks:

probe study

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Remarks on result:

other: maternal toxicity was observed in the 10 and 25 mg/kg bw/day dose groups

Conclusions:

Based on the results of this probe study, dose levels of 0.1, 1, and 7.5 mg/kg/day have been chosen for the definitive teratology study.

Executive summary:

The objective of this study was to establish the maximum tolerated dose level of the test substance administered orally to pregnant rats during the period of major organogenesis. Bred Fischer 344 rats were given 0, 1, 10, or 25 mg/kg/day of the test substance by gavage on days 6 through 15 of gestation.

Significant maternal effects were observed among pregnant rats in the 10 and 25 mg/kg groups as evidenced by dose-dependent decreases in body weight gain and food consumption, and increased liver weight. In addition, significant increases in the incidence of resorptions were observed in these groups indicating that the test material was embryolethal at these dose levels. No effects considered to be treatment-related were observed in rats given 1 mg/kg/day.

Based on the results of this probe study, dose levels of 0.1, 1, and 7.5 mg/kg/day have been chosen for the definitive teratology study.

Reference 9

Endpoint:

developmental toxicity

Remarks:

probe study

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of 7 inseminated female rabbits were given the test substance orally on days 6 through 18 of gestation at a level of 1, 10 and 25 mg/kg of test substance/day. Test animals were sacrificed on gestation day 19 and observed for gross pathological changes.

GLP compliance:

yes

Specific details on test material used for the study:

DOWCO 453 acid
Lot # AGR 192975
Purity: 99.7%

Species:

rabbit

Strain:

New Zealand White

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

deionized distilled

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

GD6-GD18

Frequency of treatment:

Daily

Dose / conc.:

1 mg/kg bw/day

Dose / conc.:

10 mg/kg bw/day

Dose / conc.:

25 mg/kg bw/day

No. of animals per sex per dose:

7

Control animals:

yes, concurrent vehicle

Statistics:

Statistical evaluation of the frequency of preimplantation loss and of resorptions among litters and the fetal population were made by the Wilcoxon test. Other incidence data were analyzed by the Fisher exact probability test. Analysis of other data were done by parametric or nonparametric analysis of variance followed by either Dunnett's test or distribution free multiple comparisons as appropriate. For food and water consumption data, statistical outliers were identified by a sequential outlier test and deleted from the calculation of means.

Mortality:

mortality observed, treatment-related

Description (incidence):

Four rabbits were found dead or sacrificed in a moribund condition during the study, one at 10 mg/kg bw/day and three at 25 mg/kg bw/day. Two deaths were attributed to intubation error; the cause of death for the two remaining animals was not determined, based on gross pathologic examination.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

No statistically significant effects on body weight gain were observed among pregnant rabbits given 1, 10 or 25 mg/kg/day of the test substance. However, the three pregnant rabbits in the 25 mg/kg group which survived to the end of the study lost weight as compared to the other groups which gained weight.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No statistically significant effects on liver weight were observed among pregnant rabbits given 1, 10 or 25 mg/kg/day of the test substance.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

There were no observations which were dose-related or considered to be the result of treatment.

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

A significant increase in the incidence of implantations undergoing resorption was observed only in the 1 mg/kg group. In the absence of a dose response, this increase in the low dose group was not considered to be treatment-related.

Key result

Remarks on result:

other: No significant treatment-related maternal or embryo toxicity was observed in any group

Conclusions:

Based on the results of this probe study, dose levels of 1, 7.5, and 20 mg/kg/day have been chosen for the definitive teratology study.

Executive summary:

The objective of this study was to establish the maximum tolerated dose level of the test substance administered orally to pregnant rabbits during the period of major organogenesis. Inseminated New Zealand white rabbits were given 0, 1, 10, or 25 mg/kg/day of the test substance by gavage on days 6 through 18 of gestation.

No significant treatment-related maternal or embryo toxicity was observed among pregnant rabbits given 1, 10, or 25 mg/kg/day. Two maternal animals in the 25 mg/kg group died during the course of the study and a definitive cause of death was not determined.

Based on the results of this probe study, dose levels of 1, 7.5, and 20 mg/kg/day have been chosen for the definitive teratology study.

Reference 10

Endpoint:

developmental toxicity

Remarks:

probe study

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

Additional documentation provided in IUCLID assesment reports (Chapter 13) supports the read across approach

Reason / purpose for cross-reference:

read-across source

Key result

Remarks on result:

other: No significant treatment-related maternal or embryo toxicity was observed in any group

Conclusions:

Based on the results of this probe study, dose levels of 1, 7.5, and 20 mg/kg/day have been chosen for the definitive teratology study.

Executive summary:

The objective of this study was to establish the maximum tolerated dose level of the test substance administered orally to pregnant rabbits during the period of major organogenesis. Inseminated New Zealand white rabbits were given 0, 1, 10, or 25 mg/kg/day of the test substance by gavage on days 6 through 18 of gestation.

No significant treatment-related maternal or embryo toxicity was observed among pregnant rabbits given 1, 10, or 25 mg/kg/day. Two maternal animals in the 25 mg/kg group died during the course of the study and a definitive cause of death was not determined.

Based on the results of this probe study, dose levels of 1, 7.5, and 20 mg/kg/day have been chosen for the definitive teratology study.

Effect on developmental toxicity: via oral route

Dose descriptor:

NOAEL

15 mg/kg bw/day

Study duration:

subacute

Species:

rabbit

Quality of whole database:

Data were available in both rats and rabbits.

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

Male and female Sprague-Dawley rats ingested 0, 0.01, 0.065 or 1.0 mg/kg/day of the test substance for 8 weeks. Ingestion of 1.0 mg/kg/day of the test substance did result in a slight decrease in flat f1a, f1b and f2a weanling body weights and f1 adult body weights. However, concentrations as high as 1.0 mg/kg/day did not affect the ability of the parental animals to mate, produce a litter of normal size and number and raise a litter. Thus the no-observable-effect level (NOEL) for reproductive parameters in Sprague-Dawley rats is 1.0 mg/kg/day for the test substance.

Another study was conducted to understand whether the low incidence of malformations, and in particular, microphthalmia, observed in a previous teratology study in which New Zealand White rabbits were administered 1, 7.5 or 20 mg/kg/day of the test substance was a spontaneous occurrence or a treatment-related effect according to the guideline EPA OPP 83-3. Inseminated rabbits were therefore administered 0, 3.0, 7.5 or 15 mg/kg/day of the test substance by gavage on days 6 through 18 of gestation and the fetuses examined for developmental alterations. There were no indications of maternal toxicity in any of the dose groups; however, four deaths occurred in the 15 mg/kg/day dose group, two of which may have been treatment-related. Examination of the fetuses revealed a low incidence of malformations in all groups, including the controls. There were no indications of ocular alterations in any of the fetuses examined. Therefore, the results of the present study support the conclusion of the previous study regarding the spontaneous nature of microphthalmia observed. Evaluation of the various alterations observed in this study did not reveal any treatment-related increases in any parameter. In conclusion, oral administration of the test substance during organogenesis at dose levels up to 15 mg/kg/day was not teratogenic or fetotoxic in New Zealand White rabbits.

Justification for classification or non-classification

There is no evidence to suggest that the test substance causes adverse effects on reproduction or development of the offspring. Therefore, the test substance is not classified for reproductive or developmental toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.