Dibutyl [(dipropoxyphosphinothioyl)thio]succinate

Endpoint summary

Description of key information

Repeated dose toxicity (oral) – 14 day

Administration of Butanedioic acid, (dipropoxyphosphinothioyl)thio]-,1,4-dibutyl ester to male and female Crl:CD(SD) rats was not well tolerated at dosage levels of 250, 500, and 1000 mg/kg/day, as evidenced by moribundity, mortality, and/or adverse clinical observations. All rats in the 1000 mg/kg/day group were found dead or euthanised in extremis by Study Day 2. Lower mean body weight gain was noted for males at 500 mg/kg/day during Study Days 0–4. Beginning on Study Day 5, animals administered 50 or 100 mg/kg/day exhibited no noteworthy clinical observations through Study Day 14. Mean body weights, body weight gains, and food consumption were generally unaffected by test substance administration at 0/50, 250, 500/100 mg/kg/day. Based on these results, dosage levels of 15, 50, and 150 mg/kg/day were selected for a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD 422) in male and female Crl:CD(SD) rats (Charles River Laboratories, 2017).

 

Repeated dose toxicity (oral) – 28 day

No test substance-related effects for Butanedioic acid, 2-(dipropoxyphosphinothioyl)thio]-, 1,4-dibutyl esterwere observed on F0 male and female fertility and mating indices, F0 male copulation index, F0 female conception index, gestation length, parturition, or reproductive organs at any dosage level, therefore, dosage levels of 150 mg/kg/day for males and 100 mg/kg/day for females, the highest doses tested, were considered to be the no-observed-adverse-effect levels (NOAEL) for reproductive toxicity. Test substance-related mortality, moribundity, and adverse clinical observations (hypoactivity, tremors, ataxia, clonic convulsions, and thin body) were noted for females at 150 mg/kg/day, resulting in the reduction of the dosage level to 100 mg/kg/day on Study Day 13. Following the reduction in dosage level for females, a single female in the 150/100 mg/kg/day group was euthanised in extremis. There were no adverse test substance-related clinical observations for males at 150 mg/kg/day or effects on body weights and food consumption for males and females at any dosage level. Test substance-related higher heart weights (absolute and relative to brain and body weights) were noted in the 150/100 mg/kg/day group F0 females. There were no adverse effects on clinical pathology parameters, thyroid hormones, or macroscopic/microscopic alterations in F0 males and females at any dosage level. Based on these results, the NOAELs for systemic toxicity were considered to be 150 mg/kg/day for males, the highest dose tested, and 50 mg/kg/day for females. The NOAEL for neonatal toxicity was 100 mg/kg/day, the highest dose tested, based on the absence of effects on F1 offspring at all dosage levels. (Charles River Laboratories, 2018).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral, other

Remarks:

Fourteen day repeated dose oral (gavage) range-finding toxicity study in the rat conducted as part of OECD 422 study, under GLP conditions.

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

22 December 2016 - 10 July 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other:

Remarks:

Range find study conducted as part of OECD 422 study, under GLP conditions.

Qualifier:

according to guideline

Guideline:

other: Range-Finding Toxicity Study in the Rat, to inform dose selection in an OECD Guideline 422 study.

Principles of method if other than guideline:

The study described in this report was conducted in a facility which operates in accordance with Good Laboratory Practice principles, however no claim of GLP compliance was intended nor is made for this study.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Description: Light yellow, clear liquid
- Storage: Room temperature (18 - 24°C), protected from light

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc.
- Age at first dose: Approximately 10 weeks of age at the initiation of dose
administration.
- Weight at first dose: 343 g to 387 g for males and from 221 g to 251 g for females on Study Day 0
- Housing: Clean, solid-bottom cages with bedding material (Bed O’Cobs®)
- Bedding: See above
- Feed: PMI Nutrition International, LLC Certified Rodent LabDiet® 5002 offered ad libitum
- Water: Filtered water was provided ad libitum
- Acclimation period: A minimum of 15 days for acclimation purposes

ENVIRONMENTAL CONDITIONS
- Temperature Range: 20 to 26°C
- Humidity Range: 33.7 to 48.5%
- Light Cycle: 12-hour light/12-hour dark
- Air Changes: Minimum of 10 air changes per hour

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

Test substance formulations and vehicle control were stirred continuously at room temperaturefor the duration of the dosing.

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Homogeneity, stability, and concentration of the test substance formulations were not assessed on this non-GLP study.

Duration of treatment / exposure:

14 days

Frequency of treatment:

Once daily during Study Days 0–2 at dosage levels of 0, 250, 500, and 1000 mg/kg/day

Dose / conc.:

0 mg/kg bw/day (nominal)

Dose / conc.:

50 mg/kg bw/day (nominal)

Dose / conc.:

250 mg/kg bw/day (nominal)

Dose / conc.:

500 mg/kg bw/day (nominal)

Remarks:

Only dosed at this level on day 0 - 2

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

Only dosed at this level for day 0 - 2

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

Group 4

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Added dose on days 5 - 14

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

The dosage levels were selected following consultation between the Charles River Study Director and the Study Monitor for the Sponsor, with consideration given to the results of a single-dose acute oral toxicity study in which a single dose of undiluted test substance was orally
given to female rats at 2000 mg/kg 1. Hunched posture, diuresis, diarrhea and dehydration were noted in some rats. No mortality and other abnormality were observed. The high dose for this range-finding study will be 1,000 mg/kg/day, as this is the maximum dose level required for the
subsequent combined repeated dose toxicity and reproductive/developmental toxicity screening study in the rat (OECD 422).

Observations and examinations performed and frequency:

All animals were observed twice daily for mortality and moribundity. Clinical observations, body weights, and food consumption were recorded at the intervals specified in the study protocol. Complete necropsies were conducted on all surviving animals on Study Day 14, and
selected organs were weighed.

Sacrifice and pathology:

A gross necropsy was conducted on all surviving animals at the scheduled euthanasia on Study Day 14.

All animals were euthanized by carbon dioxide inhalation. Necropsy included examination of the external body surface, all orifices, the cranial cavity, the external surface of the brain, and the abdominal, pelvic, and thoracic cavities, including viscera. Tissues were preserved in 10% neutral-buffered formalin only as indicated by the gross findings.

Statistics:

All statistical tests were performed using WTDMS™ unless otherwise noted. Analyses were conducted using two-tailed tests (except as noted otherwise) for minimum significance levels of 1% and 5%, comparing each test substance-treated group to the control group. Each mean was presented with the standard deviation (S.D.), standard error (S.E.), and the number of animals(N) used to calculate the mean. Statistical analyses were not conducted if the number of animals was 2 or less. Due to the use of significant figures and the different rounding conventions inherent in the types of software used, the means, standard deviations, and standard errors on the summary and individual tables may differ slightly. Therefore, the use of reported individual values to calculate subsequent parameters or means will, in some instances, yield minor variations from those listed in the report data tables. Body weights, body weight changes, and absolute and relative organ weights were subjected to a parametric one-way ANOVA3 to determine intergroup differences. If the ANOVA revealed significant (p < 0.05) intergroup variance, Dunnett's test was used to compare the test substance-treated groups to the control group.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical observations noted 1.5 hours after dosing in the 500 and 1000 mg/kgday included tremors, hypoactivity, ataxia, piloerection, decreased respiration rate, labored respiration, red material around the eyes and/or nose, clear material around the mouth, exophthalmia, and/or yellow material around the anogenital area.

There were no remarkable clinical observations noted for surviving animals when the test substance was administered to the 250 mg/kg/day group.

Clinical observations noted for surviving animals at the daily examinations, including scabbing, hair loss, and/or red material on various body surfaces, occurred infrequently and/or in a manner that was not dose-related.

Mortality:

mortality observed, treatment-related

Description (incidence):

During Study Days 0–2, 5 males and 5 females in the 1000 mg/kg/day group were found dead or euthanized in extremis following 1–3 doses of test substance.

Effects on survival were also noted for males and females in the 500 mg/kg/day group, as 2 males and 4 females in this group were found dead or euthanized in extremis on Study Day 2 following 2 doses of test substance.

In the 250 mg/kg/day group, 1 male was found dead on Study Day 11 following a lower body weight gain during Study Days 0–4. Two females in the 250 mg/kg/day group were found dead on Study Days 6 and 14, respectively. There were no remarkable clinical observations noted for the animals in the 250 mg/kg/day group that were found dead. There were no remarkable macroscopic findings for the 250 mg/kg/day group animals that were found dead.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weights not measure in 1000 mg/kg/day.

A significant (p < 0.05) mean body weight loss was noted in the 500 mg/kg/day group male and females for days 0 - 2. This group recovered when dosing was adjusted to 100 mg/kg/day.

Mean body weights and body weight gains were comparable between the 0/50 and 250 mg/kg/day group males and females.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Evaluation of food consumption not measured in 1000 mg/kg/day group.

Mean food consumption, evaluated as g/animal/day, was comparable between the 0 and 250 mg/kg/day group males and females during Study Days 0–4.

During Study Days 7–14, mean food consumption was comparable between the 0/50, 250, and 500/100 mg/kg/day group males and females.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

Tremors, hypoactivity and ataxia were observed in the 500 mg/kg/day dose group.

Tremors, hypoactivity, ataxia, and poloerection were observed in the 1000 mg/kg/day dose group.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Mean organ weights (absolute and relative to body final body weight and brain weight) were comparable across the dose groups that were measured.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

At necropsy, remarkable macroscopic findings noted in the males and females found dead or euthanized in extremis in the 1000 mg/kg/day group included dark red discoloration of the adrenal glands, lungs, and pancreas, a pale spleen, and cystic ovaries.

At necropsy, findings for the found dead or euthanized in extremis animals in the 500 mg/kg/day group included dark red discoloration or areas on the adrenal glands, kidneys, lungs, and/or thymus, cystic ovaries, and/or small thyroid gland(s).

There were no remarkable macroscopic findings for the 250 mg/kg/day group animals.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Key result

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

Key result

Critical effects observed:

not specified

The following table presents the individual animal data for males and females found dead or euthanized in extremis during the study.

 

Summary of Individual Findings for Animals Found Dead or Euthanized in Extremis

 

AnimalNo.	Dosage Level(mg/kg/day)	Sex	Study Day of Death or Euthanasia	No. of DosesReceived	Clinical Observations	Macroscopic Findings
1959	1000	M	EE SD 2	3	Clear material around mouth	Dark red discoloration of the adrenal glands
1971	1000	M	FD SD 2	2	NA	Dark red discoloration of the adrenal glands, dark red discoloration of the lungs, pale spleen, red matting on the skin in the ocular, nasal, and urogenital areas
1974	1000	M	FD SD 1	1	NA	NA
1977	1000	M	FD SD 2	2	NA	Dark red discoloration of the adrenal glands, dark red discoloration of the lungs, pale spleen, red matting on the skin in the ocular and nasal areas
1978	1000	M	FD SD 2	2	NA	Dark red discoloration of the lungs, pale spleen
1983	1000	F	EE SD 1	2	NA	Red matting on the skin in the ocular area
1989	1000	F	EE SD 1	2	Decreased respiration rate, labored respiration, red material around eyes and nose, yellow material around anogenital area, hypoactivity, red discharge from eye	Red matting on the skin in the ocular area
1992	1000	F	EE SD 1	2	Tremors, decreased respiration rate, red discharge from eyes, red material around eyes, clear material around mouth	Cystic ovary, dark red discoloration of the pancreas, red matting on the skin in theocular area
1998	1000	F	FD SD 1	2	Hypoactivity, ataxia, tremors, decreased respiration rate, redmaterial around eyes, yellow material around urogenital area, clear materialaround mouth	Yellow matting of the skin in buccal area and ventral neck, Red matting on the skin ocular area

FD = Found dead EE = Euthanized in extremis SD = Study Day

NA = Not applicable; no remarkable clinical or macroscopic observations were noted

Summary of Individual Findings for Animals Found Dead or Euthanized in Extremis (Continued)

 

AnimalNo.	Dosage Level(mg/kg/day)	Sex	Study Day of Death or Euthanasia	No. of DosesReceived	Clinical Observations	Macroscopic Findings
2001	1000	F	FD SD 1	2	Piloerection, ataxia, decreased respiration rate, red material around eye, exophthalmus (bilateral), yellow material around the urogenital area, broken tail, clear material around mouth, tremors	Yellow matting on the skin in nasal and buccal and ventral neck, red matting of the skin ocular area
1965	500	M	FD SD 2	2	NA	Dark red discoloration of the adrenal glands, renal pelvis, lungs, and thymus, red matting on the skin in the ocular and nasal areas
1981	500	M	FD SD 2	2	NA	Dark red discoloration of the lungs, red matting on the skin in the nasal area, dark red areas on the thymus
1991	500	F	FD SD 2	2	NA	Dark red discoloration of the lungs, red matting on the skin in the ocular area
1993	500	F	FD SD 2	2	NA	Dark red discoloration of the adrenal glands, red matting on theskin in the ocular and nasal areas, small thyroids
1997	500	F	EE SD 2	2	Tremors, ataxia, decreased respiration rate, red material around eyes	Red matting on the skin in the ocular area
2000	500	F	EE SD 2	2	Tremors, hypoactivity, ataxia, decreased respiration rate, clear or red discharge from eyes, red material around eyes	Dark red discoloration of the adrenal glands, red matting of the skin in the ocular area
1963	250	M	FD SD 11	11	NA	NA
1990	250	F	FD SD 6	6	NA	NA
2005	250	F	FD SD 14	14	NA	NA

FD = Found dead EE = Euthanized in extremis SD = Study Day

NA = Not applicable; no remarkable clinical or macroscopic observations were noted

All other animals survived to the scheduled necropsy.

 

There were no remarkable clinical observations noted for surviving animals when the test substance was only administered to the 250 mg/kg/day group (dosing holiday for Group 3) during Study Days 3 and 4. Following the adjustment of dosage levels on Study Day 5, clinical observations noted approximately 1.5 hours following dose administration were limited to clear or red material around the nose or mouth for 2 males in the 250 mg/kg/day group and 1 female inthe 0/50 mg/kg/day group. Clinical observations noted for surviving animals at the daily examinations, including scabbing, hair loss, and/or red material on arious body surfaces, occurred infrequently and/or in a manner that was not dose-related.

 

Conclusions:

Based on the results, dosage levels of 15, 50, and 150 mg/kg/day were selected for a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD 422) in male and female Crl:CD(SD) rats.

Executive summary:

The objective of the study was to determine dosage levels of the test material, to be evaluated in a potential combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD 422) in rats.

The test material in the vehicle (corn oil) was to be administered orally by gavage to 3 groups of 5 Crl:CD(SD) rats, each group consisting of 5 males and 5 females, once daily for 14 consecutive days at dosage levels of 250, 500, and 1000 mg/kg/day. However, due to excessive toxicity noted in the 1000 mg/kg/day group, all animals in this group were found dead or euthanized in extremis by Study Day 2. Mortality and moribundity were also noted in the 500 mg/kg/day group during the first 3 days (Study Days 0–2) of dosing; therefore, an additional

2 males and 4 females were assigned to the 500 mg/kg/day group. The surviving animals in the 500 mg/kg/day group were placed on a dosing holiday for 2 days (Study Days 3 and 4), and then subsequently dosed at a lower dosage level of 100 mg/kg/day during Study Days 5–13. Animals assigned to the 250 mg/kg/day group received the test substance at this dosage level throughout the treatment period (Study Days 0–13). A concurrent control group composed of 5 males and 5 females received the vehicle during Study Days 0–4 and were administered the test substance at a dosage level of 50 mg/kg/day during Study Days 5–13. The dosage volume was 5 mL/kg for all groups. The animals were approximately 10 weeks of age at the initiation of dose administration.

All animals were observed twice daily for mortality and moribundity. Clinical observations, body weights, and food consumption were recorded at the intervals specified in the study protocol. Complete necropsies were conducted on all surviving animals on Study Day 14, and

selected organs were weighed.

Oral administration of the test material to male and female Crl:CD(SD) rats was not well tolerated at dosage levels of 250, 500, and 1000 mg/kg/day as evidenced by moribundity, mortality, and/or adverse clinical observations. All rats in the 1000 mg/kg/day group were found dead or euthanized in extremis by Study Day 2. Lower mean body weight gain was noted for males at 500 mg/kg/day during Study Days 0–4. Beginning on Study Day 5, animals administered 50 or 100 mg/kg/day exhibited no noteworthy clinical observations through Study Day 14. Mean body weights, body weight gains, and food consumption were generally unaffected by test substance administration at 0/50, 250, 500/100 mg/kg/day. Based on these results, dosage levels of 15, 50, and 150 mg/kg/day were selected for a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD 422) in male and female Crl:CD(SD) rats.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

50 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

1

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose toxicity (oral) – 14 day

Key study:

In an OECD Guideline 422 Study (14 day), conducted according to GLP, oral administration of Butanedioic acid, (dipropoxyphosphinothioyl)thio]-,1,4-dibutyl ester to male and female Crl:CD(SD) rats was not well tolerated at dosage levels of 250, 500, and 1000 mg/kg/day, as evidenced by moribundity, mortality, and/or adverse clinical observations. All rats in the 1000 mg/kg/day group were found dead or euthanised in extremis by Study Day 2. Lower mean body weight gain was noted for males at 500 mg/kg/day during Study Days 0–4. Beginning on Study Day 5, animals administered 50 or 100 mg/kg/day exhibited no noteworthy clinical observations through Study Day 14. Mean body weights, body weight gains, and food consumption were generally unaffected by test substance administration at 0/50, 250, 500/100 mg/kg/day. Based on these results, dosage levels of 15, 50, and 150 mg/kg/day were selected for a combined repeated dose toxicity study with the reproduction/developmental toxicity screening test (OECD 422) in male and female Crl:CD(SD) rats (Charles River Laboratories, 2017).

Repeated dose toxicity (oral) - 28 day

Key study:

In an OECD Guideline 422 Study (28 day screening study), no test substance-related effects forButanedioic acid, 2-[(dipropoxyphosphinothioyl)thio]-, 1,4-dibutyl esterwere observed on F0 male and female fertility and mating indices, F0 male copulation index, F0 female conception index, gestation length, parturition, or reproductive organs at any dosage level, therefore, dosage levels of 150 mg/kg/day for males and 100 mg/kg/day for females, the highest doses tested, were considered to be the no-observed-adverse-effect levels (NOAEL) for reproductive toxicity. Test substance-related mortality, moribundity, and adverse clinical observations (hypoactivity, tremors, ataxia, clonic convulsions, and thin body) were noted for females at 150 mg/kg/day, resulting in the reduction of the dosage level to 100 mg/kg/day on Study Day 13. Following the reduction in dosage level for females, a single female in the 150/100 mg/kg/day group was euthanised in extremis. There were no adverse test substance-related clinical observations for males at 150 mg/kg/day or effects on body weights and food consumption for males and females at any dosage level. Test substance-related higher heart weights (absolute and relative to brain and body weights) were noted in the 150/100 mg/kg/day group F0 females. There were no adverse effects on clinical pathology parameters, thyroid hormones, or macroscopic/microscopic alterations in F0 males and females at any dosage level. Based on these results, the NOAELs for systemic toxicity were considered to be 150 mg/kg/day for males, the highest dose tested, and 50 mg/kg/day for females. The NOAEL for neonatal toxicity was 100 mg/kg/day, the highest dose tested, based on the absence of effects on F1 offspring at all dosage levels.(Charles River Laboratories, 2018).