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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
GLP compliance:
yes (incl. QA statement)
Limit test:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Diethyl ethylphosphonate
EC Number:
201-111-9
EC Name:
Diethyl ethylphosphonate
Cas Number:
78-38-6
Molecular formula:
C6H15O3P
IUPAC Name:
diethyl phosphonate
Test material form:
liquid

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
The Test Guideline OECD 422 is designed for use with the rat. The rats are the standard experimental rodent of choice and recommended by OECD Guideline and in the international validation program for the detection of endocrine disrupters the rat was the only species used.
55 males + 67 females
(5 males and 5 females were used as replacement animals)
Sex:
male/female
Details on test animals or test system and environmental conditions:
The animals were acclimated to the condition identical to the condition during the experiment 5 days prior to the start of treatment. The acclimation was according to standard operation procedures.
The animals were housed in plastic cages suspended on stainless steel racks in a room equipped with central air-conditioning. The room temperature was within the range of 22 ± 2°C; relative humidity was within the range of 55 ± 10 %. The light regimen was set to a 12-hour light / 12-hour dark cycle The sanitation was performed according to standard operation procedures.

Administration / exposure

Route of administration:
oral: gavage
Details on route of administration:
Diethyl ethylphosphonate, in the vehicle olive oil, was administered by gavage once daily to three groups of Wistar rats at the doses of 25, 50 and 150 mg/kg.
Vehicle:
olive oil
Details on oral exposure:
Dose volume was 2.0 mL/kg of body weight and was adjusted according to the weight development of the animals.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Once per day.
Females were treated during:
- 14-day pre-mating,
- 14-day mating (maximum)
- 22-day gestation (approximately)
- 13-day lactation
Males were treated during:
- 14-day pre-mating,
- 14-day mating (maximum)
The animals designated for post-treatment observation (5 animals
per sex in control and high groups, respectively) remained
untreated for subsequent 14 days.
Duration of treatment / exposure:
The animals were dosed daily for 7 days a week.
Frequency of treatment:
daily
Doses / concentrations
Dose / conc.:
2 mg/kg bw (total dose)
Control animals:
yes, concurrent vehicle

Examinations

Observations and examinations performed and frequency:
Blood samples were collected from fasted animals; haematology and clinical chemistry parameters were analysed preferably at the same day as blood was collected. Plasma samples for determination of coagulation test and thyroid hormone levels were stored according relevant condition for later analysis. Blood collection for haematological investigations was performed from the incision on the tail; the blood collection for clinical chemistry (serum) from retrobulbar venoplex was performed under anaesthesia (Isofluran). Blood collection for coagulation tests (citrate plasma) and thyroid hormone (EDTA plasma) was taken from the heart.
The blood collection, processing of the blood and the determination of its haematological and clinical chemistry parameters were performed according to the standard operation procedures.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Description (incidence and severity):
Animals lived through the observation period without significant visible clinical signs. Daily clinical examination only tremor in one female (ID 99) of High dose was registered. No other signs were observed.
Mortality:
no mortality observed
Description (incidence):
All other males and females at all dosage levels survived to the scheduled necropsy.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
The body weight of males of all dose groups was mildly increasing during the study. No significant differences between control and dose groups were observed. The body weight of High dose satellite males was similar in comparison with recovery control males during the whole study.
The body weight of females of all dose groups was mildly increasing during the study. No significant differences between control and dose groups were observed. The body weight of recovery High dose females was similar in comparison with recovery control females during the whole study.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Food consumption of males of all dose groups was similar to the control males during the whole study. Food consumption of recovery treated males was similar in comparison with control group during the whole application and recovery period.
Food consumption of treated females was similar in comparison with control group during the whole application period. Food consumption of recovery treated females was similar in comparison with recovery control females for the whole study.

Effect levels

Dose descriptor:
NOAEL
Effect level:
ca. 150 mg/kg bw/day (nominal)
Sex:
male/female
Basis for effect level:
body weight and weight gain

Target system / organ toxicity

Critical effects observed:
no

Applicant's summary and conclusion

Conclusions:
After consideration of the results of this study following conclusions were made regarding the test
item Diethyl ethylphosphonate.
The test item
- caused incidence of mortality in High dose (150 mg/kg) groups
- had no visible toxic effect on animals
- had no influence on haematological and clinical chemistry parameters
- did not cause changes in urine of males
- had no influence on the locomotor activity in males and reaction time and grip strength in all
animals
- caused transient decrease in motor activity in females during lactation
- had no influence on motor activity of satellite females
- did not influenced length of pregnancy, survival of pups, AGD or other variables
- caused reduction of female body weight at the age of 13 post-partum in High dose (150
mg/kg)
- caused increase retention of nipples/areolae in males offspring in High dose (150 mg/kg)
- did not cause of macroscopic findings and histopathological changes on the examined organs
No-observed-adverse-effect level (NOAEL)
Based on the reproduction toxicity
• NOAEL for males and females was concluded to be 50 mg/kg
Based on the systemic toxicity
• NOAEL for systemic toxicity in males and females was concluded to be 150 mg/kg