Registration Dossier

Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study. Adopted according to OECD SIDS (public available peer reviewed source). The original source is available and has been reviewed.
Cross-reference
Reason / purpose:
reference to same study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002
Reference Type:
secondary source
Title:
Dimethyl phosphonate - CAS No: 868-85-9 - SIDS Initial Assessment Report.
Author:
OECD
Year:
2006
Bibliographic source:
UNEP Publications

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
yes
Remarks:
food intake was recorded only during the premating period
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): dimethylphosphonate
- Physical state: liquid
- Analytical purity: 99.8%
- Purity test date: 24-10-2001
- Lot/batch No.: 1/03091
- Stability under test conditions: at least 8 days (at animal room conditions).
- Storage condition of test material: at room temperature.

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, Borchen, Germany
-Age at study initiation: (P) 12 wks
- Weight at study initiation: (P) Males: 313-345 g; Females: 193-216 g.
- Housing: rats were housed singly under conventional conditions in Makrolon Type IIa cages. During the mating periods females were co-housed overnight with their males in type IIIh cages.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 2
- Humidity (%): 55 ± 5
- Air changes (per hr): 10 passages per hour at minimum.
- Photoperiod (hrs dark / hrs light): 12 hour rhythm from 05:00 to 17:00 CET (artificial illumination: approx. 250 lux, for work in the room: approx. 450 lux). From 17:00 to 05:00 CET orientation light, approx 3-5 lux.

Occasional deviations from these standards occurred, e.g. during cleaning of the animal room. These did not have any apparent influence on the outcome of the study.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
polyethylene glycol
Remarks:
Polyethylene glycol 400 (PEG 400/Lutrol ®)
Details on exposure:
VEHICLE
- Justification for use and choice of vehicle (if other than water): PEG 400 was chosen because of the potential for chemical hydrolysis in water.
- Concentration in vehicle: 0, 6.0, 18.0, 54.0 mg/mL
- Amount of vehicle (if gavage): 5 mL/ kg bw
Details on mating procedure:
Pairing was performed overnight (from about 15:00 to 08:00 CET; on week-ends from 12:00 to 08:00 CET) by placing one F0 female animal together with one F0 male rat into a type IIIh Makrolon cage. Allocation of the female animals to the respective male animals was performed with ascending animals number, i.e. the 1st male of the relevant dose group was paired with the 1st female and so on. During the two-week mating period each female animal was paired daily. Females with positive sperm detection (taken as day 0 of gestation) were not mated again.

F0 females found sperm-positive after the first mating day but were shown to be not pregnant (no increase in weight) were co-housed again (remated) over one week with the same male without checking insemination or measuring body weight.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The analytical verification of doses and concentration was conducted by capillary gas chromatography (GC)
Duration of treatment / exposure:
Dimethyl phosphonate or vehicle was administered to each of the female F0 rats once daily for 2 weeks prior to mating, during the subsequent mating and remating period, during gestation and up to the day before necropsy (day 4 to 6 post partum) of their pups.
The F0 males were each given dimethyl phosphonate or vehicle once daily for 2 weeks prior to mating, during the following mating up to day 37.

Frequency of treatment:
Daily between 06:00 and 12:30 CET.

Doses / concentrations
Remarks:
Doses / Concentrations:
0, 30, 90, 270 mg/kg body weight/day
Basis:
actual ingested
No. of animals per sex per dose:
12
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: the dose levels used were selected according to results of a preceding pilot parental tolerability study with dose level of 0, 30, 100, and 350 mg/kg bw/day. In this study two rats per group and sex were treated two weeks prior mating, as well as mating and lactation period up to 4 day post partum. At 350 mg/kg bw/day all parental rats had to be killed prescheduled because of poor general condition and body weight loss. Necropsies of these rats as well as those of animals, which were necropsied prescheduled, revealed no treatment related gross lesions. In F1 pups no toxic effects were noted up to 100 mg/kg bw/day. From these results it was concluded that the parental toxicity would occur between 100 and 350 mg/kg bw/day. Therefore, the dose levels of 0, 30, 90, and 270 mg/kg bw/day were selected in the present study.
Positive control:
No

Examinations

Parental animals: Observations and examinations:
Clinical signs: Appearance, behaviour and mortality were monitored twice daily (once daily on weekends, public holidays and on day of necropsy) by cage side examination during the entire treatment period in male and female animals (only clinical findings were recorded individually).
A detailed clinical observation was performed once a week in males (up to necropsy) and females (up to birth, at birth an on day 4 of lactation).

Body weights: Male F0 rats were weighed prior to the study and thereafter weekly and on the day of their necropsy. F0 females were weighed prior to the study and thereafter weekly. In inseminated females body weights was recorded up to the day of delivery, on day 0 and 4 post partum as well as on the day of their necropsy.

Measurement of food consumption was performed weekly during the premating period in both genders. The feed consumption was determined based on the differences in weight of feed provided and feed which remained unconsumed.

Gross pathological examination of all male and female animals during necropsy on unscheduled or scheduled deaths.
Oestrous cyclicity (parental animals):
The following female specific data were recorded and evaluated for all female rats assigned to the present study during the study or at the time of necropsy:
-Duration of gestation
-Livebirth index [%]: Number of viable pups at birth x 100/Number of pups born
-Course of birth
-Number of corpora lutea in the right and left ovary
-Number of implantation sites by staining with 10% ammoniumsulfide
The following organs were investigated histopathologically: ovaries (all groups)
Sperm parameters (parental animals):
The following male specific data were recorded and evaluated in the present study at the time of necropsy: testicular and epididymal weight (left and right testis/epididymis individually).


Litter observations:
The following parameters were investigated and assessed for the F1 pups at birth and up to day 4 to 6 post partum:
-Appearance (including externally visible malformations), general behaviour and mortality: twice daily (once at the weekends, on public holidays and on the day of sacrifice). Only clinical findings were documented by individual animal.
-A detailed clinical observation was done on the day of birth and on day 4 post partum.
-Sex ratio of the pups at birth.
-Individual pup weights at birth (day 0 post partum) and on day 4 post partum.

Postmortem examinations (parental animals):
Scheduled necropsies: Males on day 37 and females on day 4 to 6 post partum of their pups.
All animals were killed by exsanguination under deep carbon dioxide anesthesia.
At necropsy the following organs were fixed: testes and epididymes in Davidson´solution for 3 to 5 days before transferred to 10% neutral buffered formalin solution.
Prostate, seminal vesicles with coagulation glands, uterus with cervix, vagina, ovaries with oviducts, stomach, esophagus, mamma with skin and gross lesions and physical identifiers in 10% neutral buffered formalin solution.

Postmortem examinations (offspring):
The pups were killed by carbon dioxide asphyxia on day 4 to 6 post partum.
Statistics:
a) Analysis of variance (ANOVA) and in case of signifcant results Dunnett´s test (organ weights, time to insemination, duration of gestation, number of implantation sites per females, prenatal loss per female, live birth and viability index, number of pups delivered, stillborn, died, missing and/or cannibalized, number of live pups per female at the individual weighing times, sex ratio of pups, pup weights and pup weight changes)

b) 2 by N CHI² test, in case of significant differences Fisher´s exact test with Bonferroni correction for insemination, fertility and gestation index, number of females with live pups, stillborn pups, all pups stillborn, number of females with total postnatal litter loss up to day 4 post partum.

c) F-test and additional t-test or Welch t-Test (number of implantation sites per female)
These calculations were preformed using an HP Vectra personal computer (Basic program) in case there were differences with respect to control group.

d) Dunnett-Test in connection with a variance analysis for body weights of parent animals.
e) The Kruskal-Wallis-Test with a Steel-Test for food consumption data.
These calculation were performed using SAS® routine on a HP 3000 computer system.
Reproductive indices:
-Insemination index [%]: number of females inseminated x 100/ number of females paired;
-Fertility index [%]: number of females with implantation sites x 100/number of females inseminated;
-Gestation index [%]: number of females with viable pups x 100/number of females with implantation sites.
Offspring viability indices:
live birth index [%]: number of viable pups at birth x 100/ number of pups born.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Other effects:
not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
effects observed, treatment-related
Description (incidence and severity):
at 270 mg/kg bw : Effects were secondary to the severe maternal toxicity in this group
Reproductive function: sperm measures:
effects observed, treatment-related
Description (incidence and severity):
at 270 mg/kg bw : Effects were secondary to the severe maternal toxicity in this group
Reproductive performance:
effects observed, treatment-related
Description (incidence and severity):
at 270 mg/kg bw : Effects were secondary to the severe maternal toxicity in this group

Details on results (P0)

APPEARANCE, BEHAVIOUR AND MORTALITY OF F0 RATS
Up to the dose of the clinical symptoms occurred with remarkable incidences. At 90 mg/kg bw/day soft feces and/or diarrhoea were noted more frequently in both sexes than at 0 mg/kg bw/day. At 270 mg/kg bw/day several clinical signs of severe toxicity such as poor general condition, apathy, high stepping gait, squatting position, bloody muzzle, piloerection, emaciation, tremor and/or desiccation of the skin were noted in males and /or females.

One control male had to be killed since of poor general condition. This animal exhibited discolorations in the forestomach and thymus as well as little collapsed lungs possibly due to a misapplication.
Two 270 mg/kg bw /day males were found dead. Necropsy of these males revealed a discoloured liver and/or lungs and showed a clear fluid in the body cavity.
All 270 mg/kg bw/da females had to be killed in moribund condition during mating or gestation. There were no specific organ changes at necropsy among high dose females.
Taken together there was an increased mortality in both sexes at 270 mg/kg bw/day.

FOOD CONSUMPTION DURING THE PRE-MATING PERIOD
A toxicologically relevant effect on food intake during the premating period was not evident in males and females at dose level of up to 270 mg/kg bw/day.

BODY WEIGHT DEVELOPMENT
A treatment-related effect on body weight development of males was not evident at dose levels of up to 90 mg/kg bw/day. At 270 mg/kg bw/day there was a severe and increasing body weight reduction from week 2 onwards (p< 0.02) and severe body weight loss beginning with week 3 and with a maximum in week 4.

The mean body weight gain of females was not remarkably changed up to 90 mg/kg bw/day during the premating, mating gestation and lactation period.
At 270 mg/kg bw/ day body weight loss was noted in week 2.

WEIGHT OF TESTES AND EPIDIDYMIDES
Individual weight of the testes and epididymides were determined in male animals at necropsy.
At 270 mg/kg bw /day relative testis weights were increased and absolute epididymis weights were significantly decreased (each = 0.01)

GROSS PATHOLOGICAL FINDINGS
At scheduled necropsies more 270 mg/kg bw/day males showed a thickened urinary bladder wall.

HISTOPATHOLOGICAL INVESTIGATIONS
There was a reduction in frequency and severity score of "large corpora lutea" as well as of granular luteal cells in 270 mg/kg bw/day females, which all had been necropsied prescheduled.

EFFECTS ON REPRODUCTION OF MALE AND FEMALE F0 ANIMALS
The insemination, fertility, and gestation indices were unchanged up to 90 mg/kg bw/day. At 270 mg/kg bw/day very low insemination and fertility indices were calculated, which was secondary to the severe maternal toxicity in this group. This was the reason that all females of the 270 mg/kg bw/day dose group were sacrificed moribund at the end of the mating period or during early gestation. Therefore, no gestation index could be calculated for this dose and evaluation of data regarding reproductive performance of this dose group was thus limited.

TIME TO INSEMINATION
Determination of the time to insemination revealed no treatment-related effect.

DURATION OF GESTATION
The data on gestation length do not indicate any treatment up to 90 mg/kg bw/day.

COURSE OF BIRTH
The actual process of giving birth could be observed only in a few cases since the animals generally littered at night. Observations indicating a substance-related effect on course of birth were not made at dose levels up to 90 mg/kg bw/day.

LACTATION BEHAVIOUR
The was no F1 pup without a visible milk ingestion up to 90 mg/kg bw/day indicating that there was no treatment effect on lactation behaviour up to 90 mg/kg bw/day.

REPRODUCTION DATA OBTAINED AT NECROPSY
The mean number of macroscopically visible corpora lutea, implantation sites and prenatal loss was not affected up to a dose of 90 mg/kg bw/day. Data received at 270 mg/kg bw/day could not be evaluated due to prescheduled deaths during mating period.

Effect levels (P0)

open allclose all
Dose descriptor:
NOEL
Remarks:
General toxicity in males and females
Effect level:
90 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Mortality and body weight development were not affected up to the dose 90 mg/kg bw/day
Dose descriptor:
LOEL
Remarks:
General toxicity in males and females
Effect level:
270 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Dose descriptor:
NOEL
Remarks:
Reproduction/Developmental Toxicity
Effect level:
90 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Dose descriptor:
LOEL
Remarks:
Reproduction/Developmental Toxicity
Effect level:
270 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Description (incidence and severity):
up tp 90 mg/kg bw/day
Mortality / viability:
no mortality observed
Description (incidence and severity):
up tp 90 mg/kg bw/day
Body weight and weight changes:
no effects observed
Description (incidence and severity):
up tp 90 mg/kg bw/day
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Histopathological findings:
not examined

Details on results (F1)

POSTNATAL DEVELOPMENT OF THE F1 PUPS
There were no clinical symptoms or necropsy findings in F1 pups, which could be attribute to the treatment up to 90 mg/kg/bw/day. Malformed pups were not observed in this study.

LITTER SIZE
The litter size at birth as well the number of pups alive on day 0 and 4 post partum were not affected by treatment at dose levels up to 90 mg/kg bw/ day.

MORTALITY OF THE F1 PUPS AND VIABILITY INDEX
No adverse effect could be detected up to 90 mg/kg/bw/day.

SEX RATIO OF THE F1 PUPS
Up to the dose 90 mg/kg bw/day no change in the sex ratio was found.

BODY WEIGHT DEVELOPMENT OF THE F1 PUPS
There was no toxic effect on pup weights up to 90 mg/kg/bw/day.

Effect levels (F1)

Dose descriptor:
NOEL
Generation:
F1
Effect level:
90 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: In all prenatal, birth and postnatal parameters of F1 pups were unaffected up to 90 mg/kg bw/day

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Reproductive parameters of male and female F0 animals

Since all 270 mg/kg bw/d females had to be killed in moribund state before littering, most of the reprotoxicological parameters could not be investigated in this group.

At 30 and 90 mg/kg bw/d insemination parameters, fertility and gestation indices, number of implantation sites, and macroscopically visible corpora lutea as well as gestation lenght were not affected. At 270 mg/kg bw/d the insemination and fertility index were lower than in controls secondary to the severe toxicity. The prenatal loss as well as the number of macroscopically visible corpora lutea and implantation sites could not be evaluated in this group.

Table 1. Final body weight and mean weight of testes and epididymes [g]

 DOSE (mg/kg bw/day)  0  30  90  270
 Final Body Weight  378.5  389.0  388.3  306.5**
Absolute Testis Weight right 1.7084  1.7444 1.6540 1.5974
Absolute Testis Weight left 1.6630  1.7276 1.6586 1.5878
Absolute Testes Weight 3.3714  3.4720 3.3126   3.1852
 Relative Testis weight right  0.4516  0.4494  0.4267  0.5224**
 Relative Testis weight left  0.4393  0.4452  0.4277  0.5193**
 Relative Testes Weight  0.8909  0.8946  0.8544  1.0417**
 Absolute Epididymis Weight right  0.7134  0.7169  0.6908  0.5475**
Absolute Epididymis Weight left  0.6871  0.6969  0.6793  0.5474**
 Absolute Epididymides Weight  1.4005  1.4138  1.3701  1.0949**
 Relative Epididymis weight right  0.1888  0.1854  0.1780  0.1791
 Relative Epididymis weight left  0.1819  0.1801  0.1750  0.1789
 Relative Epididymides Weight  0.3707  0.3655  0.3530  0.3580

* statistically significantly different from control, p< 0.05

** statistically significantly different from control, p<0.01

Table 2. Insemination Index, Fertility Index and Gestation Index

DOSE (mg/kg bw/day) Females Used

Females  Inseminated

   Females with Implantations 

Females

with Viable pups    

   n  % of those paired Insemination Index n  % of those InseminatedFertility Index  n % of those with ImplantationsGestation Index
0 12  12 100 10  83.3  9  90.0
30 12  12 100 12  100 11   91.7
90 12  12 100 11  91.7  11  100
270 121  51  41.7  21  40.0  0 1  0


1 all females sacrificed moribund at the end of the mating period or during early gestation.

Table 3. Time to insemination [days] (remated female excluded)

DOSE (mg/kg bw/day)  0  30  90  270
 Inseminated females  11  8  8  5
Time to insemination 2.1  2.0 2.1 2.2

Table 4. Duration of gestation [days]

DOSE (mg/kg bw/day)  0  30  90  270
   21.88  21.63  21.88  no data

Table 5. Reproduction Data

DOSE (mg/kg bw/day)  0  30  90  270
No. of Corpora Lutea*all females  10.75  11.67  11.92  $
No. of Corpora Lutea*pregnant female only 12.90  11.67 13.00 $
No. of Implantation Sites per litter  11.00  11.33  12.91  $
 Prenatal Loss per litter  1.20  0.75  1.00  $

* macroscopically visible

$ data could not be evaluated or not availble

Parameters investigated on pups

Prenatal loss, life birth index, pup birth ratio, pup birth weight, overall litter size, pup weight development and viability of F1 rats were unaffected at 30 and 90 mg/kg bw/d.

There were also no remarkable clinical or necropsy findings in pups and no adverse effect on the course of birth or lactation behavior of the dams in these groups.

All in all prenatal, birth and postnatal parameters of F1 pups were unaffected up tp 90 mg/kg bw/d.

Table 6. Litter Size

DOSE (mg/kg bw/day)  0  30  90  270
 Group means per litter
Pups delivered 10.89  11.55 11.91 no data
No.of Implantation Sites per litter 10.78  11.55 11.91 no data
 Prenatal Loss per litter 10.78  11.45 11.73 no data

Table 7. Survival indices of the pups [%]

DOSE (mg/kg bw/day)  0  30  90  270
Live Birth Index 99.26  100 100 no data
Viabilty Index (day 4 p.p) 100  99.30 98.64 no data

Table 8. Sex ratio of the F1 pups [% males per litter]

DOSE (mg/kg bw/day)  0  30  90  270
Day 0 p.p. 54.85  58.72 58.92 no data

Table 9. Mean Body Weight on the F1 Pups [g]

DOSE (mg/kg bw/d)  0  30  90  270
Day 0 p.p. 5.92  5.81 5.73 no data
Day 4 p.p. 9.97 9.33 9.56 no data

Applicant's summary and conclusion

Executive summary:

Eiben E (2002)

Groups of 12 male and female Wistar rats each were treated daily orally (by gavage) for two weeks before mating as well as during the mating, gestation and lactation period (up to day 4 or 5 post partum) with dimethyl phosphonate dissolved in Polyethylene glycol 400 in doses of 0, 30, 90 and 270 mg/kg bw/day, respectively. Males were necropsied when have been dosed at least 28 days. Females and their pups were necropsied between day 4 to 6 post partum. Investigations were performed on general tolerance on the test compound by the parental animals including histopathology of testes, epididymides and ovaries as well as with regard to effects on reproduction including early postnatal development of F1 pups. Necropsies were done on all animals. Selected organs of F0 rats were weighed. The study was performed according OECD Guideline No.421 of 1995 with the exception that food intake was recorded only during the premating period. At 270 mg/kg bw/day clinical signs (poor general condition, apathy, high stepping gait, squatting position, bloody muzzle, piloerection, emaciation, tremor and/or desiccation of the skin) and severe body weight depression were found indicating a severe parental toxicity and resulting in increased mortality in males and complete mortality in females. The food intake during the premating period was unaffected up to 270 mg/kg bw/day. At 270 mg/kg bw/day relative testis weights were increased and absolute epididymis weights were decreased secondary to changes in body weight. The frequency and severity score of "large corpora lutea" as well as of granular luteal were reduced in 270 mg/kg bw/day females. These findings are attributed to the effects on the body weights and severe somatic toxicity. Reproductive Parameters At 30 and 90 mg/kg bw/day insemination parameters, fertility and gestation indices, gestation length, prenatal loss, number of implantation sites and macroscopically visible corpora lutea, life birth index, sex ratio, pup birth weight, overall litter size, pup weight development, viability and lactation of F1 rats were not affected. At 270 mg/kg bw/day the reproductive parameters were distinctly reduced secondary, could not be evaluated or could not be measured due to severe somatic toxicity and lethality of the 270 mg/kg bw/day females. No remarkable clinical or necropsy findings in pups occurred in the groups up to 90 mg/kg. Thus, the following no-observed-effect levels (NOEL) were determined: General Toxicity in Males and Females: 90 mg/kg body weight/day Reproduction/Developmental Toxicity: 90 mg/kg body weight/day.