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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Remarks:
Combined Repeated Dose Toxicity Study with Reproduction/Developmental Toxicity Screening Test
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2001-12-28 to 2001-10-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report date:
2002

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test)
Version / remarks:
adopted 1996-03-22
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Diammonium hydrogenorthophosphate
EC Number:
231-987-8
EC Name:
Diammonium hydrogenorthophosphate
Cas Number:
7783-28-0
Molecular formula:
H3N.1/2H3O4P
IUPAC Name:
diammonium hydrogen phosphate

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals or test system and environmental conditions:
TEST ANIMALS
male and CD rats, Crl:CD (TM) (SD)IGS BR strain
- Source: Charles River (UK) Limited, Margate, Kent England
- Age at study initiation: 7 - 8 weeks
- Weight at study initiation: Males: 298 - 386 g; Females: 191 - 263 g
- Housing: singly in RB3 modified cages
- Diet (e.g. ad libitum): Rat and Mouse No. 1 Maintenance Diet (Special Diets Services Ltd., Witham, E
ssex, England)
- Water (e.g. ad libitum): tap water from public supply
- Acclimation period: 16 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 23 °C
- Humidity (%): 40 - 70 %
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12
IN-LIFE DATES: From: 2001-12-12 To: 2002-02-10 (necropsy)

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
Dosing volume: 10 ml/kg bw for each group
Details on mating procedure:
All 10 males in each group (toxicity and reproductive subgroups) were mated with the 10 reproductive
subgroup females after all animals had received 2 weeks of treatment. Pairing was on a one-to-one basis
within treatment groups for up to 2 weeks, although all animals mated and were separated within 1 week
.
Each morning following pairing the trays beneath the cages were checked for ejected copulation plugs
and a wet vaginal smear was prepared from each female and examined for the presence of spermat
ozoa. The day on which a sperm positive vaginal smear or at least three copulation plugs were found was
designated Day 0 of gestation. Once mating had been confirmed, males and females were separated
and the males were returned to their normal group housing.
Duration of treatment / exposure:
Exposure period: not clearly defined
Premating exposure period (males): 2 weeks
Premating exposure period (females): 2 weeks
Duration of test: not clearly defined
See free text below
Frequency of treatment:
once daily
Doses / concentrationsopen allclose all
Dose / conc.:
250 mg/kg bw/day (actual dose received)
Dose / conc.:
750 mg/kg bw/day (actual dose received)
Dose / conc.:
1 500 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
5 males and 5 females per group (toxicity subgroups);
5 males and 10 females per group (reproductive subgroups)
Control animals:
yes, concurrent vehicle

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Details on results:
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Treatment at all dosages was well tolerated and there were no treatment-related deaths.
A dosage dependent increase in transient post-dosing salivation was apparent, which was considered to
be due to the palatability of the test formulations rather than toxicity. A dosage-dependent increase in the
number of animals with reddening of the extremities was also apparent mainly during the early stages of
treatment.
BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Body weight gain and food consumption of males at 1500 mg/kg bw/day appeared to be suppressed whe
n compared with the control group, such that gain between weeks 0-5 for this group was 78% of contr
ols. The body weight gain for reproductive subgroup females receiving 1500 mg/kg bw/day was reduced
during the first week of gestation, after which the values returned to levels comparable with the control.
REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Mating performance and fertility were unaffected by treatment, and parental treatment had no apparent
effect on the offspring to day 4 of age.
ORGAN WEIGHTS (PARENTAL ANIMALS)
Relative kidney and liver weights for females at 1500 mg/kg bw/day were greater than in the control
group, but there were no histological changes associated.
GROSS PATHOLOGY, HISTOPATHOLOGY (PARENTAL ANIMALS)
A number of treated animals at 750 and 1500 mg/kg bw/day exhibited horizontal banding on the incisors
at necropsy; histological processing of these tissues failed to detect any change in the areas examined
suggesting that the banding was restricted to the enamel of the teeth. The only histological findings
related to treatment were the inflammatory/degenerative stomach changes in all treated groups that were
considered likely to have arisen due to an irritant effect of the test formulations.
OTHER FINDINGS (PARENTAL ANIMALS)
HAEMATOLOGY, CLINICAL CHEMISTRY
Some treatment-related effects on hematology were evident (reduction in activated partial thromboplasti
n time for males at 750 and 1500 mg/kg bw/day, a non dosage-dependent elevation of alkaline phospha
tase levels at 750 and 1500 mg/kg bw/day, reduced glucose and phosphorous levels at 1500 mg/kg bw/
day, a dosage-dependent reduction in total protein at 750 and 1500 mg/kg bw/day with a slight elevated
albumin/globulin ratio at the top dosage. Changes in females were limited to a decrease in phosphorous
levels and a non-significant increase in alkaline phosphatase level at 1500 mg/kg bw/day).
BEHAVIOUR
There were no changes apparent at behavioral testing.

Effect levels (maternal animals)

Remarks on result:
other: based on inflammatory/degenerative stomach changes recorded at histopathological examination and extending to the lowest dosage investigated,no NOAEL for general toxicity could be established

Results (fetuses)

Effect levels (fetuses)

open allclose all
Key result
Dose descriptor:
NOAEL
Effect level:
1 500 mg/kg bw/day (actual dose received)
Sex:
male
Basis for effect level:
other: Highest dose applied
Key result
Dose descriptor:
NOAEL
Effect level:
1 500 mg/kg bw/day (actual dose received)
Sex:
female
Basis for effect level:
other: Highest dose applied

Overall developmental toxicity

Developmental effects observed:
no

Any other information on results incl. tables

Tabular Summary of effects on reproduction /development

 Observations

Dosage (mg/kg/day)

 

0 (ctr)

 

250

 

750

 

1500

Pairs started (N)  10  10   10 10 
 Females showing evidence of copulation (N)  10  10 10  10 
 Females achieving pregnancy (N)  9  10  10 10 
Conceiving days 1 -5 (N)  10   10  10
  Conceiving days 6 -14 (N)   0
Pregnancy=21.5 days (N)   0  1
  Pregnancy=22 days (N)   6  9
 Pregnancy=22.5 days (N)    3
  Pregnancy=23 days (N)   0
Dams with live young born (N)   9 10   10 10 
  Dams with live young at day 4 pp (N)   9  10  10  10
 Implants/dam (mean)  15.7 15.7  14.1  15.4 
 Live pubs/dam at birth (mean) 14.8  14.6  12.7  14.0 
 Live pubs/dam at days 4 (mean)   14.6 14.3  12.7  14.0 
 Sex ratio (%m) at birth (mean)  54.2 52.7  50.0  48.5 
 Sex ratio (m/f) at day 4 (mean) 54.2  53.0  50.0  48.5 
 Male pub weight at birth (mean) 6.4  6.3  6.6  6.3 
   Male pub weight at day 4 (mean)  8.7 8.5  9.2  8.7 
 Female pup weight at birth (mean) 5.9  6.0  6.1  6.0 
 Female pup weight at day 4 (mean)   8.2 7.9  8.6  8.4 
         
Abnormal Pups: Necropsy finding unremarkable         
         
Loss of offspring         
 Post implantation survival index 95.2  93.5  90.0  94.8 
 Live birth index 99.3  99.4  100.0  95.9 
 Viability index 98.6  98.2  100.0  100.0 
         

Applicant's summary and conclusion