Ammonia, anhydrous

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline comparable, proprietary GLP study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

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:

no

Test material

Test material information

Constituent 1

Reference substance name:

Diammonium phosphate (DAP)

IUPAC Name:

Diammonium phosphate (DAP)

Constituent 2

Reference substance name:

Diammonium hydrogenorthophosphate

EC Number:

231-987-8

EC Name:

Diammonium hydrogenorthophosphate

Cas Number:

7783-28-0

IUPAC Name:

diammonium hydrogen phosphate

Details on test material:

Diammonium phosphate (DAP), 17.93% NH4 and 46.86% P2O5 equivalent

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female Crl:CD(SD)IGS BR rats

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: water purified by reverse osmosis

Details on exposure:

The substance was administered daily via gavage.

Details on mating procedure:

Rats were cohabited for a maximum of 14 days to ensure mating

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No information

Duration of treatment / exposure:

The exposure period for the toxicity subgroup was 35 days, while the exposure period for the reproductive subgroup was at most 28 days among male and 53 days among females.

Frequency of treatment:

Daily

Details on study schedule:

Females were allowed at least 25 days to litter and rear their young until day 4 of age (and were exposed during this time)

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

250 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

750 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 500 mg/kg bw/day (nominal)

No. of animals per sex per dose:

There were 5 males and 5 females per dose group in the toxicity group, and 5 males and 10 females per dose in the reproductive toxicity group.

Control animals:

yes

Details on study design:

Doses were selected based on parameters assessed in a range-finding study at concentrations up to 1,000 mg/kg/day. Animals comprising the toxicity subgroup (5 males and 5 females per dose group) were administered Diammonium Phosphate (DAP) for 5 weeks (7 days/week) via gavage administration. Animals comprising the reproductive subgroup (5 males and 10 females) were administered DAP for a period encompassing approximately 53 continuous days via oral gavage: 14 days of initial treatment, plus a maximum of 14 days of cohabitation to ensure mating, and among females, at least 25 days to litter and rear their young until day 4 of age.

Positive control:

Not examined

Examinations

Parental animals: Observations and examinations:

Histology for reproductive subgroup animals was restricted to retained reproductive organs (and any other abnormalities observed at necropsy).

Oestrous cyclicity (parental animals):

Not investigated

Sperm parameters (parental animals):

Not investigated

Litter observations:

Offspring were observed up to Day 4 post partum

Postmortem examinations (parental animals):

The females were allowed to litter and rear their young until day 4 of age when parent females and litters were subjected to macroscopic necropsy.

Postmortem examinations (offspring):

The females were allowed to litter and rear their young until day 4 of age when parent females and litters were subjected to macroscopic necropsy.

Statistics:

Various appropriate tests were employed

Reproductive indices:

Mating and fertiliy indices; live birth index

Offspring viability indices:

Live birth and viability indices were calculated

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

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:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

effects observed, treatment-related

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

Treatment at all dosages was well tolerated and there were no reatment-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 gain and food consumption of males at 1500 mg/kg bw/day appeared to be suppressed when compared with the control group, such that gain between weeks 0-5 for this group was 78% of controls. 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.

Some treatment-related effects on hematology were evident (reduction in activated partial thromboplastin time for males at 750 and 1500 mg/kg bw/day, a non dosage-dependent elevation of alkaline phosphatase 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). 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.

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. There were no changes apparent at behavioural testing.

Mating performance and fertility were unaffected by treatment. There were no effects on the time to achieve conception, and pregnancy length.


Summary of effects on reproduction/development (control, low, mid, high dose):
Females achieving pregnancy: n= 9, 10, 10, 10.
Dams with live young born: n = 9, 10, 10, 10.
Implants/dam (mean): 15.7, 15.7, 14.1, 15.4.
Live pups/dam at birth (mean): 14.8, 14.6, 12.7, 14.0.
Live pups/dam at day 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) at day 4 (mean): 54.2, 53.0, 50.0, 48.5.
Male pup weight at birth (mean): 6.4, 6.3, 6.6, 6.3.
Male pup 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.
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.

Effect levels (P0)

1

Dose descriptor:

NOAEL

Effect level:

1 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reproduction/developmental toxicity

2

Dose descriptor:

LOAEL

Effect level:

> 1 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Reproduction/developmental toxicity

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

Parental treatment had no apparent effect on the offspring to day 4 of age; necropsy findings were unremarkable

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

1 500 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: reproductive & developmental toxicity

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

There were no treatment-related deaths and no signs of overt clinical toxicity. Bodyweight gain for reproductive subgroup females receiving 1,500 mg/kg/day was reduced during the first week of gestation (82% of control), after which they returned to levels comparable to the controls for the remainder of the study. Mating performance and fertility were unaffected by treatment, and parental treatment had no apparent effect on the offspring to day 4 of age.

Applicant's summary and conclusion

Conclusions:

Diammonium phosphate NOAEL: 1,500 mg/kg/day (reproduction/developmental toxicity)
Diammonium phosphate LOAEL: >1,500 mg/kg/day (reproduction/developmental toxicity)

Executive summary:

The toxicity of diammonium phosphate (DAP) was assessed in a combined repeated dose toxicity study with a reproduction / developmental toxicity screening test in rats. The NOAEL was found to be: 250 mg/kg/day (general toxicity); 1,500 mg/kg/day (reproduction/developmental toxicity). The LOAEL was found to be: 750 mg/kg/day (general toxicity); >1,500 mg/kg/day (reproduction/developmental toxicity). Mating performance and fertility were unaffected by treatment, and parental treatment had no apparent effect on the offspring up to age 4 days.