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Toxicological information

Repeated dose toxicity: oral

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Administrative data

sub-chronic toxicity: oral
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
19.07.1976 to 17.07.1978 (for full study)
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Version / remarks:
Conducted prior to guideline adoption.
GLP compliance:
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Disodium dihydrogen (1-hydroxyethylidene)bisphosphonate
EC Number:
EC Name:
Disodium dihydrogen (1-hydroxyethylidene)bisphosphonate
Cas Number:
Molecular formula:
disodium dihydrogen (1-hydroxyethane-1,1-diyl)bis(phosphonate)
Test material form:
not specified
Details on test material:
Described in associated chronic toxicity report as disodium etidronate. Stated doses have been calculated from report, with correction of error in report relating to food intake. Previous IUCLID entries are lower for unstated reasons.

Test animals

Details on test animals or test system and environmental conditions:
- Source: Anglia Laboratory animals, UK
- Age at study initiation: No data
- Weight at study initiation: 75-90 g
- Fasting period before study: No
- Housing: Five per cage in suspended cages with wire-mesh floors.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Six days

- Temperature (°C): 21 ±2
- Humidity (%): 50 ±5
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 19.07.76 To: 17.07.78

Administration / exposure

Route of administration:
oral: feed
unchanged (no vehicle)
Details on oral exposure:
- Rate of preparation of diet (frequency): Weekly
- Mixing appropriate amounts with (Type of food): Powdered laboratory rat food: Spratts Laboratory Diet 2.
- Storage temperature of food: No data
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
Dietary samples were sent to the Sponsor for analysis of diets fed during week 30 and at approximately three month intervals thereafter. No further details provided. Therefore dietary concentrations not verified during interim study period.
Duration of treatment / exposure:
90 d
Frequency of treatment:
Doses / concentrationsopen allclose all
Dose / conc.:
500 ppm
males: 41 mg/kg bw/day
females: 50 mg/kg bw/day (calculated by the reviewer)
Dose / conc.:
2 000 ppm
males: 169 mg/kg bw/day
females: 195 mg/kg bw/day (calculated by the reviewer)
Dose / conc.:
10 000 ppm
males: 817 mg/kg bw/day
females: 1000 mg/kg bw/day (calculated by the reviewer)
No. of animals per sex per dose:
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: No data
- Rationale for animal assignment (if not random): Based on body weight
- Rationale for selecting satellite groups: Used to provide blood and urine samples during the first 26 weeks of the study, and were therefore subjected to the stresses of collecting these samples. Hence the main group animals were not subjected to these stressors until the end of the 102 week exposure period.
- Post-exposure recovery period in satellite groups: None
- Section schedule rationale (if not random): No data
Positive control:


Observations and examinations performed and frequency:
- Time schedule: Daily

- Time schedule: Daily

- Time schedule for examinations: Weekly for the first eight weeks, and two-weekly thereafter

- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No, mean weekly intake calculated.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

- Time schedule for examinations: During week 4 for a 5-day period for each cage in control and high dose level main groups. During weeks 11 and 26 for a 5-day period for each cage of all main groups.

- Time schedule for collection of blood and parameters measured: Weeks 0 and 5 from 10 males and females from Control and highest dose; Week 12 from 10 males and females in all groups; Weeks 25 from 10 males and females from control, mid and highest dose groups: packed cell volume, haemoglobin, red cell count, mean corpuscular haemoglobin concentration and mean cell volume, total white cell count and differential count. Platelet count and thrombotest were conducted in weeks 12 and 25 only. A visual estimation of red cell count and RBC osmotic fragility was conducted on the blood from high dose satellite group animals immediately prior to post-mortem.
- Anaesthetic used for blood collection: Yes (not identified)
- Animals fasted: Yes

- Time schedule for collection of blood: Week 5, 12 and 25: 5 males and 5 females from control and 10000ppm; plasma urea, plasma glucose, total serum proteins, serum alkaline phophatase, serum glutamic pyruvic transaminase, sodium, potassium, calcium, inorganic phosphorus, serum creatinine. Week 7: 5 males from control, 2000 ppm and 10000 ppm for glucose and serum alkaline phosphatase. Week 12: 5 males from 500ppm and 2000 ppm for serum alkaline phosphatase and serum glutamic pyruvic transaminase. Week 13: 5 females from all groups - plasma glucose. Week 25: 5 males from 2000ppm group for serum alkaline phosphatase and 5 females from 2000ppm group for plasma glucose.
- Animals fasted: Yes

- Time schedule for collection of urine: Weeks 6 and 25: 5 males and 5 females from control and highest dose: pH, specific gravity, protein, reducing substances, glucose, ketones, bile pigments, urobilinogen, haemoglobin, microscopy of spun deposits, urinary calcium, urinary phosphorus. Week 7: samples collected from 5 males and 5 females from all groups for estimation of pH, specific gravity and volume. During week 12: individual overnight urine samples from 5 males and 5 females from all groups. Urinary hydroxyproline measured in control and top dose at week 26.
- Metabolism cages used for collection of urine: No data
- Animals fasted: Yes

Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see table 1)
HISTOPATHOLOGY: Yes (see table 1)
Other examinations:
None reported
One way analysis was performed on each parameter and treated groups compared with control using Student's t- test. Used for organ weight data, urinalysis, haematology, blood chemistry and bodyweights, food consumption, water consumption.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
effects observed, treatment-related
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY: Mortality: one control female died under anaesthesia for blood collection. Severe pallor of skin in rats receiving 10000 ppm and slight pallor in rats receiving 2000 ppm from week 6.

BODY WEIGHT AND WEIGHT GAIN: During the first 12 weeks of treatment, a significantly reduced body weight gain was recorded for the 10000 ppm group. There were no other statistically significant differences between the control and treated groups.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Food intake marginally (but statistically significant) reduced in highest dose group male rats.  All other groups as for controls.


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): reduced in highest dose groups in line with reduced food consumption

HAEMATOLOGY: During weeks 5 and 7, the 10000 ppm group had a statistically significant decrease in red cell parameters. Neutrophil and lymphocyte counts were significantly higher than controls. There was also a decrease in red cell values and higher neutrophil and lymphocyte counts for 2000 ppm males at week 7 (not studied at week 5). There were no such statistically significant differences for females. During week 12 there was a reduction in red cell parameters for both sexes at 10000 ppm and for males at 2000 ppm.  Also, a slightly higher platelet count for the 10000 ppm male group was observed. Examination of blood smears indicated a retardation of bone marrow development and prolonged anaemia at weeks 5, 7, 12 in both sexes at 10000 ppm. During week 7 a slight retardation was seen in the 2000 ppm male group.

CLINICAL CHEMISTRY: Higher alkaline phosphatase at week 5, 7 and 12 in males receiving 10000 ppm.  No effects seen in 2000 ppm at week 7. All other parameters were similar in control and treated males. Higher plasma glucose level in females receiving 10000 ppm at week 12 and 13.  No effects were observed in the lower dose females.

URINALYSIS: Urinary volume was greater in the male treated groups at weeks 6 and 7, but there were no differences at week 12. Non-dose-related sporadic increases in pH were detected in some rats, but they were not considered of toxicological significance. Increased calcium in highest dose males at weeks 6 and 12 where reported, but only when expressed in terms of volume of urine and not in absolute terms.

ORGAN WEIGHTS: There was a statistically significant decrease in liver weights recorded for males and females of the 10000 ppm group. At 2000 ppm the effect was observed in males, but at a much smaller magnitude. There was also a statistically significant decrease in kidney weight for highest dose males.

GROSS PATHOLOGY: No findings of toxicological significance.

HISTOPATHOLOGY: NON-NEOPLASTIC: There were no treatment-related findings.

OTHER: the bone marrow smears revealed a decrease in myeloid/erythroid and lymphocyte/erythroid ratios for rats in the highest dose group.

Effect levels

open allclose all
Dose descriptor:
Effect level:
41 mg/kg bw/day (actual dose received)
Basis for effect level:
other: juvenile rats (500 ppm of HEDP-2Na)
Remarks on result:
other: Effect level refers to disodium salt
Dose descriptor:
Effect level:
169 mg/kg bw/day (actual dose received)
Basis for effect level:
other: anaemia (2000 ppm HEDP-2Na)
Remarks on result:
other: Effect level refers to disodium salt

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

In a well conducted and reported, pre-GLP, study (reliability score 2), conducted using a protocol according to OECD 408 (Repeated Dose 90-Day Oral Toxicity in Rodents), the NOAEL for Complexing Agent - Henkel (sodium salt of 1-hydroxythane-1,1-diphosphonic acid (disodium etidronate)) was 41 mg/kg bw/day, based on anaemia at high doses. This study is part of a combined chronic toxicity / carcinogenicity study (equivalent to OECD 453), reported separately in chapter 7.5.1, fist entry.
Executive summary:

In order to reduce the number of animals used, a combined dietary chronic toxicity and carcinogenicity study in rats has been carried out using a protocol similar to OECD 453. Four satellite groups of 10 animals of each sex (dose and control groups) were fed diets containing 0-10000 ppm disodium etidronate and used to provide blood and urine samples during the first 26 weeks of the study. After the first 26 weeks of the study all surviving rats in the satellite groups were killed for interim examination. The results of the interim report for the satellite groups are reported separately because juvenile rats during their growth phase seem to be more susceptible to effects of HEDP related to perturbations of iron homeostasis than adult rats. The doses quoted in the interim report (0, 500, 2000, and 10000 ppm corresponding to 0, 41, 169, 817 mg/kg bw/d for males and 0, 50, 195 and 1000 mg/kg bw/d for females) take into account the higher feed intake as a function of bodyweight during the first few weeks of the study. A decrease in red blood cell parameters was seen in the top dose group for both sexes, and for males at 169 mg/kg by week 12 although some improvement was noted from the week 7 values. Blood smears indicated prolonged anaemia in both sexes at the top dose, with a slight retardation of bone marrow development. Severe pallor of the skin of the top dose group animals and slight pallor in the mid dose rats was seen. A pale color was also noted for organs well supplied with blood (spleen and kidneys). These observations are consistent with perturbation of iron homeostasis. During week 25, values relating to red cell parameters among rats receiving 2000 ppm were similar to control values. For rats receiving 10000 ppm the packed cell volume and haemoglobin concentrations were only marginally lower than control values although the differences attained a level of statistical significance. The NOAEL for juvenile rats is assigned to the lowest dose group (500 ppm) where no indication of anaemia was seen.