Trisodium dihydrogen -N,N-[bis[2-[bis(carboxylatomethyl)amino]ethyl]]glycinate

Endpoint summary

Description of key information

 Using a read-across extrapolation approach from a GLP, OECD 407 guideline study on the structural analogue DTPA pentasodiuum salt, the sub-acute NOAEL of DTPA trisodium salt in rats is predicted to be circa 75mg/kg bw/day or above (taking into account stoichiometric considerations). The two substances are structurally similar and have the same metal ion, chelating mode of action.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The source substance (DTPA 5Na) and the target substance (DTPA 3Na) are the pentasodium and trisodium salts of the same organic acid (Diethylenetriaminepentaacetic acid) and are therefore structurally very similar. The two substances have comparable high water solubility and would be rapidly and fully dissociated into common anions and cations in the gastro-intestinal tract. The absorption, distribution and metabolism of the two substances would therefore be expected to be essentially identical. The common organic acid moiety has a chelating mode of action and would be expected to exert long-term, secondary adverse effects by the sequestration of essential metal ions, rather than direct organ toxicity.

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

99% w/w

Species:

rat

Sex:

male/female

Route of administration:

oral: drinking water

Vehicle:

water

Duration of treatment / exposure:

4 weeks

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 75 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: bodyweight and clin chem changes in the mid dose group of 150 mg/kg bw/day

Critical effects observed:

yes

Lowest effective dose / conc.:

300 mg/kg bw/day (nominal)

System:

other: Urinary system

Organ:

kidney

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Executive summary:

The 28-day NOAEL repeated dose oral toxicity of DTPA pentasodium salt is 75 mg/kg/day (OECD 407 guideline). DTPA pentasodium salt is structurally similar to DTPA trisodium salt and the analogue has a similar chelating mode of action to the target substance. Based on a read-across approach, and taking into account stoichiometry, DTPA trisodium salt is predicted to elicite similar sub-acute oral toxicity, with a NOAEL of ca 75 mg/kg/day or above. 

 

Reference 2

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP and guideline study

Justification for type of information:

The source substance (DTPA 5Na) and the target substance (DTPA 3Na) are the pentasodium and trisodium salts of the same organic acid and are therefore structurally very similar. The purity/impurity profile for the source material is not characterised in the sub-acute oral toxicity robust summary, but since the target material is > 99.9% pure and contains no detectable impurities, the extrapolation of acute oral toxicological properties from the source material to the target material is considered valid as a ‘worst case' scenario. The source material sub-acute oral toxicity study was conducted according to OECD test guideline 407 and is considered reliable (Category 1).

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes (incl. QA statement)

Remarks:

testing lab.

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female Wistar rats (Chbb:THOM (SPF)) supplied by Dr . Karl Thomae GmbH, Biberach/Riss, Germany, which were free of signs of disease were used for the investigations.
The rats were identified clearly by tattooing of the respective animal number into the ears.
The rats were housed singly in type DK III stainless steel wire mesh cages supplied by Becker & Co., Castrop-Rauxel, Germany (floor area about 800 cm2). Underneath the cages, waste trays were fixed containing absorbent material (type 3/ dustfree embedding, supplied by SSNIFF, Soest, Germany). The animals were housed in a fully air-conditioned room. Central air-conditioning guaranteed a range of 20 - 24°C for temperature and of 30 - 70% for relative humidity. The day/night rhythm was 12 hours (12 hours light from 06.00 a.m. - 06.00 p.m., 12 hours dark from 06.00 p.m. - 06.00 a.m.). Deviations from these ranges did not occur. The animal room was completely disinfected using a disinfector ("AUTEX", fully automatic, formalin-ammoniabased
terminal disinfector). The floor and the walls were cleaned once a week. The cleansing liquid used was water containing about 0.1 % Incidin perfect® (supplied by Henkel, Düsseldorf, Germany). The food used was basic maintenance diet rat/mouse/hamster, meal, supplied by Klingentalmühle AG, Kaiseraugst, Switzerland. Food and drinking water (from water bottles) were available ad libitum.

Route of administration:

oral: drinking water

Details on oral exposure:

The test substance was administered as a solution in drinking water.
The test substance was weighed for the specific test group, and the appropriate amount of drinking water was added (also weighed). This mixture was subsequently stirred with a magnetic stirrer for at least 30 minutes to reach complete solubility of the test substance in the drinking water. The drinking water solutions were prepared twice a week (Monday to Friday).
Before the beginning of the study, the stability of the test substance in the vehicle over a period of 4 days at room temperature was ordered. At the start of the study one sample of each concentration was sent to the analytical laboratory for determination of the correctness of the concentration of the test substance preparations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability of the test substance in the vehicle over a period of 4 days at room temperature and the correctness of the concentrations were verified analytically.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

daily

Remarks:

Doses / Concentrations:
600 ppm; 3,000 ppm and 12,000 ppm
Basis:

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

Selction of the doses for this study was based on the results of a previous palatability study.
In this study, Trilon C flüssig was administered in the drinking water to 3 male and 3 female Wistar rats per group for 2 weeks .
Following substance-induced changes were observed:
15,000 ppm:
• Discoloration of the feces in both sexes
• Decreased food consumption in both sexes
• Decreased water consumption in both sexes
• Piloerection and reduced general state in 1 male and 1 female
• Diminished adipose tissue in 1 male and 2 females
5,000 ppm:
• Discoloration of the feces in both sexes
Therefore, the following doses were chosen for the 4-week administration in the drinking water (doses of active ingredient):
600 ppm: as the lowest dose level
3,000 ppm: as the intermediate dose level
12,000 ppm: as the high dose, resulting in a substance intake of > 1,000 mg/kg body weight

Positive control:

none

Observations and examinations performed and frequency:

Clinical observations: A check was made twice Mondays to Fridays and once a day on Saturdays, Sundays and public holidays for general observations. Once a week an additional comprehensive clinical examination was carried out. In order to prepare tables of the clinical symptoms observed, the data were entered offline into the computer systems; according to the particular health status of the individual animals, sometimes several, different clinical signs were documented during one week.
Mortality: A check was made twice Mondays to Fridays and once a day on Saturdays, Sundays and public holidays for any dead or moribund animals.
CLINICAL PATHOLOGY: Blood was taken from the retroorbital venous plexus in the morning from fasted animals without anesthesia. The blood sampling procedure and the subsequent analysis of the blood and serum samples were carried out in a randomized sequence.
The following parameters were determined in blood with EDTA-K3 as anticoagulant using a particle counter (S Plus model, by Coulter, Krefeld, Germany) :
• leukocytes
• erythrocytes
• hemoglobin
• hematocrit
• mean corpuscular volume
• mean corpuscular hemoglobi n
• mean corpuscular hemoglobin concentration
• platelets
Clinical chemistry: The following parameters were determined :
• alanine aminotransferase
• aspartate aminotransferase
• alkaline phosphatas e
• serum-y-glutamyltransferase
• sodium
• potassium
• chlorid e
• inorganic phosphate
• calcium
• urea
• creatinine
• glucose
• total bilirubin
• total protein
• albumin
• globulins
• triglycerides
• cholesterol
• magnesium
Urinalyses: The following examinations were carried out:
• volume
• color
• turbidity
• nitrite
• pH
• protein
• glucose
• ketones
• urobilinogen
• bilirubi n
• blood
• specific gravity
• sediment

Sacrifice and pathology:

A check was made twice Mondays to Fridays and once a day on Saturdays, Sundays and public holidays for any dead or moribund animals.
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

Statistics for clinical examinations, clinical chemistry and hematology, urinalyses.

Clinical signs:

no effects observed

Mortality:

no mortality observed

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:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

12,000 ppm (about 1,775 mg/kg body weight): discoloration of the feces in both sexes; decreased food consumption in both sexes; significantly decreased body weight, resulting in reduced values of about 22% (males) and 7% (females) at the end of the study; significantly reduced body weight change, resulting in reduced values of about 46% (males) and 21 % (females) at the end of the study; increase in alanine aminotransferase in the males; increase in specific gravity, renal epithelial cells and casts in the urines of individual males; dark yellow colored urines in individual males; decrease in urine volume in both sexes; decrease in alkaline phosphatase in the females; transitional cell hyperplasia in the urinary bladder of 4 male and 2 female test animals.
3,000 ppm (about 420 mg/kg body weight): significantly decreased body weight change in the males in the last test week (about 10% below controls); increase in alanine aminotransferase in the males; decrease in alkaline phosphatase in the females.
600 ppm (about 75 mg/kg body weight): no substance-induced changes were detected.

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 75 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: Clear changes in urinalaysis, histopathology, clinc chem parameters and body weight in the high dose group, and bodyweight and clin chem changes in the mid dose group.

Critical effects observed:

not specified

Conclusions:

Clear effects of body weight and histopathological changes of the urinary tract with corroborating results of the urinalyses were obtained at 12,000 ppm. At 3,000 ppm, only minor effects were obtained. Although the clinicochemical findings at 12,000 and 3,000 ppm are difficult to explain, they must be assessed as substance-related. A clear "no observed adverse effect level" was obtained at 600 ppm (about 75 mg/kg body weight) under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

75 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliable without restrictions (Category 1)

System:

other: Urinary

Organ:

kidney

Additional information

The sub-acute oral toxicity NOAEL of DTPA pentasodium salt is circa 75 mg/kg bw/day (OECD 407). DTPA pentasodium salt is structurally similar to DTPA trisodium salt and the analogue has the same metal sequestering mode of action as the target substance. Based on a read-across approach, DTPA trisodium salt is predicted to have a similarly oral NOAEL of 75 mg/kg bw/day or above (taking stoichiometric considerations into account).

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Justification for classification or non-classification

DTPA trisodium salt is considered not to meet the CLP criteria for classification for repeated dose oral toxicity.