Trisodium nitrilotriacetate

Repeated dose toxicity: other routes

Administrative data

Endpoint:

short-term repeated dose toxicity: other route

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: well-documented publication which meets basic scientific principles

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Reference 3

Reference Type:

publication

Title:

No information

Author:

Bahnemann, R., et al.

Year:

1988

Bibliographic source:

Toxicol. Sciences, 46, 166-175

Reference 4

Reference Type:

publication

Title:

No information

Author:

Leibold, E., et al.

Year:

1997

Bibliographic source:

Arch. Pharmacol., 356, Suppl. 1, R 60

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Compare qualitatively the kidney toxicity after repeated administration of Na3NTA with the the kidney toxicity after repeated administration of FeNTA.

GLP compliance:

yes (incl. QA statement)

Remarks:

testing lab.

Test material

Test material information

Constituent 1

Reference substance name:

Trisodium nitrilotriacetate

EC Number:

225-768-6

EC Name:

Trisodium nitrilotriacetate

Cas Number:

5064-31-3

Molecular formula:

C6H9NO6.3Na

IUPAC Name:

trisodium 2-[bis(carboxylatomethyl)amino]acetate

Details on test material:

Trilon A92, Tri-sodium salt of nitrilotri(acetic)acid, monohydrate, purity 92.4%
FeNTA, Nitrilo-tri acetic acid, Fe(III)-salt; the test substance had a water content of 0.5g/100g and a iron content of 11.8g/100g

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Administration / exposure

Route of administration:

other: oral feed and for Fe.NTA: i.p. and gavage

Vehicle:

other: 0.9% NaCl-solution

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
Na3.NTA: 9; 926 mg/(kg bw*d) (150; 20000 ppm oral feed); Fe.NTA: 25 mg/(kg bw*d) (i.p.) and 50, 200, and 1000 mg/(kg*d) (gavage)

No. of animals per sex per dose:

5

Control animals:

yes

Examinations

Observations and examinations performed and frequency:

The following examinations were carried out : Clinical examinations, urinalyses, blood examinations, determination of 8-OH-2-deoxyguanosine
and of lipid peroxidation in kidneys, histopathology of several organs and ultrastructural pathology of the kidneys as well as determination of DNA-synthesis in the kidneys.

Results and discussion

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

150 ppm

Sex:

male

Basis for effect level:

other: Na3NTA

2

Dose descriptor:

NOAEL

Effect level:

9 mg/kg bw/day

Sex:

male

Basis for effect level:

other: Na3NTA

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Na3NTA: 20,000 ppm (926 mg/kg body weight/day): Kidney toxicity was characterized clinically by redbrown discolored urine and increased water consumption. Urinalysis showed increased urinary excretion of lactate dehydrogenase, blood (macrohematuria), amount of urine and transitional epithelial cells, increased turbidity and discoloration of urine specimens, decreased urinary excretion of creatinine and crystals, decreased urinary specific gravity, increased concentrations and increased amounts of zinc in the urine. Lipid peroxidation in the kidney was increased. After 1 week of administration, histopathology revealed only very few numbers of vacuolated or hyperplastic proximal tubules. The extent and number of lesions was increased after 4 weeks of administration. Some animals developed necrosis and loss of papilla. The most striking finding showed a patchy pattern and was characterized by strongly vacuolated, hyperplastic tubules with a large amount of sloughed off cells in their lumen. The vacuolation was found to represent a vesiculation and dilation of the rough endoplasmatic reticulum, and a ballooning of the mitochondria. These lesions seemed to cause lysis of cells and were found predominantly in the proximal and exceptionally in the distal tubules. In accordance with the cytotoxic alterations, DNA-synthesis showed a 10- to 19-fold increase in the proximal tubules of the cortex and the outer medulla and to a significantly lesser extent in the distal tubules. As a consequence of compensatory proliferation the absolute and relative kidney weights were increased, whereas the terminal body weight was decreased at the same time.

Na3NTA: 150 ppm (9 mg/kg body weight/day): No substance-related effects.

FeNTA: 25 mg/kg body weight: Urinalyses showed increased urinary excretion of lactate dehydrogenase, blood, renal tubular epithelial cells, transitional epithelial cells and granular casts, and decreased excretion of crystals. The lipid peroxidation in the kidney was increased as was the level of 8-OH-2-deoxyguanosine in kidney-DNA. In contrast to Na3NTA, histopathology revealed a severe tubular degeneration already after one week of administration. These findings were associated with a large number of cells sloughing off, and restricted to the proximal tubules of the cortex and outer stripe of the outer medulla. DNA-synthesis was enhanced more than 5-fold. After four weeks of application, the number of degenerated tubules increased, but the amount of cells sloughing of decreased. There was an 8-fold increase of DNAsynthesis in the cortex and an 18-fold in the outer stripe of the outer medulla, respectively. These alterations were still restricted to the proximal tubules, but no clear substance-related findings were found by ultrastructural examination. Additionally storage of iron particles was observed in the cortical tubular cells, as well as in liver, pancreas and spleen. The relative kidney weights were increased . Hematology resulted in decreases in serum iron, transferrin and total iron binding capacity.

Applicant's summary and conclusion

Conclusions:

The comprehensive examinations demonstrate that Na3NTA and FeNTA differ in the extent, pattern and mechanism of inducing kidney toxicity. The results indicate that the Na3NTA-related effects are not mediated by an internal formation of FeNTA. The NOAEL for Na3NTA under the conditions of this study was 150 ppm (9 mg/kg bw/day).