Trisodium nitrilotriacetate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

testing lab.

Type of assay:

micronucleus assay

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 A 92 R, purity: 92 g/ 100 g

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male

Details on test animals or test system and environmental conditions:

Animals with a mean weight of about 29 g (with an age range of about 5 - 8 weeks according to the information from the breeder) were used for the study. For the duration of at least 5 days the animals were housed in Makrolon cages. During this time the animals were accommodated in fully air-conditioned rooms in which central air conditioning guaranteed a temperature range of 20 - 24°C and a relative humidity range of 30 - 70%. Before the start of the treatment the animals were transferred to Makrolon cages, type MI, and housed individually under the same conditions until the end of the test. The day/night rhythm was 12 hours (12 hours light from 6. 00 - 18.00 hours and 12 hours darkness from 18.00 - 6.00 hours). Standardized pelleted feed (Maus/Ratte Haltung "GLP", Provimi Kliba SA, Kaiseraugst, Switzerland) and drinking water from bottles were available ad libitum.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

PBS

Details on exposure:

The stability of the test substance at room temperature in water was verified analytically. For the determination of the test substance concentrations in the vehicle, 3 samples of each dose were taken from the test substance preparations, kept at room temperature until the treatment of the last animal (approximately 1 hour) and then deep-frozen until they were determined analytically. The determination of the concentrations in the vehicle was carried out by means of HPLC.

Duration of treatment / exposure:

twice orally, with a 24-hour interval between administrations

Frequency of treatment:

2 applications

Doses / concentrations

Remarks:

Doses / Concentrations:
500, 1000, 2000 mg/kg b.w.
Basis:

No. of animals per sex per dose:

5

Control animals:

yes, concurrent no treatment

Positive control(s):

Cyclophosphamide and Vincristine Sulphate

Examinations

Tissues and cell types examined:

Bone marrow

Details of tissue and slide preparation:

In a pretest for the determination of the acute oral toxicity, all animals (male and female) survived following two treatments with 2000 mg/kg body weight recommended as the highest dose according to the OECD Guideline without clinical signs. Thus, only male animals were used for the cytogenetic investigations. Therefore, a dose of 2000 mg/kg body weight was selected as the highest dose in the present cytogenetic studies. 1000 mg/kg and 500 mg/kg body weight were administered as further doses.

Evaluation criteria:

The mouse micronucleus test is considered valid if the following criteria are met: The quality of the slides must allow the identification and evaluation of a sufficient number of analyzable cells, i.e. >2000 PCEs and a clear differentiation between PCEs and NCEs. The ratio of PCEs/NCEs in the untreated animals (negative control) has to be within the normal range for the animal strain selected. The number of cells containing micronuclei in negative control animals has to be within the range of the historical control data both for PCEs and for NCEs. The two positive control substances have to induce a significant increase in the number of PCEs containing small and large micronuclei within the range of the historical control data or above.
A finding is considered positive if the following criteria are met: Significant and dose-related increase in the number of PCEs containing micronuclei. The number of PCEs containing micronuclei has to exceed both the concurrent negative control and the highest value of the historical control range.
A test substance is considered negative if the following criteria are met: The number of cells containing micronuclei in the dose groups is not significantly above the negative control and is within the historical control data.

Statistics:

The asymptotic U test according to MANN-WHITNEY (modified rank test according to WILCOXON) was carried out to clarify the question whether there were significant differences between the control group and dose groups with regard to the micronucleus rate in polychromatic erythrocyte. The relative frequencies of cells containing micronuclei of each animal was used as a criterion for the rank determination for the U test.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Both control groups gave frequencies of micronucleated polychromatic erythrocytes within the historical control range.
Both of the positive control chemicals, i.e. cyclophosphamide for clastogenic effects and vincristine (both experiments) for induction of spindle poison effects, led to the expected increase in the rate of polychromatic erythrocytes containing small or large micronuclei.
Animals which were administered the vehicle or the positive control substances cyclophosphamide or vincristine did not show any clinical signs of toxicity.
According to the results of the present study, the two oral administrations of Trilon A 92 R did not lead to any increase in the number of polychromatic erythrocytes containing either small or large micronuclei. The rate of micronuclei was always close to the range as that of the concurrent negative controls in all dose groups and within the range of the historical control data in two experiments carried out independently of each other.
No inhibition of erythropoiesis, determined from the ratio of polychromatic to normochromatic erythrocytes, was detected.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
According to the results of the present study, the two oral administrations of Trilon A 92 R did not lead to any increase in the number of polychromatic erythrocytes containing either small or large micronuclei. The rate of micronuclei was always close to the range as that of the concurrent negative controls in all dose groups and within the range of the historical control data in two experiments carried out independently of each other. No inhibition of erythropoiesis, determined from the ratio of polychromatic to normochromatic erythrocytes, was detected. Thus, under the experimental conditions chosen here, the test substance Trilon A 92 R does not have any chromosome-damaging (clastogenic) effect, and there were no indications of any impairment of chromosome distribution in the course of mitosis (aneugenic activity) in bone marrow cells in vivo.