Chromium trichloride

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

supporting study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant guideline study without significant deviation, performed under the US NTP program

Data source

Reference

Reference Type:

publication

Title:

STUDIES OF CHROMIUM PICOLINATE MONOHYDRATE (CAS NO. 27882-76-4) IN F344/N RATS AND B6C3F1 MICE (FEED STUDIES)

Author:

National Institutes of Health Public Health Service U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Year:

2010

Bibliographic source:

NTP TR 556, NIH publication No. 10-5897, June 2010

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

27882-76-4

Cas Number:

27882-76-4

IUPAC Name:

27882-76-4

Constituent 2

Reference substance name:

chromium picolinate monohydrate

IUPAC Name:

chromium picolinate monohydrate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Purity: 95 - 96%
Chemical Formula: C18H12CrN3O6.H2O
Molecular Weight: 436 g/mol
Synonyms: Chromium 2-pyridine-carboxylate; chromium tripicolinate; chromium tris (picolinato)-; chromium, tris (2-pyridinecarboxylato-N(1), O(2))-(9CI); picolinic acid, chromium salt
Chromium picolinate monohydrate was obtained from TCI America (Portland, OR) in one lot (OGJ01) and from Sigma-Aldrich (St. Louis, MO) in one lot (CHESS0204DFCI). Lot OGJ01 was used in the 3-month studies; the unused remainder of lot OGJ01 was combined with lot CHESS0204DFCI by the analytical chemistry laboratory, Battelle Toxicology Northwest (Richland, WA), and assigned lot number 672002, which was used in the 2-year studies.
Lots OGJ01 and 672002 of the chemical, a reddish-purple crystalline powder, were identified as chromium picolinate monohydrate by infrared and proton nuclear magnetic resonance spectroscopy, X-ray diffraction, and electrospray ionization-mass spectrometry (EI-MS).
Cr(VI) impurity: < 0.025%

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female B6C3F1 mice were obtained from Taconic Farms, Inc. (Germantown, NY), for use in the subchronic studies. Mice were quarantined for 12 days before the beginning of the studies. Five male and five female mice were randomly selected for parasite evaluation and gross observation of disease. Mice were approximately 6 weeks old at the beginning of the studies. The health of the animals was monitored during the studies according to the protocols of the NTP Sentinel Animal Program.
Male mice were housed individually and female mice were housed five per cage. Feed and water were available ad libitum. Feed consumption was measured weekly. Polycarbonate cages were changed and rotated weekly (male mice) or twice weekly; racks were changed and rotated every 2 weeks. Bedding was changed twice weekly. Animals were tail-tattoed for identification.
Room temperature: 72 ±3 °F
Relative humidity: 50 ±15%
Room fluorescent light: 12 hours/day
Room air changes: 10/hour

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle) in feed

Details on exposure:

The dose formulations were prepared by mixing chromium picolinate monohydrate with feed. Homogeneity studies of 82 and 50,000 ppm dose formulations and stability studies of the 82 ppm dose formulation were performed by the analytical chemistry laboratory using ICP-AES. Additional homogeneity studies of 80 and 50,000 ppm dose formulations were performed by the study laboratory using HPLC-UV.

Duration of treatment / exposure:

14 weeks (3 month) as parallel group to subchronic studies with mice (see Supp_Repeated dose toxicity: oral mouse_CPM_NTP_2010)

Frequency of treatment:

continuous via feed ad libitum

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 80, 240, 2000, 10000 and 50000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes, plain diet

Positive control(s):

none

Examinations

Tissues and cell types examined:

peripheral blood samples were obtained from male and female mice. Slides were scanned to determine the frequency of micronucleated cells in 1,000 normochromatic erythrocytes (NCEs) in each of 10 animals per exposure group. In addition, the percentage of polychromatic erythrocytes (PCEs) in a population of 1,000 erythrocytes was determined per animal as a measure of bone marrow toxicity.

Details of tissue and slide preparation:

A detailed discussion of this assay is presented by MacGregor et al. (1990). At the end of the 3-month feed study with chromium picolinate monohydrate, peripheral blood samples were obtained from male and female mice. Smears were immediately prepared and fixed in absolute methanol. The methanol-fixed slides were stained with acridine orange and coded. Slides were scanned thereafter for evaluation.

Evaluation criteria:

In the micronucleus test, an individual trial is considered positive if the trend test P value is less than or equal to 0.025 or if the P value for any single exposed group is less than or equal to 0.025 divided by the number of exposed groups. A final call of positive for micronucleus induction is preferably based on reproducibly positive trials (as noted above). Ultimately, the final call is determined by the scientific staff after considering the results of statistical analyses, the reproducibility of any effects observed, and the magnitudes of those effects.

Statistics:

The frequency of micronucleated cells among NCEs was analyzed by a statistical software package that tested for increasing trend over dose groups with a one-tailed Cochran-Armitage trend test, followed by pairwise comparisons between each exposed group and the control group (ILS, 1990). In the presence of excess binomial variation, as detected by a binomial dispersion test, the binomial variance of the Cochran-Armitage test was adjusted upward in proportion to the excess variation.

Results and discussion

Test results

Test results 1

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

not examined

Test results 2

Sex:

female

Genotoxicity:

other: equivocal due to trend in 50,000 ppm group

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

not examined

Additional information on results:

No increase in the frequency of micronucleated NCEs was observed in male B6C3F1 mice administered chromium picolinate monohydrate (80 to 50,000 ppm) in feed for 3 months, indicating no potential for chromium picolinate monohydrate to induce chromosomal alterations in dividing cell populations in this test system. In female mice, however, the small increase in micronucleated NCEs noted in the highest exposure concentration group (50,000 ppm) was not significant at P = 0.0396, but it resulted in a significant trend test (P=0.005) and, therefore, the test with chromium picolinate monohydrate was judged to be equivocal in female mice.
No significant alterations in the percentage of PCEs among total erythrocytes was observed in exposed mice, indicating that these exposure concentrations of chromium picolinate monohydrate did not induce bone marrow toxicity.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
In male mice negative and in female mice equivocal for inducing chromosomal alterations in dividing mouse cells. A small increase in micronucleated NCEs noted in the highest exposure concentration group (50,000 ppm) of female mice was not significant at P=0.0396, but it resulted in a significant trend test (P=0.005) . Therefore, the findings inmice were considered equivocal. No bone marrow toxicity was induced in male and female mice.

Executive summary:

No increase in the frequency of micronucleated NCEs was observed in male B6C3F1 mice administered chromium picolinate monohydrate (80 to 50,000 ppm) in feed for 3 months, indicating no potential for chromium picolinate monohydrate to induce chromosomal alterations in dividing cell populations in this test system. In female mice, however, the small increase in micronucleated NCEs noted in the highest exposure concentration group (50,000 ppm) was not significant at P = 0.0396, but it resulted in a significant trend test (P = 0.005) and, therefore, the test with chromium picolinate monohydrate was judged to be equivocal in female mice. No significant alterations in the percentage of PCEs among total erythrocytes was observed in exposed mice, indicating that these exposure concentrations of chromium picolinate monohydrate did not induce bone marrow toxicity.