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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
other: read-across from constituent CrIII
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Chromium as an essential nutrient for humans
Author:
Anderson RA
Year:
1997
Bibliographic source:
Regulatory Toxicology and Pharmacology, 26:S35–41

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
yes
Remarks:
20 weeks instead of 13 weeks of exposure
GLP compliance:
not specified
Limit test:
no

Test material

1
Reference substance name:
Cr III
Molecular formula:
Cr III
IUPAC Name:
Cr III
Details on test material:
CrCl3.6H2O or CrCl3

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals or test system and environmental conditions:
Four-week-old male Harlan Sprague-Dawley rats (eight per group)

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: diet
Details on oral exposure:
CrCl3 was fed a diet supplemented with 0, 5, 25, 50, or 100 mg Cr/kg as chromium chloride for a period of 20 weeks.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
20 wk
Frequency of treatment:
1x daily
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
5 mg/kg bw/day (nominal)
Dose / conc.:
25 mg/kg bw/day (nominal)
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
as chromium chloride, Daily Cr3+ intakes can be estimated to correspond to 0.35 – 7 mg/kg
No. of animals per sex per dose:
8
Control animals:
yes, plain diet
Details on study design:
Four-week-old male Harlan Sprague-Dawley rats (eight per group) were fed a diet supplemented with 0, 5, 25, 50, or 100 mg Cr/kg as chromium chloride for a period of 20 weeks as reported by Anderson et al. (1997). The daily Cr3+ intakes can be estimated to correspond to 0.35 – 7 mg/kg bw using the default reference values given in Appendix VI of European Commission [2003]). If 200 g is used as a mean body weight, the highest dose corresponds to 7 mg chromium/kg bw (corresponds to 21.3 mg CrCl3/kg bw.
Positive control:
No

Examinations

Observations and examinations performed and frequency:
Effects on body weights, selected organ weights, and the histology of liver and kidneys were evaluated.
Sacrifice and pathology:
Histopathological examination was performed on four high-dose and four control rats. Haematology and biochemical analyses of blood (serum glucose, cholesterol, triglycerides, liver enzymes, blood urea nitrogen, total protein, and creatinine) were performed on animals at 11, 17, and 24 weeks of age.
Other examinations:
Blood was collected from the tail after ll and l7 weeks and following decapitation after 24 weeks, allowed to clot 30 minutes at room temperature and then stored on ice prior to centrifugation at 4000 g for 30 minutes. Serum glucose, cholesterol, triglycerides, blood urea nitrogen, total protein, creatinine, actate dehydrogenase, alanine amino transferase and aspartate amino transferase were determined.
Statistics:
Statistical analyses of the data were performed by analysis of variance. Individual mean comparisons were identified with Duncan’s multiple range test. All values are mean ± SEM. There were eight animals per group. Using eight rats per group would be sufficient to detect a difference at the 0.05 level (power 0.9) with an expected difference between means of 0.4 and a standard deviation of 0.2 .

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
Some sporadic, statistically significant changes were seen in some clinical chemistry parameters (lactate dehydrogenase, aspartate aminotransferase, serum creatinine levels). However, no relation with time or dose. In addition effects occur only at specific time points with no general trend.
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Immunological findings:
not specified
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not specified
Other effects:
no effects observed
Details on results:
No changes compared to control in body weights were observed in any dose group and all animals appeared normal with no visible differences amongst the groups. Weights of heart, liver, kidney, spleen, pancreas, testes and epididymal fat pad were not altered by dietary Cr. Hematocrit was also similar among all the groups. No changes in body or organ weights, no general signs of toxicity, and no changes in liver or kidney histopathology were seen. Some sporadic, statistically significant changes were seen in some clinical chemistry parameters (lactate dehydrogenase, aspartate aminotransferase, serum creatinine levels), but because these changes did not show any dose or time dependency, they were not considered to be treatment related. Glucose, cholesterol and triglycerides were similar for all groups at 11, 17 and 24 weeks.

Effect levels

Dose descriptor:
NOAEL
Effect level:
> 21.3 mg/kg bw/day (nominal)
Based on:
test mat.
Remarks:
Chromium chloride
Sex:
male
Basis for effect level:
clinical biochemistry
Remarks on result:
not determinable due to absence of adverse toxic effects
Remarks:
Some sporadic, statistically significant changes were seen in some clinical chemistry parameters

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
Based on these results, the highest dose level (7 mg chromium III/kg bw/day ) can be considered as a no-observed-adverse-effect level (NOAEL) for repeated dose toxicity (using 200 g as a mean body weight). Accordingly, this relates to a NOAEL of >21.3 mg/kg bw/d based on chromium chloride.
Executive summary:

his study was conducted to evaluate the toxicity of chromium chloride in rats exposed to 0, 5, 25, 50, or 100 mg Cr/kg chromium trichloride in the diet for 20 weeks (estimated to correspond to 0.35–7 mg/kg bw). No morphological changes of liver and renal damage were observed based on histopathological examination of kidneys and did not result in significant alterations in body weight gain. No alterations in testes or epididymis weights were observed in rats at the highest dose.

Therefore, the no-observed-adverse-effects-level(NOAEL) of chromium trichloride is estimated to be 7 mg chromium (III)/kg bw/day. This value can be converted to a NOAEL of > 21.3 mg/kg bw/d based on molecular mass of chromium chloride.