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Reference
Endpoint:
basic toxicokinetics, other
Remarks:
Literature review
Type of information:
other: Review
Adequacy of study:
key study
Study period:
Assessment
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
There are many reviews on the role of Chromium as an essential element and the impact of dietary supplements. The findings have been summarised.
Objective of study:
absorption
distribution
excretion
metabolism
Qualifier:
no guideline followed
Version / remarks:
Assessment
Principles of method if other than guideline:
Assessment of agency reviews: Much of the information cited is taken from European Scientific Committee for food safety using assessments for the use of chromium as food supplements.
GLP compliance:
no
Specific details on test material used for the study:
Assessment based on chromium ions
Details on absorption:
The rate of absorption will depend greatly on the solubility of the salt, but on ingestion, it is likely that there will be significant dissociation in the stomach at low pH.However, an oral gavage study for chromium oxide reported coloured faeces suggesting a large proportion is not absorbed if ingested in large quantities. There is no direct evidence of absorption dermally, but data suggest that sensitisation can occur from contact with the skin which implies some movement of ions at least through the outer layers of skin. A study looking at effects on reproduction by inhalation at maximum achievable levels failed to show any changes in organs or reproductive parameters and it is not conclusive whether absorption can occur by inhalation.
Details on distribution in tissues:
No adverse systemic effects were observed in reported toxicity tests, other than perhaps effects to reproductive organs at very high concentrations. Hepatic and renal chromium concentrations in rats were roughly 2- to 6-fold greater when chromium picolinate was fed compared to chromium chloride. Due to the natural presence of chelating agents in the diet the bioavailability of chromium from food can vary significantly and although this demonstrates distribution.As an essential element, it is accepted that at least ‘normal’ concentrations will be actively distributed
Details on excretion:
Since there is a general background dietary intake of chromium and no evidence of accumulation, levels of excretion will normally match levels of intake.Most work on excretion of chromium is linked to elimination of chromium VI ions.Urinary chromium excretion of excess chromium following work exposure reflected absorption over the previous one to two days in an occupational setting. A urinary chromium concentration of 40 μg/L to 50 μg/l was reported immediately after a work shift, compared to a reported background level of typically less than 10 μg/l.These reports from workers showed that elimination of excess chromium was rapid and it is also worth noting that although exposure in these cases were to chromium VI, there had been conversion to chromium III prior to elimination.
Metabolites identified:
not measured
Details on metabolites:
Chromium is considered to be an essential part of glucose metabolic processes, but precise mechanisms have not been described. Chromium III will not itself metabolise, but will be linked into chelates where ion-exchange will occur.
Conclusions:
Despite the absence of specific toxicokinetic data from animal testing on the metal, the fact that chromium is present is food and is considered an essential element for metabolism suggests that mechanisms exist for absorption, distribution and excretion and that the metal is not accumulative.
Executive summary:

It is clear from data presented that the bioavailability is dependent in part on the solubility (dissociation). But even the least soluble salts will be sufficiently soluble under acidic stomach conditions to significantly absorb.

 

There is no direct evidence of absorption by dermal route, but data indicates that chromium is potentially sensitising and this would imply a degree of absorption through the skin. There is also no indication of respiratory.

 

As an essential element, chromium is transportable in the body, but in the absence of chronic toxic effects, there is no evidence of specific target organ effects.

 

Chromium will excreted as part of natural balance of ions in animals and there is no evidence of accumulation.

Description of key information

Despite the absence of specific toxicokinetic data from animal testing on the metal, the fact that chromium is present is food and is considered an essential element for metabolism suggests that mechanisms exist for absorption, distribution and excretion and that the metal is not accumulative

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

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