Sodium chromate

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Review of published studies

Data source

Reference

Reference 1

Reference Type:

other: EU RAR

Title:

European Union Risk Assessment Report: chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate, potassium dichromate

Author:

European Chemicals Bureau

Year:

2005

Bibliographic source:

3rd Priority List; Volume 53

Reference 2

Reference Type:

review article or handbook

Title:

Criteria Document for Hexavalent Chromium

Author:

Cross HJ et al

Year:

1997

Bibliographic source:

Institute of Occupational Health

Materials and methods

Test guideline

Qualifier:

no guideline followed

Deviations:

not applicable

Principles of method if other than guideline:

The reviews report a number of older investigative studies performed using non-standard methods.

GLP compliance:

no

Remarks:

Older, literature studies

Test material

Test material information

Constituent 1

Reference substance name:

Sodium chromate

EC Number:

231-889-5

EC Name:

Sodium chromate

Cas Number:

7775-11-3

Molecular formula:

CrH2O4.2Na

IUPAC Name:

sodium chromate

Details on test material:

Studies were performed using aqueous solutions of sodium chromate

Radiolabelling:

yes

Remarks:

51Cr

Test animals

Species:

guinea pig

Strain:

not specified

Sex:

not specified

Administration / exposure

Type of coverage:

not specified

Vehicle:

water

Duration of exposure:

Five hours

Doses:

The test material was administered at concentrations of between 0.48 mM to 4.87 M.

No. of animals per group:

Not reported

Control animals:

no

Remarks:

Not required

Results and discussion

Conversion factor human vs. animal skin:

Not relevant

Any other information on results incl. tables

The results of the reviewed studies indicate that the dermal absorption of chromate from water soluble Cr (VI) compounds is likely to be low. Dermal absorption values of 1 -4% were found in guinea-pig studies, however these are likely to be over-estimates.

Applicant's summary and conclusion

Conclusions:

The dermal absorption of chromate from water-soluble Cr (VI) compounds is likely to be low in occupationally-exposed humans. It is possible that local irritant/corrosive effects may enhance dermal penetration.

Executive summary:

The dermal absorption of Cr (VI) has been stdueis in guinea pigs following the application of aqueous solutions of 51Cr-labelled chromate. Generally less than 1% of the dose was absorbed when animals were exposed to concentrations of between 0.48 mM and 4.87 M for 5 hours. At concentrations of 0.261 M and 0.398 M, 4% and 2.8% of the applied dose was absorbed, respectively. The UK IOH review cautions that, as dermal absorption was deteremined by measuring the disappearance of radiolabel from the applied dose, the reported figures include material residual in the skin at study termination. The reported dermal absorption figures may therefore be overestimates as material in the skin may not be systemically available.

An additional guinea pig study reported absorption (radioactivity in the carcass and excreta) of 1.4% after 24 hours; the findings of this study are therefore consistent with the earlier studies. Based on considerations of the comparative structure of human and guinea-pig skin, it can be concluded that the dermal absorption of water-soluble hexavalent chromium compounds in occupationally-exposed humans is likley to be negligible.