Sodium chromate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The following information is taken from the EU RAR:

 

Skin sensitisation resulting from occupational contact with Cr(VI) compounds is relatively common in humans. This has also been demonstrated in patch testing of contact dermatitis patients and in investigations of various occupational groups. In addition, the skin sensitisation potential of Cr (VI) compounds has been clearly demonstrated in standard and modified guinea pig maximisation tests and in the mouse ear swelling test. The current understanding of the mechanism involved in the sensitisation indicates that Cr (III) is the ultimate hapten. Skin contact with Cr (VI) leads to penetration of Cr (VI) into the skin where it is reduced to Cr (III). There is some evidence for cross-reactivity between Cr (III) and Cr (VI); Cr(VI)-sensitised subjects may also react to Cr (III). Overall, it is not possible to reliably determine a threshold for either induction or challenge in an exposed population using the available data, however it is assumed that all water soluble Cr (VI) compounds are human skin sensitisers.

 

Short description of key information:

No studies are available and testing of this group of compounds for skin sensitisation is not proposed, based on the low pH and classification as corrosive.  Data from human exposure indicate that the water-soluble Cr(VI) compounds are skin sensitiers, therefore testing is not required.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

No suitable animal tests are available for the detection of respiratory sensitisation. The EU RAR discusses reports of occupational asthma in workers exposed to Cr(VI) compounds:

 

'Asthma arising from exposure to Cr(VI) was first suggested in the 19th century. A number of case reports, mainly within the chrome plating industry, provide evidence that inhaled Cr (VI) can cause asthma, although the total number of reported cases is small in relation to the number of workers potentially exposed. Positive findings are available from several well-conducted bronchial challenge tests. No information is available on the dose-response relationships for induction of the hypersensitive state or elicitation of an asthmatic response in hypersensitive individuals. The available case reports and evidence from well-conducted bronchial challenge tests, show that inhalation of Cr (VI) compounds can cause occupational asthma. As with skin, Cr (VI)- sensitised subjects may react to Cr (III). It is not possible to determine a no-effect level or exposure-response relationship for induction or elicitation of occupational asthma.'

 

It is therefore concluded that chromic acid (as other Cr(VI) compounds) has the potential to cause respiratory sensitisation in exposed humans and should be classified.

 

Short description of key information:

A number of reports of respiratory sensitisation (occupational asthma) are available.  These have been previously discussed in a number of reviews,

including (most recently) the EU RAR.

Justification for classification or non-classification

Chromium trioxide, sodium chromate, sodium dichromate and potassium dichromate are listed on Annex I of Directive 67/548/EEC with classification as (R43) 'May cause sensitisation by skin contact' based on findings in occupationally-exposed humans. No change to this classification is proposed.

Chromium trioxide, sodium chromate, sodium dichromate and potassium dichromate are listed on Annex I of Directive 67/548/EEC with classification as (R42) 'May cause sensitisation by inhalation'. Based on read across, potassium chromate should also be classified wit R42: May cause sensitisation by inhalation.