PLEASE USE CAUTION WHEN HANDLING INDICATING DESICCANTS

 

Background

Cobalt (II) chloride, the blue indicator in self-indicating silica gel and calcium sulfate desiccants (e.g., Drierite), has been revealed to be a confirmed animal carcinogen at relatively high doses.  A European Commission Directive (98/98/EC) reclassified cobalt chloride as a potential carcinogen by inhalation.  The International Agency for Research on Cancer (IARC) indicates there is limited evidence for carcinogenicity of cobalt (II) chloride in experimental animals, and has assigned cobalt and cobalt compounds as possibly carcinogenic to humans (group 2B).

 

It is important to note that the EC directive was for the pure chemical, whereas self-indicating desiccants contain only about 1% w/w cobalt chloride, and this is confined within the desiccant material itself.  The risk of exposure to the products that we use in the field and laboratory is considered insignificant provided the materials do not become powdered or crushed to the extent that the resulting dust becomes easily airborne.

 

Procedural Precautions

Since there is a finite health risk associated with blue indicating desiccants when handling the material and being exposed to the dust, the following safety precautions shall be adopted immediately by all Clean Air Engineering employees.

 

1.        Pure self-indicating (blue) desiccants should be handled in the fume hood whenever there is a significant risk of generating dust.  This includes the task of mixing indicating silica gel with the non-indicating gel to prepare the field product, and when adding or replacing desiccant materials in desiccators.

2.        Dusty silica gel or Drierite-type desiccants should be gradually removed from service.  Materials should be placed in a tough plastic bag and sealed prior to disposal into the municipal waste stream.

3.        Self-indicating desiccants should not be powdered/crushed or handled in any way likely to cause significant dust exposure.

4.        If there is any concern that handling a desiccant may create an inhalable dust cloud, and no fume hood is available, then use a regular dust mask or dust respirator while working with the material.


Page last updated on April 17, 2002