Exposure to Osmium Tetroxide

Below is a summary of an incident that occurred here at the University. Please share with your departments.

EHS received a call concerning a chemical hood problem at one of our facilities. Osmium tetroxide was being used in a chemical fume hood and reportedly one of the researchers was feeling the effects of an exposure. The researcher left the lab and returned a short time later after the symptoms diminished. Upon his return he again felt symptomatic, closed the fume hood and left the lab. At this time facilities maintenance was contacted to check the performance of the chemical fume hood, however the osmium tetroxide had not yet been removed. Fortunately our Facilities Maintenance personnel as well as the researcher were not injured.

It is important to remember that if there is ever a question concerning your engineering controls, (i.e. chemical fume hood, walk-in fume hood, and paint spray booths), the environment must be cleared of recognizable hazards before Facilities is contacted for maintenance. This is achievable either by contacting the departmental safety representative or someone from our office.

Additionally, if there is a question concerning the possibility of an exposure please initiate the basic emergency procedures. This should include evacuating and closing off the area, immediately seeking medical attention and contacting the departmental Chemical Hygiene Officer or our office to initiate an investigation. An exposure evaluation will be conducted for all employees who, as a consequence of a laboratory operation, procedure, or activity, reasonably suspect or believe they have sustained an overexposure to a toxic substance. Attached below is a link to our University's Chemical Hygiene Plan for more information. University of Delaware Chemical Hygiene Plan Exposure Evaluations.

Please also review the University Emergency Response Policy 7-06 for information.

This incident emphasizes why it is important to review the material safety data sheets prior to working with chemicals. Osmium tetroxide is extremely hazardous via inhalation and has an exposure limit of 0.0002 parts per million (ppm). It is also extremely volatile with a vapor pressure comparable to xylene (though xylene's exposure limit of 100 ppm is much higher).