NZIMRT - MARJ GORDON MEMORIAL SEMINAR, 15 March, 1997, Palmerston North, NZ:
AIRBORNE CONTAMINANTS FROM X-RAY PROCESSING CHEMICALS:
Mr Geof Care, Managing director of Photosol, London, questioned why people are sensitised in Xray areas when the highest recorded levels are much lower than in endoscopy units. He demonstrated that pure glutaraldehyde aerosols are formed by condensation of the vapour as it cools. Aerosols arethe dispersion of a liquid or a solid in a gas and they have particles 1/1,000 to 1/1,000,000 of a micron. The eye can see thecollective properties of an aerosol eg tobacco smoke. Smaller aerosols are invisible and behave as air. He used the Bristol University mass spectrometer to measure the concentration of GA over the developer, then passed fixer vapour over the top. Instantly the GA readout fell. Essex University measured the number of particles generated and showed that when sulphur dioxide was passd over GA vapour, a high number of particles were formed - again good evidence for an aerosol. Most particles were below 1 micron and were highly respirable and capable of reaching the alveoli in the bottom of the lung.
At the AEA, Harwell, GA was heated to 20-35°C to form a saturated vapour concentration, and humidified air and SO² injected in in a controlled manner. The initial concentration of particles increased rapidly whatever the carrier gas used, then the concentration reduced as the carrier gas swept away the GA, the available vapour was reduced and cooling set in - a classic condensation aerosol. (A different pattern would have been produced had SO² been reacting to the GA).
Thus the aerosol contains droplets of pure glutaraldehyde. Sticky deposits were noticed on the walls of the equipment before it reached the counter so the apparatus was made shorter and there was an enormous increase in the number of particles regardless of the carrier gas. SO² gave particles of about 2 microns, and the mixture of humidified air and SO² gave 4 microns. Anything over 1 micron settles out quite rapidly. Significant levels of aerosols were obtained over the whole temperature range therefore these aerosols are viable in a hospital environment. Any of the chemicals may potentially appear as constituents of aerosols formed above the developer for instance acetic acid was demonstrated although it is probably not nearly as significant as the GA aerosol.
In 1988 a mass spectrometer in an Xray dept picked up nothing until a radiographer walked past. For 4 minutes the concentration of GA on the film (and on her hands) was tremendous and that was highest single exposure measured. In 1980/81 Dr Robert Zach and Dr A Fisher in the States, had already confirmed the presence of contact dermatitis and sensitisation to GA from handling film, and suspected asthma was a consequence[1].
In 1995, Dr Sherwood Burge mentioned a secretary with no previous health problems employed in Birmingham Hospital admin, well away from Xray processing. After 6 months she developed asthma and challenge tests showed GA to be the cause. The culprit? Stacks of freshly processed film placed on the desk beside her. The cooling film with a fairly reactive surface may be acting as a condensing medium (this may be the same concentrating-up process as cigarette smoke on clothing ) so the work environment may be ‘taken home’. Film driers at approx 55°C may make the process even more volatile[2].
[1] Zach Robert .J. How prevalent is glutaraldehyde sensitivity? Consultant May, 1980, 116.
Fisher A.A. Reactions to glutaraldehyde with particular reference to radiologists and technicians. Cutis 1981, 28, 113-12.
[2] G Care, Airborne Contaminants from Xray Processing Chemicals. G Care, Managing Director, Photosol, London. Presented at the Marjorie Gordon Memorial Seminar, March 15, 1997, Palmerston North.
