Enzymes in cleaning solutions used to clean endoscopes could be a health hazard, finds report

End users need better information about the potential hazardous properties of microbial enzymes

Enzyme based solutions used to decontaminate endoscopy and surgical equipment may pose a risk to health, a study prepared for the Health and Safety Executive has found.

Exposure by inhalation to enzymes derived from micro-organisms (bacteria and fungi) is a recognised risk factor for the development of respiratory allergy (asthma) and in contact with the skin some enzymes (proteases) can cause dermatitis.

The Health and Safety Laboratory report, A survey of exposure to enzymes in cleaning solutions used to clean endoscopes, examined exposure of health workers to enzyme solutions used to clean endoscopes and site visits were undertaken to collect air samples and surface wipe samples at three hospitals in the UK and a total of 7 endoscopy units.

Different types of enzyme solution were used in the endoscopy units, and the selection of the product varied within hospitals and between units undertaking similar clinical work.

Healthcare workers had limited knowledge about the constituents of these cleaning solutions and were generally unaware of the risk of respiratory allergy and skin damage associated with concentrated microbial enzymes, the study found.

Users need better information about the potential hazardous properties of microbial enzymes and advice about how to work safely with them

The low content of enzyme in these solutions does not require their identification on material safety data sheets, which was the case with the products examined. However, the absence of this information may contribute to a lack of awareness that sensitisation and allergy can result from exposure to microbial enzymes at very low levels of exposure (e.g. less than 100ng/m-3), the survey found.

The results demonstrated levels of protease in 4 out of 14 personal air samples and 6 out of 14 static air samples that may pose a risk for allergic sensitisation. In contrast, surface levels of enzyme were very high in all but one of the endoscopy units.

Overall the air sampling results did not suggest that inhalation exposure was the most likely route of exposure but the likelihood for exposure of skin was greater (via spread of droplets and through contact with contaminated surfaces). Investigation at one site also showed contamination of work clothes and hands providing further evidence of the risk for personal exposure by contact.

The highest levels of enzyme deposits were concentrated around areas used to hand wash the endoscopes, but lower levels of contamination were also found throughout these rooms.

Hospital staff were provided with personal protective equipment (PPE) but they were uncertain when to use respiratory protective equipment or about the need to fit test it. Staff generally did not know how to remove contaminated gloves safely or how to avoid skin contamination.

Much lower levels of surface enzyme were found at one endoscopy unit where regular wet surface cleaning was undertaken throughout the working day.

The endoscopy cleaning rooms examined were typically small and filled with equipment, making it difficult to implement good cleaning regimes.

The survey concludes that exposure to these enzymes during manual cleaning is mainly by skin contact but the risk of this occurring can be minimised by practical control measures. The effective use of these controls is dependent on providing end users with better information about the potential hazardous properties of microbial enzymes and advice about how to work safely with them.