The recent article by Vyaset al 1 raises some concerns to which I would be grateful if they could respond.

(1) In the abstract one of the objectives is stated as finding the nature and incidence of symptoms experienced by a large sample of hospital endoscopy nurses. The study design is cross sectional and used an adapted version of the MRC questionnaire for respiratory symptoms. This study design normally records disease prevalence rather than incidence.2 It would be helpful to know if the questionnaire sought information on new symptoms in a given period in the past, or the presence of symptoms.

(2) For the purposes of the study, work related symptoms of contact dermatitis were defined as contact skin rash, which occurred when working on the endoscopy unit and could not be attributed to known non-occupational agents. It is not clear what validation process was performed before this section of the questionnaire in the study was used. The authors have indicated that eight of the 13 subjects with a positive test to IgE specific to latex had work related symptoms of dermatitis, and indicate that this is non-significant. The authors' definition of contact dermatitis would have resulted in staff with contact urticaria answering positively to this section. As such, the presence of IgE specific to latex could well be of importance as staff would have used latex gloves.

(3) Cross sectional studies are enhanced by the inclusion of ex-employees. In this study only 18 of 68 ex-employees participated in this study. All 18 were among 26 staff who had left within the past 5 years for health reasons. As such a selection bias exists and the interpretation of the frequency of work related symptoms in ex-employees should be cautious. Also, it is noted that eight of the 18 ex-employees continue to work as nurses and may experience work related symptoms from circumstances related to current workplaces rather than endoscopy suites. The absence of a control group of nurses working in areaswithout exposure to glutaraldehyde would have been of help in interpreting the results obtained.