Possible negative human health effects by particle emissions from laserprinter devices were investigated in application-typical scenarios with volunteers in a climatic chamber at Ludwig-Maximilians-Universität (LMU) in Munich under controlled conditions. An explicit identification of possible health effects and an assessment on the influence of factors such as particle size and particle concentration was be made possible with a specialized experimental design.
Four laser printers - two with very high (High Emitter, HE) and two with very low (Low Emitter, LE) emissions of ultrafine particles - were selected from a test pool of printers at BAM. The experimental setup and conditions for these printers in an exposure room of the LMU were optimized and standardised. For HE exposures the concentrations of ultrafine particles based on printer activity were kept at approximately 100.000 per cm3. During LE exposures there was no quantifiable contribution from printers to the background level of fine and ultrafine particles in the exposure room, which typically was 2000-4000 per cm3. This standardised scenario was used to study different groups of volunteers as participants in a randomised, cross-over, single-blinded manner: 23 healthy subjects (controls), 14 subjects with stable mild asthma and 15 subjects (patients) with self-reported symptoms related to laser printers in two exposures (effective duration 75 min). The screening visit included a methacholine inhalation challenge in order to stratify subjects also according to bronchial hyperreactivity. Before / at the start and after / at the end of exposures assess- ments were performed: spirometry, body plethysmography, diffusing capacity for CO and NO; exhaled CO and hydrogen peroxide (H2O2), exhaled NO at 4 flow rates (bronchial, alveolar NO); blood samples/nasal secretions; questionnaires (symptoms, well-being); d2-, labyrinth-, Benton-test (cognitive function).
In the group of all patients there were no statistically significant changes of the values of spirometry and body plethysmography. The volume-related diffusing capacity for NO showed a slight decrease, which was higher after HE compared to LE exposure but without statistically significant difference. Bronchial and alveolar exhaled NO were unaffected. H2O2 increased after both exposures in a similar manner. The analysis of serum revealed an increase in the concentration of the eosinophilic cationic protein (ECP) after both exposures, slightly stronger after HE, but without significant difference. Total IgE was slightly elevated after both exposures. Cytokine levels and the marker of oxidative stress 8-OHdG in serum showed no significant or no interpretable changes. In nasal secretions there was an increase of IL-6 levels after both exposures, with a tendency toward greater changes after HE exposure. Overall, the observed functional and biochemical changes did not yield a coherent picture, in particular no consistent relationships regarding the groups of patients, subjects with asthma, or subjects with bronchial hyperreactivity. Affectivity and chemical olfactory sensitivity differed between groups. Regarding the perception of the exposure situation patients showed the strongest responses and there was a tendency toward a higher rating of smell intensity after HE compared to LE exposure. Symptoms ranged at very low levels relative to the maxima of scales. There was a tendency for higher increases of symptoms after HE compared to LE exposures, which was dominated by the eye symptoms of the patients. Overall no coherent patterns regarding different effects of the two exposures emerged; it seems possible that the experimental situation per se influenced some of the results. The tests on cognitive function showed only few and weak systematic changes which were partly attributable to large differences in the values assessed prior to exposures in patients; this makes interpretation difficult. In summary the authors consider it likely and reasonable to assume that the observed changes were not clinically relevant, as they were small or very small and incoherent, although subjects were included who might be considered as particularly sensitive on the basis of their clinical history and/or physiological characteristics. The results of this study based on a wide spectrum of methods and subjects do not support the hypothesis that exposure to high levels of laser printer emissions elicits an objectifiable disease process that correlates with the spectrum of diseases and symptoms typically reported by patients.
prevention, dust, fibers, particles, chemical working substancesDescription, key words:
printer, copiers, laserprinter, toner, climatic chamber, emissions