Submesothelial deposition of carbon nanoparticles after toner exposition: case report

Particle emissions by office printers show differences between printer types, printers of the same type and a significant increase during working times [ 5 ]. The average diameter of emitted particles from different printers was found to be in between 40-76 nm and well fitting to our results. The study checked up 62 different printers, but the type used in our case was not included [ 5 ]. About a possible respiratory uptake of CNP in human office workers no systematic morphological investigations exist. A study about the respiratory health of workers handling printing toners showed a higher prevalence rate of thoracic radiographic abnormalities and a strong tendency towards a decline of lung function in long time exposed persons [ 8 ]. In a case of granulomatous pneumonitis and mediastinal lymphadenopathy with photocopier toner dust exposure containing copper, this metal was detected in the tissue investigated by SEM and EDX [ 10 ]. Metal oxides were detectable on the surface of toner particles in our case as well, but deposition in tissue has not been seen. In cases of anthracosilicosis dust deposits in the liver have been reported [ 13 ]. This demonstrates that particle transport of inhaled dust via the blood stream with deposition in other organs can be found in humans [ 11 , 13 ]. Ultra fine carbon particles cause a strong down-regulating effect on the cytochrome P450 1B1 protein in monocytes. These data suggest that the induced reduction of gene expression may interfere with the activation and/or detoxification capabilities of inhaled toxic particles. In primary bronchial epithelial cells this effect showed remarkable inter-individual differences, which emphazises the role of polymorphisms [ 14 ]. In the case reported here there were no obvious repiratory symptoms. Clinical studies revealed negative effects on respiratory health after toner exposure [ 7 , 8 , 10 ], therefore further studies concerning morphology, genetics and clinical consequences are needed.

CNP: carbon nanoparticles; EDX: energy dispersive x-ray analysis; LM: light microscopy; NP: nanoparticles; SEM: scanning electron microscopy; TEM: transmission electron microscopy

Written informed consent was obtained from the patient for publication of this case report including images. A copy of the written consent is available for the Editor-in-Chief of this journal.

DT did LM of the peritoneum (second opinion) and TEM, supervised SEM and EDX and wrote the manuscript. SB performed SEM and EDX, SP has done LM of the peritoneum and colon and initiated further investigations. OA discussed the clinical background and revised the manuscript. All authors read and approved the final version.

The authors declare that they have no competing interests.

Several studies have reported that laser printers are significant sources of ultrafine particles [ 1 - 6 ]. Workers with long time exposure to toner dust showed a significantly higher prevalence of radiographic lung abnormalities in a cross sectional study [ 7 ]. Also a significant higher prevalence of temporary coughing and sputum production has been reported [ 8 ]. In general nanoparticles (NP) will play a fundamental role in the future and risk assessment seems to be a relevant issue [ 9 ]. Office printers were detected to emit carbon nanoparticles (CNP) in a variable extend [ 5 ]. Granulomatous pneumonitis and mediastinal lymphadenopathy has been reported in a case of photocopier toner dust exposure [ 10 ]. Inhaled 99m technetium-labeled CNP can be transported with the human blood circulation and deposited in other organs [ 11 ]. We present a female open office worker with toner dust exposure and CNP deposits in the peritoneum.

We have shown that workers with toner dust exposure from laser printers can develop submesothelial deposition of CNP in the peritoneum. Transport of CNP via lymphatic and blood vessels after inhalation in the lungs has to be assumed. Impact of toner dust exposure on the respiratory health of office workers, as suspected in other studies, has to be evaluated further.