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August 19, 2009

Study Claims Link Between Occupational Lung Disease and Nanoparticle Exposure

Lynn L. Bergeson

The September 2009 issue of the European Respiratory Journal will contain a study entitled “Exposure to nanoparticles is related to pleural effusion, pulmonary fibrosis and granuloma.”  The study examines the relationship between a group of workers presenting with “mysterious” symptomatic findings and their nanoparticle exposure. The authors conducted surveys of the workplace, made clinical observations, and examined the patients — seven young female workers (aged 18 to 47 years), exposed to nanoparticles for five to 13 months, all with shortness of breath and pleural effusions.  According to the study abstract, polyacrylate, consisting of nanoparticles, was confirmed in the workplace.  Using transmission electron microscopy, nanoparticles were observed to lodge in the cytoplasm and caryoplasm of pulmonary epithelial and mesothelial cells, but are also located in the chest fluid.  The authors state that these cases “arouse concern that long-term exposure to some nanoparticles without protective measures may be related to serious damage to human lungs.” The study is not yet available on the European Respiratory Journal website.

To help place the study in context, Dr. Andrew Maynard, Chief Science Advisor to the Woodrow Wilson International Center for Scholars Project on Emerging Nanotechnologies (PEN), has posted a blog item entitled “New study seeks to link seven cases of occupational lung disease with nanoparticles and nanotechnology” on the SAFENANO and 2020 Science websites. Maynard notes that the seven women were all working for some months, in an enclosed space with little natural ventilation, in a facility spraying a polyacrylic ester paste onto a polystyrene substrate that was subsequently heat-cured.  Five months before the lung disease was identified, the local exhaust ventilation in the facility broke down, and apparently was never mended. Maynard states that the issues discussed in the paper and the Journal’s press release, including nanoparticle safety, worker deaths, and parallels with asbestos, will attract attention.

 Review of the study yields important factors to consider.  Importantly, the facility lacked even the most basic industrial hygiene and worker protection safeguards.  Dr. Maynard  cautions that it is important to understand specific limitations of the study: (1) it was a clinical study rather than a toxicology study; (2) it is not possible to draw any general conclusions on the safe use of nanotechnologies from it; (3) interpretation of the study is hampered by a lack of exposure data; (4) there are no electron microscope images of the nanoparticles found in the workplace; (5) there is no chemical analysis of the particles found in the workplace or biological samples; (6) there is no assessment of other plausible causes of the symptoms seen; and (7) in discussing the relevance of the study, the authors make no distinction between different types of nanomaterials and their potential impacts.  According to Maynard, “[d]espite these limitations, this is a strong clinical study, and if viewed appropriately, will most likely help avoid similar incidents in the future.” His final observation is that “the illnesses and deaths observed would most likely not have occurred if long-accepted occupational practices had been followed. The tragedy here is that, irrespective of the presence of nanoparticles, the illnesses and deaths could have been prevented if simple steps had been taken to reduce exposures.”