We are writing to express concern about the recent paper by Song et al. 1, which was published in a recent issue of the European Respiratory Journal. We read the paper with great interest, as it would constitute the first report of human nanoparticle-related disease and death. The title attracted our attention, as well as that of the international media: “Exposure to nanoparticles is related to pleural effusion, pulmonary fibrosis and granuloma.” Note the use of the word “is.” The title appears to state a fact. We object.
We write as individuals committed to the science of nanotoxicology. It is known that nanomaterials have unusual physical and chemical properties 2 and that these unusual characteristics, combined with the ever expanding use of nanomaterials, deserve careful investigation 3, 4. It is not the time for complacency. Serious methodical investigations of potential toxicity from nanoparticles and nanofibers are clearly warranted. We believe wholeheartedly in the cautionary principle and in providing the best possible data to protect workers and consumers.
This paper, however, draws premature conclusions and does not add objective evidence permitting us to evaluate the possibility of adverse health effects of nanoparticles in humans 1. We do not agree with the implied conclusion that it was nanoparticles which caused the pulmonary problems and the deaths of two workers. The study by Song et al. 1 clearly describes a primitive workplace characterised by a total lack of even the most rudimentary precautions. In the face of dangerous activities, including air spraying and curing polymers with heat, exposure controls were absent. Song et al. 1 state, “It is estimated that the air flow or turn over rates of indoor air would be very slow, or quiescent due to the lack of windows and the closed door”.
Moreover, adequate exposure assessment is utterly lacking. We are especially concerned about a variety of hazards in this workplace. Yes, there is some evidence for the existence of nanoparticles, but the list of chemicals and dusts to which these workers were exposed is extensive. Many chemicals were used in this space where ventilation was inadequate or even absent. During spraying and related procedures, indoor concentrations of a variety of toxic materials were probably very high. All seven females who worked there for 5–13 months had a variety of symptoms; there is convincing evidence of that. The title of this article should have read, “Poor working conditions cause pleural effusion, pulmonary fibrosis and granuloma”. It would have been appropriate if the presence of nanoparticles had been mentioned, and even speculations made that they may have contributed to the resulting pathology. But the current message that nanoparticle exposure is primarily responsible is not warranted. Song et al. 1 fail to provide any information about other respirable toxic agents which were inhaled both as solid aerosols and in the gas phase. Hence, the conclusion that nanoparticles are causally related to these pulmonary diseases is much too premature and scientifically not acceptable.
The outcome is certainly tragic and deserves the attention of the public and the international community of chest physicians, pneumologists and lung biologists. But this study primarily emphasises the importance of implementing appropriate industrial hygiene practices. It fails to provide evidence about unusual risks posed by nanoparticles. We simply do not know to what extent exposures to nanoparticles in this workplace contributed to the evident pulmonary pathology and to the documented unfortunate consequences.
We encourage careful studies of nanotoxicology, both in the laboratory and in the workplace. But we ask that excellent journals, such as the European Respiratory Journal, critically review papers like this. Eliciting concerns through provocative but unfounded titles and conclusions which are not justified by the data does not enhance the reputation of the European Respiratory Journal, its reviewers or its editors.
Statement of interest
A statement of interest for P. Gehr can be found at www.erj.ersjournals.commisc/statements.dtl
- © ERS Journals Ltd
