The warnings about adverse human health effects from exposure to engineered nanomaterials (EN) began several years ago. It gained popular momentum with press reports in 2006 that a cleaning product called "Nano Magic" had caused respiratory problems for dozens of German consumers. Turned out "Nano Magic" had no nano.
Other reports, published in the peer-reviewed literature, sounded their own alarms, equating, for example, the effects from exposure to carbon nanotubes with the effects from asbestos exposure. However, none of these studies involved humans; they were animal and in vitro studies. In other words, problems were found in mice and cells in petri dishes, not in people.1
But a recent study out of China has changed all that—sort of.
The new study, "Exposure to nanoparticles is related to pleural effusion, pulmonary fibrosis and granuloma," was published this summer in the European Respiratory Journal.2 The authors claim that an association exists between exposure to nanoparticles, and the deaths of two female workers and the illnesses of five others, in a horribly ventilated, cramped Chinese factory. The workers were admitted to a hospital with shortness of breath and pleural effusions after exposure to a paste mixture that contained, among other components, polyacrylate nanoparticles. Pathology on the workers that died allegedly showed that nanoparticles were "lodge[d] in the cytoplasm and caryoplasm of the pulmonary epithelial and mesothelial cells, but are also located in the chest fluid."3 The authors infer that while polyacrylate has low toxicity, nano-sized particles of this compound "appear to produce the toxicities seen in the exposed workers."4
Although the authors conclude that this incident "arouse[s] concern that long-term exposure to some nanoparticles without protective measures may be related to serious damage to human lungs,"5 these concerns are woefully unsupported by the study itself, which suffers from several significant flaws. First, the composition of the nanoparticles implicated is unknown, as is the complete composition of all the other compounds to which these workers were exposed. The authors apparently had no product samples to analyze. Second, there is absolutely no data indicating how much of which chemicals (and in what chemical state) these workers were exposed to. Third, there is no mechanistic data, explaining in any coherent fashion how these engineered nanoparticles could have caused these injuries. Fourth, this study is simply a case study—a single case study, and as such cannot be used to draw causal conclusions.
But while the study's findings are not scientifically significant, and they leave more questions begged than answered, the findings will inevitably garner the attention of media outlets, scientists in the field, regulators, and, of course, the plaintiff's bar—a group always looking for the next new toxic tort. For this reason, companies working with these materials do need to pay attention and do need to continue monitoring the scientific literature and draw whatever lessons they can from these sorts of studies.
For example, although the recent Chinese factory study tells us little about the health risks of ENs, it does serve to highlight two very important components of risk mitigation that were lacking: the use of engineering controls and personal protective equipment. The shocking undercurrent of this study is just how abysmal the working conditions were for these women. The room in which they worked had one door and no windows, and the ventilation unit was broken. The door was closed during cold weather. The only personal protective equipment worn, and only occasionally, was a cotton gauze mask.6 The room itself was only 70 m2 and the women worked up to 12-hour shifts. Whatever these women were exposed to, much of it was going straight into their lungs.
The lesson? Companies making or using ENs must ensure they are employing appropriate risk-management practices—installing state-of-the-art engineering controls, mandating the use of personal protective equipment, utilizing exposure surveillance systems, keeping track of who is working with ENs, and continually reviewing all scientific studies available on their products—in the event that the next study shows a verifiable connection between nanoparticles and human health risks. And it is not just the lawyers talking.
Diane Mundt, Ph.D., an epidemiologist at Environ International Corporation, with whom the authors have worked on nanotechnology issues, agrees with this approach. Dr. Mundt concluded after review of the Chinese worker study that, "while the study on the Chinese workers does not clearly implicate nanoparticles as the cause of the workers' illnesses, the report should put nanotechnology companies on notice that the government and the scientific community are watching the research on possible health effects and toxicity of ENs very closely to determine whether exposures are hazardous. Companies must stay vigilant and proactive in ensuring that the materials they use and the products they manufacture, integrate or sell are safe for their workforce and their consumers."