A research paper released today in the European Respiratory Journal documents for the first time a clinical case in which a team of medical doctors concluded that exposure to nanoparticles was determined to have resulted in harm to workers. [The link is not live but an abstract is available here.] The medical case study documents in clinical detail the cases of seven women who were hospitalized for pulmonary health problems after workplace exposure to ~30 nm nanoparticles contained in or produced by the spraying of a polyacrylic ester paste. An extensive clinical evaluation was undertaken to determine the cause of the workers’ respiratory symptoms, which included shortness of breath, buildup of fluid in the chest cavity (pleural effusion) and around the heart (pericardial effusion) and itching on the face and arms. The clinical findings included nonspecific pulmonary inflammation, pulmonary fibrosis and foreign-body granulomas in the pleura. Ultimately, two of the women died from respiratory failure and others exhibited persistent lung dysfunction 20 months after first being hospitalized. The women’s clinical symptoms are consistent with the outcomes of animal studies in which nanoparticles have been intentionally introduced into the lungs.
The evidence for implicating nanoparticles in the Chinese factory incident is persuasive. The paper contains electron microscopy images of the fluid and lung tissues extracted from the patients that clearly show round nanoparticles or nanoparticle clusters of ~30 nm. The nanoparticles were found in the chest fluid and in cytoplasm and nucleoplasm of the pulmonary epithelial cells. Yes, these were nanoparticles, and yes, some nanoparticles may be able to gain access to parts of the deep lung that are less accessible to larger particles which the body more effectively filters out. Less clear is what the nanoparticles were composed of and whether they were intentionally introduced into the paste or created as a result of the spraying or heating processes. If the latter, then they were what we call “incidental” nanoparticles rather than the intentionally designed “manufactured” nanoparticles.
The exposures, which could not be quantified, took place over the course of between 5-13 months in which the workers operated a machine that converted a polyacrylic ester paste into tiny droplets and sprayed these droplets onto large boards used in the printing and decorating industry. The boards were then heated and dried with the resulting vapor removed via a gas ventilation unit on the machine.Except the vapor wasn’t ventilated.
According to the article, the gas ventilator had broken 5 months before the onset of symptoms, which, when coupled with the lack of windows and closed door, meant that there was little air circulation and therefore no mechanism to remove the vapor from the workspace. Moreover, the only personal protective equipment available to the workers were cotton gauze masks, which would not be expected to filter out particles as small as ~30 nm. Even if the masks had been protective, they were worn only sporadically as the women appeared to have been uninformed about the possible toxicity of the materials to which they were exposed.
This almost certainly could have been avoided by the application of the “Golden Rule” of workplace safety: when you’re not sure of the hazards, do everything you can to minimize exposure. This is just the kind of industrial accident the GoodNanoGuide is intended to help prevent. For example, the page on liquid nanodispersion spraying controls describes the importance of ventilating the exhaust from the process and employing personal protective equipment as a secondary measure of protection. According to the latest research from the National Institute for Occupational Safety and Health, the 30-nm particles could have been blocked by an inexpensive, spray-paint respirator sold at your local home improvement store such as these or even these. It is possible to work safely with nanoparticles IF the hazards are recognized and the exposures limited.What a tragedy.
Here are three important take-aways from this incident.
Workplace safety is of paramount importance wherever hazards are possible. When hazards are unknown or poorly understood, steps must be taken to reduce exposure to the hazard. In this case, this means first employing engineering controls such as ventilation of fumes and then relying on personal protective equipment such as respiratory masks but only as a secondary measure of protection. Such tools exist and could have prevented this tragedy if used correctly.
More investigation is needed to establish the facts surrounding the exposures so that similar incidents can be avoided. The evidence demonstrating that nanoparticles ended up in the workers’ lungs is compelling and persuasive. What is less well established is the type of nanoparticle found in the tissues and cells, the dose received by the workers and the mechanism of injury. It is not clear, for example, whether the nanoparticles themselves caused the injury or whether the combination of nanoparticles and other chemicals in the complex mixture resulted in an antagonistic effect. Regardless of these details, this work is a significant and well-documented clinical case study.
Research on and the development of tools for communication about occupational health issues associated with nanoparticles should be accelerated. Analysis of the ICON Nano-EHS database reveals a critical gap in nanomaterial research of relevance to occupational health as compared with research on nanotechnology environmental, health and safety research in general. So while knowledge about toxicity and hazard grows, understanding how to apply this knowledge in a practical occupational setting still presents a major challenge. While this study highlights a need for fundamental worker protections, better tools are also needed to communicate about potential risk along the supply chain, including during business-to-business transactions, so that consumers of all types have the information they need to handle nanomaterial-containing or nanomaterial-producing products safely. International trade agreements may be a mechanism for better enforcement of worker protections.
For more perspectives from an international group of experts, please click on over to Andrew Maynard’s 2020science blog.