Summary

Two reviews of the literature were done for the purpose of collecting as much information as possible on additive manufacturing (or 3D printing) and its implications for the workplace. More specifically, they sought to (1) identify all the techniques used in 3D printing and the associated materials, as well as the different areas of application and the professional activities concerned; (2) highlight the rates of emission of ultrafine particles (UFPs) and volatile organic compounds (VOCs) during a 3D printing process; and (3) identify the main printer use parameters that can affect UFP and VOC emissions. Although the data for the first review came mainly from the grey literature, 509 scientific publications on UFP and VOC emissions were consulted in the second review. Twenty-nine of them, published between 2013 and 2019, were retained to provide an overview of knowledge of workers’ exposure to UFPs and VOCs emitted during 3D printing processes. Particular attention will be paid to the use of this new technology in workplaces in Canada and Quebec.

Additive manufacturing is used in almost all sectors, from transportation, energy, defence and aerospace, to health care. It makes it possible to design unique parts much faster than traditional manufacturing technologies, in a single block and at a lower cost. Although the major industries have been identified, it is much harder to identify the professions, and especially the numbers of workers, affected by this new technology. Indeed, as studies of the labour market reveal, the number of workers in additive manufacturing is growing, but these figures include not only printer operators but also designers of the plans for objects to be manufactured, who do not have direct contact with the equipment. In addition, certain professions make regular or occasional use of subcontractors.

Seven major additive manufacturing technologies were identified, some of which are already widely used in workplaces, such as material extrusion and powder bed technologies, while others are less widespread or are still being fine-tuned. The current and future achievements enabled by additive manufacturing should not disguise the disadvantages they cause, such as the emission of numerous particulate and gaseous contaminants, some of which are potentially harmful to the health of workers who are frequently exposed to them. This risk is strongly increased by the wide variety of printable materials. In fact, each technology is associated with one or more types of materials such as thermoplastic or thermosetting polymers, technical ceramics, or biocompatible materials, all of which emit UFPs and VOCs with different chemical characteristics.

Although these emissions are closely related to the type of material used, the parameters of use for 3D printers also play a major role. For example, the extrusion temperature and speed must be taken into consideration in the variations in the emission rates and concentrations of UFPs and VOCs. A printer dysfunction can lead to a sharp increase in the amount of particles emitted. Although these conclusions seem to be confirmed, several other manufacturing parameters have not yet been studied. In particular, no systematic study has yet been conducted, which makes it difficult to compare the results of different studies. Finally, almost all the publications report on work conducted in the laboratory, in controlled environments, which does not reflect the UFP and VOC exposure of 3D printer users in the workplace.

The many knowledge gaps highlighted during this study should lead to the establishment of research programs designed to assess worker exposure in the workplace and propose solutions to reduce emissions at source by optimizing printer manufacturing parameters.

Before the first results are obtained, it is necessary to protect workers who use one or more of these technologies, by applying the precautionary principle. For workers who are exposed to these technologies every day, it is recommended that they wear appropriate personal protective equipment and engage in preliminary training so that workers are better prepared and their attention is drawn to the basic rules to follow. This precautionary principle is crucial because, unlike the case for VOCs, no exposure limit value is currently available for UFPs.