WHO Guidelines to Protect Workers from Nanomaterials

December 15, 2017 by John Howard, MD, and Vladimir Murashov, PhD

Introduction from NIOSH Director, John Howard, MD

The National Institute for Occupational Safety and Health (NIOSH) has been at the forefront of research on working safely with nanomaterials. NIOSH leads the U.S. federal government health and safety initiative for nanotechnology coordinating research and activities through the NIOSH Nanotechnology Research Center (NTRC) established in 2004. The release of World Health Organization’s Guidelines on Protecting Workers from Potential Risks of Manufactured Nanomaterials is an important step in protecting workers worldwide from the potential risks of manufactured nanomaterials (MNMs).

The World Health Assembly identified the assessment of health impacts of new technologies, work processes and products as one of the activities under the Global Plan of Action on Workers’ Health adopted in 2007, and the WHO Global Network of Collaborating Centres in Occupational Health has selected MNMs as a key focus of its activity. I would like to personally thank NIOSH’s Vladimir Murashov, Ph.D., who chaired the WHO Guidelines development process, for his tireless efforts to protect all workers from the potential risks of MNMS.

On December 12, 2017 World Health Organization (WHO) published Guidelines on Protecting Workers from Potential Risks of Manufactured Nanomaterials . Distinct from other international organizations that have been active in the safety of nanomaterials, WHO targets these guidelines for workplaces in small- and medium-size enterprises and low- and middle-income countries. The increased production of manufactured nanomaterials (MNMs) and their use in consumer and industrial products means that workers in all countries will be at the front line of exposure to these materials, placing them at increased risk for potential adverse health effects. Currently there is a lack of precise information about human exposure pathways for MNMs, their fate in the human body and their ability to induce unwanted biological effects such as generation of oxidative stress. For background on the potential risks of working with nanomaterials see the NIOSH Nanotechnology Topic Page. These guidelines, which are the result of seven years of work by experts around the world, make 11 recommendations and reach two additional conclusions covering hazard and exposure assessments and risk mitigation measures for nanomaterials in the workplace:

Assess Health Hazards of MNMs

- The Guideline Development Group recommends assigning hazard classes to all MNMs according to the Globally Harmonized System of Classification and Labelling of Chemicals for use in safety data sheets. For a limited number of MNMs this information is made available in these guidelines (strong recommendation, moderate-quality evidence).
- The Guideline Development Group recommends updating safety data sheets with MNM-specific hazard information or indicating which toxicological end-points did not have adequate testing available (strong recommendation, moderate-quality evidence).
- For the respirable fibres and granular biopersistent particles’ groups, the Guideline Development Group suggests using the available classification of MNMs for provisional classification of nanomaterials of the same group (conditional recommendation, low-quality evidence).

Assess Exposure to MNMs

- The Guideline Development Group suggests assessing workers’ exposure in workplaces with methods similar to those used for the proposed specific occupational exposure limit (OEL) value of the MNM (conditional recommendation, low-quality evidence).
- Because there are no specific regulatory OEL values for MNMs in workplaces, the Guideline Development Group suggests assessing whether workplace exposure exceeds a proposed OEL value for the MNM. A list of proposed OEL values is provided in Annex 1 of these guidelines. The chosen OEL should be at least as protective as a legally mandated OEL for the bulk form of the material (conditional recommendation, low-quality evidence).
- If specific OELs for MNMs are not available in workplaces, the Guideline Development Group suggests a stepwise approach for inhalation exposure with, first an assessment of the potential for exposure; second, conducting basic exposure assessment and third, conducting a comprehensive exposure assessment such as those proposed by the Organisation for Economic Co-operation and Development or Comité Européen de Normalisation (the European Committee for Standardization) (conditional recommendation, moderate-quality evidence). For dermal exposure assessment, there was insufficient evidence to recommend one method of dermal exposure assessment over another.

Control Exposure to MNMs

- Based on a precautionary approach, the Guideline Development Group recommends focusing control of exposure on preventing inhalation exposure with the aim of reducing it as much as possible (strong recommendation, moderate-quality evidence).
- The Guideline Development Group recommends reduction of exposures to a range of MNMs that have been consistently measured in workplaces especially during cleaning and maintenance, collecting material from reaction vessels and feeding MNMs into the production process. In the absence of toxicological information, the group recommends implementing the highest level of controls to prevent workers from any exposure. When more information is available, the group recommends taking a more tailored approach (strong recommendation, moderate-quality evidence).
- The Guideline Development Group recommends taking control measures based on the principle of hierarchy of controls, meaning that the first control measure should be to eliminate the source of exposure before implementing control measures that are more dependent on worker involvement, with personal protective equipment (PPE) being used only as a last resort. According to this principle, engineering controls should be used when there is a high level of inhalation exposure or when there is no, or very little, toxicological information available. In the absence of appropriate engineering controls, PPE should be used, especially respiratory protection, as part of a respiratory protection programme that includes fit-testing (strong recommendation, moderate-quality evidence).
- The Guideline Development Group suggests preventing dermal exposure by occupational hygiene measures such as surface cleaning, and the use of appropriate gloves (conditional recommendation, low-quality evidence).
- When assessment and measurement by a workplace safety expert is not available, the Guideline Development Group suggests using control banding for nanomaterials to select exposure control measures in the workplace. Owing to a lack of studies, the group cannot recommend one method of control banding over another (conditional recommendation, very low-quality evidence).
Health Surveillance
- The Guideline Development Group cannot make a recommendation for targeted MNM-specific health surveillance programmes over existing health surveillance programmes that are already in use owing to the lack of evidence.
Training and Involvement of Workers
- The Guideline Development Group considers training of workers and worker involvement in health and safety issues to be best practice but cannot recommend one form of training of workers over another, or one form of worker involvement over another, owing to the lack of studies available.
The recommendations and conclusions arise from results of eleven systematic reviews accompanying these guidelines. The systematic reviews followed the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) systematic review process, on which WHO relies exclusively for the development of any guidelines. Since The GRADE systematic review process was developed for medical topics, where clinical trials could be conducted, it is not suited well for other health topics such as environmental and occupational health. Thus the development of these guidelines also provided invaluable experience on adapting the GRADE systematic review process to occupational health and other non-medical topics.
This project did not have a dedicated funding, instead all of the work was done through voluntary contributions of experts and organizations: eight organizations participating in the WHO Global Network of Collaborating Centers on Occupational Health and five non-member organizations. In addition, experts from 15 countries participated in the external review.
NIOSH led the effort to develop the guidelines by chairing the Guideline Development Group, by contributing one of the eleven systematic reviews (Eastlake A, Zumwalde R, Geraci C. Can control banding be useful for the safe handling of nanomaterials? A systematic review. J Nanoparticle Res. 2016;18:169. doi: 10.1007/s11051-016-3476-0) and by participating in the external expert review.
Experience gained during the development of these guidelines contributed to the NIOSH effort to advance a systematic review process tailored for the occupational safety and health topics (for more information see NIOSH Science Blog on the systematic review for occupational safety and health questions. NIOSH plans to continue supporting this WHO effort at the guideline implementation phase, which will focus on turning these guidelines into practice.

John Howard, MD, NIOSH Director
Vladimir Murashov, Ph.D., Senior Scientist, NIOSH Office of the Director and Chair of the WHO Guidelines Development Group.