Chemicals

Two Key Steps for Assessing Worker Nano Exposure

According to the Occupational Safety and Health Administration (OSHA), examples of workplaces that may use nanomaterials include chemical or pharmaceutical laboratories or plants, manufacturing facilities, medical offices or hospitals, and construction sites. And the list is growing. Should you be concerned about your workers’ exposure to nanomaterials? Here are some tips to help environment, health, and safety (EHS) managers assess exposure to nanomaterials in the workplace.

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The National Institute for Occupational Safety and Health (NIOSH) recently updated its Nanomaterial Exposure Assessment Technique, known as NEAT2.0. NEAT2.0 is for assessing worker and workplace exposures to engineered nanomaterials (ENM). It is a refinement of the Nanoparticle Emission Assessment Technique (NEAT1.0) that was developed in 2009. NIOSH claims that NEAT2.0 is a more robust sampling strategy that places a stronger emphasis on full workday exposures, incorporates background monitoring, and emphasizes the importance of integrated filter sampling in the worker’s personal breathing zone (PBZ) over the use of direct reading instruments (DRIs).

Note: Engineered nanomaterials are materials created by manipulation of matter at the nanoscale to produce new materials, structures, and devices. Unbound engineered nanoparticles are loose particles, particularly, that are easily dispersible in the air. They can also be in liquid suspensions that can get into the air as mists or as dried suspensions that leave unbound particles on surfaces.

Two key steps in the NEAT2.0 approach for assessing nanomaterial exposure are collecting basic workplace information and designing and implementing a sampling plan.

Collect Workplace Information

The information you need to collect to help in assessing nanomaterial exposure in your workplace falls into five basic categories.

  1. The ENMs themselves. Learn everything you can about ENMs at your facility. The data needed include the chemical composition of the ENM, its physical characteristics (e.g., size, particle size distribution, anticipated shape), coatings or binding materials, possible contaminants from processing or use, and physical state during processing or use (e.g., is it bound in a solid, in a liquid suspension, or unbound). Review your safety data sheets (SDSs) for data on the physical and chemical characteristics of the ENM and for information on its potential toxicology. Even if the information on SDSs is not specific to the ENM you are concerned with, it might instead provide data on the parent or bulk form of the material.
  2. Potential exposure. Have an estimate of the number of workers potentially exposed to the ENM along with a description of their job responsibilities. You will need to develop a complete description of all tasks associated with the process in order to identify where possible exposure could occur.
  3. Work practices. Examine all work practices in order to understand your workers’ job responsibilities, including routine versus nonroutine job tasks, and the frequencies and durations of potential exposures. Document the entire process, including tasks involved from the time the ENM enters the facility, through processing and manufacturing, and then the final product handling, packaging, shipping, and/or disposal.
  4. Sources of emissions. Identify sources of possible ENM emissions using process flow diagrams, building schematics, descriptions of the process, and standard operating procedures.
  5. Control devices. Document existing exposure control devices, such as enclosures and ventilation.

 

Design and Implement Your Sampling Plan

In order to quantify worker exposure, NEAT2.0 guidance materials suggest that you collect both task-based and full-shift area and personal breathing zone (PBZ) samples. You can use the information collected from the task-based samples to identify processes, areas, or tasks that may contribute to exposures. Collection of short-term, task-based samples helps to verify the airborne release of ENMs at specific steps in the process or during a specific task activity. To ensure that a sufficient amount of sample is collected with short-term sampling, you should use a 25-millemeter, open-face filter operated at the highest flow rate possible.

NEAT2.0 guidance suggests concurrently collecting a second open-face filter sample for analysis using an electron microscope since they are capable of much higher magnifications and have a greater resolving power than a light microscope, allowing you to see much smaller objects in finer detail—key in nanomaterial assessments.

You can use portable DRIs to identify sources of emissions and to determine what activities affect their release. Place the DRIs as close as possible to the process or task, alongside the filter-based samples, and run simultaneously throughout the sampling period. Set them in data-log mode so you can download the data and evaluate it at a later date. Document worker activities to provide some indications of the potential correlation between specific activities and increased ENM emissions.

Key Takeaways for EHS Managers

Nanomaterials are either already in your workplace, or they will likely be there soon. There are steps you can take to protect your workers from hazards associated with nanomaterials. But, it all starts with knowing what you have in the workplace and being able to assess potential exposure. What may seem exotic and extraneous now will be commonplace in the very near-future work environment.

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