Environmental, Health and Safety Services

Nanomaterials Risk Level Management System

Introduction

A typical approach to evaluating worker exposure to potentially harmful nanoparticles in the workplace would be to conduct personal air monitoring in the workers breathing zone while they are handling the nanomaterials and compare the analytical results to an exposure limit as defined by the Occupational Safety and Health Administration or other regulatory agency. If the concentration exceeds any established limits, then corrective actions such as the use of engineering controls, personal protective equipment, adjustment of work practices, and/or administrative controls would be recommended to reduce the ambient concentration in the environment and the worker's exposure.

While obtaining an air sample is not the more difficult challenge to the hygienist, the appropriate index of exposure has yet to be determined. Many studies suggest that total surface area concentration may be a better exposure index than mass concentration. Particle number concentration has also been suggested as an alternative to mass concentration. Thus, there's no consensus on how to actually measure nanoparticle exposure. Not only do we not know what to measure, but, we also have very little toxicological data for determining nanomaterial-specific occupational exposure limits. Without having this critical information, it is impossible to conduct an exposure assessment that would be conclusive and well-founded.

Control Banding

Control banding is a qualitative instrument that uses categories, or "bands" of health hazards, combined with exposure potentials or scenarios to determine the desired levels of control. The concept of control banding started in the pharmaceutical industry approximately 20 years ago due to the limited availability of pharmacological and toxicological data of products being handled by laboratory workers. It was used as a simplified method to assess worker risks and implement appropriate controls.

In the Nanomaterials Risk Level Management System the control bands are based on four overall risk levels. These risk levels are determined as a function of the severity and probability scores that are assigned to the nanomaterials project based on a series of identified factors.

Severity Factors

Based on what is known about the toxicological effects of nanoparticles, the following factors are considered in determining the overall severity of Nanoscale materials:

  • The ability of nanoparticles to reach the respiratory tract
  • The ability of nanoparticles to deposit into various regions of the respiratory tract
  • The ability of nanoparticles to penetrate or be absorbed through the skin
  • The ability for the nanoparticles to elicit a biological response

Some of the physicochemical and toxicological characteristics of the Nanoscale material that may contribute to its severity are:

  • Surface chemistry
  • Particle shape
  • Particle diameter
  • Solubility
  • Carcinogenicity
  • Reproductive toxicity
  • Mutagenicity
  • Dermal toxicity
  • Toxicity of the parent material
  • Carcinogenicity of the parent material
  • Reproductive toxicity of the parent material
  • Mutagenicity of the parent material
  • Dermal hazard potential of the parent material

Probability Factors

The probability score is based on the potential for the Nanoscale material to become airborne and the likelihood of exposure by route of inhalation. The following factors were considered when determining the overall probability score:

  • The estimated amount of nanomaterial used during the task
  • Dustiness/mistiness of the task
  • Number of employees with similar exposures
  • Frequency of the operation
  • Duration of the operation

Until quantitative methods have been established to assess worker exposure risks, EHS has developed this on-line control banding nanotool as a qualitative risk assessment to control nanoparticle exposure.

If you are a Principal Investigator conducting research that involves the use of nanomaterials, you are required to answer the questions presented in the Nanomaterials Risk Level Management System so that an overall risk level can be assigned to your operation. This data entry should be conducted for each project that will use a specific nanomaterial or process.

To begin this process:

  • Log in to the Safety Management System.
  • If you have not done so previously, register your lab space within the SMS.
  • Indicate that you work with Nanomaterials, either during the lab registration process, or by editing the lab configuration on the Summary tab.
  • On the Nanomaterials tab, which should now be visible, you may now register your nanomaterials project.