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The graphene family of nanomaterials (GFNs) is at the forefront of technological innovation, offering promise in fields as diverse as semiconductors, energy storage, composites, sensors, functional inks, polymer additives, tires, coatings, and much more. However, with great innovation comes responsibility, especially in managing potential workplace risks associated with its production and application.

Despite the growing use of GFNs, no international authoritative organizations have established occupational exposure limits (OELs) to ensure safe workplace handling. Several independent researchers have proposed exposure guidelines, including a recommended limit of 18 µg/m³ and 212 µg/m³. However, these values lack consensus and formal regulatory backing.

In this context, occupational and environmental health and safety (OEHS) professionals face challenges in managing graphene exposure risks within their workplaces. To address similar challenges for other exposures, NIOSH developed the Occupational Exposure Banding Process for Chemical Risk Management. This framework categorizes substances into health-protective bands based on available toxicological data and provides a structured approach to assess exposure risks in the absence of OELs.

A recently published article in the Journal of Occupational and Environmental Hygiene (JOEH) demonstrated the feasibility of using the NIOSH banding process to derive an occupational exposure band (OEB) for GFNs. This case study can be a resource for OEHS professionals to guide risk management and exposure control decisions for GFNs in the absence of formal OELs.

Study

The NIOSH OEB framework consists of three tiers, each reflecting varying levels of data availability and user expertise. In this case study, Tier 1 and 2 assessments were first attempted. However, the absence of Globally Harmonized System (GHS) H-codes/statements for GFNs made Tier 1 analysis infeasible, and we had insufficient data from authoritative sources to support banding in a Tier 2 assessment. Consequently, a Tier 3 assessment was applied, which relies on a comprehensive evaluation of health effects. A literature review provided dose-response data from animal studies, including qualitative and quantitative findings across nine different toxicological health endpoints.

For each endpoint, GFN potency estimates were determined, and endpoints were assigned to OEBs ranging from “A” (highest concentration range) to “E” (lowest concentration range). Band assignments were independently replicated by three toxicology and industrial hygiene experts to ensure reliability. The final OEB was selected based on majority agreement.

Findings

A literature search identified 56 in vivo (in living animal) GFN toxicological studies. The JOEH authors assessed these articles for OEB framework eligibility. Twenty-four articles were eligible and used to derive an OEB in this Tier 3 assessment.

The overall OEB for GFNs was “E,” representing an exposure air concentration of 10 µg/m³ or less. This means that GFNs could potentially pose health effects at relatively low concentrations. The OEB developed in this case study was similar to the recommended limit of 18 µg/m³ published in Toxicology Research by Lee et al. but lower than the 212 µg/m³ limit published in the International Journal of Hygiene and Environmental Health by Spinazzè et al.

Some OEB estimates were lower than the current NIOSH band “E”. This may suggest the need for a risk manager to consider limiting exposures to a level lower than the “E” band based on the effect levels presented in the data.

Conclusions

This case study demonstrates the feasibility of using the NIOSH OEB framework as an interim measure for mitigating GFN exposure risks in the absence of an OEL. The OEB can be used, in combination with exposure assessment data, to inform workplace risk management decisions and may provide a reasonable initial estimate for recommended workplace exposure and control measures. However, this derived band is voluntary and only serves as a consideration for OEHS professionals until a traditional and more thorough risk assessment is performed by an authoritative public health agency to develop an OEL.

Resources

International Journal of Hygiene and Environmental Health: “Probabilistic Approach for the Risk Assessment of Nanomaterials: A Case Study for Graphene Nanoplatelets” (January 2019).

Journal of Applied Toxicology: “Pulmonary Persistence of Graphene Nanoplatelets May Disturb Physiological and Immunological Homeostasis” (March 2017).

Journal of Occupational and Environmental Hygiene: “Application of the Tier 3 NIOSH Occupational Exposure Banding Process for the Graphene Family of Nanomaterials: A Case Study” (January 2025).

Toxicology Research: “Derivation of Occupational Exposure Limits for Multi-Walled Carbon Nanotubes and Graphene Using Subchronic Inhalation Toxicity Data and a Multi-Path Particle Dosimetry Model” (May 2019).