The Organization for Economic Cooperation and Development (OECD) has published the latest edition of the Developments in Delegations on the Safety of Manufactured Nanomaterials and Advanced Materials — Tour de Table. The Tour de Table compiles information provided by delegations on the occasion of the 23rd meeting of the OECD Working Party on Manufactured Nanomaterials (WPMN) in June 2023. The Tour de Table lists U.S. developments on the human health and environmental safety of nanomaterials. Risk assessment decisions, including the type of nanomaterials assessed, testing recommended, and outcomes of the assessment include:

• The U.S. Environmental Protection Agency (EPA) completed review of four low volume exemptions (LVE) that included a graphene material, a titanium dioxide material, and two graphene oxide materials, one of which was a modification to an existing exemption. EPA denied two of the LVEs and granted two under conditions that limited human and environmental exposures to prevent unreasonable risks.
• According to the Tour de Table, EPA has under review 17 premanufacture notices (PMN), 16 of which are for multi-walled carbon nanotube chemical substances and one of which is for a graphene material. The Tour de Table states that EPA is still reviewing these 17 chemical substances for potential risks to human health and the environment. EPA completed its review of one significant new use notice (SNUN) for a single-walled carbon nanotube, regulating it with a consent order due to limited available data on nanomaterials. The consent order limits uses and human and environmental exposures to prevent unreasonable risks.

The Tour de Table includes the following information regarding risk management approaches in the United States:

• Between June 2022 and June 2023, EPA received notification of two nanoscale substances based on metal oxides that met reporting criteria pursuant to its authority under the Toxic Substances Control Act (TSCA) Section 8(a), bringing the total number of notifications to 87. Reporting criteria exempted nanoscale chemical substances already reported as new chemicals under TSCA and those nanoscale chemical substances that did not have unique or novel properties. According to the Tour de Table, most reporting was for metals or metal oxides.
• Since January 2005, EPA has received and reviewed more than 275 new chemical notices for nanoscale materials under TSCA, including fullerenes and carbon nano-onions, quantum dots, semiconducting nanoparticles, and carbon nanotubes. EPA has issued consent orders and significant new use rules (SNUR) permitting manufacture under limited conditions. A manufacturer or processor wishing to engage in a designated significant new use identified in a SNUR must submit a SNUN to EPA at least 90 days before engaging in the new use. The Tour de Table notes that because of confidential business information (CBI) claims by submitters, EPA may not be allowed to reveal to the public the chemical substance as a nanoscale material in every new chemical SNUR it issues for nanoscale materials. EPA will continue to issue SNURs and consent orders for new chemical nanoscale materials in the coming year.
• Because of limited data to assess nanomaterials, the consent orders and SNURS contain requirements to limit exposure to workers through the use of personal protective equipment (PPE), limit environmental exposure by not allowing releases to surface waters or direct releases to air, and limit the specific applications/uses to those described in the new chemical notification.

Regarding updates, including proposals, or modifications to previous regulatory decisions, the Tour de Table states that “[t]he approaches used, given the level of available information, are consistent with previous regulatory decisions. EPA’s assessments now assume that the environmental hazard of a nanomaterial is unknown unless acceptable hazard data is submitted with nanomaterial submission.”

The Tour de Table lists the following new regulatory challenge(s) with respect to any action for nanomaterials:

• Standards/methods for differentiating between different forms of the same chemical substance that is a nanomaterial;
• Standardized testing for the physical properties that could be used to characterize/identify nanomaterials; and
• Differentiation between genuinely new nanoscale materials introduced in commerce and existing products that have been in commerce for decades or centuries.