EPA allowed the TSCA Nanoscale Materials Reporting rule, 82. Fed Reg. 3641 (Jan. 17, 2017), to go into effect on Monday August 14, 2017. This followed a 90-day deferral of the effective date to allow EPA to complete reporting implementation guidance. EPA simultaneously issued a revised reporting guidance document.

For companies that have manufactured, imported or processed the subset of nanoscale materials covered by the rule at any time between August 14, 2014 and August 14, 2017, their reports for those substances are due to EPA no later than August 14, 2018. Companies that commence manufacturing, importing or processing after August 14, 2017 must submit their reports for those substances either 135 days before commencing manufacture, import or processing, or, if they have formed the intent less than 135 days before such commencement, then within 30 days after forming the intent to manufacture, import or process reportable nanoscale materials. EPA estimates each report will require 175 man hours to complete. Between the lead time for reporting and the effort required to prepare and submit a report, the reporting rule has the potential to dissuade new users and applications. However, EPA has signaled willingness to consider revised reporting procedures that may reduce this burden.

Not all nanoscale materials are reportable. Reporting is required only for materials that are solid at 25 °C, processed in a form where any particles, including aggregates and agglomerates, are in the size range of 1-100 nm in at least one dimension, and, importantly, that are intentionally manufactured or processed to exhibit "unique and novel," size-related properties. These criteria and other reporting criteria and exemptions raised many practical reporting questions as applied to particular circumstances.

The revised guidance issued August 14 addresses a number of issues raised in the comments, including clarification that particle size and continuously scaling properties, such as surface area and reactivity, are not "unique and novel" properties; applicability to nanoscale materials dispersed in liquids and matrices; joint and consolidated reporting; the significance of different types of surface treatments and coatings on reporting; EPA's interpretation of when a company will be deemed to have formed the "intent to manufacture" or process; starting the 30-day reporting clock; and approaches to protecting otherwise reportable confidential business information of vendors and customers. However, it does not address all of the comments and use scenarios raised in the comments, and encourages case by case consultations with EPA to resolve remaining uncertainties.