Japan Japan Publishes Guidance for Polymer Flow Scheme Under CSCL New Chemical Evaluation

Japan Chemical Substances (Products) Industrial Chemicals
29 May 2026  AOKI Kenji  AOKI Kenji (EnviX, Ltd.)
Japan Publishes Guidance for Polymer Flow Scheme Under CSCL New Chemical Evaluation

On April 24, 2026, the Ministry of Health, Labour and Welfare (MHLW), the Ministry of Economy, Trade and Industry (METI), and the Ministry of the Environment (MOE) jointly released the results of the public comment on the proposed revisions to test methods related to the determination of new chemical substances under the Chemical Substances Control Law (CSCL), and promulgated the revised Notification. The new procedures under the revised Notification will take effect on June 1, 2026. In advance of this implementation, on April 24, 2026, the ministries also published the Guidance for Notification of the “Polymer Flow Scheme Based on the Evaluation of Chemical Structure and Properties” Version 1.0, which reflects the practical application of a more streamlined approach to polymer safety assessment. This Guidance serves as the implementing document for the above‑mentioned revised Notification.

 

The core of the revised Notification and the new Guidance is the introduction of a “polymer flow scheme based on chemical structure and properties,” designed to streamline the safety evaluation of polymeric substances. Previously, the CSCL required that polymers meet certain criteria based on the analysis data of properties, such as physicochemical stability and solubility. Under the revision, new evaluation criteria combining “chemical structure” and “properties” have been added. As a result, if a polymer meets certain structural or property requirements—such as having a stable backbone composed of robust bonds, containing no concerning structures in its branches or end groups (side chains and end groups), being insoluble in water or organic solvents, or having an extremely large molecular size (number‑average molecular weight of 100,000 or more)—the polymer flow scheme tests previously required may now be omitted.

 

Overview of the Polymer Flow Scheme Based on Structure and Properties

The newly introduced “polymer flow scheme based on structure and properties” allows certain polymers that meet specified requirements to forgo tests such as physicochemical stability testing and solubility testing. Instead, the evaluation can rely on information of the polymer’s structure and properties. The guidance published on April 24, 2026 outlines the following criteria for applying the new polymer flow scheme.

1. Requirements for the Main Chain

First, it must be confirmed that the polymer’s central backbone consists solely of specific stable bonds that do not readily degrade or transform in the natural environment. Examples include carbon–carbon bonds, phenylene groups, imide bonds, amide bonds, carboxylic ester bonds, urethane bonds, ether bonds (excluding acetals), and siloxane bonds.

2. Requirements for Side Chains and End Groups

If the backbone is composed exclusively of particularly stable components, the next step is to examine the polymer’s branches and end groups. If these portions do not contain certain structurally concerning chemical groups—such as salts, alkoxysilanes, acetals, acid anhydrides, amide bonds, ester bonds, or urethane bonds—the polymer flow scheme tests may be omitted. (Certain conditions apply, including limits on the content of components with a molecular weight below 1,000.)

3. Requirements for Properties (Characteristics and Size)

If the side chains contain concerning structures or if the backbone does not fully meet the required conditions, the polymer’s properties must be assessed. Specifically, if the polymer is either “insoluble in both water and organic solvents” or has a “number‑average molecular weight of 100,000 or more,” the polymer flow scheme tests may be omitted.

 

Streamlining Preparation of Notification Materials

The Guidance also outlines procedures for preparing notification documents. By entering information on the main chain, side chains, and properties into the Excel format provided by the METI, the system automatically determines whether the polymer qualifies for the flow scheme. When submitting a notification, companies convert this Excel format into a PDF and submit it.

 

EnviX Comment

Until now, the criteria for determining how to apply the polymer flow scheme under the CSCL were not always clearly defined. With the publication of this Guidance, which organizes the structural and property requirements, it is expected that notification requirements may be relaxed in cases where conducting tests or analyses is technically difficult. This is anticipated to significantly reduce the time and cost associated with the notification review process.

 

Reference URLs

Author / Responsibility

AOKI Kenji

Senior Consultant, EnviX Ltd.
General Director, E&H Consulting Co., Ltd.

Business Performance

Expertise in EHS (environment, health and safety) consulting in ASEAN region.
- Environmental regulations updating
- Chemical regulations consulting

Background

MSc in Earth Science, The University of Tokyo

AOKI Kenji