Strengthening One-Stop Support System for Chemical Substances Control Law Testing and Applications

[Summary]

Toray Research Center, Inc. (Location: 1-7-2 Nihonbashi-Honcho, Chuo-ku, Tokyo; President: Yoshiki Makabe, hereinafter "TRC") and Toray Techno Co., Ltd. (Location: 1-1-1 Sonoyama, Otsu-shi, Shiga; President: Tsuneyuki Yamane, hereinafter "TTK") have strengthened their one-stop support system, which provides comprehensive services from the design of testing schemes required for new chemical substance applications to test execution and application consulting. This enhancement is in response to the revisions of the Chemical Substances Control Law (CSCL) (Note 1) notifications scheduled for after 2025, achieved through the expansion of specialized personnel and the advancement of know-how to adapt to regulatory changes. This will enable the proposal of optimal testing plans and schedules that comply with regulations, contributing to the reduction of customer application risks, acceleration of product launches, and alleviation of internal workload.

[Background]

When manufacturing or importing new chemical substances, it is necessary to undergo a prior review of their hazardous properties from the perspective of preventing harm to human health via the environment, based on the CSCL. For low molecular weight compounds, multiple tests are required, including biodegradability, bioaccumulation, ecotoxicity, and genotoxicity. For high molecular weight compounds, however, the polymer flow scheme test is applied as a relatively simple evaluation method, considering their low permeability through biological membranes. This test evaluates stability, solubility, and the content of low molecular weight components to determine the environmental impact of the chemical substance. With the regulatory revisions after 2025, the scope of application for utilizing existing data and omitting tests is expanding, further increasing the importance of designing appropriate testing schemes and application strategies.

[Support Details and System Enhancement Points by TRC and TTK (hereinafter "TRC/TTK")]

In the polymer flow scheme test, it is crucial not only to conduct the test but also to design an optimal testing scheme by predicting solubility and biodegradability in advance based on the chemical structure and composition ratio of the substance to be tested. This process requires advanced judgment that integrates the interpretation of regulations and chemical knowledge, and the setting of test conditions and decisions on feasibility significantly impact the application results.

Since the establishment of this test in 1987, TRC/TTK has a track record of conducting tests and providing application support for a wide range of materials, including organic solvent-soluble polymers, water-soluble polymers, solvent-insoluble polymers, and polymers degradable by acids and alkalis. Based on this experience, they provide integrated support for designing testing schemes tailored to the characteristics of the target substance, formulating application strategies, and optimizing schedules. In particular, the decision-making process in the polymer flow scheme test involves branching based on solubility, as shown in Figure 1, making design capability, including prior prediction, essential.

Figure 1: Composition and decision flow of the polymer flow scheme test. In the polymer flow scheme test, continuous branching decisions based on physical property evaluation are involved, making prior prediction based on chemical structure and appropriate scheme design crucial.

This system enhancement is in response to the revisions of the operational notification (Note 2) in 2025 and the existing data notification (Note 3) in 2026, which have expanded the options for test omission and evaluation methods. TRC/TTK has increased the number of specialized technicians well-versed in the CSCL and related regulations, and has systematized test design and application know-how to align with regulatory changes. This further strengthens their ability to provide integrated services from the formulation of testing schemes to application consulting, enabling more efficient and accurate support compared to previous individually tailored services.

[Future Developments]

Regulations concerning chemical substances are diverse, extending beyond the CSCL, and ongoing revisions and operational reviews are expected to continue.

Based on the strengthened one-stop support system, TRC/TTK will not only provide application support but also promote the dissemination of the latest regulatory trends through in-house seminars and offer consulting services from the early stages of development, thereby contributing to the smooth product development and social implementation for their customers.

[Glossary]

Note 1) CSCL (Chemical Substances Control Law)

A law enacted in 1973 with the aim of regulating the manufacture, import, and use of chemical substances that may harm human health via the environment, triggered by environmental pollution and damage caused by PCBs (polychlorinated biphenyls). When manufacturing or importing new chemical substances, it is mandatory to apply to the government in advance and undergo screening for human toxicity and other factors.

Note 2) Operational Notification (Revised October 6, 2025; Effective April 1, 2026)

Guidelines indicating specific operational methods and judgment criteria for the CSCL. The main revisions in this amendment are as follows:

1 Clarification of the definition of existing chemical substances, etc.

The criteria for determining which substances are treated as "existing chemical substances, etc." have been organized.

2 Revision of rules regarding content ratios (so-called 99%, 98%, 90% rules)

The criteria for the treatment of monomers incorporated into the skeleton of main components that are existing chemical substances, etc., have been revised, allowing for more flexible application of application categories under certain conditions.

3 Expansion of the handling of salts of organic compounds

The scope of substances that can be treated as existing substances has been expanded for some metal salts (sodium, potassium, calcium, magnesium, etc.).

These revisions enable more rational and efficient handling in determining the classification of chemical substances and the necessity of application.

Note 3) Existing Data Notification (Revised April 24, 2026; Effective June 1, 2026)

Rules that define how already known properties and data of chemical substances (existing data) can be utilized during application. The following points have been expanded in this revision:

1 Expansion of test omission for polymers with specific structures

If the structure of the main chain or side chains meets certain conditions, a portion of the polymer flow scheme test, which was previously required, can now be omitted.

2 Simplification of evaluation based on polymer physical property conditions

If conditions such as low solubility in water or organic solvents, or very large molecular weight (e.g., number-average molecular weight of 100,000 or more) are met, some tests can be omitted based on the knowledge that such polymers are stable.

This allows for efficient evaluation utilizing existing data, and is expected to reduce the burden and shorten the time required for application tests.

For details, please refer to "Guidance on Notification Related to 'Polymer Flow Scheme Based on Structure and Property Evaluation' Version 1.0," published on April 24, 2026.