Japan updates its guidance for risk assessments of PACS under the CSCL

On July 15, 2022, the Ministry of Health, Labor, and Welfare (MHLW), the Ministry of Environment (MoE), and the Ministry of Economy, Trade, and Industry (METI) announced that they have revised the guidance documents to "rationalise and expedite classifications of substances for risk assessment and management". Revised technical guidance and related documents were expected to be published in September 2022, however, to date (October) nothing has been published. 

The Japanese Chemical Substances Control Law (CSCL) defines the risk assessment for Priority Assessment Chemical Substances (PACS) as, “the assessment to determine whether there exists a risk of damage to human health or to the population and/or growth of animals and plants in the human living environment, due to environmental contamination attributable to chemical substances.”

This risk assessment enables the Minister of Health, Labor and Welfare, the Minister of Economy, Trade, and Industry and the Minister of the Environment to determine the necessity for their exercise of regulatory authority such as the “Designation as Class II Specified Chemical Substances” and the “Rescission of Designation as Priority Assessment Chemical Substances” under the Japanese Chemical Substances Control Law.

As of April 1 2022, Japan has added 4 substances and removed of another 13 from its PACS list under the country's Chemical Substances Control Law (CSCL). Currently, there is a total of 218 substances on the PACS list, according to METI.

The guidance documents in the following list have been revised. These documents were previously revised in 2019:

• The basic concept of screening assessments for PACS
• Screening assessment methods
• The basic concept of risk assessments for PACS
• The methods of risk assessment

The sections of the Technical Guidance on Risk Assessment for PACS under the CSCL listed below have also been revised: 

• Assessment criteria for the removal of substances with no risk concerns from the PACS list
• Methods for prioritizing chemicals for risk assessment
• Evaluating risk from mutagenic substances using carcinogenicity test results or existing quantitative information 
• Screening requirements for mutagenic and hazardous substances using in vivo test results

While evaluating PACS, METI gathers detailed information from the industry regarding their production and uses. Based on the collected information the ministry then performs a risk assessment (Tier 1) to decide whether to reclassify the substance, cancel its PACS designation, or prioritise it for further environmental exposure studies and a follow up risk assessment (Tier 2). In some cases, the government might also request toxicity studies of the substances before a final risk assessment.