On March 31, 2026, Japan's Ministry of Health, Labour and Welfare (MHLW) issued a notification (MHLW Notification No. 173 of 2026) amending the "List of Substances Requiring Indicated Measures" under the Industrial Safety and Health Act (ISHA), adding 40 substances to the roster of designated carcinogenic chemicals. The additions become applicable on April 1, 2028, giving employers about two years to put the required worker-protection measures in place for any of the substances they handle.
The carcinogenic substances list, set under MHLW's occupational health rules, flags chemicals for which employers must go beyond basic labeling and safety data sheets to actively cut worker exposure. For each designated carcinogen, employers must apply the "indicated measures", engineering controls, safe work practices and protective equipment to reduce exposure, and arrange the medical examinations the ISHA requires for workers handling them.
The addition is the latest step in MHLW's rolling tightening of workplace chemical management, which has steadily widened both the hazard-communication scope and the set of substances demanding hands-on exposure control. Many of the 40 newcomers were surfaced through the government's GHS-based hazard assessment work, which screens chemicals for carcinogenicity and other chronic health effects before they reach the regulated list.
Because the obligations bite on April 1, 2028, manufacturers, importers and downstream users in sectors from chemicals and metals to construction and electronics should use the lead time to check whether any of the 40 substances appear in their processes, set up the engineering and protective measures the ISHA prescribes, and arrange the worker medical exams. Companies already managing designated carcinogens should fold the new entries into their existing programmes, so that full compliance is in place well before the date arrives.
