Safety and Prevention

To eliminate accidents and occupational injuries, the Mitsui Chemicals Group promotes proactive safety activities based on risk assessment, in addition to identifying potential hazards before work begins. At each Works, employees identify risks inherent in their operations through safety talks^* and the sharing of near-miss incidents, and implement measures according to the priority level of each risk. We also continue to provide education and support to domestic and overseas affiliates with the aim of fostering a strong safety culture. Through these efforts, we are cultivating a workplace culture in which every employee takes proactive responsibility for ensuring safety.

In addition to the above, the following initiatives are routinely implemented.

The Mitsui Chemicals Group introduces and maintains equipment that ensures safe and stable operation.

When introducing new facilities, we not only satisfy the relevant laws and regulations, but also design them in accordance with company rules based on our experience and accumulated technology, and introduce facilities that prevent accidents such as explosions, fires, and leaks  through repeated change management based on various technical evaluations.

After an equipment is installed, we formulate maintenance plans and conduct periodic inspections and regular maintenance from the perspective of preventive maintenance.

In recent years, many of our facilities have been in operation for more than 40 years. While focusing on countermeasures against age-related deterioration, we have worked on developing appropriate maintenance plans, improving construction quality, and strengthening change management to maintain and improve the reliability and soundness of our facilities.

In the non-financial metric of VISION 2030, we define incidents resulting in losses of 100 million yen or more per case as "problems involving high-value losses" and have set the number of such occurrences as a KPI. With the goal of achieving zero incidents involving high-value losses by 2030, we are placing particular emphasis on strengthening facility management and addressing the challenges associated with aging facilities. Furthermore, by actively adopting advanced technologies that are becoming practical due to recent technological advancements, we will seek to streamline and optimize our maintenance, design, and construction operations.

In FY2025, the Mitsui Chemicals Group reported one major accidents^*1 against a target of zero. We recognize the chlorine based gas leak that occurred at the Omuta Works of Mitsui Chemicals on July 27, 2025, as a major accident. The accident is presumed to have resulted from the ingress of industrial water into a chlorine gas pipeline, generating hydrochloric acid that accelerated corrosion-induced wall thinning and ultimately caused a rupture of the pipeline. Following the accident, Mitsui Chemicals conducted a comprehensive investigation in consultation with the relevant authorities. We identified the presumed causes of the incident and implemented recurrence prevention measures, including the elimination of potential water ingress, mitigation of leaked gas dispersion, and enhancement of initial public communication. Operations were resumed only after these measures had been reviewed and validated by independent third-party experts. In addition, the number of abnormal conditions and accidents^*2 decreased from the previous year to 23, not meeting the target of 8 or fewer. There were 16 leakage incidents, six fire incidents including minor fires, and one rupture incident. Preventing the recurrence of these incidents remains a key challenge. To prevent recurrence, we are focusing on implementing countermeasures for particularly critical incidents, identified through analysis of the causes and other factors.

Example) Equipment-related: external corrosion; Process-related: human error (such as operational mistakes)

In fiscal 2025, the Mitsui Chemicals Group recorded one serious occupational injury^*1,2 that must not occur, against a target of zero.

We aim to achieve the world’s highest safety standards and have set a target frequency rate of 0.15 or lower for work-related significant occupational injuries^*3. Our current injury frequency rate remains at a high level compared to the Japanese overall industry average and the chemical industry average. However, our overseas affiliates and construction subcontractors unfortunately did not meet the target.

In light of this situation, the Mitsui Chemicals Group will continue working to foster personnel with a high sensitivity to danger and to instill a safety culture across the Group. Particular focus will be placed on preventing incidents with a high potential to result in serious injuries, such as falls from height and being caught or entangled in machinery. These include "crashing and falling" and "being caught or entangled in machinery." Regarding construction subcontractors, we will have them trained using content from the VR (virtual reality) safety training programs at our Plant Operation Technology Training Center, which is intended for them. This enables them to experience simulated hazards for the purpose of cultivating human resources who have high sensitivity to danger. Through these efforts, we will also enhance education in order to reduce occupational injuries among construction subcontractors.