Spray electrification, the electrostatic charging of liquids during ejection from nozzles, is known to depend strongly on the liquid type and nozzle material. The author previously proposed a simplified method to evaluate the hazard of spray electrification for various liquid-material combinations. This method has proven to be useful for reproducing spray electrification and assessing associated hazards. However, the experimental conditions used in those studies were provisional and not necessarily optimal. In particular, ambient humidity during measurement may significantly affect the amount of charge generated and could potentially lead to misjudgment of electrostatic hazards. This study examines the effect of relative humidity on charge generation for eight liquids (kerosene, mineral spirits, butyl acetate, ethyl acetate, methyl acetate, acetone, ethanol, and tap water) and four materials (SUS304, PTFE, MC nylon, alumina). In most cases, higher humidity significantly reduced the charge amount. However, some combinations showed increased charging at higher humidity. These results indicate that humidity has a substantial impact on spray electrification and must be carefully considered in hazard assessments using the proposed method.

In occupational health studies, it is important to understand the toxic effects of industrial chemical exposure. In addition to comprehending these toxic effects on humans through disaster surveys, experimental data obtained from animal studies are indispensable not only for establishing the existence of adverse effects but also for clarifying their toxicological mechanisms. As we encounter a wide variety of chemicals in our daily lives, including industrial chemicals, pharmaceuticals, agricultural chemicals, and food additives. Thus, it is necessary to assess the toxicity of several chemicals, including the re-evaluation of existing chemical substances and the evaluation of new chemical substances. Consequently, it is imperative to establish appropriate animal models with various advantages, such as high reconstructability, reproducibility, sensitivity, and throughput, while also considering cost, time, labor, animal welfare, and extrapolation to humans. This article describes the effective usage and perspectives of rodents (mice and rats) and nematodes (i.e., Caenorhabditis elegans) as animal models that are currently used by the authors for toxicity studies in the occupational health field.

This study aimed to clarify the status of chemical substance management efforts in accordance with the revision of the Industrial Safety and Health Act at workplaces in Wakayama Prefecture.

Anonymous questionnaires were mailed to 781 workplaces identified as handling chemical substances.

Questionnaires were collected from 191 workplaces, and 155 workplaces that handled chemical substances were analyzed (valid response rate: 19.8%). Only 36.1% of small workplaces (less than 50 employees) were aware of amendments to the Industrial Safety and Health Act. Small workplaces were significantly less likely than other sizes to provide safety and health education based on labeling and Safety Data Sheets, to clearly indicate the names of ingredients, or to conduct risk assessments of chemical substances. Workplaces that implement special health examinations, workplaces that take follow-up measures based on these results, workplaces that provide safety and health education at the time of employment, and workplaces that plan to appoint chemical substance management officers and protective equipment management officers were significantly less.

In small workplaces, it is necessary to support the creation of systems for communicating information regarding chemical substances, to encourage the implementation of special health examinations, and to establish safety and health education system.

Among accidents resulting in death, injury, or disease in the workplace that results in absence of four days or more, approximately 800 per year are caused by hazardous substances. Of these there were nearly 400 cases of fatal and injury accidents caused by hazardous substances per year from 2020 to 2022, and more than 80% of these were accidents caused by burns. In this paper, to clarify the actual situation of workplace injuries or diseases by hazardous substances resulting in absence from work for less than four days, investigation of the data at three Labor Standards Inspection Offices were done, and the comparison of workplace accidents of hazardous substances resulting in absence from work for four days or more and for less than four days was made. In addition, the comparison of the estimated number of workers resulting in absence from work for less than four days with the number of workers compensated for occupational injuries or diseases (assumed to be total number of occupational accidents and diseases), suggesting that there may be a considerable number of accidents that do not result in absence from work and that reports of worker casualties involving less than for four days of absence may not be submitted properly.

The Ministry of Health, Labor and Welfare releases public data on occupational accidents. However, there are still problems in utilizing this data, such as replacing incorrectly entered data and processing columns that contain different values for each year, which are necessary when tabulating data across multiple years. In this report, we processed the data for each fiscal year and combined them into a single file so that consistency is maintained even after such aggregation. In addition, a web application that enables easy search, tabulation, and visualization of the combined files was created and made publicly available (https://factory-health.shinyapps.io/sibou-saigai/). Further, a script file describing the data processing procedures in a programming language was made publicly available to enable the addition of files for new fiscal years and the validation of data (https://github.com/ironwest/sibou-saigai). The use of the script files and application created in this research is expected to reduce the effort required for research and surveys on fatalities and the collection of information in practice, as it enables the creation and processing of data with guaranteed reproducibility and the retrieval and compilation of fatal injury data without the need for particular skills.