In recent years, long working hours have become a social problem, causing workers to develop cerebrovascular diseases and mental illnesses, and in some cases even taking their own lives. The government advocates the reform of the way of working and revised the labor-related laws in April 2019, and implemented a measure to prevent overwork by changing the upper limit of overtime work from the previous system of “practically no upper limit” to an upper limit of less than 100 hours per month for a single month and an average of 80 hours per month for multiple months, with penalties for exceeding the upper limit.

In this study, with the aim of verifying the validity of the government’s upper limit on overtime, we analyzed the relationship between working hours and the subjective health, using panel data on the number of working hours during which the subjective health deteriorates. As a result, it became statistically clear that the subjective health of workers deteriorates when their monthly working hours exceed 210 hours. 210 hours of monthly working hours is equivalent to 50 hours of overtime work and the upper limit of 100 hours of overtime work in a single month and an average of 80 hours per month in multiple months established in April 2019 is insufficient from the perspective of preventing health problems among workers. In addition, the number of working hours by which a worker’s subjective health deteriorates differs depending on gender, and it has become clear that the threshold for women is low. Meaningful implications were obtained in terms of the utilization of women while ensuring their health in the future.

Falls on the same level now occur in one out of four cases in occupational accidents involving four or more days off work. It is the most common occupational accident that should be prevented. Some exertions have been made to improve the working environment and educate workers about exercise. However, there are no signs of a decrease in the number of accidents involving falls. In order to reduce the risk of fall, it is necessary to focus on behaviors immediately before the occurrence of a fall, which has not been considered until now, and to clarify the influence of the behaviors on the fall risk. Therefore, in this study, we focused on the occupational accidents in 2017 involving four or more days off work of which the type was falls, and classified and analyzed the behaviors immediately before a fall occurred. The classifications were performed by age group, by industry, by cause of falls (slip, trip, miss step), and by cause of slips (wet, ice and snow). As a result, it was found that the tendency of the actions immediately before a fall occurred differed according to age, industry, cause of fall, and cause of slip.

During the first year of the accident at the Fukushima Daiichi Nuclear Power Station caused by the Great East Japan Earthquake in March 2011, a total of about 45,000 employees of Japan Atomic Energy Agency (JAEA) left their original workplaces to engage in telephone counseling, assistance of temporary return, and environmental monitoring. In particular, the staff who worked on the telephone counseling service, which directly contacted the residents, suffered from the stress associated with emotional labor. Systematic mental health care to the staff who engaged in these tasks was provided them in the Nuclear Fuel Cycle Engineering Laboratories of the JAEA. This paper considers this activity as a concrete example of "support for supporters" and discusses the mental health of the staff who provide support to the residents in a nuclear disaster.

MOCA (4,4’-methylenebis (2-chloroaniline)) , an aromatic amine, is industrially used as a curing agent for urethane resins; however, it is classified as a Group 1 compound (carcinogenic to humans) by the International Agency for Research on Cancer, and there is concern regarding its health effects on workers. The mechanism underlying MOCA-mediated carcinogenesis is thought to be related to DNA damage caused by reactive oxygen species (ROS) and DNA adducts, which are mainly generated during metabolism in the liver. 8-Oxoguanine (8-OHdG), a product of ROS-induced oxidation, occurs at high frequency and can induce G→T transversion mutations during DNA replication. However, to the best of our knowledge, no study has examined whether MOCA induces the formation of highly mutagenic 8-OHdG in experimental animals. Here, F344 rats were orally exposed to 0, 0.4, 2, 10, or 50 mg/kg/day MOCA three times a week for 2 weeks; this is expected to exert toxicity through the hepatic metabolism of MOCA. Livers obtained from these animals were examined for pathology and 8-OHdG levels. In pathological sections, vacuolar degeneration was observed with 50 mg/kg/day MOCA. Further, MOCA-induced 8-OHdG levels showed a slight increasing trend, except at 0.4 mg/kg/day. However, none of these differences were significant. Thus, 8-OHdG is unlikely the main cause of carcinogenesis.

The number of industrial accidents in social welfare facilities in 2019 had increased by 15% from that in 2017. Responding to increasing those numbers in social welfare facilities in recent years, the Ministry of Health, Labour, and Welfare (MHLW) established the 13th occupational safety & health program and has promoted various schemes to prevent industrial accidents in social welfare facilities. Using the reports about industrial accidents occurring in social welfare facilities provided by MHLW, this study investigates the trend of industrial accidents associated with awkward movement and falls. Moreover, this study categorizes the facilities providing similar services into service series uniquely defined and explores the trend of indus-trial accidents in each service series. Based on a sample survey by simple random sampling, this study ex-tracted items characterizing industrial accidents in social welfare facilities, such as age, experience term, working situation, and cause of accidents, from the industrial accident reports in 2019. As a result, this study provided the following perceptions: (1) the occurrence ratio of industrial accidents in social welfare fa-cilities was high among the older and non-expert workers; (2) industrial accidents associated with the awk-ward movement almost consisted of low back injuries and were frequently occurred by transfer tasks of the care recipient with single-person; (3) industrial accidents associated with falls were frequently occurred in which are slipping on wet surface and in tripping on obstacles; and (4) the trend in the type of occurring acci-dents, work situation, cause of accidents, etc. were varied by differing service series.

Occupational cancer has been associated with chronic exposure to cytotoxic agents (chemicals, radiation) in the workplace. In an attempt to formally link these malignancies to specific causative agents, a large number of in vitrostudies have been carried out, in which cells in culture were treated with a range of putative causative agents. However, most of these studies used only single treatments with the respective substances, and may thus be poor models of chronic exposure. Here, we describe the comparison of treating human cultured cells with either a single or repeated doses MOCA [4,4’-methylene bis(2-chloroaniline)], an aromatic amine suspected of causing occupational bladder cancer. To this end, we evaluated its cytotoxicity and its effect on cellular proliferation and on the survival signaling pathways ERK and Akt, as well as on the expression level of cytochrome P450 (CYP) that metabolically activates MOCA.

We show that the cytotoxicity induced by repetitive MOCA treatment was lower than that caused by the same dose used singly, which agrees with our finding that ERK activation by a single MOCA administration required higher drug concentrations than by repetitive treatment. This may provide chronically exposed cells with a survival advantage, which could allow them to acquire further mutations necessary for transformation to malignancy. The latter results demonstrate the potential of our assay in occupational hygiene research, given that it appears able to reveal clear differences between chronic and acute treatments in a simple in vitro setting. We are currently attempt ing to optimize the assay conditions further and search for additional biomarkers; as Akt and CYP1A1 levels varied already in the negative controls, the latter markers are unlikely to provide a reliable readout in an assay of this type.

Various engineering and administrative measures have been implemented at construction sites. However, these are not sufficient to prevent workers’ intentional risk-taking behaviors. It is necessary to quantitatively examine the factors that facilitate risk-taking behaviors or safety behaviors of workers, and to consider effective safety measures based on these factors. This study interviewed 18 experienced construction workers about their risk-taking behaviors in stepladder work to extract factors that facilitate risk-taking behaviors or safety behaviors as a preliminary study.Four categories of factors facilitating risk-taking behaviors were extracted for both experienced and novice workers: internal factors, experiential factors, situational factors, and influence of other people. However, more subcategories were identified for novice workers than for experienced workers. On the other hand, the factors facilitating safety behaviors were not characterized by work experience, and seven categories of factors were extracted: knowledge and skills related to safety and work, awareness of one's own ability and position, awareness of the effects of injuries and accidents, awareness of work, proactive involvement in work, experience and specific actions, and support and influence of other people. In future, based on these findings, we will quantitatively examine a cognitive-behavioral model focusing on workers' safety behavior and propose effective safety measures.