National Institute of Occupational Safety and Health

BackgroundOccupational low back pain (LBP) has increased in Japanese social welfare facilities and hospitals. Understanding its occurrence is the first step in addressing this issue.AimThis study investigated the caregiving activities that cause occupational LBP incidents in these contexts.MethodsThe study analyzed 2,722 incidents of occupational LBP among staff in social welfare facilities and hospitals resulting in four or more days absent from work. Data were extracted from accident occurrences and causes in the 2018–2019 Reports of Worker Casualties. The caregiving situations related to the occupational LBP incidents at each facility were then analyzed.ResultsApproximately half of the occupational LBP incidents surveyed occurred during transfer assistance. This assistance was mainly associated with eating, bathing, and toileting in both facilities and frequently occurred during patient transfers between a bed and a wheelchair. In social welfare facilities, nontransfer assistance also contributed significantly, which included bathing, toileting, childcare, diaper changing, lying, standing, sitting, walking, and car transportation. In hospitals, nontransfer assistance such as providing support for lying, diaper changing, medical care, and sitting were occupational LBP risk factors. Furthermore, most incidents of occupational LBP occurred among staff who worked alone during day shifts.ConclusionCaregiving activities involving transfer assistance, such as bathing, toileting, and eating, were common risk factors in social welfare facilities and hospitals. However, the specific nontransfer assistance activities contributing to occupational LBP varied by facility. To effectively reduce the incidence of occupational LBP, prevention strategies should focus on these high-risk activities according to facility type and the types of caregiving required.

Historically, the toxicological evaluation of poorly soluble low toxicity particles (PSLTs), such as titanium dioxide nanoparticles (TiO2 NPs), distinct from conventional pigment-grade TiO2, has focused on carcinogenicity and lung overload, leaving their pathological function in the development of pneumoconiosis undefined. In this study, we initiated a "Pneumoconiosis Renaissance", redefining the human "Gold Standard" of pneumoconiosis pathology as a primarily interstitial "Dust Macule (DM) to Mixed Dust Fibrosis (MDF) axis". In contrast, rats developed a species-specific "Airspace-Dominant Phenotype" (Pulmonary Dust Foci) driven by airspace stagnation. Integrating recent continuous inhalation exposure and recovery after inhalation exposure studies, we demonstrate that this overwhelming alveolar pathology in rats acts as a "Biological Mask", physically superimposing upon and obscuring human-relevant interstitial sequestration. Crucially, however, extended recovery periods can unmask these interstitial events, revealing the true underlying pathology. We propose that future risk assessments and Adverse Outcome Pathways (AOPs) must incorporate spatial resolution. By rigorously segregating sensitive rat-specific airspace events from human-relevant interstitial remodeling, we can accurately bridge the interspecies gap. This review argues that rather than discarding the rat model, we must learn to decode it-using spatial distinctions to filter the airspace mask and evaluate the true interstitial risk of inhaled biodurable particles.

This study examined whether or not the coexistence of smoking and metabolic syndrome synergistically increases the risk of cardiovascular disease (CVD) beyond their individual effects. This prospective cohort study included 68,743 workers from the Japan Epidemiology Collaboration on Occupational Health Study. The participants were categorized into four groups based on their smoking status and metabolic syndrome. Biological interactions were evaluated using relative excess risk due to interaction (RERI), attributable proportion (AP), and synergy index (S). During a mean follow-up of 7.2 (range: 0.1-10.9) years, 346 participants developed CVD. Current smokers with metabolic syndrome had the highest CVD risk (hazard ratio: 6.45, 95% confidence interval [CI]: 4.73-8.80). Approximately 35% of CVD cases among individuals exposed to both factors were attributed to their biological interactions (RERI: 2.27, 95% CI: 0.56-3.98; AP: 0.35, 95% CI: 0.15-0.55; S: 1.71, 95% CI: 1.16-2.52). An analysis of CVD subtypes revealed a significant biological interaction for myocardial infarction (RERI: 5.14, 95% CI: 0.65-9.62; AP: 0.52, 95% CI: 0.26-0.78; S: 2.38, 95% CI: 1.22-4.62) but not for stroke (RERI: 1.34, 95% CI: -0.46-3.13; AP: 0.25, 95% CI: -0.03-0.53; S: 1.44, 95% CI: 0.89-2.34). Smoking and metabolic syndrome interact synergistically to elevate CVD risk, particularly for myocardial infarction. Targeting both factors is essential for CVD prevention.

多くの労働災害防止啓発資料が転倒リスクの軽視を前提として作成されている一方，労働者が労働災害，ことに転倒のリスクについてどのように認識しているかのデータは乏しい．そこで我々は，小売業の労働者324名を対象にオンライン労働災害意識調査を実施し，労働災害で休業・死亡するリスクがどのように認識されているかを検証した．質問紙では参加者の属性を尋ねたほか，転倒を含む労働災害5型（「転倒」・「交通事故（道路）」・「切れ，こすれ」・「転落，墜落」・「動作の反動，無理な動作」）について休業や死亡に至る可能性の見積もりを求めた．統計解析の結果，転倒の可能性評価値は他の労働災害のそれと有意に異ならず，また，転倒に限らず5種すべてについて3割程度の参加者は休業・死亡可能性をゼロと回答していた．一方，可能性評価値と実頻度とを標準化し比較したところ，転倒による休業可能性が実頻度に比べ特に過小評価されていた．参加者の属性との関連については，年齢が高いほど転倒による休業・死亡可能性評価値が高くなる傾向がみられた．この研究が示唆するのは，啓発資料の訴求力を上げるには転倒で休業する実頻度が予想より高いと伝えることが重要ということである．ただし，この調査は小売業労働者の労働災害意識に限られた内容であり，今後，第三次産業の他分野への展開や，可能性評価が低いと不安全行動を選びやすいかの検討が求められる．

Abstract Background Previous research has linked job demands and resources to safety behavior. While most studies focus on habitual safety behaviors, responses under dynamic conditions remain less explored. We focus on the influence of workplace factors (job demands, job resources, and management commitment to safety) on employees’ safety behaviors to prevent slip and fall incidents. Slip and fall incidents represent major occupational hazards, with retail workers experiencing higher accident rates than the general workforce does. Methods We recruited 146 supermarket employees in Japan through an online survey panel. The survey comprisesthree parts: demographics, workplace factors, and scenario-based items. Workplace factors included work overload, job control, interpersonal support, and fall prevention measures. The scenario-based items presented six situations where workers could reduce time or social pressures by violating safety rules, and participants rated their intentions, perceived benefits, and perceived risks of safety violations on visual analog scales. Path analysis was conducted using R. Results After exclusions, 118 supermarket employees (mean age = 51 years) were analyzed. Path analysis indicated that a lack of job control increased perceived time-saving benefits and that work overload increased fall risk recognition. Conversely, a greater variety of workplace prevention measures reduced both perceived stress-reduction and time-saving benefits. Perceived time-saving and stress-reduction benefits were positively associated with the intention to violate safety rules, whereas fall risk recognition was negatively associated. Indirect effects were also observed: prevention measures reduced the intention to violate rules via lowered perceived benefits, and lack of job control marginally increased intentions through stress-reduction benefits. Conclusions This study explored supermarket employees’ intentions to violate safety rules, considering job demands, resources, and perceived benefits and risks. Perceived time-saving benefits had the strongest influence on employees’ intentions to violate safety rules, reflecting the role of acute time pressure. In contrast, work overload increasesfall risk recognition. The variety of fall prevention measures indirectly reduced violation intentions by lowering perceived benefits, suggesting that management’s commitment to safety shapes a culture where rule violations are seen as less advantageous. Overall, perceptions of workplace safety mediate the link between conditions and behaviors.

To clarify the pollution characteristics of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) in the East Asian monsoon region under different atmospheric environments and to assess their potential influences on receptor areas, this study selected two background monitoring stations with different environments in Shimane Prefecture, Japan: a marine station (MB) and a forest station (SF). PM2.5 samples were simultaneously collected using a high-volume sampler during the summer and winter of 2022–2023, and ten PAHs and three NPAHs were quantified using HPLC. The concentrations of PAHs and NPAHs at MB and SF exhibited significant seasonal variations in 2022 (winter > summer). However, in 2023, a clear seasonal difference was observed only at MB. Isomer ratio analysis of PAHs at both stations indicated that traffic emissions and biomass or coal combustion were major contributors. Seasonal variations in the [2-NFR]/[1-NP] ratio indicated that, while high ratios at MB and SF during summer were mainly associated with local photochemical formation, low ratios in winter reflected long-range transportation of combustion-derived PAHs and NPAHs from the Asian continent. Incremental lifetime cancer risk values (10−7 to 10−11) indicated that even at background stations, the atmospheric environment poses certain health risks. This first comparative investigation of PAHs and NPAHs at two distinct background stations in Shimane again highlights the importance of international cooperation among East Asian countries for effective air pollution control.

BackgroundDNA polymerase κ (Polk), a member of Y-family DNA polymerases, plays an important role in translesion DNA synthesis (TLS), allowing DNA replication forks to bypass DNA damage or DNA adducts to continue daughter strand synthesis. Polk is also believed to contribute to the replication-independent repair of DNA lesions such as cross-links. TLS circumvents stalls of DNA replication and promotes gap filling in DNA repair which would otherwise result in DNA double-strand breaks (DSBs) and cell death. Mitomycin C (MMC) is a widely used chemotherapeutic drug which generates DNA cross-links and induces DSBs. To clarify how Polk contributes to the prevention of MMC-induced DSB in various organs or tissues, immunohistochemical staining of γH2AX was conducted in catalytically inactivated Polk knock-in (Polk KI) mice and Polk wild-type (Polk+) mice treated with MMC or saline.ResultsThe γH2AX induction by MMC was enhanced by inactivation of Polk across many organs or tissues to varying degrees. Obvious enhancement was observed in liver, bladder, adrenal cortex, thyroid, and spermatids, whereas less enhancement was shown in brain and retina. The results suggest that Polk plays a role in preventing DSBs caused by MMC in most organs or tissues. Elevated DSB frequencies were observed in both proliferative cells, such as bladder epithelium cells, and less or slowly proliferative cells, such as hepatocytes. Increased DSB levels in inactivated Polk KI mice relative to Polk+ mice were also observed in saline-treated mice in the adrenal cortex and other tissues.ConclusionPolk plays a systemic role in mitigating MMC-induced DSBs, likely through both DNA replication-dependent and -independent mechanisms. Furthermore, Polk appears to protect against DSBs caused by endogenous mutagens in some organs such as the adrenal cortex, prostate, and retina.Supplementary InformationThe online version contains supplementary material available at 10.1186/s41021-025-00343-x.