Association between relatively low blood lead levels and urinary δ-aminolevulinic acid concentrations among male workers at a Japanese battery factory.

OBJECTIVES: Whether the known positive association between blood lead (PbB) levels and urinary δ-aminolevulinic acid (ALAU) also exists at relatively low PbB levels (<40 µg/dL) remains unclear. We aimed to investigate this association at lower PbB levels. METHODS: We analyzed data from biannual medical examinations of workers at a Japanese factory from August 2013 to August 2023. We excluded records from female workers and those with missing data, resulting in a dataset consisting of 1396 records from 155 male workers. We employed mixed-effect linear regression models with a random intercept for workers and additional adjustments for age and smoking status. RESULTS: The median PbB level across all the analyzed records was 8 µg/dL (range: 1, 31 µg/dL). Significant positive associations were observed between PbB and ALAU, with a one-unit increase in natural logarithm-transformed PbB corresponding to a 10.0% increase in ALAU (95% CI: 2.7, 17.9%). Categorized PbB analyses showed a 23.8% increase in ALAU (95% CI: 2.7, 49.2%) for PbB levels at 20-24 µg/dL and an 83.1% increase (95% CI: 30.1, 157.7%) for PbB levels ≥25 µg/dL, compared to those <5 µg/dL. The exposure-response curve analysis indicated a plateau followed by an increasing trend. CONCLUSIONS: A positive and non-linear association between PbB and ALAU levels was observed at relatively low PbB levels.

Association between the number of teeth and incident pre-diabetes among middle-aged adults with periodontal disease: a retrospective cohort analysis of Japanese claims data.

OBJECTIVES: To investigate the association between the number of teeth and the new onset of pre-diabetes. DESIGN: Retrospective cohort study. SETTING: The National Database of Health Insurance Claims and Specific Health Checkups of Japan, which holds information from both the yearly health check-up programme known as the 'Specific Health Checkup' and health insurance claims data. PARTICIPANTS: 1 098 371 normoglycaemic subjects who participated in the Specific Health Checkup programme every year from fiscal year (FY) 2015 to FY 2018 and had dental insurance claims data with a diagnosis of periodontal disease during FY 2016. OUTCOME MEASURES: Incidence of pre-diabetes or diabetes observed at the Specific Health Checkup during FY 2018. RESULTS: Among the participants, 1 77 908 subjects developed pre-diabetes, and 579 developed diabetes at the check-up during the subsequent follow-up year. Compared with the subjects with 26-28 teeth, those with 20-25, 15-19 or 1-14 teeth were associated with an increased likelihood of developing pre-diabetes or diabetes onset with adjusted ORs of 1.03 (95% CI: 1.02 to 1.05), 1.06 (1.03 to 1.09) and 1.07 (1.04 to 1.11), respectively. No clear modifications were observed for age, sex, body mass index or current smoking. CONCLUSIONS: Having fewer teeth was associated with a higher incidence of pre-diabetes. Due to the limitations of this study, however, causality remains undetermined.

Risk Factors for Duty-Related Posttraumatic Stress Disorder among Police Officers in the Mt. Ontake Eruption Disaster-Support Task Force.

Mount Ontake in Nagano Prefecture, Japan erupted on 27 September 2014. Many police officers were called in for duty as a disaster-support task force. We investigated the association between the peritraumatic situation and posttraumatic stress disorder (PTSD) symptoms in these police officers. In January 2015, a health survey (OHS) on disaster stress related to the Mt. Ontake eruption disaster support work was distributed to all of the police officers and staff involved in the disaster support. We analyzed the 213 participants who had PTSD symptoms following the eruption and no missing OHS data. Logistic regression analyses were conducted to clarify the relationship between the participants' symptom severity and their peritraumatic situation (i.e., stressors and daily support prior to the eruption, disaster-support work duties, and postdisaster stress relief). The symptom severity was associated with 'more than seven cumulative days at work' (odds ratio [OR] = 2.47, 1.21-5.06), 'selecting drinking and/or smoking as stress relief after disaster-support work' (OR = 2.35, 1.09-5.04), and 'female' (OR = 3.58, 1.19-10.77). As disaster-support work, 'supporting the victims' families' (OR = 1.99, 0.95-4.21) tended to be associated with symptom severity. The number of days of disaster-support work, stress-relief behavior, and gender were associated with the severity of PTSD symptoms.

Control banding assessment of exposure of offset printing workers to organic solvents.

OBJECTIVES: We aimed to assess the exposure of offset printing workers to hazardous substances in the rinsing processes of small-sized companies using a control banding method. METHODS: We obtained half-year amounts of hazardous substances purchased through a questionnaire survey and the hazardous information from the safety data sheets (SDSs) and related literature. RESULTS: The amount of petroleum kerosine and carbon hydride markedly increased in 2013 compared with that in 2010. In contrast, the amount of dichloromethane (DCM) decreased in 2013, and 1,2-dichloropropane (DCP) was not used in either 2010 or 2013. Mineral oil and xylene were allocated to Hazard Group D and judged to require Control Approach 3. In addition to DCM with Global Harmonization System's carcinogenic category 1, mildly treated mineral oil and solvent naphtha, allocated into Hazard Group E, are carcinogenic to humans and were judged to require Control Approach 4. There are two limitations of the control banding assessment: first, only limited and scarce hazard information could be obtained from SDSs, and second, safe-sided judgment for control technology for industrial hygiene. CONCLUSION: Small-sized enterprises are encouraged to implement control banding assessment for hazardous substances and to access expert advice available from Regional Industrial Health Centers. Easy access to appropriate expert advice is important to compensate for the limited and scarce hazard information and safe-sided judgment for control technology for Control Approaches 3 and 4.

Liver failure after hepatocellular carcinoma surgery.

PURPOSE: The aim of this study was to construct a prediction model for posthepatectomy liver failure (PHLF), as defined by the International Study Group of Liver Surgery, and evaluate its accuracy in hepatocellular carcinoma (HCC) patients with cirrhosis or chronic hepatitis. METHODS: A total of 277 consecutive hepatectomies for HCC between 2005 and 2013 were analyzed retrospectively. Multivariate logistic regression analysis was used to develop a predictive model for PHLF. The sensitivity, specificity, and area under the receiver operating characteristic (AUROC) curve were evaluated. The Hosmer-Lemeshow goodness-of-fit test was used to assess the model calibration. The constructed model was internally validated by k-fold cross-validation (k=5). RESULTS: PHLF developed in 12.6% of hepatectomies. Multivariate analysis identified the following variables as predictors of PHLF: elevated preoperative serum bilirubin level, elevated preoperative international normalized ratio, and intraoperative packed red blood cell transfusion. The predictive model allowed discrimination between patients who developed PHLF and those who did not, with a sensitivity of 82.9%, specificity of 72.3%, and AUROC curve of 0.81 (95% CI, 0.74 to 0.89). The Hosmer-Lemeshow test indicated a good fit (P=0.545). The AUROC curve of the developed model was significantly greater than that of the model for end-stage liver disease (MELD) score (P=0.014), suggesting that the former model is better at predicting the PHLF than the latter one. CONCLUSIONS: The developed model could be useful for predicting the occurrence of PHLF in HCC patients with underlying liver disease.

Occupational exposure to N,N-dimethylformamide in the summer and winter.

We evaluated total body burden of N,N-dimethylformamide (DMF) taken through the lung and skin by personal exposure of workers to DMF and urinalysis of N-methylformamide (NMF) and N-acetyl-S(N-methylcarbamoyl)-cysteine (AMCC). A total of 270 workers were engaged in four different jobs in a workplace distant from main production lines emanating high levels of DMF. They were not required to wear any personal protective equipment including respirators or gloves. We found that log-transformed urinary levels of NMF and AMCC increased with an increase in log-transformed concentrations of exposure to DMF. Urinary levels of NMF and AMCC were significantly higher in the summer than the winter, although there was no significant seasonal difference in the concentrations of exposure to DMF. Our findings suggested that the increased urinary levels of NMF and AMCC in the summer resulted in increased skin absorption of DMF due to an increased amount of DMF absorbed by the moisturized skin under humid and hot conditions. Seasonal changes in the relative internal exposure index confirmed the present finding of enhanced summertime skin absorption of DMF. AMCC is thought to be a useful biomarker for assessments of cumulative exposure to DMF over a workweek and for evaluations of workers' health effects.

Seasonal difference in percutaneous absorption of N,N-dimethylformamide as determined using two urinary metabolites.

OBJECTIVE: We evaluated the percutaneous absorption of N,N-dimethylformamide (DMF) in DMF-exposed workers in the summer and winter by assessing their urinary levels of DMF metabolites. METHODS: Breathing-zone concentrations of DMF and workers' urinary levels of N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoyl)-cysteine (AMCC) were simultaneously measured in the summer and winter in 193 male workers wearing a respirator and chemical protective gloves. RESULTS: The mean breathing-zone concentrations of DMF in both seasons were below the occupational exposure limit of 10 ppm. Although there was no significant seasonal difference in the breathing-zone concentrations of DMF, workers' urinary levels of NMF and AMCC were significantly higher in the summer than in the winter. Log-transformed urinary levels of the metabolites were significantly correlated with log-transformed breathing-zone concentrations of DMF in the summer, whereas no significant correlation between AMCC and DMF was found in the winter. The urinary levels of AMCC were dispersed more widely than those of NMF, suggesting that urinary AMCC reflected the cumulative exposure to DMF over a workweek. CONCLUSIONS: Percutaneous absorption was the principal route of exposure to DMF for the respirator-wearing workers. Increased urinary levels of NMF and AMCC in the summer were attributed to increased percutaneous absorption of DMF resulting from the increased amount of water-soluble DMF absorbed by sweaty skin caused by the increased summertime room temperature and humidity.

Accuracy of ECG-based screening for sleep-disordered breathing: a survey of all male workers in a transport company.

PURPOSE: Sleep-disordered breathing (SDB) is associated with increased risk for cardiovascular morbidity and mortality and for sleepiness-related accidents, but >75 % of the patients remain undiagnosed. We sought to determine the diagnostic accuracy of ECG-based detection of SDB when used for population-based screening. METHODS: All male workers, mostly truck drivers, of a transport company (n = 165; age, 43 ± 12 years) underwent standard attended overnight polysomnography. Cyclic variation of heart rate (CVHR), a characteristic pattern of heart rate associated with SDB, was detected from single-lead ECG signals during the polysomnography by a newly developed automated algorithm of autocorrelated wave detection with adaptive threshold (ACAT). RESULTS: Among 165 subjects, the apnea-hypopnea index (AHI) was ≥5 in 62 (38 %), ≥15 in 26 (16 %), and ≥30 in 16 (10 %). The number of CVHR per hour (CVHR index) closely correlated with AHI [r = 0.868 (95 % CI, 0.825-0.901)]. The areas under the receiver operating characteristic curves for detecting subjects with AHI ≥5, ≥15, and ≥30 were 0.796 (95 % CI, 0.727-0.855), 0.974 (0.937-0.993), and 0.997 (0.971-0.999), respectively. With a predetermined criterion of CVHR index ≥15, subjects with AHI ≥15 were identified with 88 % sensitivity and 97 % specificity (likelihood ratios for positive and negative test, 30.7 and 0.12). The classification performance was retained in subgroups of subjects with obesity, hypertension, diabetes mellitus, dyslipidemia, and decreased autonomic function. CONCLUSIONS: The CVHR obtained by the ACAT algorithm may provide a useful marker for screening for moderate-to-severe SDB among apparently healthy male workers.

A novel device (SD-101) with high accuracy for screening sleep apnoea-hypopnoea syndrome.

BACKGROUND AND OBJECTIVE: The SD-101 is a non-restrictive, sheet-like medical device with an array of pressure sensors, to detect sleep-disordered breathing by sensing gravitational alterations in the body corresponding to respiratory movements. This study evaluated the accuracy of the SD-101 for screening sleep apnoea-hypopnoea syndrome (SAHS) by comparison with polysomnography. METHODS: Nocturnal polysomnography and SD-101 monitoring were conducted simultaneously and compared in 201 patients with suspected SAHS (suspected SAHS group) and 165 male employees of a transport company (screening group). RESULTS: Polysomnography revealed an AHI of <5, 5 < or = AHI < 15, 15 < or = AHI < 30, 30 < or = AHI < 60 and AHI > or = 60 events/h in 39, 35, 38, 68 and 21 subjects in the suspected SAHS group and 103, 34, 12, 12 and four subjects in the screening group, respectively. Central SAHS and obstructive SAHS were subsequently diagnosed in 11 (5.5%) and 135 (67.2%) of subjects in the suspected SAHS group and five (3.0%) and 39 (23.6%) of subjects in the screening group, respectively. Significant correlations were apparent between AHI and the respiratory disturbance index (RDI) measured with the SD-101 in both the suspected SAHS group (r = 0.88) and screening group (r = 0.92). Receiver operating characteristic curve analysis revealed 89.5% sensitivity and 85.8% specificity in identifying SAHS, using an RDI of 14.0 events/h. CONCLUSIONS: These findings suggest that the SD-101 is a useful device for screening SAHS.

Lead levels in urine of never-smoking adult women in non-polluted areas in Japan, with references to cadmium levels in urine.

The present study was initiated to assess current level of general population exposure to lead (Pb) in terms of Pb in urine (Pb-U). For this purpose, spot urine samples were collected from 2,332 never-smoking adult women in 10 areas all-over Japan, and were subjected to analysis for Pb-U by graphite furnace atomic absorption (GFAA). Data on cadmium in urine (Cd-U) as measured by GFAA were cited from a previous publication). The grand geometric means (GM) for Pb-U as observed, as corrected for creatinine (cr) and as corrected for a specific gravity of 1.016 were 1.06 microg/l, 1.28 microg/g cr and 1.14 microg/l, respectively, with small intra- and inter-variations with geometric standard deviations of about 2 or less. Arithmetic means of the 10 GMs (one each for the 10 areas) were 1.05 microg/l, 1.19 microg/g cr and 1.18 microg/l, respectively. The levels observed appeared to be lower than levels reported for other populations in the world. Chronological comparison within Japan suggested a gradual decrease in Pb-U in past over 20 yr. No close correlation was detected between Pb-U and Cd-U.

Dietary cadmium intake in polluted and non-polluted areas in Japan in the past and in the present.

OBJECTIVE: The purpose of this data compilation is to overview past and current dietary exposure (primarily via rice) of general populations to cadmium (Cd) in environmentally polluted and non-polluted areas in Japan, and to compare the levels with counterpart levels in other areas in Asia. METHODS: A literature survey was conducted for publications on this subject, in either Japanese or international languages, since the early 1970s. Most of the studies identified employed the food-duplicate method in combination with atomic absorption spectrometry for Cd determination, although a few studies utilized other methods, such as the market basket method and dithizon-colorimetry. RESULTS: The highest estimate of dietary Cd intake (Cd-D), 600 microg Cd/day, was reported in the late 1960s for the local population in the Jinzu river basin, where Itai-itai disease had been endemic, and the Cd-D levels were 300 microg/day or higher in other polluted areas. Cd-D dropped to well below 100 microg/day when the polluted soil was replaced in the late 1970s and thereafter. In non-polluted areas, the Cd-D was reported to be approximately 100 microg/day in 1969, followed by a gradual decrease to approximately 40 microg/day in the late 1970s, to reach the current level of less than 30 microg/day. There is a trend of gradual reduction at the rate of 0.3 to 0.6 microg/day per year. Cd from rice accounted for 30 to 40% of the Cd-D in non-polluted areas, but a higher contribution was observed in some polluted areas. Nevertheless, the current Cd-D is still higher than the levels in other rice-dependent populations in east and south-east Asia. CONCLUSION: The Cd-D levels reported for polluted areas were in excess of 300 microg Cd/day. Substantial reduction in Cd-D to the level below 100 microg/day was observed after remediation, such as replacement of polluted paddy soil. In non-polluted areas, there has been a gradual decrease in Cd-D in the past 25 years. Nevertheless, the levels in the current intake of the general population in Japan (25 to 30 microg/day, or <1/10 of the levels in polluted areas in the past) is still higher than the levels in other rice-dependent areas in Asia.

Rice as the most influential source of cadmium intake among general Japanese population.

The objective of the present study is to examine whether rice is still a leading source of cadmium (Cd) burden among general populations in Japan. For this purpose, 10 prefectures were selected from all over Japan (including the northern- and southern-most Hokkaido and Okinawa prefecture, respectively). Cadmium levels in urine of never-smoking women (corrected for creatinine; Cd-Ucr) were compared with the rice- and wheat product-based Cd intake, which were estimated from Cd contents in rice and wheat (in the forms of bread, noodle and flour) consumed by residents in the areas, and per-capita daily consumption of rice and wheat. Stepwise multiple regression analysis taking Cd-Ucr as a dependent variable and rice- or wheat product-based Cd intakes as independent variables showed that rice was the most influential and almost exclusive variable with a partial correlation coefficient of 0.770-0.832, explaining 59-69% of total variation in Cd-Ucr. The effects of other sources including wheat were essentially negligible.

Effects of iron-deficiency anemia on cadmium uptake or kidney dysfunction are essentially nil among women in general population in Japan.

In the present study, 1476 adult women in 6 prefectures in Japan volunteered to offer peripheral blood and spot urine samples, and to complete questionnaires on social habits and health. Blood samples were analyzed for iron, ferritin and TIBC in serum in addition to RBC, Hb and Cd in whole blood. Urine samples were analyzed for Cd, alpha1-MG, and beta2-MG; the measures were corrected for creatinine and were expressed as e.g., Cd-Ucr. Among 1212 never-smokers, 37 women with < 25 ng ferritin/ml serum and < 10 g Hb/100 ml blood were classified as the anemics, whereas 701 women with > or = 25 ng/ml ferritin and > or = 10 g/100 ml Hb were taken as controls. Matching by age and the prefecture of residence was successful for 34 anemics. Comparison (by paired t-test) of Cd in blood, and Cd, alpha1-MG and beta2-MG in urine (as corrected for creatinine) of the anemics with that of matched controls showed no significant differences. Thus, it appeared likely that the current level of iron insufficiency among general women population in Japan may not induce substantial increase in Cd absorption or Cd-associated kidney dysfunction.