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Jelmini JD, Ross J, Whitehurst LN, Heebner NR. The effect of extended shift work on autonomic function in occupational settings: A systematic review and meta-analysis. J Occup Health 2023; 65:e12409. [PMID: 37287085 PMCID: PMC10247865 DOI: 10.1002/1348-9585.12409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 04/28/2023] [Accepted: 05/12/2023] [Indexed: 06/09/2023] Open
Abstract
OBJECTIVE To examine the effect of 24-h shift work on autonomic nervous system function via heart rate variability (HRV) methodologies. METHODS Electronic databases (indexed in either PubMed, MEDLINE, CINAHL, SPORTDiscus, or OpenDissertations) were searched from January 1964 to March 2023. A modified Downs and Black checklist was used for assessing methodological quality and the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the quality of evidence. Study design, study population, study sample, shift work description, and assessment of HRV metrics and methods were extracted from each study. FINDINGS A total of 58 478 study articles were identified, of which 12 articles met inclusion criteria. Sample sizes varied from eight to 60 participants, with the ratio of low- to high-frequency HRV (LF/HF) as the most common frequency-domain variable reported. Of the nine included studies that observed LF/HF, three (33.3%) demonstrated a significant increase after 24-h shift work. Moreover, of the five studies that reported HF, two (40%) noted a significant decrease after 24-h shift work. When observing risk of bias, two (16.6%) studies were low quality, five (41.7%) were moderate quality, and five (41.7%) were high quality. INTERPRETATION There were inconsistent findings demonstrating an effect of 24-h shift work on autonomic function, with a suggested shift away from parasympathetic dominance. Discrepancies in HRV methodologies, such as the duration of recordings and hardware used for measurement, may have contributed to the disparity in findings. In addition, differences in roles and responsibilities across occupations may explain the incongruence in findings across studies.
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Affiliation(s)
- Jacob D. Jelmini
- College of Health Sciences, Sports Medicine Research InstituteUniversity of KentuckyLexingtonKentuckyUSA
| | - Jeremy Ross
- College of Health Sciences, Sports Medicine Research InstituteUniversity of KentuckyLexingtonKentuckyUSA
| | | | - Nicholas R. Heebner
- College of Health Sciences, Sports Medicine Research InstituteUniversity of KentuckyLexingtonKentuckyUSA
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Narita K, Amiya E. Social and environmental risks as contributors to the clinical course of heart failure. Heart Fail Rev 2021; 27:1001-1016. [PMID: 33945055 DOI: 10.1007/s10741-021-10116-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/22/2021] [Indexed: 11/28/2022]
Abstract
Heart failure is a major contributor to healthcare expenditures. Many clinical risk factors for the development and exacerbation of heart failure had been reported, including diabetes, renal dysfunction, and respiratory disease. In addition to these clinical parameters, the effects of social factors, such as occupation or lifestyle, and environmental factors may have a great impact on disease development and progression of heart failure. However, the current understanding of social and environmental factors as contributors to the clinical course of heart failure is insufficient. To present the knowledge of these factors to date, this comprehensive review of the literature sought to identify the major contributors to heart failure within this context. Social factors for the risk of heart failure included occupation and lifestyle, specifically in terms of the effects of specific occupations, occupational exposure to toxicities, work style, and sleep deprivation. Socioeconomic factors focused on income and education level, social status, the neighborhood environment, and marital status. Environmental factors included traffic and noise, air pollution, and other climate factors. In addition, psychological stress and behavior traits were investigated. The development of heart failure may be closely related to these factors; therefore, these data should be summarized for the context to improve their effects on patients with heart failure. The present study reviews the literature to summarize these influences.
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Affiliation(s)
- Koichi Narita
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-8655, Tokyo, Japan
| | - Eisuke Amiya
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-8655, Tokyo, Japan. .,Department of Therapeutic Strategy for Heart Failure, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-8655, Tokyo, Japan.
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Affiliation(s)
- Erin Andersen
- University of California at San Francisco, Employee Health Center, and University of California, San Francisco, San Francisco, CA
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Altered circadian rhythm, sleep disturbance, and gastrointestinal dysfunction: New evidence from rotating shift workers. ADVANCES IN DIGESTIVE MEDICINE 2016. [DOI: 10.1016/j.aidm.2016.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Altered anorectal function in rotating shift workers: Association with autonomic dysfunction and sleep disturbance. ADVANCES IN DIGESTIVE MEDICINE 2015. [DOI: 10.1016/j.aidm.2015.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Kikuchi Y, Ishii N. [The relationship between self-awareness of fatigue symptoms and working conditions in female nurses]. SANGYO EISEIGAKU ZASSHI = JOURNAL OF OCCUPATIONAL HEALTH 2015; 57:230-240. [PMID: 26156409 DOI: 10.1539/sangyoeisei.e14005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVES The aim of this study was to clarify the relationship between self-awareness of fatigue symptoms and working conditions, in female nurses. METHODS We studied personal background, working conditions, physical symptoms, "Pittsburgh Sleep Quality Index - Japanese version (PSQI-J)", and 13 items that represented the parts related to self-awareness of the "the self-Diagnosis Checklist for Workers' Accumulated Fatigue" in 3,855 female nurses. The targets for analysis were 983 nurses ("all subjects") and among those, 765 "shift workers". The total score (fatigue symptoms self-awareness score) was calculated for 13 items that represented the parts related to self-awareness of the "the self-Diagnosis Checklist for Workers' Accumulated Fatigue". The Mann-Whitney U test and the Kruskal-Wallis test were performed, and the fatigue symptoms self-awareness score was studied, based on personal background, working conditions, physical symptoms and the PSQI-J score. RESULTS For "all subjects", there was a significant difference in the fatigue symptoms self-awareness score for department in which they work, the form the work takes, and the PSQI-J score. The fatigue symptoms self-awareness score of nurses with a PSQI-J score of 5.5 or higher was a significantly high value. For "shift workers", there was a significant difference in the fatigue symptoms self-awareness score for presence or absence of a caregiver role, department in which they work, the form the work takes, the form the nap takes during night work and PSQI-J score. There was a significantly high value in the fatigue symptoms self-awareness score of subjects with a caregiver role, subjects working in surgical wards or internal medicine wards, subjects working on a three-shift system, and subjects who were unable to take naps during night work, subjects with a PSQI-J score of 5.5 or higher. DISCUSSION These survey results suggest that it is important to set up a system that will ensure the ability to have naps during night work. It will also be necessary to consider the caregiver role and so on as items related to the fatigue of nurses.
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Affiliation(s)
- Yukiko Kikuchi
- Department of Basic Nursing, Akita University Graduate School of Health Sciences, 1-1-1 Hondo, Akita 010-8543, Japan
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Mason JW. Timing of pre-dose baseline electrocardiograms in clinical trials: increased sampling over a prolonged baseline period worsens variance of QTc. J Electrocardiol 2014; 47:716-20. [PMID: 25060126 DOI: 10.1016/j.jelectrocard.2014.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND PURPOSE The US Food and Drug Administration (US FDA) currently recommends recording of electrocardiograms (ECGs) prior to drug administration in thorough QT studies over an hour or more time to improve reliability of baseline ECG values. However, the baseline period is usually in the morning during a period of intense trial activity and rapid circadian change in QTc. The purpose of this study was to determine if the practice of recording an extended baseline does, in fact, decrease QTc variance at baseline. METHODS ECG data from three thorough QT studies (TQTS) in which three ECGs (commonly referred to as triplicates) were recorded at each of three pre-specified time points during the 60 to 90 minutes before drug administration were analyzed by determining the intra-subject and inter-subject standard deviation (SD) of QTcF (Fridericia-correct QT) for each of the three pre-drug time points and for the three time points combined. RESULTS QTcF was relatively normally distributed in each study. Intra-subject variability of QTcF was greater for the combined triplicate recordings than for the individual triplicates at baseline treatment time points in 39 of 42 cases (93%). This was the case in 48% of the comparisons in the inter-subject analysis. CONCLUSIONS The practice of recording three sets of triplicate ECGs over an hour or more before drug administration in a TQTS increases variability of baseline QTcF consistently in cross-over designed trials, and in roughly half of parallel comparisons. Higher variability suggests that the three-triplicate approach does not provide a more reliable baseline value. Less variability of QTcF can be obtained by simply recording one triplicate prior to drug administration. This principal may apply to other ECG and other physiological variables that have a monotonic circadian trend or that may be affected by intense trial activity during the pre-drug hour.
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Affiliation(s)
- Jay W Mason
- University of Utah, Salt Lake City, UT, USA.
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Matsumoto Y, Toyomasu K, Uchimura N. Assessment of physical and mental health in male university students with varying sleep habits. Kurume Med J 2013; 58:105-15. [PMID: 23047140 DOI: 10.2739/kurumemedj.58.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Healthy sleep habits entail not only sleeping for a sufficient period (quantity) but also regularity of the sleep cycle and getting sound sleep (quality). University students often have erratic schedules that cause irregular sleep patterns even though sleep durations remain relatively constant. This study compared the physical and mental health of 90 male university students with different sleep habits. We created sleep habit scales using the Tokyo Metropolitan Institute for Neuroscience life habits inventory (TMIN-LHI; Miyashita, 1994) by performing a factor analysis and classifying sleeping habits based on regularity, quality, and quantity. Four types of sleep habits were identified by cluster analysis; good sleep was characterized by regular and high quality sleep but of relatively short sleep duration; long sleep was regular and relatively long but of low quality; short sleep was of high quality but short and irregular, while poor sleep was irregular, of low quality, and relatively long. The good sleep group had a significantly lower average waist circumference, and lower systolic and diastolic blood pressure. The long and poor sleep groups, which both had low quality sleep, scored lower than the national standard on the mental component summary (MCS) calculated from the Social Functioning-36 (SF-36) short-form health survey. Furthermore, the average MCS score of the poor sleep group was significantly lower than that of any other sleep habit group. Subjects with poor sleep also scored lowest on the Self-rating Depression Scale (SDS). In addition, the short and poor sleep groups were prone to glucose or lipid metabolism disorders. Maintaining good physical and mental health without sound sleep and a regular sleep cycle is difficult, even if sleeping hours are kept constant. Therefore, we included the assessment of regularity and quality in addition to hours of sleep in order to develop appropriate sleep guidelines for improved physical and mental health.
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Affiliation(s)
- Yuuki Matsumoto
- Kurume University Graduate School of Medicine, Kurume University School of Medicine, Kurume, Japan.
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Factors affecting hand tremor and postural sway in children. Environ Health Prev Med 2012; 11:17-23. [PMID: 21432371 DOI: 10.1007/bf02898203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 09/09/2005] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVES It is crucial to consider covariates relevant for outcome variables in developing dose-effect relations of environmental hazardous toxins. The aim of this study was to clarify the covariates affecting hand tremor and postural sway in children. METHODS Hand tremor and postural sway, as well as hair mercury concentrations, were measured in 155 boys and 148 girls at age 7 years. RESULTS Current mercury concentrations in child hair ranged from 0.35 to 6.32 μg/g (geometric mean, 1.71 μg/g for boys and 1.58 μg/g for girls), and were not significantly correlated with the neuromotor parameters. All hand tremor and postural sway parameters, except for tremor intensity at 1-6 Hz with non-dominant hand, were significantly larger in the boys than in the girls. Using multiple regression analysis, some postural sway parameters were related negatively to age in the boys and girls (p<0.05), and positively to height (p<0.05). Similarly, hand tremor parameters were positively related to age, height and heart rate either in the boys or in the girls (p<0.05). Also, there were positive relationships between tremor intensity at 1-6 Hz and transversal and sagittal sways at 1-2 Hz and 2-4 Hz (p<0.05). CONCLUSIONS Heart rate and postural sway, together with age, sex, and height, should be considered in interpreting hand tremor in children. Hand tremor or postural sway may not be so sensitive or specific to methylmercury exposures at levels of less than 7 μg/g in hair.
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Hwang DS, Kim HK, Seo JC, Shin IH, Kim DH, Kim YS. Sympathomodulatory effects of Saam acupuncture on heart rate variability in night-shift-working nurses. Complement Ther Med 2010; 19 Suppl 1:S33-40. [PMID: 21195293 DOI: 10.1016/j.ctim.2010.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 10/26/2010] [Accepted: 11/01/2010] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVE We assessed the effects of Saam (traditional Korean) acupuncture on the autonomic nervous system in night-shift nurses using power-spectral heart-rate variability (HRV) analysis. METHODS This study had a 2 × 4 cross-over design with a series of six (n = 1) controlled trials. Six night-shift nurses were randomly divided into two groups, and each nurse received four acupuncture treatments on the third day of night-shift work. One group started with Saam acupuncture (gallbladder jeonggyeok), while the other started with sham acupuncture. Saam acupuncture and sham acupuncture were applied in turn. HRV was measured before and after treatment. For statistical analysis, the results of the two groups were combined, and a Bayesian model was used to compare the changes in HRV values before and after treatment, between Saam and sham acupuncture. RESULTS As the ratio of low- to high-frequency power (LF/HF) for HRV increased on the third day of night-shift work in the pilot study, HRV measurements were made on the third day. Compared with sham acupuncture, Saam acupuncture reduced sympathetic activity; the overall median treatment effect estimate in LF normalised units decreased by -17.4 (confidence interval (CI): -26.67, -8.725) and that for LF/HF decreased by -1.691 (CI: -3.222, -0.3789). The overall median treatment effect estimate in HF normalised units increased by 17.41 (CI: 6.393, 27.13) with Saam acupuncture, suggesting an increase in parasympathetic activity. CONCLUSION Saam acupuncture may attenuate the imbalance between sympathetic and parasympathetic activities induced by night-shift work in nurses.
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Affiliation(s)
- Deok-Sang Hwang
- Department of Oriental Gynecology, College of Oriental Medicine, Kyung Hee University, Seoul, South Korea
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Lo SH, Lin LY, Hwang JS, Chang YY, Liau CS, Wang JD. Working the night shift causes increased vascular stress and delayed recovery in young women. Chronobiol Int 2010; 27:1454-68. [PMID: 20795886 PMCID: PMC4673565 DOI: 10.3109/07420528.2010.498067] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Shiftwork has been associated with elevated blood pressure (BP) and decreased heart-rate variability (HRV), factors that may increase the long-term risk of cardiovascular-related mortality and morbidity. This study explored the effect of shiftwork on dynamic changes in autonomic control of HRV (cardiac stress), systolic BP and diastolic BP, i.e., SBP and DBP (vascular stress), and recovery in the same subjects working different shifts. By studying the same subjects, the authors could reduce the effect of possible contribution of between-subject variation from genetic predisposition and environmental factors. The authors recruited 16 young female nurses working rotating shifts—day (08:00–16:00 h), evening (16:00–00:00 h), and night (00:00–08:00 h)—and 6 others working the regular day shift. Each nurse received simultaneous and repeated 48-h ambulatory electrocardiography and BP monitoring during their work day and the following off-duty day. Using a linear mixed-effect model to adjust for day shift, the results of the repeated-measurements and self-comparisons found significant shift differences in vascular stress. While working the night shift, the nurses showed significant increases in vascular stress, with increased SBP of 9.7 mm Hg. The changes of SBP and DBP seemed to peak during waking time at the same time on the day off as they did on the working day. Whereas HRV profiles usually returned to baseline level after each shift, the SBP and DBP of night-shift workers did not completely return to baseline levels the following off-duty day (p < .001). The authors concluded that although the nurses may recover from cardiac stress the first day off following a night shift, they do not completely recover from increases in vascular stress on that day. (Author correspondence: jdwang@ntu.edu.tw)
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Affiliation(s)
- Shih-Hsiang Lo
- Department of Internal Medicine, Zhongxing Branch of Taipei City Hospital, Taipei, Taiwan
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Abstract
Problemi rada u smjenamaU radu se raspravlja o negativnim utjecajima smjenskog rada koji su klasificirani u četiri kategorije učinaka: na biološke funkcije, radnu efikasnost, društvene / obiteljske aspekte života te na zdravlje. Dan je sustavni pregled dosadašnjih istraživanja zdravstvenih problema smjenskih radnika u čijoj je osnovi narušavanje cirkadijurnih ritmova organizma koju nameće smjenski / noćni rad. Zdravstveni problemi koji se dovode u vezu sa smjenskim radom su ovi: problemi sa spavanjem, gastrointestinalne i kardiovaskularne bolesti, karcinom, problemi s reproduktivnim funkcijama žena te lošije psihičko zdravlje.U radu se također raspravlja o toleranciji smjenskog rada. Pri tome je kao teoretski okvir povezanosti smjenskog rada i negativnih zdravstvenih posljedica rabljen procesni model koji su postavili Smith i suradnici 1999. Poseban naglasak stavljen je na individualne i organizacijske faktore o kojima ovisi mogućnost prilagodbe na smjenski rad te tolerancija takvog rada. Značajni prediktori tolerancije smjenskog rada su: dob, spol, jutarnjost-večernjost, rigidnost-fleksibilnost u navikama spavanja, obiteljska situacija, higijena spavanja te zdrava prehrana. S obzirom na rezultate istraživanja koji upućuju na povezanost nekih karakteristika organizacije smjenskog rada s tolerancijom prema smjenskom radu, kao što su: broj radnih smjena i trajanje smjene, broj sukcesivnih noćnih smjena, regularnost smjena, brzina i smjer rotacije smjena, preporučene su intervencijske strategije u organizaciji smjenskog rada.
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KANTERMANN T, JUDA M, VETTER C, ROENNEBERG T. Shift-work research: Where do we stand, where should we go? Sleep Biol Rhythms 2010. [DOI: 10.1111/j.1479-8425.2010.00432.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Smith DR. Longitudinal trends of alcohol and tobacco consumption among Australian physicians and nurses, 1989–2005. JOURNAL OF SUBSTANCE USE 2009. [DOI: 10.1080/14659890601157679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Lin YC, Hsiao TJ, Chen PC. Persistent Rotating Shift-Work Exposure Accelerates Development of Metabolic Syndrome among Middle-Aged Female Employees: A Five-Year Follow-Up. Chronobiol Int 2009; 26:740-55. [DOI: 10.1080/07420520902929029] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ando S, Iwata T, Ishikawa H, Dakeishi M, Murata K. Effects of acute alcohol ingestion on neuromotor functions. Neurotoxicology 2008; 29:735-9. [DOI: 10.1016/j.neuro.2008.04.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 04/08/2008] [Accepted: 04/24/2008] [Indexed: 10/22/2022]
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Iwata T, Yano E, Karita K, Dakeishi M, Murata K. Critical dose of lead affecting postural balance in workers. Am J Ind Med 2005; 48:319-25. [PMID: 16216016 DOI: 10.1002/ajim.20220] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The threshold blood lead (BPb) level for nervous system dysfunction in adults has been estimated to be 30-40 microg/dl. This study was carried out to estimate the critical dose of lead affecting the neuromotor function in workers by introducing the benchmark dose (BMD) approach, as well as to identify the specific postural sway to lead exposure. METHODS Postural sway parameters with spectral analysis were compared between 121 lead workers with BPb levels of 6-89 (mean 40) microg/dl and 60 unexposed controls. RESULTS All sway parameters, except for sagittal sways with eyes open, were significantly larger in the lead workers than in the controls; also, the Romberg quotient for sagittal sway was significantly higher in the lead workers. The BPb level in the lead workers was significantly related to sagittal sways at 1-2 Hz and 2-4 Hz with eyes open, and sagittal and transversal sways at 1-2 Hz and 2-4 Hz with eyes closed. The BMD levels of BPb (i.e., lower 95% confidence limits of BMD) were estimated to be 12.1-17.3 (mean 14.4) microg/dl for postural sway. CONCLUSIONS Neuromotor dysfunction in lead workers may be initiated at BPbs below the level previously accepted as effectless, and be characterized mainly by an increased sway of high frequency (1-4 Hz) in the sagittal direction with eyes closed (high Romberg quotient).
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Affiliation(s)
- Toyoto Iwata
- Department of Environmental Health Sciences, Akita University School of Medicine, Akita, Japan
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Ishii N, Dakeishi M, Sasaki M, Iwata T, Murata K. Cardiac autonomic imbalance in female nurses with shift work. Auton Neurosci 2005; 122:94-9. [PMID: 16202660 DOI: 10.1016/j.autneu.2005.08.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2005] [Revised: 08/05/2005] [Accepted: 08/31/2005] [Indexed: 10/25/2022]
Abstract
The pathophysiology underlying the shift work-related cardiovascular disease is still poorly understood. The chronic effects of shift work on cardiac autonomic functions were assessed in 47 hospital nurses working under a rotating three-shift system (shift nurses) and 36 public health nurses without shift work (non-shift nurses). The heart rate variability, %LF and %HF (i.e., proportions of sympathetic and vagal activities, respectively), and LF/HF ratio were calculated from the electrocardiographic RR intervals by using autoregressive spectral analysis, and heart rate-corrected QT interval (QTc and QT index) was also measured. The LF/HF ratio, %LF, and QT index were significantly larger in the shift nurses than in the non-shift nurses; also, the power spectral density of HF (PSD(HF)) was significantly decreased in the shift nurses. There was a significant, inverse correlation between the corrected QT interval and PSD(HF) in the non-shift nurses, but not in the shift nurses. It is suggested that shift work in female nurses may cause a sympathodominant state due to depressed vagal tones. Also, a pathophysiology of shift work-related cardiovascular disease, derived from the present and previous findings, may be characterized by the attenuation of the inverse association between the corrected QT interval and vagal activity observed in non-shift workers.
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Affiliation(s)
- Noriko Ishii
- Department of Environmental Health Sciences, Akita University School of Medicine, Japan
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Iwata T, Mori H, Dakeishi M, Onozaki I, Murata K. Effects of Mixed Organic Solvents on Neuromotor Functions among Workers in Buddhist Altar Manufacturing Factories. J Occup Health 2005; 47:143-8. [PMID: 15824479 DOI: 10.1539/joh.47.143] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To clarify the neuromotor effects of long-term exposure to mixed organic solvents, postural sway and tremor were measured in 62 solvent workers of four Buddhist altar manufacturing factories who had worked for 1-46 (mean 12) yr. By using the passive gas sampler, 8-h time-weighted average concentrations in the workers were estimated to be 0.02-8.7 ppm for toluene, 0.02-7.7 ppm for xylene, 0.02-5.5 ppm for styrene and 0.02-40.5 ppm for n-hexane. Sagittal sway and sway area of the posturography with eyes closed were significantly larger in the solvent workers than in 35 age-matched controls (p<0.05), and there was a significant difference in Romberg quotient of sagittal sway between the two groups (p<0.05). Also, tremor intensities at 1.0-5.9 Hz, 6.0-9.9 Hz and 10.0-13.9 Hz with the right hand, and at 6.0-9.9 Hz with the left hand were significantly stronger in the solvent workers than in the controls. Among the solvent workers, transversal and sagittal sways with eyes open and tremor intensity at 10.0-13.9 Hz were significantly related to toluene exposure (p<0.05), which may have been due to the acute effects of such solvents. These findings suggest that long-term exposure to mixed organic solvents may impair neuromotor functions as measured by postural sway and tremor.
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Affiliation(s)
- Toyoto Iwata
- Department of Environmental Health Sciences, Akita University School of Medicine, 1-1-1 Hondo, Akita 020-8543, Japan
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Murata K, Yano E, Hashimoto H, Karita K, Dakeishi M. Effects of shift work on QTc interval and blood pressure in relation to heart rate variability. Int Arch Occup Environ Health 2005; 78:287-92. [PMID: 15824915 DOI: 10.1007/s00420-004-0592-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 11/03/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVES There is evidence that shift work contributes to excess cardiovascular mortality. The purpose of this study was to determine the effects of shift work on heart rate-corrected QT (QTc) and blood pressure in relation to heart rate variability (CV(RR)). METHODS The study population consisted of 153 male shiftworkers and 87 male day workers who were employed at a copper-smelting plant. The QTc interval, total power spectral density (t-PSD) of 100 RR intervals, PSDs with frequencies of 0.01 Hz-0.15 Hz and 0.15 Hz-0.40 Hz (PSD(LF) and PSD(HF)), CV(RR), low frequency (LF) component variability and high frequency (HF) component variability (CCV(LF) and CCV(HF)) and %LF (PSD(LF)/(PSD(LF)+PSD(HF)) .100) were measured (LF and HF components are thought to reflect the sympathetic and parasympathetic activities, respectively). RESULTS The QTc interval was significantly longer in the shiftworkers than in the day workers, although there was no significant difference in systolic or diastolic blood pressure between the two groups. Also, the CCV(LF) and log(PSD(LF)) were significantly depressed in the shiftworkers. In the day workers, the QTc interval was significantly related to the CV(RR), log(t-PSD), CCV(HF), log(PSD(HF)),%LF, and log(LF/HF ratio) (partial correlation coefficient r=-0.305, -0.377, -0.312, -0.355, 0.297, and 0.277, respectively). In the shiftworkers only two relations of the QTc interval to non-specific CV(RR) and log(t-PSD) were significant. CONCLUSION The clear association between long QTc interval and reduced parasympathetic activity observed in the day workers did not exist in the shiftworkers. Rather, the shiftworkers had a selective reduction in sympathetic drive, which may have compensated for prolonged QTc interval due to shift work. On the other hand, the impact of shift work on hypertension remains unclear, although reduced sympathetic drive in the shiftworkers may explain the absence of differences in blood pressure between shiftworkers and day workers to some extent.
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Affiliation(s)
- Katsuyuki Murata
- Division of Environmental Health Sciences, Department of Social Medicine, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
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