Pre-work Values Research Articles

Evaluation of the effect of photoplethysmograms on workers' exposure to methyl bromide using second derivative.

Methyl bromide (MB) is worldwide the only effective fumigant heavily used for quarantine pre-shipment treatment and has a critical use exemption for soil fumigations due to its excellent permeability and insecticidal effect. However, MB should be replaced as it is an an ozone-depleting substance and also highly toxic to humans. Recently, MB has been shown to be hazardous even for asymptomatic workers, affecting their central and autonomic nervous systems. However, the effects of MB exposure on vascular health have not been explored. This study aimed to determine whether MB affects the arterial system of asymptomatic workers. We measured the second derivative of the photoplethysmogram (SDPTG) indices, which are indicators of vascular load and aging, and urinary bromide ion (Br-) concentrations in 44 fumigators (study group) and 20 inspectors (control group) before and after fumigation. In fumigators, the mean values of post-work SDPTG indices (b/a, c/a, d/a, e/a, and SDPTG aging index) and Br- levels were significantly changed compared to their pre-work values (p < 0.05), indicating a negative effect on their cardiovascular health. In contrast, SDPTG indices and Br- levels in inspectors did not show any differences before and after work. All SDPTG indices except c/a showed significant correlations with Br- levels in all individuals (p < 0.05). In conclusion, the Br- levels and SDPTG indices of fumigators varied after MB work, and they experienced negative effects on their health despite being asymptomatic.

Heart Rate Variability Analysis in Workers Exposed to Methyl Bromide as a Quarantine Treatment.

Objective:To determine whether methyl bromide (MB) fumigation work for plants imported in Korea affects workers’ health by assessing heart rate variability (HRV).Methods:We measured HRV indices (TP, VLF, LF, HF, HR, SDNN, pNN50 and HRV-index) and urinary bromide ion (Br−) in 62 fumigators (study group) and 34 inspectors (the control group) before and after fumigation work. In addition, the relationship between Br− concentration and HRV indices was analysed.Results:The fumigators’ post-work HRV indices and Br− level were changed compared with their pre-work values (P < 0.001). Conversely, inspectors’ values were not shown a difference before and after work. The HRV indices in all subjects were negatively correlated with the Br− levels (P < 0.05).Conclusions:Fumigators with high Br− concentrations and low post-work HRV indices following MB fumigation work experienced adverse effects on their autonomic nervous systems.

Negative effect of methyl bromide fumigation work on the central nervous system.

Methyl bromide (MB) is a fumigant that has been widely used for killing pests on plants in trade, soils, and structures worldwide due to its excellent permeability and insecticidal effect; however, MB should be replaced because it is an ozone-depleting substance. It is well-known that MB is highly toxic and hazardous to workers, but the effects of exposure in asymptomatic workers have not been explored. The purpose of this study is to investigate the impact of MB fumigation on the health of fumigators at a sensitive level. The electroencephalogram (EEG) and urinary bromide ion levels of 44 fumigators (the study group) and 20 inspectors (the control) were measured before and after fumigation work from February to August 2019 in Busan, Korea. The mean post-work concentration of bromide ion (18.311 μg/mg CRE) in the fumigators was significantly increased from the pre-work level (7.390 μg/mg CRE) (P<0.001). The fumigator post-work median frequencies (MDF) and alpha-to-theta ratios (ATR) of EEG index were significantly decreased compared to the pre-work values (P<0.05 for all indices). In contrast, there were no significant differences in inspector EEG indices and urinary bromide ion. The urinary bromide ion levels in all the subjects were negatively correlated with MDF (P = 0.032). In conclusion, fumigators’ EEG indices and urinary bromide ion suggested that occupational exposure to MB negatively affected the health of workers, although the workers were asymptomatic.

Cardiovascular and muscular strain during a tree planting season among British Columbia silviculture workers

Cardiovascular and muscle strain were determined in 16 British Columbia reforestation workers during a period of tree planting (75 days). Serial data collected from each worker included pre- and post-work blood chemistry on the first day of the work shift; working heart rate (HR), a PWC170 fitness test, and a daily diary of an individual's work-rest schedule. Repeated blood samples from each planter were analysed for the elevated serum enzyme activities (ESEA) of creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate transaminase (AST), and for the blood haematology parameters (BH) of haematocrit (Hct), red blood cell count (RBC), and haemoglobin (Hgb). HR and BH were used as an index of cardiovascular strain and ESEA was used as an index for musculoskeletal strain. A group mean working heart rate of 116.5 +/- 9 b.min-1 (range 100.0-139.1) was sustained throughout the period of an 8.0 hour day representing 39.2% of the delta Heart Rate ratio (ratio of elevated working Hr above resting to maximum HR). Grouped data were analysed by sample day for a subset of planters (n = 10) participating in six sample dates during the first 32 days of planting. Pre- and post-work ESEA were significantly higher throughout the entire planting period when compared with a pre-season resting control group (n = 9, p < or = 0.01). The post-work rise in CK and AST from pre-work values decreased during successive weeks of work as some adaptation to the work rate occurred. LDH continued to rise and was significantly elevated on day 32 compared with day 1. No significance was found in the BH variables between sample dates, yet a decreasing trend was observed. However, pooled data from all subjects for all sample dates showed a highly significant difference (p < or = 0.01) between pre- and post-work samples for both ESEA and BH. ESEA increased and BH decreased. These data present evidence that the work rate and rest time of a tree planter are not well ordered within the daily and seasonal working routine, and may compromise worker well-being in the silviculture industry.

Work load in culture of shiitake mushroom

Plugging-in of a wood piece for the culture of shiitake mushroom is one of machine-assisted works in forestry, and is achieved by the use of an electric drill. The purpose of this study is to evaluate the effects of this work on the psychophysiological functions of workers. The work consisted of two conditions ; working on a work table and working on the bare ground. The work load was examined by multifaceted observation. Results indicated that the CFF and the function of concentration (TAF-test) when compared with pre-work values were not significantly reduced after approximately 50 minutes of work. But the work perfonuance produced a local muscular load due to work in unnatural work postures and the workers feel fatigue due to work itself. However, working on the work table had effects on mitigation on the work load, shortening of the working time and improvement of the work postures.

Stress and Aging Effects on Female Workers

In this project, the mental stress of both young and middle to elderly aged female sales clerks in a large-scale department store in Japan was investigated. Six subjects in each of the two age groups were from 27–33 years and 49–56 years. Measures were recorded regarding the function of concentration TAF-test), CFF-test, multiple choice reaction time, the displacement of body's center of gravity per one minute with eyes opened, tapping ability test per 20 sec., crural circumference and blood pressure. Heart rate was also measured during working hours. Questionnaires were administrated to establish their attitude toward their jobs, and to evaluate their subjective feelings of fatigue and state of health. Results indicated that the function of concentration (TAF) when compared with pre-work values was significantly reduced only in the middle to elderly group. In both groups, the CFF showed a significant lowering and the crural circumference was significantly increased compared with pre-work values. The level of CFF value and tapping ability in the middle to elderly group lowerd significantly in comparison with the younger group. However, compared with the younger group, the middle to elderly group felt a decrease in sujective feelings of fatigue and bordom. Moreover, another interesting finding was that the displacement of body's center of gravity in the middle to elderly group was markedly smaller than that of the younger group due to years spent standing erect during their work.

Enhanced excretion of thioethers in urine of operators of chemical waste incinerators.

Thioether concentrations were determined in urine samples obtained from ten workers in the despatch department (n = 69), three chemical waste incinerator operators (n = 67), and an analyst (n = 21), all working in the same chemical plant. Urine samples (n = 196) obtained from non-exposed men, including smokers, served as controls. Enhanced excretion of thioethers was found in urine samples taken from incinerator workers at the end of work. A regular pattern in the time course of the urinary thioether excretion was shown by a non-smoking incinerator worker; end-of-work values were always higher than prework values. This phenomenon was not found in samples obtained from the analyst. These findings suggest that incinerator workers inhale or otherwise absorb electrophilic compounds or their precursors, which are subsequently metabolised to, and excreted as, thioethers in urine.

Studies on the function of concentration maintenance (TAF). 14. In relation to myographical changes in muscular work

In the previous paper the authors reported that a muscular work load resulted in the lowering of the function of concentration maintenance (TAF), the grade of which significantly correlated with the volume of oxygen consumed for the work.The present experiment has been carried out to discuss about the lowering of TAF due to muscular work from the viewpoint of excitability level of spinal motoneurone, the final common path of motor nerve system, in relation to the physiological function as one of the factors of the change of TAF.Eighteen healthy male students were loaded with bicycle ergometric work of oxygen consumption of 710ml/min. for 90 minutes. Before and after the work load, they were administered the TAF test, measurement of eye-hand reaction time and recording of H-wave recovery curve from the right lower extremity.The results obtained were as follows:1. The function of concentration maintenance tended to lower with muscular work.2. Comparing the reflexes appeared in H-wave at time intervals of 50 to 900 msec between the conditioning shock and the test shock, the suppression in H-wave recovery curve with ergometric work was noticeable at both 100 and 400 msec against the pre-work values.3. Lowering of the excitability of spinal motoneurone corresponding to muscular fatigue was revealed by a significant correlation between the inhibition rate in H-wave (post-to-pre value) at 400 msec of shock interval and the time of appearance of irregular Piper's rhythm as myographical fatigue.It is reasonable that the excitability of spinal motoneurone lowers at 100 msec in the process of after-hyper-polarization, while the fact that even beyond the rage of the process, at 400 msec, a significant suppression in H-wave recovery curve was observed may suggest also a lowering of its excitability without regard to the relative refractory period of after-hyper-polarization.These results lead us to recognize that the lowering of TAF due to a physical load may be caused by the central depressive action in relation to muscular fatigue.

集中維持機能(TAF)に関する研究(II) : 銀行年末業務における疲労の評価

Industrial fatigue may be understood as an out-put of lowered physiological functions and mental activities resulting from work. Our studies on fatigue have made clear correlations between various kinds of fatigue tests. Reasonable approaches to the evaluation of fatigue may be provided by our new method called "TAF test", the principle of which comes from an idea that fatigue may be grasped by observing ability in target-aiming as a representation of mental activities and ability in keeping up the concentration of aiming as a representation of physiological functions. In the present stage the examinee aims at the target as a distance of two meters with the gun-barrel for one minute continuously and rests for ten seconds, while in sitting he must avoid keeping his body stable by grasping the table with his free hand or by putting his elbow on the table or by touching his face with the gun-barrel to make aiming easier. In this manner aiming is repeated until he has aimed for a total of three minutes. When the target center is accurately sighted, the level is designated as O and in proportion to the inaccuracy in sighting the numerical figure increases up to 10. From each of the three curves shown during the three minutes, level (L) and deviation (D) are determined. L indicates the height of the average level of these curves and D indicates the standard deviation from L. In this sense the function of concentration maintenance can be expressed by the numerical values of L and D, and variances in TAF values due to metal and physical stresses are analysed statistically. (Jap. J. of Hygiene, 18 (2), 241&sim;246, 1963) For this study, 17 healthy male bank employees were selected. The average year of age was 23.5 and that of experience was about 4. The experiment covered 6 days from December 26 to 31, since this period is included in the busiest season of the year in Japanese banking business. There was overtime work daily from about December 10 to the last day of the year. Especially in the period selected for the experiment work ended usually at 8 to 10 p.m. During this period the density of work was also high and the actual working hours on most of the days were 10 to 12 hours. Because of this condition, pre-work values on the first day cannot be considered as normal. Therefore, for the control the pre-work values in the normal business time were used. The tests administered were TAF test (TAF), measurement of flicker frequency (FF), aesthesiometry (Es), blocking test in continuous colour naming (Bl), Donnagio reaction (Do), and Ogawa's reaction (O). In addition to these objective tests, the subjective fatigue questionnaire was also given. The results obtained were as follows: In the pre-work/control ratio (changes in pre-work values compared to the control values) FF, Es and Bl failed to indicate any lowering tendency except on the first day. TAF showed a lowering throughout the 6 days. The average difference in TAF L for each individual showed a significant lowering on every day except on the 4th and 5th days. In regard to changes in the post-work/pre-work ratio (changes during the day) FF, Es and Bl showed no lowering of functions. According to TAF, almost no changes in ratio occurred during the first 4 days, while in the last 2 days the lowering was observed. The average difference in TAF L for each individual showed a lowering tendency on every day, especially significant in the last 2 days. In urine tests, both O and Do showed changes that were either normal or slight. From the facts mentioned above, it may be said that the employees were fatigued already before the first day of this study, and that only toward the end of the week did the daily additional fatigue by work manifest itself as an accumulation of fatigue. As for the appearance ratio of subjective fatigue symptoms, the pre-work values were higher than those of the control. Values were also higher after work than before work in regard to this period.