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.

Development of a Concurrent Treatment Technique of Ethyl Formate and Mixtures (Nitrogen, Phosphine) to Control Citrus Mealybug (Planococcus citri).

Currently, the fumigant ethyl formate (EF) is stored as a liquified gas in metal cylinders mixed with carbon dioxide (CO2), but this product type is expensive to manufacture, transport, and maintain in cylinders. To address these problems, we developed a new EF fumigation technique with a nitrogen (N2) carrier. In this report, the susceptibility of citrus mealybugs, one of the most resistant mealybugs to fumigants, to EF was assessed; the phytotoxicity of an EF + N2 concurrent treatment applied to banana fruit was examined to evaluate the efficacy compared to the current EF + CO2 product; and the increased efficacy with a phosphine (PH3) addition to EF + N2 was also assessed. Concurrent treatment of EF and N2 was performed at an LC50 concentration of EF. N2 was applied in seven doses from concentrations of 79% to 95%. The phytotoxicity of EF to bananas was assessed by applying EF at 35 mg/L with N2 at 79%, and the color, sugar content, and weight loss of bananas were measured for 14 days after treatment. The EF with N2 treatment resulted in more than 50% mortality at all growth stages of the mealybug, and there was no significant difference between the untreated and treated banana fruits. EF mixed with PH3 showed a higher efficacy than treatment with EF alone, but only a slight increase in efficacy was observed when the PH3 concentration increased. These results indicate that concurrent treatment with EF and N2 can be used to control mealybugs on banana fruits, and combined treatment with EF and PH3 can also enhance the efficacy against mealybugs.

Ethyl Formate Fumigation for Control of the Scale Insect Asiacornococcus kaki, a Quarantine Pest on Sweet Persimmon, Diospyros kaki: Efficacy, Phytotoxicity and Safety.

Sweet persimmons are a valuable export commodity. However, the presence of live insects such as Asiacornococcus kaki limits their access to many export markets. Methyl bromide, traditionally used for pest control, is damaging to human health and the environment. Ethyl formate (EF) is a viable alternative; however, its effectiveness against A. kaki on sweet persimmon fruit is unknown. We evaluated the effectiveness of EF fumigation in controlling A. kaki present under the calyx of persimmon fruit. The hatching rate of eggs and the survival rates of nymphs and adults of A. kaki at low temperatures, its LCt50 and LCt99 after EF exposure, and phytotoxic damage caused by EF were evaluated in laboratory-scale and commercial-scale tests. The dose-response tests showed that the EF LCt99 at 5 °C was 9.69, 42.13, and 126.13 g h m-3 for adults, nymphs, and eggs, respectively. Commercial-scale tests demonstrated EF efficacy against all A. kaki stages without causing phytotoxic effects on persimmons, though the eggs of A. kaki were not completely controlled in linear low-density polyethylene (LLDPE)-packaged fruit. This study demonstrated that EF is a potential fumigant for quarantine pretreatment, especially before persimmon fruit is packed with LLDPE film, to control A. kaki infesting sweet persimmon fruit.

Comparison of Methyl Bromide and Ethyl Formate for Fumigation of Snail and Fly Pests of Imported Orchids.

Invasive snails and flies are major pests of imported orchids, controlled by methyl bromide (MB) fumigation in Korea. We compared the efficacy and phytotoxicity of ethyl formate (EF) and MB on four species of imported orchids using juvenile stages of Achatina fulica and third and fourth instars of Lycoriella mali. EF was as effective as MB. The LCt99 values of EF were 68.1 and 73.1 g h/m3 at 15 °C; and those of MB were 95.9 and 78.4 g h/m3 at 15 °C for A. fulica and L. mali, respectively. In the scale-up trials, EF treatment at 35 g/m3 for 4 h at 15 °C resulted in complete control of both pests. MB treatment based on the current treatment guidelines for imported orchids (48 g/m3, 2 h, at >15 °C) resulted in complete control of L. mali but not of A. fulica. Chlorophyll content and hue values of treated orchids were not affected by EF treatment but significantly changed by MB (p-value < 0.05). All four treated species of orchids died within 30 d of MB treatment, while only one species died from EF treatment. Our results suggest that EF is a potential alternative to MB in phytosanitary treatment of imported orchids.

Variations in the Second Derivative of a Photoplethysmogram with Age in Healthy Korean Adults.

Second derivative of photoplethysmogram (SDPTG) indices correlate with aging and vascular health. The trend of SDPTG indices with age has not yet been studied in the Korean population. Various SDPTG indices were measured in 300 healthy Koreans (150 men and 150 women), aged 19−69 years, stratified into five age groups consisting of 60 people (30 men and 30 women) in each age group from their 20s to 60s. The values of the SDPTG indices clearly showed distinct variations with age in healthy Korean groups (p < 0.001 for all indices). b/a increased linearly with age (y = 0.0045x − 0.803), as did SDPTG aging index (SDPTG-AI) (y = 0.0162x − 1.1389). c/a decreased linearly with age (y = −0.0044x + 0.1017), as did d/a (y = −0.0062x + 0.034) and e/a (y = −0.001x + 0.2002). A significant sex difference was shown in b/a and e/a ratios and SDPTG-AI (p < 0.001 for all indices); women had a higher b/a ratio (−0.55 ± 0.14 versus −0.65 ± 0.13) and SDPTG-AI (−0.33 ± 0.3 versus −0.52 ± 0.33) and a lower e/a ratio (0.13 ± 0.06 versus 0.18 ± 0.07) than men. A linear regression model of diverse SDPTG indices was provided according to the age of healthy Koreans, which may be valuable in preventing diseases related to vascular conditions by estimating the degradation of arterial function.

Ethyl Formate as a Methyl Bromide Alternative for Fumigation of Citrus: Efficacy, Fruit Quality, and Workplace Safety.

Ethyl formate (EF) was evaluated as a potential alternative to methyl bromide (MB) for phytosanitary treatment of imported citrus fruit in the Republic of Korea. Planococcus citri (Risso) (Hemiptera: Pseudococcidae), a mealybug with known tolerance against EF and MB, was used as a representative pest to test efficacy of the two fumigants against eggs. In nine commercial-scale refrigerated container (67.5 m3) trials using imported orange, lemon and grapefruit, EF applied at the currently approved dose for citrus (70 g·m-3 at 5°C for 4 h, developed for Aspidiotus excisus Green (Hemiptera: Diaspididae), a species less EF tolerant than P. citri) resulted in 76.9-98.3% mortality of P. citri eggs. The EF treatment did not affect the sugar content or the color of peel and pulp of the treated fruit. When oranges were treated according to the current MB (64 g·m-3 at >5°C for 2 h) or EF treatment guidelines, the concentration of fumigant around the fruit fluctuated between 9.4 and 185.1 ppm for EF and 9.5-203.0 ppm for MB during the 72-h post-fumigation processes (venting [0-2 h], transportation to storage [2-24 h], and storage periods [24-72 h]) with both EF and MB maintained between 10 and 100 ppm during the storage period. Considering the efficacy of EF, its apparent lack of phytotoxicity, and its more manageable threshold limit value for humans (100 ppm EF compared to 1 ppm MB for an 8-h time weighted average exposure), our results suggest that EF may be a promising alternative to MB for the phytosanitary treatment of imported citrus in Korea.

Preliminary study to evaluate ethanedinitrile (C2 N2 ) for quarantine treatment of four wood destroying pests.

BACKGROUND: Methyl bromide is an ozone depleting substance and is still being used for quarantine treatment of wood products and logs. Ethanedinitrile (C2 N2 ) is a new potential alternative fumigant and has been investigated as a timber fumigant because it has shown better penetration through timber and responds fast to insects and nematodes. This article reports on laboratory and commercial-scale trials with C2 N2 for important wood destroying pests namely Tomicus piniperda (Pine bark beetle) adults, Hyphantria cunea (Fall webworm) lavae, Reticulitermes speratus (Japanese Termite) adults and Cryphalus fulvus (Scolytidae) (Yellow minute bark beetle) which naturally infests pine logs. RESULTS: Tomicus pi:niperda adults were more tolerance than H. cunea lavae and R. speratus adults with lethal concentration × time affecting 99% mortality (LCt99 ) values of 27.84, 7.49 and 3.30 g h m-3 , respectively. Ethanedinitrile shows exceptionally high toxicity to adult R. speratus which was almost 26 times more toxic than methyl bromide. The complete control of larvae and adults stages of C. fulvus was achieved at concentration × time (Ct) products from 89.6 g h m-3 in a 6-8 L fumigation chamber. Temperature-depending trials on C. fulvus were conducted with C2 N2 doses of 30 at 21 ± 6 and 40 g m-3 at 9 ± 3 and 2 ± 2 °C for 24 h. The Ct products of 182.2, 227.8 and 268.6 g h m-3 were obtained and C. fulvus was completely controlled at all tested temperatures. CONCLUSION: Ethanedinitrile could offer quarantine treatment for wood products and logs for the control of wood destroying insect pests and termites.

Variations in methyl bromide concentration with distance and time during quarantine fumigation.

Methyl bromide (MB) is a highly toxic and ozone-depleting substance and should be replaced. Worker exposure to high MB concentrations during fumigation has been previously reported. However, variations in MB concentration as a function of distance from fumigated objects or of time after degassing have not been reported so far. In this study, air samples were collected at various distances from fumigated objects (oranges, wood in containers, and wood in tarpaulin) during injection and degassing and analyzed via gas chromatography according to the Occupational Safety and Health Agency method. In addition, MB concentrations were directly measured over time using a gas detector during degassing. Non-linear regression analysis of the logarithmically transformed data indicated a clear decrease in MB concentration with distance as well as time. Non-linear regression models were constructed to describe the decrease in MB concentration with distance from the objects and with time during degassing (P < 0.05 for all models). The results of this study could aid in establishing appropriate safety guidelines, and hence, in preventing risks related to MB exposure.

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.

Declining Trends of Heart Rate Variability According to Aging in Healthy Asian Adults.

Heart rate variability (HRV) indices correlate with aging and are related to the autonomic nervous system. However, the trend of HRV with age has not been explored for the Asian population. Therefore, we proposed a linear regression model of HRV indices that decreased with aging in healthy Asian adults. HRV parameters [High frequency (HF), Low frequency (LF), Very low frequency (VLF), Total power (TP), HRV triangular index (HRV-index), Standard deviation of the normal-to-normal interval (SDNN), and Proportion of normal-to-normal intervals greater than 50 ms (pNN50)] were measured in a total of 300 healthy participants (150 men and 150 women) aged 19-69 years stratified into five age groups: 19-29, 30-39, 40-49, 50-59, and 60-69 years comprising 60 people each in Seoul, South Korea. A simple regression analysis was performed to reveal the linear declining trend of HRV indices with age. Independent t-tests were conducted to investigate the gender differences in HRV values depending on each age group. The values of all HRV indices showed a decreasing trend with age in healthy Korean adults, as observed in the Western population (P < 0.001 for all indices); HF (Y = -0.039x + 6.833, R 2 = 0.287), LF (Y = -0.047x + 7.197, R 2 = 0.414), VLF (Y = -0.025x + 6.861, R 2 = 0.177), TP (Y = -0.034x + 8.082, R 2 = 0.352), HRV-index (Y = -0.125x + 15.628, R 2 = 0.298), SDNN (Y = -0.502x + 53.907, R 2 = 0.343), and pNN50 (Y = -0.650x + 53.852, R 2 = 0.345) all decreased with age. There was no significant gender difference in any HRV parameter. A linear regression model of various HRV indices has been presented considering the age of healthy Asians, which may be useful to prevent diseases related to the autonomic nervous system by estimating or tracking autonomic functional degeneration in the Asian population.

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.

Ethyl Formate as a Methyl Bromide Alternative for Phytosanitary Disinfestation of Imported Banana in Korea With Logistical Considerations.

Methyl bromide (MB) use for quarantine and phytosanitary purposes is being phased out. Several effective MB alternatives have been identified depending on the target system. Industry commitment for the shift to new technologies will depend not only on the efficacy of alternatives but also on their compatibility and integrability into existing operations. We compared the efficacy of MB and ethyl formate (EF) for disinfestation of Planococcus citri (Risso) (Hemiptera: Pseudococcidae) as a representative surface pest on banana and evaluated whether EF fumigation is compatible with the current packaging materials and loading ratio used by the South Korean banana import industry. Fumigation trials with P. citri adults and eggs showed that EF was at least as effective as MB at the EF and MB concentrations recommended under the current phytosanitary disinfestation guidelines. From a logistical standpoint, EF gas could not effectively penetrate plastic bagging typically used in banana cartons during commercial shipping. Also, EF sorption to bananas and packing materials (used as cushioning inside bagging) further lowered realized EF concentrations around bananas. These reductions in EF concentration translated into reduced mortality of P. citri eggs, indicating that despite similar efficacy of MB and EF for controlling P. citri, further consideration and optimization of other industry logistics such as packaging and loading ratio is necessary to enhance the adoption of this MB alternative.

Assessing the Retest Reliability of Prefrontal EEG Markers of Brain Rhythm Slowing in the Eyes-Closed Resting State.

Objective. We examined whether prefrontal lobe EEG markers of slower brain rhythms, which are correlated with functional brain aging, can reliably reflect those of other brain lobes, as measured by a multichannel device. Methods. EEG measurements were taken of 112 healthy individuals aged 20 to 69 years in the eyes-closed resting state. A 5-minute measurement was taken at 8 regions (Fp1, Fp2, F3, F4, T3, T4, O1, O2). Indices (median frequency [MDF], peak frequency [PF]) that quantitatively reflect the characteristics of EEG slowing, and traditional commonly used spectral indices (absolute powers as delta, theta, alpha, beta, and relative power as alpha-to-theta ratio [ATR]), were extracted from the EEG signals. For these indices, the differences between the prefrontal lobe and other areas were analyzed and the test-retest reproducibility was investigated. Results. The EEG slowing indicators showed high conformity over all brain lobes and stable reproducibility. On the other hand, the typical EEG spectral indicators delta, theta, alpha, beta, and ATR differed between brain regions. Conclusion. It was found that EEG slowing markers, which were used for assessing the aging or degeneration of brain functions, could be reliably extracted from a prefrontal EEG alone. Significance. These findings suggest that EEG prefrontal markers may reflect markers of other brain regions when a multi-channel device is used. Thus, this method may constitute a low-cost, wearable, wireless, easily accessible, and noninvasive tool for neurological assessment that could be used in the early detection of cognitive decline and in the prevention of dementia.

Postharvest treatment of mandarin fruit using a combination of methyl bromide and phosphine against Bactrocera dorsalis (Diptera: Tephritidae).

BACKGROUND: Chinese Nanfeng mandarin (Citrus reticulate Blanco '2-6') fruit is host to the oriental fruit fly Bactrocera dorsalis Hendel, and therefore requires phytosanitary treatment before exporting abroad. The use of methyl bromide (MB) should be reduced because it has phytotoxic and ozone depleting properties. In the present study, fumigations with mixtures of gaseous phosphine (PH3 ) and MB were conducted to disinfest B. dorsalis. The effect of combined fumigation on postharvest quality of Nanfeng mandarin fruit was then evaluated. RESULTS: There was a clear synergistic effect between MB and PH3 against B. dorsalis at 20 °C. The third-instar larvae of B. dorsalis were the most tolerant to treatment with both MB alone and combined with PH3 . Toxicity assay of third instars indicated that higher PH3 concentrations increased MB toxicity, and 1.42-2.84 g m-3 of PH3 was optimal when combined with MB. Probit analysis showed that, combined with 2.13 g m-3 PH3 , similar mortality was achieved with 50% of the MB required when applied alone. Furthermore, the fruit quality test showed that MB fumigation resulted in a higher respiration rate and >40% fruit rot after storage. The combined treatment reduced these effects and did not have adverse effects on fruit firmness, soluble solid content, titratable acidity, or vitamin C content. CONCLUSION: Our findings demonstrate the synergistic effect between PH3 and MB and indicate that this treatment has potential as a novel strategy for postharvest control of B. dorsalis, especially in MB-sensitive fruit. © 2019 Society of Chemical Industry.