Evaluation of methyl bromide exposure on the plant quarantine fumigators by environmental and biological monitoring

The Impact of Hydrogen Peroxide (H2O2) Fumigation on Bacterial Levels in Dental Office Environments: A Randomized Clinical Trial Investigation

BACKGROUND

Fumigation with hydrogen peroxide has proven to be a highly effective approach to maintaining biological safety within dental offices. The main purpose of this research was to investigate the efficacy of hydrogen peroxide (H2O2) fumigation in reducing bacterial levels in dental office environments.

METHODS

The study involved 30 participants diagnosed with moderate caries decay (ICDAS 3 and 4) in their mandibular molars. Sixty Petri dishes (two per patient) with Columbia Agar and 5% Sheep Blood were opened at the beginning of the caries treatment. After the completion of caries treatment and tooth restoration, 30 plates (G1 group) were closed. Following this, a 20 min fumigation procedure with 6% hydrogen peroxide biosanitizer using a compressed air device was conducted. After the fumigation, the remaining plates were closed (G2 group). The total number of bacteria CFUs (colony-forming units) in the dental office air was determined using the Koch sedimentation method.

RESULTS

The total bacterial colony (TBC) level, measured in cfu/m3, demonstrated a significant decrease in the number of bacteria following room environment fumigation (163.1 ± 145.7; G2 group) compared to non-fumigated samples (817.2 ± 208.2; G1 group) (p < 0.001). The predominant bacteria observed in the microbiological plates before fumigation were Micrococcus and Bacillus species, found in 80% (24/30) and 60% (18/30) of the plates, respectively. Application of H2O2 room fumigation resulted in a significant reduction in bacterial numbers: 79.2% (5/30) for Micrococcus species (p < 0.001), 83.3% (3/30) for Bacillus species (p < 0.001), and 100% (0/30) for Staphylococcus arlettae (p < 0.05).

CONCLUSION

Fumigation with 6% H2O2 is an effective method for reducing bacterial counts in a dental office environment.

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.

Analysis of biomonitoring data to assess employer compliance with OSHA's permissible exposure limits for air contaminants

BACKGROUND

The Occupational Safety and Health Administration (OSHA) regulates exposures to hazardous chemicals in workplace air. When contemporaneous exposure measurements are unavailable, retrospective analysis of biomarkers could provide valuable information about workers' exposures.

METHODS

Single-compartment pharmacokinetic (PK) models were created to relate the concentration of a chemical in the air to the concentration of the chemical or its metabolite in workers' blood or urine. OSHA utilized the PK models in investigations of three fatal incidents in which workers were exposed to nickel carbonyl, methyl bromide, or styrene. To obtain the minimum plausible estimate of each exposure, OSHA used conservative assumptions about parameters such as workers' inhalation rates, baseline levels of biomarker, and chemicals' volumes of distribution.

RESULTS

OSHA analyzed a worker's urinary nickel concentration and concluded that his 8-h time-weighted average exposure to nickel carbonyl was at least 0.06 mg/m³ . Analysis of a worker's postexposure, premortem blood bromide level revealed that his exposure to methyl bromide was at least 181 mg/m³ . Post-mortem blood styrene measurements suggested that a third worker's exposure to styrene was at least 625 mg/m³ . These exposures exceeded OSHA's permissible exposure limits of 0.007 mg/m³ for nickel carbonyl, 80 mg/m³ for methyl bromide, and 426 mg/m³ for styrene. OSHA successfully cited the three employers for violations of chemical exposure limits.

CONCLUSIONS

Analysis of biomarkers via PK modeling enables retrospective evaluations of workers' acute exposures to hazardous chemicals. These techniques are useful to occupational regulators who assess employer compliance with mandatory exposure limits.

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

To determine whether methyl bromide (MB) fumigation work for plants imported in Korea affects workers’ health by assessing heart rate variability (HRV).

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.

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.

Health Profiles of Methyl Bromide Applicators in Greenhouses in Turkey

Introduction: Methyl bromide is a toxic substance that has hazardous effects on human health with acute and chronic exposure. Our previous study showed that methyl bromide applicators frequently use large amounts of methyl bromide haphazardly in greenhouses in the prefectures of Narlidere and Balcova in the Aegean city of Izmir. This study aims to evaluate the health conditions of these workers. Materials and Methods: Our previous study showed that there are 38 methyl bromide applicators in our study area. After the informed consent of methyl bromide applicators was obtained, a questionnaire was used for a survey of demography and symptoms. Each subject was examined before and after application of the compound. Blood and urine samples were collected and stored. Blood samples were analysed for methyl bromide and bromide ion, kidney and liver function tests and lipid profile. Results: The age range of subjects was 19 to 53 years (mean age: 41 ± 8.57). This study showed that methyl bromide applicators use large amounts of methyl bromide disregarding legal regulations and that some of them had non- specific complaints. Subjects had been working as methyl bromide applicators for approximately 9.7 ± 4.15 years. A total of 69.7% of methyl bromide applicators reported that they did not use protective equipment while 33.3% of them had a history of acute methyl bromide intoxication. A statistically significant relationship was found between the usage of protective equipment and the level of blood bromide ion in the blood (P <0.05). Conclusion: Usage of methyl bromide, training, screening and follow-up of applicators must be rigorously controlled in accordance with national legal arrangements and international protocols. Greater efforts are required in the implementation of controls to achieve the targets set by the legal regulations and to ensure continual improvement in the limitation of the risks of this environmental hazard. Key words: Applicator’s health, Chronic exposure, Forensic medicine, Greenhouse workers

Photometric determination of human serum bromide levels--a convenient biomonitoring parameter for methyl bromide exposure

Methyl bromide is one of the most important pesticides for the control of insects, fungi and nematodes. Serum bromide has been proposed as a biomonitor for occupational exposure to methyl bromide. Therefore, a novel, sensitive photometric method was developed for the determination of serum bromide at concentrations relevant for such exposure. Further possible applications are monitoring of intoxication victims and halothane narcosis. Using the method we have established a mean serum bromide level of 4.13 +/- S.D. 1.05 mg/l (n/64) in a group of healthy female and male volunteers not knowingly exposed to bromide or bromine containing organics. Serum of a subject accidently exposed to methyl bromide revealed a bromide level of 11.5 mg/l serum, while two individuals exposed to methyl iodide had no elevated levels. A group of 30 agricultural workers showed a mean serum bromide level of 15.33 +/- S.D. 1.90 mg/l at the end of the methyl bromide application season.