Determination of methyl isobutyl ketone in urine by headspace coupled with gas chromatography-mass spectrometry / 中华劳动卫生职业病杂志

Objective: To establish a method for the determination of methyl isobutyl ketone (MIBK) in urine samples by headspace-gas chromatography-mass spectrometry. Methods: Automatic headspace sampling technique was adopted to optimize the headspace conditions (headspace bottle heating temperature and equilibration time) and gas chromatographic conditions. A total of 5 ml samples were taken and added with 3.0 g ammonium sulfate into a 20 ml headspace bottle. After heated at 60 ℃ for 30 mins, gas from the upper part of headspace bottle was injected into gas chromatography with an injection volume of 100 μl. The target was separated by HP-5MS UI (30 m×0.25 mm×0.25 μm) capillary column and then detected by mass spectrometry detector. The retention time and external standard method were used for qualitative and quantitative analysis of MIBK in samples, respectively. Results: The standard curve of MIBK showed significant linearity between 20.0-1 000.0 μg/L. The standard curve was y=62.9x-652.5, and the correlation coefficient r=0.9998. The detection limit of MIBK was 5.0 μg/L and the quantification limit of MIBK was 16.0 μg/L. The average recovery rate was 95.3%~100.2% at three spiked concentrations of low (50.0 μg/L) , medium (200.0 μg/L) and high (500.0 μg/L) . The intra-day and inter-day precisions were 1.7%~3.8% (n=6) and 1.2%~4.0% (n=6) respectively. This method was stable for the determination of MIBK, and the urine could be kept 14 d at -20 ℃ without significantly loss. Conclusion: This method is proved to be simple, practical and highly sensitive. It can satisfy the request for the determination of urine samples of workers exposed to MIBK.

Persistence and efficacy of a new formulation based on dog allomonal repellents against Rhipicephalus sanguineus sensu lato tick / Persistência e eficácia de uma nova formulação baseada em repelentes alomônios de cães contra o carrapato Rhipicephalus sanguineus sensu lato

Abstract Beagles are less susceptible to Rhipicephalus sanguineus sensu lato tick due to the production of the allomones benzaldehyde and 2-hexanone. Our previous published work showed that these compounds can reduce tick burden on susceptible dogs. Here we tested the hypothesis that an increase in repellent dose and release rate could increase repellent efficacy and persistence. Slow-release formulations of these compounds, with higher doses and release rates, were tested on artificially-infested dogs. Ten dogs were randomly assigned to two groups with five dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted once a day for 40 days. No significant increase in repellent efficacy was observed with the higher doses and release rates, whereas a greater persistence in repellent activity was observed. Treatment with the formulations resulted in a two-to-three-fold reduction in the number of immature stage ticks for up to three weeks. However, the number of adults was similar in both groups. Loss of repellent activity after the third week of testing coincided with a marked change in the relative release rates for the two compounds. It is hypothesized that relative amounts, rather than absolute amounts, of repellent release from slow-release formulations are important for repellent activity. We also hypothesize that the avoidance of less-preferred hosts by ticks relies on olfactory-mediated perception of specific blends of volatile cues from less preferred hosts.

Resumo Beagles são menos suscetíveis ao carrapato Rhipicephalus sanguineus sensu lato devido à produção de benzaldeído e 2-hexanona. Nosso trabalho anterior já publicado mostrou que esses compostos podem reduzir a carga de carrapatos em cães suscetíveis. Aqui testamos a hipótese de que um aumento na dose destes repelentes e na taxa de liberação poderia aumentar a eficácia e a persistência do efeito repelente. As formulações de liberação lenta destes compostos, com doses e taxas de liberação mais elevadas foram testadas em cães infestados artificialmente. Dez cães foram distribuídos aleatoriamente em dois grupos com cinco cães cada. O grupo tratado recebeu colares contendo formulações de liberação lenta dos compostos, enquanto o grupo controle recebeu colares com formulações limpas. Cinco infestações ambientais foram realizadas, com o número de carrapatos (em todas as fases) nos cães sendo contados, uma vez ao dia, por 40 dias. Não se observou aumento significativo na eficácia do repelente com doses e taxas de liberação mais elevadas e, enquanto observou-se maior persistência na atividade repelente. O tratamento com as formulações resultou em uma redução de duas a três vezes no número de carrapatos dos estágios imaturos, por até três semanas. No entanto, o número de adultos foi semelhante em ambos os grupos. A perda de atividade repelente após a terceira semana de teste coincidiu com uma mudança nas taxas de liberação relativa para os dois compostos. A hipótese é que as quantidades relativas, ao invés das quantidades absolutas de liberação lenta, são importantes para a atividade repelente. Então, a hipótese é de que a repelência apresentada por hospedeiros menos susceptíveis aos carrapatos depende da percepção pelos carrapatos de misturas específicas de voláteis liberados por estes hospedeiros.

Work Environments and Exposure to Hazardous Substances in Korean Tire Manufacturing

OBJECTIVES: The purpose of this study is to evaluate the tire manufacturing work environments extensively and to identify workers' exposure to hazardous substances in various work processes. METHODS: Personal air sampling was conducted to measure polycyclic aromatic hydrocarbons, carbon disulfide, 1,3-butadiene, styrene, methyl isobutyl ketone, methylcyclohexane, formaldehyde, sulfur dioxide, and rubber fume in tire manufacturing plants using the National Institute for Occupational Safety Health Manual of Analytical Methods. Noise, carbon monoxide, and heat stress exposure were evaluated using direct reading instruments. Past concentrations of rubber fume were assessed using regression analysis of total particulate data from 2003 to 2007, after identifying the correlation between the concentration of total particulate and rubber fume. RESULTS: Workers were exposed to rubber fume that exceeded 0.6 mg/m3, the maximum exposure limit of the UK, in curing and production management processes. Forty-seven percent of workers were exposed to noise levels exceeding 85 dBA. Workers in the production management process were exposed to 28.1degrees C (wet bulb globe temperature value, WBGT value) even when the outdoor atmosphere was 2.7degrees C (WBGT value). Exposures to other substances were below the limit of detection or under a tenth of the threshold limit values given by the American Conference of Governmental Industrial Hygienists. CONCLUSION: To better classify exposure groups and to improve work environments, examining closely at rubber fume components and temperature as risk indicators in tire manufacturing is recommended.

Occupational Diseases in Workers Exposed to Organic Solvents / 한양의대학술지

Organic solvents are hydrocarbon-based substances that dissolve another substance. Organic solvents are usually lipid soluble, volatile and commonly used for painting, printing, degreasing, cleaning, thinning and extraction. Due to their volatility and lipid solubility, organic solvents are easily absorbed across the alveolar-capillary membrane and through the skin. Because organic solvents are lipophilic, they tend to be distributed to lipid-rich tissue, such as adipose tissue, nervous system and liver. Almost all organic solvent can induce skin diseases such as acute irritant dermatitis and chronic eczema. Some organic solvents are associated with allergic contact dermatitis. General and nonspecific central nervous system depression is another common toxic effect induced by most organic solvents. It shows symptoms which are the same as those from alcohol drinking, and those symptoms are completely resolved by removal from exposure to solvents. Long term and repeated exposures to organic solvents can also lead to chronic adverse neurobehavioral effects. These effects are also called as chronic toxic encephalopathy, chronic solvent intoxication and psycho-organic syndrome, and commonly reported symptoms of them are headache, depression, anxiety, and impairment of recent memory. Organic brain lesions can be found in workers suffering from psycho-organic syndrome, and in this case, there is a possibility of persistent disabilities. Carbon disulfide, n-hexane, and methyl n-butyl ketone are specifically toxic to the peripheral nervous system, and cause a symmetric ascending sensory and motor polyneuropathy. Halogenated hydrocarbons including carbon tetrachloride show toxic effects on the heart, liver, kidney, and blood. Toluene can sensitize the heart to arrhythmogenic effects of epinephrine, so sudden death in young and healthy people can be ensued from glue sniffing. Benzene is able to induce any type of leukemia, especially in victims with benzene-associated aplastic anemia. Exposure to some solvents during pregnancy has potential to induce congenital malformation and spontaneous abortion. In the treatment of diseases by organic solvents, the first step should be removal from exposure to the causative solvent.

Ototoxicidad en trabajadores expuestos a disolventes orgánicos / Ototoxicity in workers exposed to organic solvents

Objetivo: describir los efectos ototóxicos que provocan diversas mezclas de disolventes orgánicos en trabajadores expuestos. Diseño: estudio observacional, descriptivo y comparativo de trabajadores activos, expuestos y no expuestos a mezclas de disolventes orgánicos. Material y métodos: 111 trabajadores de tres empresas expuestos directamente a disolventes orgánicos en las áreas de producción; y 111 de un centro hospitalario, no expuestos. Se registraron los resultados de los estudios audiométricos, los de la medición ambiental de disolventes orgánicos y de sonidos de gran magnitud en el medio ambiente laboral.Resultados: los trabajadores expuestos a disolventes orgánicos tuvieron un riesgo 12 veces mayor para alteraciones auditivas, a diferencia de los no expuestos, con una p < 0.0008 (IC95 por ciento = 1.21-84.29). La ototoxicidad se caracterizó por cortipatía bilateral. No se identificó sintomatología en ninguno de los grupos examinados. Resultados: de los trabajadores expuestos, 63 presentaron hipoacusia sensorial superficial o media, identificada a través de estudios audiométricos y con diapasón; el perfil fue característico. En los restantes no se observó daño auditivo. De los trabajadores no expuestos, cinco presentaron alteraciones auditivas ocasionadas por procesos infecciosos. Conclusión: la frecuencia de cortipatía bilateral en trabajadores expuestos laboralmente a mezclas de disolventes fue mayor que en el grupo no expuesto. El daño predominante fue hipoacusia sensorial, superficial o media.