Half help 2010.03.19

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Mar 19, — Kaiser Permanente San Jose Medical Center has begun employing a ZigBee-based real-time locating system RTLS to help its staff more easily locate items for equipment maintenance or clinical use, as well as to track the temperatures of its cooling and warming units. The bed facility handles 35, outpatient visits and delivers 2, babies annually. The article, published in The Permanente Journal , further found that 6. The statistics in the report were based on data collected at 36 hospital medical-surgical units within 17 health-care systems and 15 states.

Login and post your comment! Login Register Now Not a member? Very—this will likely boost NFC's adoption in consumer markets. Somewhat—it's a big step, yes, but a rather over-hyped one. Not very—many retailers still don't accept NFC payments. Terms of Use Privacy Policy. By Claire Swedberg Tags: Several on-line, real time or near real time samplers have been develop to provide temporal information of benzene concentrations. Occupational exposures at the ppm levels can be measured using mid-infrared diode laser with Fourier transform infrared FTIR single-beam spectrophotometer [ 19 ], while ppb have been reported using automated GC systems concentrate air prior to injection [ 20 , 21 ], mass spectrometers with atmospheric pressure interfaces [ 22 , 23 ], proton transfer reaction mass spectrometer PTR-MS [ 24 ], and membrane interface mass spectrometry [ 25 ].

Biomarkers of benzene exposure include unmetabolized benzene in the blood, breath and urine, urinary benzene metabolites and benzene adducts in DNA, hemoglobin and albumin. It is essential when measuring benzene blood levels in the general populations to take special care to clean all components, particularly any rubber, such as the tops of vacutainers [ 28 , 29 ]. Since benzene is volatile, losses during collection, storage and analysis are possible. Ring hydrolyzed urinary benzene metabolites: Some metabolites can be excreted as glucuronide or sulphate conjugates which require hydrolysis by acid or enzymatically to measure the total amount excreted and the proportion bound and unbound excreted [ 33 , 34 ].

Use of an internal standard is routine to improve precision. Urine excretion rate varies within and between individuals depending on the amount and types of liquid ingested over the course of a day, Collection of complete urine voids over time is difficult. Therefore, some researchers correct urinary concentrations by comparing the metabolite levels to the amount of creatinine excreted or to the specific gravity of the sample, though others have suggested that actual concentration is the better metric to report since creatinine excretion rate is not constant in active people over the course of a day [ 49 ].

However, a review of the benzene exposures in the shoemaking industry in China through still identified concentrations exceeding ppm [ 6 ] which appears to continue currently [ 50 ] and as reported elsewhere in this journal for the Shanghai Health Study. The need for regulation and better working conditions in small work shops in China has been suggested [ 51 ].

Time weighted average TWA air concentrations ppm across different industries that have potential benzene exposures. Workers who are part of the transportation industry, such as drivers and service station workers, and individuals in occupation that are near traffic, such as police officers are exposed to levels of tens to hundreds of ppb [ 52 — 55 ]. Peak values for mechanics who are exposed directly to gasoline fumes can approach ppm levels [ 56 — 58 ]. A recent study from Thailand identified that temple workers who continually burn incense are exposed to benzene at 0.

San Jose Medical Center Installs ZigBee-based RTLS Across 10 Buildings

Personnel air concentrations on average exceed indoor air concentrations, which exceed outdoor air concentrations Table 3. This trend is most evident for the highest personal air concentrations where the outdoor levels serve as a baseline for the levels indoors. Further, proximity to sources and specific activities can add to benzene exposures. Since people spend the majority of their time in indoor microenvironments, contributions to exposures indoors have a larger influence on exposure than time spent outdoors [ 62 — 64 ].

Exposure levels for individuals who are and live with smokers are higher because benzene, along with other VOCs and particulate matter, are emitted from cigarette smoke [ 65 ]. Therefore, a number of studies measuring personal and indoor air have recruited populations of non-smokers to better understand non-cigarette sources for these compounds. Typical US personal exposure concentrations and outdoor air levels have declined from a range of 2—10 ppb includes smokers and 0. Levels in urban settings in South Korea and Thailand were 5—10 times higher for outdoors, indoors and personal air [ 55 , 70 ].

Therefore avoiding ETS can reduce benzene exposures. Average and maximum personal, residential indoor and outdoor air concentrations ppb for environmental studies. A source of benzene to residences is evaporation of gasoline from the residual in the engine and from the fuel tank in cars parked in garaged attached to homes, particularly since the car is hot after it has been driven.

The benzene levels in a garage can be tens to hundreds of ppb but decline with time presenting short term high exposure when the garage is entered. The levels in the home are increased by several ppb with the value being dependent upon the tightness of the seal between the home and the garage and the air exchange between the two [ 77 — 80 ].

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Benzene has been measured in non-residential indoor environments in the US, Europe and Australia Table 4 [ 82 — 86 ]. One major policy issue that has decreased benzene exposure in public places has been a ban on cigarette smoking in many public spaces and in workplaces. This has resulted in reducing benzene air levels in those locations and an effective decline in general population benzene exposures [ 65 , 87 , 88 ].

Average and maximum non-residential indoor air concentrations ppb for environmental studies. The benzene levels within automobiles and encountered during commuting are higher than in other microenvironments resulting in these activities contributing to a considerable percentage of the total daily benzene exposure [ 89 ].

Benzene exposures vary across different modes of transportation, dependent upon the traffic density surrounding and the design of the vehicle driven. Older cars with carburetors released more benzene and were subject to more frequent leaks of small amounts of gasoline into the engine block that could penetrate into the automobile cabin than fuel injection engines [ 90 ].

This could still be an issue in developing countries where cars are kept for a longer time and can be maintained by individuals with little formal training on repairs. Exposure during walking or bicycle riding adjacent to or in roadways is 2—3 times background levels [ 85 , 95 ]. Since gasoline emissions affect benzene air concentrations during transportation and in homes with attached garages, reducing the permitted benzene content in fuel has had a direct decline in exposure for the general public.

Personal, microenvironmental and ambient air samples for benzene are typically collected over an extended time period, 12 to 48 h, therefore do not identify peak concentrations [ 96 ]. Short term excursions in benzene air concentrations and exposures exist around activities close to sources [ 97 ]. Refueling of automobiles results in exposure to benzene levels of 20— ppb over 2—5 min both to the individuals fueling the car and within the vehicle being fuelled [ 57 , 98 — ].

However, differences in the emissions occur based upon whether or not control devices are present at the fuel pump. Included are Stage II vapor recovery systems which recycle the fumes from within the gasoline tank and displaced by gasoline to the underground storage tank [ ]. Individuals who have hobbies that results in exposure to gasoline, such as fixing automobile engines, can receive elevated short term or long-term benzene exposures. However, if the prevalence of the hobbies is low in the general population few of these individuals would be captured in typical exposure studies so the highest exposures that occur in the general population would be poorly characterized.

These activities could possibly be identified within surveys of activities if the appropriate questions are asked. Dermal and ingestion exposure to benzene can also occur in the general public from contact with contaminated water or food. The measurement of benzene in blood, breath or urine definitively documents a benzene exposure. However, the biological resident time of benzene in the body is minutes to hours [ ] so it is difficult to determine the actual and in some cases even the relative exposures across individuals from a single benzene measurement in blood or breath unless details of when the sample was collected relative to the exposure are known.

Routine exposures to benzene can increase the background body burden so differences in benzene levels in blood, breath and urine can help distinguish between exposed and non-exposed populations particularly for occupational exposures and for smokers vs. For example, benzene blood concentrations distinguished three groups of occupationally exposed workers in Mexico: Individual benzene blood levels were not highly matched to the paired air concentration as the latter were average values over time while the blood concentrations were reflective of the exposure during the last minutes prior to the blood collection.

Thus, if short term excursions or valleys of durations of a few minutes exist in the exposure just prior to the blood collection, the air sample and blood sample would represent different exposure concentrations. Benzene blood levels measured as part of the National Health and Nutritional Examination Survey NHANES [ , ], have been compared to benzene air concentrations to determine their applicability as a biomarker and have been used to try to distinguish between benzene exposed and non-exposed workers on a population basis.

A larger difference was identified in both the geometric mean and 75th percentile benzene blood concentration of smokers compared to non-smokers factor of 3 than across the range of air concentrations for these two groups. Smoking workers who are exposed to low occupational benzene exposures also have higher blood benzene levels than non-smokers in the same industry, though urinary benzene levels of smokers were not consistently higher than nonsmokers Table 5. Benzene blood levels are higher after work shifts compared to before work shifts while no differences were noted in pre- and post-shift samples for a reference group not exposed to benzene.

Individual paired urinary benzene concentration pre and post-shift samples do not always show increases in the post-shift samples which may reflect benzene exposure that occurred during the previous work shift and from the environment. Blood and breath benzene levels have biological half lives of seconds to minutes while urinary benzene levels reflect exposures since the previous one to two voids for single exposure.

Individuals who are routinely exposed to benzene will have elevated background benzene in these biological fluids compared to a non-exposed population, though their peak benzene levels will be within minutes of the end of the exposure. Thus, while these metabolites have been used as biomarkers in early occupational studies when the exposures exceeded 10ppm their background urinary levels preclude their use as a biomarker for exposures at lower occupational or environmental exposures. Urinary metabolite levels represent exposures of the previous several hours for brief exposures though can be elevated for days for routinely exposed individuals after the exposure has stopped.

These results suggest that it is a valid biomarker for sub-ppm exposures Table 5. However, level of urinary t,t MA have not always been related to air concentrations of benzene [ ]. One possible reason is t,t MA is also a metabolite of sorbic acid a common food additive resulting in increases in urinary t,t MA in the absence of benzene exposure [ 39 , ]. The population mean t,t MA urinary levels across a number of occupations with benzene exposures from 10 to several hundreds of ppbs traffic policeman, oil refinery worker, press worker, fishermen, gas station attendants, mechanics were 2—33 times higher than levels in controls in a number of studies [ ].

Urinary s PMA has been proposed as a better biomarker than t,t MA for benzene exposure below 1ppm [ ]. Urinary s PMA has been shown to increase with benzene exposure at sub-ppm levels and has no other known sources besides benzene exposures Table 5. One study though, did not find either t,t MA or s PMA related to benzene exposure ranging from 10 ppb to ppm levels while urinary benzene was and observed that smoking status was a key factor influencing urinary benzene levels [ ].

1. Introduction

Benzene adducts have been proposed as biomarkers of longer term benzene exposure since several benzene metabolites include reactive electrophiles: Hemoglobin adducts have biological half lives approximate four months, the average lifespan of red blood cell, while DNA adducts can have longer residence time dependant upon how long cells containing the DNA remain in the body.

Protein adducts in serum were higher in exposed workers compared to controls 0. Hemoglobin adducts of benzene oxide have been measured in dried blood spots of neonates and adults and suggested to be linked to benzene exposure [ ]. While benzene adducts hold promise of being a valid biomarker of exposure most laboratories do not have the analytical capability to measure them with the necessary sensitivity. The internal dose of benzene and the percentage of benzene that is metabolized to each metabolite vary with exposure level.

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In addition, genetic difference could also alter metabolism efficiencies of benzene across different pathways, with a number of different polymorphism suggested to be important, including: These variations could alter the risk extrapolation from high to low exposures and need to be considered when evaluating the potential health impact of low occupational and environmental exposures. Benzene exposures still commonly occur within both occupational and environmental settings, though they have been declining over the last several decades.

Occupational exposures are now typically below the regulatory standard of 1ppm and often below 0. A comparison of the ranges of benzene exposures is presented in Fig. Exposures to the general population from these sources have been reduced significantly outdoors and indoors by lowering the benzene content in gasoline and prohibiting smoking in many public places. Data gaps for identifying exposures potentially leading to health risks to the general population are identifying the highest non-occupationally exposed populations globally and peak environmental exposures that occur for the general population.

Several biomarkers, urinary benzene, t,t MA and s PMA along with benzene adducts are potentially valid at occupational and environmental exposures below 0. Further, the percent of the benzene dose that is excreted as each metabolite appears to vary going from 10 ppb exposures to 10ppm exposures and may be altered by polymorphisms in various genes controlling benzene metabolism.

The importance of such variations in benzene metabolism on an extrapolation of health risk from occupational exposures of tens to hundreds of ppm to exposures of tens of ppb is not known. The key to understanding and determining how to best reduce exposure will be a combination of valid biomarker measurements and an exposure analysis of important contacts to elucidate the sources of benzene exposure. National Center for Biotechnology Information , U. Author manuscript; available in PMC May 3.

The publisher's final edited version of this article is available at Chem Biol Interact. See other articles in PMC that cite the published article. Abstract Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures.

Benzene, Exposure, Biomarkers, Environmental, Occupational. Introduction Human exposure characterization is a necessary component of environmental and occupational epidemiological studies, risk characterizations and risk management. Table 1 Occupational standards for benzene air concentrations. Open in a separate window. Methodologies for measuring benzene exposure 2. Air samples To determine benzene and other non-polar volatile organic compounds VOCs air concentrations, the major pathway for benzene exposure, samples are collected from the air on either an adsorbent or by trapping whole air in a container.

Real-time monitors Several on-line, real time or near real time samplers have been develop to provide temporal information of benzene concentrations.

Benzene exposure: An overview of monitoring methods and their findings

Biomarkers measurements Biomarkers of benzene exposure include unmetabolized benzene in the blood, breath and urine, urinary benzene metabolites and benzene adducts in DNA, hemoglobin and albumin. Table 2 Time weighted average TWA air concentrations ppm across different industries that have potential benzene exposures. Table 3 Average and maximum personal, residential indoor and outdoor air concentrations ppb for environmental studies.

Table 4 Average and maximum non-residential indoor air concentrations ppb for environmental studies. Biomarkers The measurement of benzene in blood, breath or urine definitively documents a benzene exposure. Benzene in blood and urine Routine exposures to benzene can increase the background body burden so differences in benzene levels in blood, breath and urine can help distinguish between exposed and non-exposed populations particularly for occupational exposures and for smokers vs.

Benzene adducts Benzene adducts have been proposed as biomarkers of longer term benzene exposure since several benzene metabolites include reactive electrophiles: Variability in benzene metabolism The internal dose of benzene and the percentage of benzene that is metabolized to each metabolite vary with exposure level.

Discussion Benzene exposures still commonly occur within both occupational and environmental settings, though they have been declining over the last several decades. Ranges of Reported benzene air concentrations in different microenvironments. Footnotes Conflicts of interest None declared. Exposure analysis and assessment in the 21st century. Human exposure assessment in air pollution systems. The Scientific World Journal. Leukemia in benzene workers. American Journal of Industrial Medicine. Rinsky RA, et al. An epidemiologic risk assessment. New England Journal of Medicine. Wang L, et al.

Benzene exposure in the shoemaking industry in China, a literature survey, — Verma DK, des Tombe K. Benzene in gasoline and crude oil: An overview of occupational benzene exposures and occupational exposure limits in Europe and North America. The exposure of the general population to benzene. Environmental exposure to benzene: Acritique of benzene exposure in the general population. Science of the Total Environment. Hinwood AL, et al. Sexton K, et al. Estimating volatile organic compound concentrations in selected microenvironments using time-activity and personal exposure data.

Meneses F, et al. A survey of personal exposures to benzene in Mexico City. Archives of Environmental Health. Passive badges for compliance monitoring internationally. American Industrial Hygiene Association Journal. Stock TH, et al. Evaluation of the use of diffusive air samplers for determining temporal and spatial variation of volatile organic compounds in the ambient air of urban communities. Pratt GC, et al. A field comparison of volatile organic compound measurements using passive organic vapor monitors and stainless steel canisters. Wilbur S, et al.

ATSDR evaluation of potential for human exposure to benzene. Jeffers JD, et al. Real-time diode laser measurements of vapor-phase benzene. Tzoumaka P, et al. Clark A, et al. Comparison of photoionization detection gas chromatography with a Tenax GC sampling tube procedure for the measurement of aromatic hydrocarbons in ambient air.

International Journal of Environmental Analytical Chemistry. Gullett BK, et al. Real-time emission characterization of organic air toxic pollutants during steady state and transient operation of a medium duty diesel engine. Chen Q-F, et al. Journal of Hazardous Materials. Velasco E, et al. Atmospheric Chemistry and Physics. Etzkorn J, et al. Journal of Chromatographic Science.

Blount BC, et al. Quantification of 31 volatile organic compounds in whole blood using solid-phase microextraction and gas chromatography-mass spectrometry. Journal of Chromatography B: Ashley DL, et al. Measurement of volatile organic compounds in human blood. Chambers DM, et al. An improved approach for accurate quantitation of benzene, toluene, ethylbenzene, xylene, and styrene in blood.

Cardinali FL, et al. Treatment of vacutainers for use in the analysis of volatile organic compounds in human blood at the low parts-per-trillion level. Rothman N, et al. Urinary excretion of phenol, catechol, hydroquinone, and muconic acid by workers occupationally exposed to benzene. Lee BL, et al.

Simultaneous determination of hydroquinone, catechol and phenol in urine using high-performance liquid chromatography with fluorimetric detection. Journal of Chromatography A. Melikian AA, et al. Development of liquid chromatography—electrospray ionization-tandem mass spectrometry methods for determination of urinary metabolites of benzene in humans. Research Report—Health Effects Institute.

Inoue O, et al.

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Determination of catechol and quinol in the urine of workers exposed to benzene. British Journal of Industrial Medicine. Weisel CP, et al. Use of stable isotopically labeled benzene to evaluate environmental exposures. Journal of Exposure Analysis and Environmental Epidemiology. A sensitive liquid chromatographic method for the spectrophotometric determination of urinary trans, trans-muconic acid.

Hu X-M, et al. High-performance liquid chromatographic determination of urinary trans, trans-muconic acid excreted by workers occupationally exposed to benzene. Sample preparation followed by high performance liquid chromatographic HPLC analysis for monitoring muconic acid as a biomarker of occupational exposure to benzene. Marchese S, et al. Rapid Communications in Mass Spectrometry. Negri S, et al. High-pressure liquid chromatographic-mass spectrometric determination of sorbic acid in urine: Tranfo G, et al. Yu R, Weisel CP.

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