Low-cost reflective Hilger-Chance refractometer used to determine Sellmeier coefficients of bulk polydimethylsiloxane.

Refractometry is important for characterizing the optical performance of materials. The refractive index can quickly be assessed using critical angle or thin-film techniques. However, these methods only assess the material surface. Measurement of bulk refractive index is performed by measuring the refracted angle of a transmitted beam but requires precision sample geometry. The method presented here avoids costly sample preparation by measuring the sample geometry and refracted angle simultaneously, using reflections from the front and back surfaces of a wedge of material. The method is demonstrated for polydimethylsiloxane prepared under a range of curing conditions, and no significant dependence was observed. Spectral dependence is characterized, and Sellmeier coefficients are reported.

The Global Landscape of Occupational Exposure Limits--Implementation of Harmonization Principles to Guide Limit Selection.

Occupational exposure limits (OELs) serve as health-based benchmarks against which measured or estimated workplace exposures can be compared. In the years since the introduction of OELs to public health practice, both developed and developing countries have established processes for deriving, setting, and using OELs to protect workers exposed to hazardous chemicals. These processes vary widely, however, and have thus resulted in a confusing international landscape for identifying and applying such limits in workplaces. The occupational hygienist will encounter significant overlap in coverage among organizations for many chemicals, while other important chemicals have OELs developed by few, if any, organizations. Where multiple organizations have published an OEL, the derived value often varies considerably-reflecting differences in both risk policy and risk assessment methodology as well as access to available pertinent data. This article explores the underlying reasons for variability in OELs, and recommends the harmonization of risk-based methods used by OEL-deriving organizations. A framework is also proposed for the identification and systematic evaluation of OEL resources, which occupational hygienists can use to support risk characterization and risk management decisions in situations where multiple potentially relevant OELs exist.

Coccidioides exposure and coccidioidomycosis among prison employees, California, United States.

Responding to a request by corrections agency management, we investigated coccidioidomycosis in prison employees in central California, a coccidioidomycosis-endemic area. We identified 103 cases of coccidioidomycosis that occurred over 4.5 years. As a result, we recommended training and other steps to reduce dust exposure among employees and thus potential exposure to Coccidioides.

Untying a nanoscale knotted polymer structure to linear chains for efficient gene delivery in vitro and to the brain.

The purpose of this study was to develop a platform transfection technology, for applications in the brain, which could transfect astrocytes without requiring cell specific functionalization and without the common cause of toxicity through high charge density. Here we show that a simple and scalable preparation technique can be used to produce a "knot" structured cationic polymer, where single growing chains can crosslink together via disulphide intramolecular crosslinks (internal cyclizations). This well-defined knot structure can thus "untie" under reducing conditions, showing a more favorable transfection profile for astrocytes compared to 25 kDa-PEI (48-fold), SuperFect® (39-fold) and Lipofectamine®2000 (18-fold) whilst maintaining neural cell viability at over 80% after four days of culture. The high transfection/lack of toxicity of this knot structured polymer in vitro, combined with its ability to mediate luciferase transgene expression in the adult rat brain, demonstrates its use as a platform transfection technology which should be investigated further for neurodegenerative disease therapies.

Campylobacter infection in poultry-processing workers, Virginia, USA, 2008-2011.

During a health hazard evaluation, we investigated 29 cases of laboratory-diagnosed Campylobacter infection among workers at a poultry-processing plant. Most infected employees worked at the plant <1 month, worked as live hangers, and lived at a state-operated center. To lessen the infection risk, we recommended improvements to engineering and administrative controls at the plant.

The effectiveness of using interferon-gamma release assays in screening immigration employees for latent tuberculosis infection.

We assessed the prevalence of latent tuberculosis infection in immigration employees and compared two of the screening methods. Using a cross-sectional study design, we administered questionnaires regarding demographics, work, medical history, and tuberculosis risk factors to employees at two immigration facilities. Participants underwent tuberculin skin test (TST) placement and blood collection for the QuantiFERON-TB Gold in-Tube (QFT-GIT) assay. Fifty-four employees underwent QFT-GIT and TST placement. All QFT-GIT results were negative, and three employees tested TST positive. Twenty-three (49%) of 47 employees requiring two-step TST testing underwent second TST placement. Return rates for first and second TST reading were 76% and 74%, respectively. The QFT-GIT completion rate was higher than that for TST (100% vs. 39%, P < 0.001). Agreement between TST and QFT-GIT was 94%. Immigration employees had low return rates for their TST reading and second TST placement. Performing the one-visit QFT-GIT has administrative and logistical advantages in this occupational group.

Assessment of fungal contamination in moldy homes: comparison of different methods.

In an effort to better understand the relationship between different fungal sampling methods in the indoor environment, four methods were used to quantify mold contamination in 13 homes with visible mold. Swab, fungal spore source strength tester (FSSST), and air samples (total of 52 samples) were analyzed using both the microscopic (total spore count) and culture-based (CFU count) enumeration techniques. Settled dust samples were analyzed for culturable fungi only, as the microscopic enumeration was restricted by the masking effect. The relationships between the data obtained with the different sampling methods were examined using correlation analysis. Significant relationships were observed between the data obtained from swab and FSSST samples both by the total counting (r = 0.822, p < 0.05) and by the CFU counting (r = 0.935, p < 0.01). No relationships were observed between air and FSSST samples or air and settled dust samples. Percentage culturability of spores for each sampling method was also calculated and found to vary greatly for all three methods (swab: 0.03% to 63%, FSSST: 0.1% to > 100%, air: 0.7% to 79%). These findings confirm that reliance on one sampling or enumeration method for characterization of an indoor mold source might not provide an accurate estimate of fungal contamination of a microenvironment. Furthermore, FSSST sampling appears to be an effective measurement of a mold source in the field, providing an upper bound estimate of potential mold spore release into the indoor air. Because of the small sample size of this study, however, further research is needed to better understand the observed relationships in this study.

Assessment of the aerosolization potential for fungal spores in moldy homes.

UNLABELLED: The airborne fungal concentration measured with air samplers during specific time intervals may not adequately represent the indoor air quality because of the sporadic nature of spore release from sources. The conventional source evaluation (e.g. swab and tape sampling) characterizes the mold source but does not relate to the fraction of spores that can be aerosolized from a contaminated material. As an alternative to these methods, we have recently developed and laboratory-tested a novel Fungal Spore Source Strength Tester (FSSST). It allows assessing the potential of aerosolization of fungal spores from contaminated surfaces under the most favorable release conditions. In this study, the FSSST was used to characterize the release of spores from four building materials in mold-problem homes. The spores of different species were efficiently aerosolized by the FSSST, exhibiting a total spore release rate ranging approximately from 10(2) to 10(3) cm2/min. For all tested materials, <2% of the spores on the contaminated surface were released during the tests. The airborne spore concentration estimated from the release rate data was found in most cases to be significantly greater than the concentration actually measured in these environments with simultaneous air sampling. The results suggest that the FSSST can be used for the assessment of maximum potential exposure to airborne spores released from identified sources in homes. PRACTICAL IMPLICATIONS: A recently developed FSSST was found to be suitable to measure the aerosolization potential of indoor fungal sources at the most favorable release conditions. The FSSST generates the data that allows assessing the strength of mold sources in homes with respect to their maximum ability to contaminate indoor air with fungi. The novel approach bridges two conventional methods, the air sampling and the direct source evaluation (e.g. swab sampling), thus providing a better representation of the airborne fungal exposure than these methods individually. The device prototype can be used for evaluating the effectiveness of environmental interventions by taking samples before and after the intervention. As a broader application, the FSSST can be utilized for assessing the release of various hazardous biological and non-biological particles from contaminated surfaces.

Information dissemination and use: critical components in occupational safety and health.

BACKGROUND: Information dissemination is a mandated, but understudied, requirement of occupational and environmental health laws and voluntary initiatives. Research is needed on the factors that enhance and limit the development, transfer, and use of occupational safety and health information (OSH). Contemporary changes in the workforce, workplaces, and the nature of work will require new emphasis on the dissemination of information to foster prevention. METHODS: Legislative and regulatory requirements and voluntary initiatives for dissemination of OSH information were identified and assessed. Literature on information dissemination was reviewed to identify important issues and useful approaches. RESULTS: More than 20 sections of laws and regulations were identified that mandated dissemination of occupational and environmental safety and health information. A four-stage approach for tracking dissemination and considering the flow of information was delineated. Special areas of dissemination were identified: the information needs of the changing workforce, new and young workers; small businesses; and workers with difficulty in understanding or reading English. CONCLUSIONS: We offer a framework for dissemination of OSH information and underscore the need to focus on the extent to which decision-makers and others receive and use such information. More solid data are also needed on current investments in disseminating, diffusing and applying OSH information and on the utility of that information. Am. J. Ind. Med. 44:515-531, 2003. Published 2003 Wiley-Liss, Inc.

Prior stimulant treatment in adolescents with bipolar disorder: association with age at onset.

OBJECTIVES: To compare demographic and clinical characteristics between bipolar adolescents with and without a history of stimulant treatment, we hypothesized that adolescents treated with stimulants would have an earlier age at onset of bipolar disorder, independent of co-occurring attention-deficit-hyperactivity disorder (ADHD). METHOD: Thirty-four adolescents hospitalized with mania were assessed using the Washington University at St Louis Kiddie Schedule for Affective Disorders and Schizophrenia (WASH-U-KSADS). We systematically evaluated age at onset of bipolar disorder and pharmacological treatment history. RESULTS: Bipolar adolescents with a history of stimulant exposure prior to the onset of bipolar disorder had an earlier age at onset of bipolar disorder than those without prior stimulant exposure. Additionally, bipolar adolescents treated with at least two stimulant medications had a younger age at onset compared with those who were treated with one stimulant. There was no difference in age at onset of bipolar disorder between bipolar adolescents with and without ADHD. CONCLUSIONS: Our results suggest that stimulant treatment, independent of ADHD, is associated with younger age at onset of bipolar disorder. A behavioral sensitization model is proposed to explain our findings. There are several limitations to our study including the small sample size, the retrospective assessment of stimulant exposure and age at onset of bipolar disorder, and the inclusion of only hospitalized patients, who may be more likely to present with a severe illness. Nonetheless, future prospective longitudinal investigations that systematically assess the effects of stimulant medications in children with or at genetic risk for bipolar disorder are warranted.

Skin carcinogenicity of condensed asphalt roofing fumes and their fractions following dermal application to mice.

Condensed roofing asphalt fumes, generated at 316 degrees C, were collected by cold trap condensation and fractionated by preparative high performance liquid chromatography. Chemical classes in each of the fractions (A-E) were identified by gas chromatography/mass spectroscopy. The fractions, various combinations of fractions, the raw and heated asphalt, the neat asphalt fume and the reconstituted asphalt were tested for carcinogenicity, and three fractions were tested for cocarcinogenicity and tumor promotion with benzo[a]pyrene (BaP). The skin application carcinogenesis bioassay was conducted by twice weekly application of test materials in 0.05 ml of acetone/cyclohexane (1:1) for 104 weeks to 40 groups of male C3H/HeJ mice (30/group). Fractions were applied at a mass in proportion to their amount in the neat asphalt fumes. In addition, the neat asphalt fume was tested on Sencar mice to determine if this strain was more susceptible to the carcinogenic effects of the fumes. Condensed neat asphalt fumes produced similar and statistically significant increased tumor yields of papillomas and carcinomas in both strains as compared to respective vehicle controls. Recombination of all fractions resulted in a tumor response similar to neat asphalt fumes. Among individual fractions, C was most potent, followed by B. The other single fractions were without significant tumorigenic activity. Combinations containing fractions B and C were most active among the mixtures that were assayed and no evidence of enhancement of tumorigenesis in the mixtures was found. No significant cocarcinogenic or tumor promoting activity was observed with fractions A, D, or E and BaP. Raw unheated asphalt produced a few tumors in C3H mice, but no tumors were seen when raw asphalt heated to 316 degrees C, with the fumes permitted to escape, was applied.

[Use of digital photoluminescence radiography in traumatology. Report of experiences]. / Einsatz der digitalen Speicherfolienradiographie in der Traumatologie. Ein Erfahrungsbericht.

For more than 1 year we have had the opportunity of using a digital photoluminescence radiography system that allows documentation of the radiological findings on a high-contrast scale. In addition to chest X-rays this technical unit has been used to document skeletal findings in the skull, the cervical spine and the shoulder. In all, 211 cases have been evaluated in which digital and conventional X-rays have been taken during treatment. Using a 5-step confidence scale, two experienced investigators have evaluated and compared the digital and conventional X-rays. In respect of image quality, bone outline, and structure and identification of findings, digital documentation has proved at least as good as conventional documentation, and even superior in the case of shoulder X-rays. Improved image quality is caused by the superior bone outline. Therefore, we recommended digital photoluminescence radiography as a routine procedure for the documentation of findings in the skull, cervical spine and shoulder. Repeated investigations will become unnecessary and it will be possible to cope with large numbers of patients.

[The monitor findings of digitalized conventional wrist x-rays]. / Monitorbefundung digitalisierter konventioneller Handwurzelaufnahmen.

The study aimed at proving the reliability of monitor systems with the matrix of 1024 x 768 for the detection of scaphoid fractures compared to conventional X-ray. Moreover, we were interested in the significance of procedures of digital imaging post processing, depending in particular on the experience of investigators. 5 investigators with different levels of experience analysed 57 X-rays of the wrist. They compared conventional X-rays with images on a high screen monitor system after the digitalisation of these X-rays by a CCD-scanner and analysed untreated and treated images. A 5-point scale ROC analysis was used for evaluation. The analysis covered a total of 1740 evaluations. The untreated images seen on the monitor system proved slightly better than conventional X-rays. Post-processing has no evident advantage over untreated images. Differing levels of experience had no effect whatsoever on the identification of findings.

[Evaluation of underexposed conventional x-ray films following digitization]. / Auswertung fehlbelichteter konventioneller Röntgenaufnahmen nach Digitalisierung.

Inadequate exposure of analogue radiographs is reported in the literature to occur in 5-25% of cases. Therefore, the present study was performed to test whether selective image processing after digitization could reveal diagnostic details on underexposed radiographs. In addition, the minimal exposure values required for diagnostic purposes after adequate image processing were studied. Phantom studies, organ preparations and measurements of physical parameters with decreasing exposure values were performed. The detection of anatomic and pathologic (nondisplaced fracture lines, microcalcification and renal stones) structures were evaluated by 12 readers. Radiographs with exposure values 20-40% lower than "ideal" values can provide adequate diagnostic images after digital processing. The diagnostic information is significantly impaired with values under 50% of the correct exposure values. In conclusion, this method is adequate to save underexposed radiographs for diagnostic purposes and to avoid repeated examinations.

In vivo percutaneous absorption studies of volatile organic solvents in hairless mice. II. Toluene, ethylbenzene and aniline.

Percutaneous absorption studies were conducted with three single-ring, radiolabeled aromatic solvents (benzene derivatives) using a recently described direct method for studying volatile chemicals in hairless mice. Total absorption, determined from the sums of radioactivity found in the excreta, expired breath and carcass, was 2.1+, 3.4% and 4.7% of the nominal dose for toluene, ethylbenzene and aniline, respectively. Breath decay curves indicated that absorption of toluene and ethylbenzene was complete by 15 min after application and that by this time the excretion rate of aniline exceeded the absorption rate. Evaporation rates were used to derive estimated contact times, and these in turn were used in conjunction with the absorbed doses to estimate percutaneous absorption rates. Equivalent dermal exposures (cm2.min) that would yield body burdens equivalent to those expected following 8-h inhalations at existing US permissible exposure limits during light work were calculated. The data indicate that dermal absorption of these compounds could approach or exceed that from inhalation under some work conditions. Correlations between absorption and various physical properties were evaluated using Spearman's correlation coefficients. The physical properties evaluated included volatility, solubility, octanol/water partition coefficients and melting points. For this limited series of benzene derivatives, two measures of volatility, i.e. vapor pressure and boiling point, were the only physical properties significantly correlated with percutaneous absorption.

Occupational safety and health standards.

If we are to approach developing a safe and healthful workplace in a more timely fashion, a more generic approach must be considered and applied instead of developing recommendations and standards simply on a substance-by-substance basis, an approach that has been the most prominent. Some examples in which developing generic standards may be appropriate are: cholinesterase-inhibiting substances, neurotoxic agents, reproductive hazards, cold environments, and vibration syndrome, to name but a few. It is important to recognize that developing standards based on individual substances often does not allow for the role of synergism, a reaction that has had little study, but it is important in controlling occupational disease and injury. These concerns can be addressed in several ways. One is to look at processes or conditions found in the workplace; for example, coke oven emissions that OSHA has promulgated into a standard and, as NIOSH has done in their recommendations to OSHA for foundries, coal tar products, the manufacture of paint and allied coatings, field sanitation, hazardous waste management, hot environments, and confined spaces. Another is to address groups of similar substances such as NIOSH has done with alkanes, benzidine-based dyes, diisocyanates, dinitrotoluenes, and glycol ethers. A third comprehensive approach is to look at general categories of hazards, such as the generic carcinogen policy, and the hazard communication rule. Finally, risk must be considered in the development of any standard. Nelson Rockefeller once said in relation to an incidence involving a radiation hazard that, "you can't have a riskless society." I would amend this to say that you cannot have a reckless society either. Safety and health regulations are essential and must be designed, promulgated, and then enforced so that a reckless society is avoided or controlled, with a riskless society being the ultimate aim.

Interlaboratory studies with the Chinese hamster V79 cell metabolic cooperation assay to detect tumor-promoting agents.

Three laboratories participated in an interlaboratory study to evaluate the usefulness of the Chinese hamster V79 cell metabolic cooperation assay to predict the tumor-promoting activity of selected chemicals. Twenty-three chemicals of different chemical structures (phorbol esters, barbiturates, phenols, artificial sweeteners, alkanes, and peroxides) were chosen for testing based on in vivo promotion activities, as reported in the literature. Assay protocols and materials were standardized, and the chemicals were coded to facilitate unbiased evaluation. A chemical was tested only once in each laboratory, with one of the three laboratories testing only 15 out of 23 chemicals. Dunnett's test was used for statistical analysis, and differences between treated- and control-cell responses were analyzed at P less than or equal to .01. Chemicals were scored as positive (at least two concentration levels statistically different than control), equivocal (only one concentration statistically different), or negative. For 15 chemicals tested in all three laboratories, there was complete agreement among the laboratories for nine chemicals. For the 23 chemicals tested in only two laboratories, there was agreement on 16 chemicals. With the exception of the peroxides and alkanes, the metabolic cooperation data were in general agreement with in vivo data. However, an overall evaluation of the V79 cell system for predicting in vivo promotion activity was difficult because of the organ specificity of certain chemicals and/or the limited number of adequately tested nonpromoting chemicals.