Objective: Worldwide demand has increased for the development of a computed tomography (CT) classification system that supplements the ILO classification of radiographs for pneumoconioses. The authors aimed to show preliminary reliability test results for selected referent films for the CT classification system developed through an international effort by researchers from seven countries. Methods: Reading trials by eight physicians who have considerable experience in pneumoconioses using a total of 114 lung zones consisting of 6 lung zones of 19 CT films of dust-exposed workers were performed to assess reliability of the classification system by weighted κ. The results were also utilized for selecting reference films. Results: A good agreement was observed for both first and second reading trials for rounded opacities (weighted κ=0.76, 0.74, first and second trial results, respectively), irregular opacities (0.60, 0.48), emphysema (0.56, 0.70) and honeycombing (0.72, 0.79). Ground glass opacities, on the other hand, showed moderate agreement (0.43, 0.38). Intra-reader agreements among eight readers were shown in the same table as the mean and standard deviation of weighted κ statistics. The inter-reader agreement for pleural thickening was not as good as for parenchymal lesions. Discussion: The CT classification development may pioneer noble and sensitive medical screening for dust-exposed workers in selected settings. This system may be applied to radiographic borderline cases of profusion 0/1 and 1/0 by the ILO classification, in a setting that assures the occupational safety and health of workers exposed to some newly developed chemical compounds.

The valence shell spectroscopic and thermodynamic properties of thiophene have been investigated through photoabsorption and ion fragmentation studies. The absolute photoabsorption cross-section has been measured between the ionisation threshold and 35 eV using a double ion chamber and synchrotron radiation. New Rydberg series converging onto either the B∼2A1 or the G∼2A1 limits have been observed. The photoabsorption spectrum is dominated by broad features due to intravalence transitions, and tentative assignments have been proposed based upon a term value analysis. Time-of-flight mass spectra have been recorded in the photon energy range 12–28 eV and these have allowed the appearance energies for 18 fragment ions and the doubly charged parent ion to be determined. Molecular orbital calculations have been performed to compute the energies of several neutral or ionic species relevant to the lowest energy fragmentation channel. These energies, when compared with the experimental data, help to define the ion formation mechanisms.

BACKGROUND:Despite a reported decline in mortality and hospitalizations associated with silicosis [U.S. Department of Health and Human Services, 1999], this decline may be artifactual, stemming in part from underdiagnosis by physicians.METHODS:This study estimates, through radiological confirmation, the prevalence of unrecognized silicosis in a group of silica-exposed New Jersey decedents whose cause of death was chronic obstructive pulmonary disease (COPD), tuberculosis, or cor pulmonale. Two expert readers re-evaluated the chest X-rays of this group to determine the presence or absence of silicosis. The study population was considered to be presumptively exposed to silica dust by virtue of their usual industry of employment as listed on the death certificate.RESULTS:Radiographic evidence of silicosis was found in 8.5% of this population, and evidence of asbestosis was found in another 10.7%, for a total of 19.2%.CONCLUSIONS:The existence of previously unrecognized silicosis and asbestosis in 19.2% of this study group suggests that occupational lung disease is under-recognized and, hence, undercounted.

The unimolecular decomposition of internal-energy-selected furan molecular ions has been studied by means of threshold-photoelectron–photoion coincidence spectroscopy. Monochromatic synchrotron radiation was used as the ionisation source, and the molecular ion internal energy was established through the detection of a threshold electron. A pulsed electric field was applied to extract the ions from the interaction region and direct them towards a time-of-flight mass spectrometer. Breakdown curves were measured for photon energies up to 30 eV, and these have allowed appearance energies for a wide range of fragment ions to be determined. In the threshold region the breakdown curves have been measured for various ion residence times by introducing electronic delays between the detection of the threshold electron and the application of the ion extraction field. The breakdown curves have been modelled using the RRKM (Rice, Ramsperger, Kassel and Marcus)/QET (quasi-equilibrium theory) approach, and this has allowed activation energies and transition state geometries to be deduced. The threshold photoelectron spectra of furan-h4 and furan-d4 have been measured from the ionisation threshold to 28 eV, and vibrational structure has been observed and assigned in the bands due to the X2A2, the A2B1 and the G2A1 states. Vibrational progressions discernible between 16.2 and 17.3 eV have been attributed to autoionisation from a p-type Rydberg series converging onto the G2A1 state ionisation threshold.

The design, construction and performance of a threshold-photoelectron–photoion coincidence (TPEPICO) spectrometer for the study of unimolecular decomposition in polyatomic ions is described. The spectrometer incorporates a hemispherical electrostatic energy analyser and a time-of-flight (TOF) mass spectrometer. The entrance lens to the hemispherical analyser has been designed to have a high collection efficiency for low energy electrons but to discriminate strongly against energetic electrons. This arrangement has resulted in a resolution of about 3.5 meV being achieved for the threshold electron peak recorded at the krypton 2P3/2 ionisation limit. A pulsed electric field is used to extract the ions from the interaction region and propel them towards the TOF analyser. Computer modelling has been used to trace the electron and ion trajectories through their respective analysers. These simulations have enabled the effective interaction volume to be defined, and this has allowed the transmission efficiency of energetic fragment ions, formed through a process which also yielded a threshold electron, to be quantified. The ion TOF peak shape has been examined as a function of initial kinetic energy and as a function of ion residence time. The contribution of energetic fragments, having specific initial spatial and directional properties, to the TOF peak shape has been determined by tracing the paths of individual ions. The actual performance of the spectrometer is illustrated by a TPEPICO spectrum of the krypton isotopes. Experimental breakdown curves for furan are presented as an example of the use of the apparatus to study unimolecular decomposition in polyatomic ions. By introducing a delay between the detection of the threshold electron and the application of the ion extraction field, breakdown curves can be recorded as a function of ion residence time in the source region. The procedure for analysing the data is described, and the experimental factors that need to be taken into account to obtain a meaningful comparison with theoretical predictions are discussed.

BACKGROUND A cluster of biopsy-confirmed interstitial lung disease among workers at a nylon flock plant led to a request for National Institute for Occupational Safety and Health investigators to conduct a health hazard evaluation. METHODS Part of the overall evaluation, reported here, involved a cross-sectional medical survey of current employees. The survey consisted of a questionnaire, spirometry and diffusing capacity testing, and chest radiograph. RESULTS Workers assigned to production and maintenance jobs reported frequent eye and throat irritation, respiratory symptoms, and systemic symptoms (i.e., generalized aches and fevers). Most reported improvement when away from work. Frequent respiratory/systemic symptom prevalence was significantly associated with departmental category, with days and hours worked per week, and with working on a flocking range. Compared to asymptomatic workers, symptomatic workers had similar mean ratios of forced expiratory volume in one second to forced vital capacity, but lower mean percent of predicted values for both forced vital capacity and diffusing capacity. All acceptable chest radiographs were classified as category 0 for small opacities. CONCLUSIONS Findings of this study, along with those from studies reported elsewhere, implicate occupational exposure to flock-associated dust as a significant respiratory health hazard at this plant.

Obtaining an adequate occupational history requires special expertise to "ask the right questions" that are relevant to a particular patient's specific health conditions and potential exposures. This article describes a way to systematically accomplish this by means of a computer system that can overcome limited availability of necessary clinical occupational health expertise. The Intelligent Questionnaire system is a computer-based system for generating case-specific questionnaires about the influence of work on respiratory disease. Intelligent Questionnaire includes three databases: Questions, Responses, and Calls (clues to identify questions). The Questionnaire also arranges questions in a logical manner and provides a customized data entry screen for each subject. This approach provides primary practitioners with expertise on a case-by-case basis. It also facilitates occupational health surveillance because it allows acquiring detailed case-specific information in a systematic fashion. A computer-based system can facilitate obtaining occupational histories with high specificity and consistency without depending on general availability of a human occupational health clinical expertise.

The absolute photoabsorption cross-section of pyrrole has been measured between the ionisation threshold and 35 eV using a double ion chamber and monochromated synchrotron radiation. An interpretation has been proposed for some of the observed structure in terms of Rydberg series converging onto the (A) over tilde (2)B(1) state threshold. In addition, the possibility that several broad features may be attributed to pi --> pi* transitions is discussed. Time-of-flight mass spectra have been recorded for excitation energies between 11.8 and 77.5 eV, and appearance energies have been determined for seventeen fragment ions and the doubly charged parent ion. These have enabled, previously unknown, heats of formation to be estimated for five ions, including the doubly charged parent ion. A high resolution mass spectrometer, equipped with an electron impact ionisation source, has been used in B/E and B(2)/E linked scanning modes to identify reactant/product pairings. Fragmentation processes leading to the production of several high intensity fragment ions have been modelled using ab initio and semi-empirical methods. (C) 1999 Elsevier Science B.V. All rights reserved.

Three experimental techniques (photoabsorption, photoelectron, and photoion spectroscopy) have been used to study the spectroscopic and thermodynamic properties of furan. The absolute photoabsorption cross-sections of furan-h4 and furan-d4 have been measured using a double ion chamber and a new Rydberg series converging onto the G2A1 ionisation threshold has been observed. HeI-excited photoelectron spectra of the X2A2, the A2B1 and the G2A1 states of furan-d4 have been recorded. Vibrational structure has been observed in all three bands and has allowed the energies of the ν3, ν4, ν6 and ν8 vibrational modes to be determined. Time-of-flight mass spectra have been recorded using monochromatic synchrotron radiation, and appearance energies have been measured for 19 fragment ions and the doubly charged parent ion. The fragmentation processes leading to the production of several high-intensity fragment ions have been modelled using ab initio and semi-empirical methods.

The absolute photoabsorption, photoionisation and photodissociation cross-sections and the photoionisation quantum efficiency of benzene and hexadeuterobenzene have been measured from the ionisation threshold to 350 Angstrom using a double ion chamber and monochromated synchrotron radiation. The HeI excited photoelectron spectrum of C6D6 has been recorded and the vibrational structure exhibited in the (XE1g)-E-2, A(2)E(2g), (EB1u)-B-2 and F(2)A(1g) bands has been analysed with the aid of theoretical predictions and by analogy with the recently reported high-resolution photoelectron spectrum of C6H6. The photoabsorption spectrum displays extensive vibrational structure extending from the ionisation threshold to similar to 730 Angstrom, and many of these absorption features have been arranged into Rydberg series. A detailed assignment of the vibrational progressions associated with some Rydberg states has been accomplished by making use of the corresponding photoelectron spectrum. A sum rule analysis has been carried out by combining the present absolute photoabsorption measurements with similar data covering the remaining wavelength regions. (C) 1998 Elsevier Science B.V.

120 chest radiographs of dust exposed persons were classified twice by each of 39 physicians, and three times by 37 of them. All film readers used both the 22 standard films accompanying the current International Labour Office's (1980) Classification of Radiographs of Pneumoconioses, and a modified set that reproduced selected parts from some of them as quadrants of full-size films. Variability within and between readers in small opacity profusion classifications was high, but similar when using the two sets of standards. Some readers recognised irregularly shaped small opacities more frequently, in low profusion categories, when using the quadrant standards. Small rounded opacities were classified more frequently higher on the scale when using the current standards. The effects found were small although the test films included a high proportion with some small opacities. It is concluded that use of the new quadrant standards is unlikely to introduce any important bias into results from occupational health surveys.

Three experimental techniques – photoabsorption, photoelectron and photoion spectroscopy – have been combined with many-body Green's function calculations to investigate the spectroscopic and thermodynamic properties of toluene. The absolute photoabsorption cross section has been measured from the ionisation threshold to 350 Å using a double ion chamber and monochromated synchrotron radiation. Some of the structure has been arranged into Rydberg series. He I excited photoelectron spectra of toluene-h8 and toluene-d8 have been recorded and vibrational progressions have been observed in three bands. Fragmentation processes have been studied by measuring time-of-flight spectra and appearance energies have been determined for many small fragments, and the doubly-charged parent ion. The many-body Green's function approach, specially adapted for the outer valence region, has been used to calculate ionisation energies and pole strengths.

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