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J W Cherrie

Publications and source records attributed to J W Cherrie.

At least 37 records · Page 2Linked to original sources
PubMed2001

A dermal model for spray painters. Part I: subjective exposure modelling of spray paint deposition.

The discriminative power of existing dermal exposure models is limited. Most models only allow occupational hygienists to rank workers between and within workplaces according to broad bands of dermal exposure. No allowance is made for the work practices of different individuals. In this study a process-based, structured approach has been used to estimate dermal exposure from overspray generated by a spray painting process. Factors for spray technique, object shape and workers' individual work practices involved in the processes of droplet formation and deposition were incorporated into the model. The model was applied to predict dermal exposure of airless spray painters and the results were compared with exposure data. The predicted levels of exposure showed reasonable rank correlation with the measured exposure, although the model tended to over-predict the actual level of exposure. It was concluded that a structured, process-based approach has the potential to produce reliable estimates of dermal exposure. The reliability of exposure models of this type should be explored further and the relationship between the determinants of exposure should be validated by additional field studies.

Air Pollutants, Occupational↗
PubMed2001

A dermal model for spray painters. Part II: estimating the deposition and uptake of solvents.

The contribution of dermal exposure to the total body burden of a given chemical is difficult to assess. However, it is possible that as regulatory pressures lead to reductions in inhalation exposure, the proportion of uptake via the dermal route will increase. This study brings together recent work in the field of dermal exposure to provide a model to estimate both exposure and uptake of solvents through the skin. Using spray painters as an example, the process of modelling exposure is described from identifying the determinants of exposure through to calculating the flux of solvent through the stratum corneum and thus the total dermal uptake. Results from a range of exposure scenarios are presented and areas requiring further research and validation are highlighted. The model should allow the estimation of combined dermal and inhalation exposure to solvents in both current work situations and retrospective epidemiological studies. Furthermore, it is envisaged that the model may provide the basis for generic assessment of dermal exposure and uptake.

Air Pollutants, Occupational↗
PubMed2001

Development of a push-pull ventilation system to control solder fume.

Hand soldering using rosin core solder wire is common in the electronics industry and several studies have implicated the aerosol produced when rosin flux is heated in causing respiratory sensitisation. Control of solder fume is generally achieved using local exhaust hoods, simple blowers with a filter or low-volume high-velocity (LVHV) ventilation systems. None of these provide an ideal control system and so a push-pull ventilation design was developed as an alternative. Laboratory tests of the system's capture efficiency were carried out using nitrous oxide tracer gas. Capture efficiency was generally greater than 90% with the push airflow operating. However, without the push airflow, capture efficiency decreased sharply with increasing distance from the exhaust hood (between 38 and 58% at 420 mm from the front of the exhaust hood with the same exhaust airflow used by the push-pull system). The push-pull system was found to be relatively insensitive to obstructions placed in the path of the air flow or the influence of cross draughts. The system was tested in five electronics factories and the effectiveness was compared to their existing ventilation systems. Where only a small amount of soldering was carried out both the in-house and push-pull systems seemed to provide adequate control of inhalation exposure to rosin-based solder flux fume measured as total resin acids. However, the push-pull system provided more consistent control than the existing ventilation systems when larger quantities of solder were used. In these situations the mean personal exposure level was reduced to below the UK Maximum Exposure Limit (MEL) of 0.05 mg/m(3) 8-h time weighted average in most instances. The corresponding mean personal exposure level with the in-house systems in operation was about three to four times the long-term MEL. Interpretation of these data is complicated because of high background contribution to exposure from poorly controlled soldering operations elsewhere in the factories. However, this study suggests that the in-house systems were relatively inefficient.

Air Pollutants, Occupational↗
PubMed2000

Impairment of colour vision in workers exposed to organic solvents.

OBJECTIVES: To investigate loss of colour vision related to exposure to solvents and the role of three enzyme polymorphisms in modifying the risk in exposed workers. METHODS: A sample was studied of 68 male dockyard workers and 42 male community controls with and without neuropsychological symptoms from a previous cross sectional study. Indices of cumulative and intensity based exposure to solvents were calculated for all subjects. Alcohol, drug, and smoking histories were obtained. Colour vision was tested by Lanthony D15d colour vision test. Genotype of glutathione S-transferase M1 and T1 and N-acetyltransferase 2 polymorphisms were determined. RESULTS: The relation between impairment of colour vision and exposure to solvents was investigated with multiple regression techniques. Increasing annual exposure to solvents was significantly associated with reduced colour vision (p=0.029). Impairment of colour vision was not associated with neuropsychological symptoms as measured by the Q16 solvent symptom questionnaire. No significant association was found between acquired impairment of colour vision and genetic polymorphisms when GSTM1, GSTT1 or NAT2 phenotypes were included in the analyses. CONCLUSIONS: Exposure to mixed solvents is associated with impairment in colour vision, the risk increases with increasing exposure. The risk of impairment of colour vision was not altered in this study by the presence of different GSTM1, GSTT1 or NAT2 polymorphisms.

Arylamine N-Acetyltransferase↗
PubMed2000

Dermal exposure assessment.

Assessing dermal exposure is a complex task. Even the most commonly used methods face fundamental problems and there are large gaps in the documentation and validation of sampling methods. Still larger uncertainties exist regarding strategies for measurement. We propose a strategy based on a conceptual model and which draws on the considerable insight gained for airborne contaminants, including EN 689 for assessing exposure by inhalation. The vast amount of air sampling data has provided good insight into the statistical properties of short-term and long-term exposure levels, which is essential for designing cost-effective exposure studies. For surface and skin contaminants an understanding of the distribution types and parameter values is only beginning to emerge. Transport rates away from the skin contaminant layer determine the 'memory' of a dermal sample and measurement principles are proposed depending on these rates. It is argued that uptake is the ultimate dermal exposure metric for risk assessment and should be the basis for devising dermal occupational exposure limits.

Cost-Benefit Analysis↗
PubMed2000

Use of qualitative and quantitative fluorescence techniques to assess dermal exposure.

Fluorescent tracers provide a way of simultaneously assessing the mass of a contaminant hazardous substance on the surface of the skin of a worker and the area of skin exposed. These parameters, along with the duration of exposure and the estimated contaminant concentration in the skin contamination layer, can be used to calculate the likely uptake through the skin. Repeated assessment of the mass of tracer on a surface within a room or on the surface of the skin can also allow the net transfer of contaminant to that compartment to be estimated. Qualitative evaluation of transfer processes using fluorescent tracers can help identify important secondary sources of exposure.

Environmental Monitoring↗
PubMed2000

Assessment of dermal exposure during airless spray painting using a quantitative visualisation technique.

The range of dermal exposure to non-volatile compounds during spray painting was studied in a semi-experimental study involving three enterprises and 12 painters. A fluorescent tracer was added to the paint and deposition of the tracer on clothing and uncovered parts of the skin was assessed using video imaging and processing techniques. A container (volume 36 m(3)) was sprayed with a colourless laquer (varnish) containing 66.7 mg/l fluorescent whitening agent. All painters sprayed the outside of the container. Nine painters repeated the painting a second time and five also sprayed the inside of the container. The painters wore white Tyvek coveralls, but no gloves. Duration of spraying the outside ranged from 4 to 21 min with a mean of 10 min and the amount of paint sprayed ranged from 3.0 to 12.8 l (mean 6.6 l). The mass of tracer deposited on the coverall ranged from 2.2 to 471 microg (90th percentile 256 microg), whereas, mass deposited on skin (i.e. the hands, wrists, and face) ranged from 0.01 to 52 microg tracer (90th percentile 20 microg). The quantity of tracer on the coverall was three times higher after spraying the inside of the container compared to spraying the outside, whereas the quantity on the skin was similar in both cases. On average 10% of the surface area of the coverall and skin was exposed during spraying the outside. Exposures, expressed in units of mass per area exposed were slightly higher for skin compared to coverall. In this study, deposited mass of tracer was correlated with an alternative exposure metric, i.e. surface area exposed multiplied by the duration of exposure, which has been proposed as a surrogate for uptake. Using a quantitative fluorescent tracer technique, it could be demonstrated that body parts which showed the lowest mass of tracer had the highest exposure as mass per surface area. Compared to other techniques which only determine mass, the ability to identify and quantify the actual surface area exposed is a clear advantage of the quantitative fluorescent tracer technique.

Air Movements↗
PubMed1999

The effect of room size and general ventilation on the relationship between near and far-field concentrations.

Measurements of personal exposure level are generally greater than or equal to concentrations found at some fixed location in the body of the workroom. This article presents a theoretical analysis of such differences using a simple model of exposure, implemented as a two-compartment mass balance model with a constant emission rate. Simulated exposure levels (termed the near-field) and the concentration at a fixed location (the far-field) were obtained for five room sizes (30 to 3000 m3), each with five general ventilation rates (0.3 to 30 air-changes per hour) and three levels of air movement in the vicinity of the worker (generally 3 to 30 m3/min). The ratio of near- to far-field concentrations from the simulations ranged from unity in small poorly ventilated rooms to 24 in large well ventilated areas, which compares favorably with actual measurement data. The predicted concentrations obtained in small rooms (< 100 m3) with less than one air-change per hour were almost 40 times higher than in larger rooms. The results from these simulations have been used to modify the original exposure model to better reflect the likely effect of general ventilation on workers' exposure.

Air Pollution, Indoor↗
PubMed1999

Measurement of human exposure to biologically relevant fractions of inhaled aerosols.

Aerosol sampling has evolved with changes in technology and our understanding of the importance of assessing the biologically relevant fractions of the total aerosol. During the past decade there has been international agreement on the definitions for the inhalable, thoracic, and respirable fractions and instruments have been developed to collect samples according to these conventions. These measurement techniques are now well established in the workplace and are increasingly being applied to assessments of non-occupational exposure, as the practical difficulties in obtaining samples over 24 hours have been solved. It is argued that multiple aerosol size fractions should be measured for hazardous substances--such as inorganic lead--in which inhaled material may either be absorbed in the alveoli (respirable) or cleared from the ciliated airways in the lung to the gut and then absorbed (thoracic and extrathoracic). Such measurements should improve the evaluation of the risk for inhaled lead, particularly for non-occupational exposure of children. Also, passive aerosol sampling techniques may enable measurements of non-occupational exposure to be made over several weeks and this would also help improve the reliability of the risk evaluation for aerosol toxicants with a long biological half life. However, further development of these techniques is required if they are to be practicable and biologically relevant.

Aerosols↗
PubMed1999

Conceptual model for assessment of dermal exposure.

Dermal exposure, primarily to pesticides, has been measured for almost half a century. Compared with exposure by inhalation, limited progress has been made towards standardisation of methods of measurement and development of biologically relevant exposure measures. It is suggested that the absence of a consistent terminology and a theoretical model has been an important cause of this lack of progress. Therefore, a consistent terminology based on a multicompartment model for assessment of dermal exposure is proposed that describes the transport of contaminant mass from the source of the hazardous substance to the surface of the skin. Six compartments and two barriers together with eight mass transport processes are described. With the model structure, examples are given of what some existing methods actually measure and where there are limited, or no, methods for measuring the relevant mass in a compartment or transport of mass. The importance of measuring the concentration of contaminant and not mass per area in the skin contaminant layer is stressed, as it is the concentration difference between the skin contamination layer and the perfused tissue that drives uptake. Methods for measuring uptake are currently not available. Measurement of mass, concentration, and the transport processes must be based on a theoretical model. Standardisation of methods of measurement of dermal exposure is strongly recommended.

Air Pollutants↗
PubMed1999

Non-neoplastic mortality of European workers who produce man made vitreous fibres.

OBJECTIVE: To study mortality from non-neoplastic diseases among European workers who produce man made vitreous fibres (MMVF). METHODS: 11,373 male workers were studied, who were employed for at least 1 year in the production of rock or slag wool (RSW), glass wool (GW), and continuous filament (CF) in 13 factories from seven European countries. Workers were followed up from the beginning of production, between 1933 and 1950 to 1990-2 and contributed 256,352 person-years of observation. Standardised mortality ratios (SMRs) were calculated with national mortalities for reference; an internal exposure-response analyses based on multivariate Poisson regression models was also conducted. RESULTS: Mortality from bronchitis, emphysema, and asthma was not increased (SMR 1.03, 95% confidence interval (95% CI) 0.82 to 1.28). In RSW workers, there was no overall increase in mortality from non-malignant renal diseases (SMR 0.97, 95% CI 0.36 to 2.11), although there was the suggestion of an increase in risk with duration of employment. Mortality from ischaemic heart disease was not increased overall (SMR 1.03, 95% CI 0.96 to 1.11), but RSW and CF workers with > or = 30 years since first employment had a higher risk. RSW and CF workers showed an increased mortality from external causes, mainly motor vehicle accidents and suicide, which was higher among workers with a short duration of employment. CONCLUSIONS: Mortality from most non-neoplastic diseases does not seem to be related to employment in the MMVF industry. The results on mortality from ischaemic heart disease and non-malignant renal diseases, however, warrant further investigations.

Cause of Death↗
PubMed1998

Selecting an adequate respiratory protective device: the choice between a respirator and breathing apparatus.

An adequate respiratory protective device should keep the concentration of the pollutant inside the facepiece below the appropriate occupational exposure limit. Filtering respirators will not provide adequate protection if the device fails in an atmosphere which is immediately dangerous to life or health (IDLH). It has therefore been suggested that in contaminant concentrations above an IDLH level it is more appropriate to select breathing apparatus with an emergency breathing facility. In this paper IDLH levels published by the US National Institute of Occupational Safety and Health have been compared with UK occupational exposure limits. For some substances there was a relatively small difference between the IDLH level and the short-term occupational exposure limit (STEL). The median ratio of the IDLH level to the STEL was 10 for gases and vapours and 50 for aerosols. For almost half the substances with UK occupational exposure limits there is no IDLH value. It is concluded that the published IDLH concentrations are, on their own, an insufficient basis for selecting breathing apparatus over a filtering respirator. It is equally important to consider the likelihood that a filtering device may fail catastrophically since this determines the risk from wearing a respirator in an IDLH atmosphere. More emphasis should be placed on the control of potentially high exposure levels by means other than respiratory protection.

Equipment Failure↗
PubMed1998

Factors influencing personal magnetic field exposure: preliminary results for power utility and office workers.

Epidemiological studies and laboratory research suggest that exposure to extremely low frequency (< 300 Hz) magnetic fields is associated with an increase in risk of developing a number of rare diseases including leukaemia. Overall the risks to health appear to be small but a more accurate exposure assessment technique would help evaluate the true extent of any health effects. In this pilot study we aimed to identify and evaluate personal, work and environmental factors and their influence on measured exposure levels with a view to developing a method of reconstructing exposure. Office workers and power utility workers were studied using personal dosimeters to measure magnetic field exposure, along with frequent observation or measurement of factors related to exposure. Factors such as average and closest distance to source, time at position and current flow were combined in a series of metrics to investigate simple models of personal exposure. The results indicate that mean and peak magnetic field exposure levels are linked to current flow and the average distance of a worker from the source of the magnetic field. These factors are more accurate predictors of high exposures than they are of lower and average levels. It may be possible, with further work, to produce a model of exposure to magnetic fields for use in epidemiological studies.

Electromagnetic Fields↗
PubMed1998

Does risk perception affect behaviour and exposure? A pilot study amongst asbestos workers.

It is hypothesised that there is a causal association between workers' perceptions of the risks from handling hazardous materials, their behaviour while working and their consequent exposure. This has been investigated in a small group of workers carrying out remedial work on amosite insulating boards and similar products. Risk perception was first assessed using a questionnaire and then the workers' behaviour was recorded alongside task-based measurements of fibre exposure. There was a clear association of higher cumulative exposures when workers used power tools compared to manual methods (about seven times higher). Careful bagging was shown to reduce exposures by a smaller margin, (approximately half). Workers whose perception of the risks was poorer were found to be more likely to use power tools to remove the asbestos containing material. However, fibre exposure was not found to be directly associated with risk perception. Further work is necessary to clarify the validity of the original hypothesis.

Adult↗
PubMed1998

Lung cancer mortality among European rock/slag wool workers: exposure-response analysis.

OBJECTIVES: The purpose was to analyze the relationship between semi-quantitative indices of exposure to manmade vitreous fibers and lung cancer mortality among European rock/slag wool (RSW) workers. METHODS: The study population comprised 9,603 male workers employed in RSW production in seven factories in Denmark, Norway, Sweden, and Germany, followed up for mortality as of 1990-91. Estimates of past exposure to respirable fibers were used to calculate cumulative exposure with a 15-year lag and maximum annual exposure based on employment history up to 1977. Rate ratios were estimated via multivariate Poisson regression, adjusting for country, age, calendar year, time since first employment, and employment status. RESULTS: A total of 159 lung cancer deaths were included in the analysis of which 97 among workers with more than one year of employment. We found nonstatistically significant trends in lung cancer risk according to cumulative exposure. Relative risks (RR) in the four quartiles were 1.0 (reference), 1.3 (95 percent confidence interval [CI] = 0.8-2.4), 1.2 (CI = 0.7-2.1), and 1.5 (CI = 0.7-3.0, P test for trend = 0.4). When workers with less than one year of employment were excluded, there was no increased risk; the RRs in the four quartiles were 1.0, 0.9 (CI = 0.4-2.0), 0.8 (CI = 0.3-1.9), and 1.0 (CI = 0.4-2.7). No trend was present according to maximum annual exposure. The results were not consistent among countries. CONCLUSIONS: We found a positive association between exposure to respirable fibers and lung cancer mortality. However, the lack of statistical significance, the dependence of the results on inclusion of short-term workers, the lack of consistency among countries, and the possible correlation between exposure to respirable fibers and to other agents reduce the weight of such evidence.

Adult↗
PubMed1998

Quartz exposures and severe silicosis: a role for the hilar nodes.

BACKGROUND: Two stonemasons working together in an environment with high concentrations of quartz pursued very different clinical courses; one died of rapidly progressive silicosis and the other developed hilar adenopathy and, later, early massive fibrosis. The exposures to quartz of these two men were investigated to allow comment on the pathogenesis of severe silicosis relative to concentrations of dust. METHODS: Estimates of exposure were based on previously taken personal dust samples, detailed lifetime occupational histories, and semiquantitative exposure modelling. RESULTS: One of the men who died had a 30 year exposure estimated to have averaged < 0.1 mg/m3, leading to hilar node fibrosis and calcification, followed by a five year exposure to about 2 mg/m3 which proved fatal. Estimates of exposure tallied with postmortem measurement of lung burden, suggesting retention of all dust deposited in the lungs over his final period of work. The younger man, working from the start of his apprenticeship alongside the older one, had a six year exposure to about 1.5 mg/m3, which caused hilar node enlargement and subsequent calcification but minimal lung involvement. CONCLUSIONS: Exposures to relatively low concentrations of quartz may be capable of causing hilar node fibrosis, impairing the clearance of any quartz inhaled subsequently. The findings support the concept that destruction of the hilar nodes by silicotic fibrosis, impairing lung clearance, has an important pathogenic role in the development of massive fibrosis, and in men subsequently exposed to very high concentrations of respirable quartz, rapidly progressive silicosis.

Adult↗
PubMed1997

Estimation of exposure from spilled glutaraldehyde solutions in a hospital setting.

Glutaraldehyde is commonly used in hospitals for cold disinfection of instruments which may be damaged by autoclaving. The increased use of automatic washer/disinfection machines has resulted in a greater risk of spills than with manual methods. A series of experiments was conducted to answer two related research questions: what was the likely range of airborne concentrations when glutaraldehyde is spilled, and are commonly used personal protective equipment ensembles effective and practicable in use? Objective measurements using three sampling methods (two pumped methods based on OSHA 64, one using treated filters and the other based on adsorbent tubes, and a Glutaraldemeter direct reading instrument) were conducted with spills of various surface areas of both 2 and 50% solutions of glutaraldehyde. Results ranged between < 0.01 and 1.4 ppm. Two personal protective equipment ensembles were tested. One was based on a half-facepiece respirator with gas-tight goggles, while the other comprised a full-facepiece cartridge respirator. Both ensembles gave adequate protection against irritation, although in use the half-facepiece respirator and goggles tended to interfere with each other. The direct reading instrument generally underestimated the glutaraldehyde concentrations, although there was a significant association with the results obtained using the method based on adsorbent tubes.

Accidents, Occupational↗