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Biomedical subjects

J W Cherrie

Publications and source records attributed to J W Cherrie.

At least 19 recordsLinked to original sources
PubMed2005

Lung fibre burden in lung cancer cases employed in the rock and slag wool industry.

OBJECTIVES: To evaluate the relationship between estimated exposure to man-made vitreous fibres (MMVF) and to asbestos fibres and their concentration in the lung tissue of lung cancer cases amongst MMVF production workers. METHODS: Retrospective retrieval of available lung tissue specimens was conducted following a case-control study that assessed estimated occupational exposures of MMVF workers. Fibre recovery and analysis by transmission electron microscopy (TEM) were conducted to determine fibre type, fibre dimension and numbers per gram of dry lung tissue. For cases with detailed exposure data, geometric mean (GM) concentrations were compared across the exposure categories, and regression models were used to investigate the relationship between the lung fibres and the variables of estimated exposure, with and without additional variables that may affect fibre retention. RESULTS: A total of 24 samples from 17 cases of lung cancer were available for analysis: MMVF were detected in all cases. Asbestos fibres were detected in 16. No difference or trend in GM MMVF concentration was observed across the estimated exposure categories. Odds ratio (OR) for MMVF g(-1) dry lung was 0.5 (95% confidence interval: 0.1-2.4) for the second, and 3.5 (0.6-18.9) for the third quartile of index of average exposure to MMVF in industry, compared with the first (lowest exposed) quartile (no cases in the highest quartile). CONCLUSIONS: No observable relationship existed between estimated exposure and directly-measured lung fibres among this sample of cases. Retrospective specimen collection, intra-individual variability in fibre concentration, effect of unknown factors on fibre retention and small sample size militated against this study providing evidence for or against a relationship between estimated exposure and lung fibre concentrations.

Adult↗
PubMed2005

Development of a biologically relevant dermal sampler.

There are currently no appropriate methods for measuring dermal exposure to volatile agents. To address this we have produced a prototype Institute of Occupational Medicine (IOM) dermal sampler consisting of an adsorbent sandwiched between a permeable membrane and an impervious backing. The concentration of solvent on the membrane surface may be estimated from the mass collected on the adsorbent and the known permeation rate through the membrane. We have developed the prototype IOM dermal sampler for measurement of toluene exposures. Evaluation of the prototype sampler was undertaken in two stages: laboratory performance in controlled exposure situations and two short-field evaluations, which included simultaneous measurement of inhalation exposure. In all cases we compared the prototype IOM dermal sampler with activated charcoal cloth (ACC). Laboratory trials were split into spray, pour and immersion tests. The data from these suggest that the sampler responds to concentration rather than the mass on the surface of the sampler. The field study showed that the prototype sampler was suitable for measuring dermal exposure. However, the mean permeation rate of the best membrane was 78 000 mug cm(-2) h(-1), which is higher than the permeation rate through skin. This high permeation rate created difficulties throughout the study, particularly as it allowed the adsorbent to become rapidly saturated. The prototype IOM dermal sampler is the first practical dermal exposure sampler to mimic uptake through the skin. The sampler gave reproducible results in the laboratory and field trials. Future work is required to identify a less permeable membrane, which has characteristics closer to that of human skin. Additionally, a higher capacity adsorbent would be desirable. We have demonstrated a major difference when calculating the total contribution to body burden via the dermal exposure pathway using the prototype IOM dermal sampler and ACC patches, 1.5% of the total body burden compared with 95%. The prototype IOM dermal sampler provides a more biologically relevant exposure metric than the alternatives.

Air Pollutants, Occupational↗
PubMed2005

Evaluation and further development of EASE model 2.0.

EASE (Estimation and Assessment of Substance Exposure) is a general model that may be used to predict workplace exposure to a wide range of substances hazardous to health. First developed in the early 1990s, it is now in its second Windows version. This paper provides a critical assessment of the utility and performance of the EASE model, and on the basis of this review, recommendations for the structure of a revised model are outlined. Twenty-seven stakeholders were interviewed about their previous use of EASE, perceived advantages and limitations of the model and suggestions for improvement. A subset of stakeholders was contacted on a second occasion to determine their views on the preferred outputs for an ideal exposure assessment model. Overall, stakeholders felt that the model should be updated to provide more accurate and precise exposure assessments. However, users also expressed the view that the simplicity and usability of the software model should not be compromised. Six studies investigating the validity of the inhalation exposure assessment section of EASE were identified. These showed that the model generally either predicted close to the measured exposures or overestimated exposure; though performance was highly variable. Two studies investigated the validity of the dermal exposure assessment and found that EASE produced considerable overestimates of actual dermal exposure (the amount of a substance that actually lands on the skin). A conceptual model of exposure was developed to investigate whether the structure of the EASE model is appropriate. Although EASE has a number of characteristics that describe exposure, it is a greatly simplified model and does not include all the important exposure determinants. More importantly, EASE can produce estimates of exposure that are ambiguous or incomplete. Our conceptual model may provide a rational basis for developing an improved version of EASE but further consultation is needed to decide the purpose and intended use of any successor to EASE.

Air Pollutants, Occupational↗
PubMed2004

Is colour vision impairment associated with cognitive impairment in solvent exposed workers?

AIMS: To determine whether acquired colour vision deficits in solvent exposed individuals are associated with cognitive impairment. METHODS: A sample of 82 painters and 38 other subjects were studied. Alcohol, drug, and smoking histories were obtained. Colour vision was tested using the Lanthony D-15-d colour vision test. Cognitive impairment was measured using the Benton visual retention test, Trail making A, and Trail making B tests. Pre-morbid IQ was estimated using the National Adult Reading Test. Solvent exposure in all subjects was estimated using a previously validated, structured subjective assessment methodology. RESULTS: After exclusion of subjects with competing causes of colour vision impairment the final group of men numbered 78. There was a significant association on multiple linear regression between the mean colour confusion index (CCI) and three measures of cognitive impairment, the Benton visual retention test, Trail making A, and Trail making B tests after adjusting for the effects of age (or IQ as appropriate), alcohol, and smoking. CONCLUSION: Acquired colour vision loss is associated with cognitive impairment in solvent exposed workers. However, given the prevalence of acquired colour vision losses in the adult population, colour vision testing is unlikely to be of value as a screening test.

Adult↗
PubMed2003

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects.

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.

Air Pollution, Indoor↗
PubMed2003

The beginning of the science underpinning occupational hygiene.

Sherwood and Greenhalgh's 1960 paper is a seminal one for the development of the science of human exposure. There are three key elements in the paper that deserve to be highlighted: the development of the first personal sampling pump and sampling head; the first comparison between personal sampling and static sampling; the first observation of the possible effect of personal sampling on the individual being sampled.

Environmental Monitoring↗
PubMed2003

Chronic fatigue and organophosphate pesticides in sheep farming: a retrospective study amongst people reporting to a UK pharmacovigilance scheme.

The Department of Health has recently published a report from the CFS/ME Working Group which concluded that chronic fatigue syndrome (CFS) should be recognized as a chronic illness. Symptoms consistent with CFS are often reported by people who consider their health has been affected by exposure to pesticides, but the Working Group concluded that this type of exposure is not a common trigger for the syndrome. The Veterinary Medicines Directorate (VMD) collects self-assessed reports of ill health in humans associated with veterinary medicines under their Suspected Adverse Reaction Surveillance Scheme. The reporters have mainly been sheep farmers. These reports were used to investigate the possible relationship between chronic fatigue (CF) and exposure to organophosphate pesticides in sheep farming. The overall aim of the study was to investigate a possible association between exposure to organophosphates and the development of CF amongst people who consider their health has been affected by pesticides in sheep farming. The hypothesis investigated was that repeated exposure to organophosphate pesticides in sheep dip may increase the probability of developing CF. A group of mostly sheep farmers who had reported to the VMD surveillance scheme were identified. We planned to use a retrospective case-control study design but the initial symptoms reports were not sufficiently reliable to enable this. The study population was asked to complete two questionnaires. The first questionnaire was designed to identify the history of exposure of subjects to organophosphate pesticides, and their exposure was then reconstructed using a metric specifically developed for this purpose. The second questionnaire collected detailed information to identify whether the subjects had CF when they originally reported to the VMD and at the time of the survey. The questionnaire was sent to a total of 206 subjects, of whom 28 had moved home. A total of 37% of the remaining 178 subjects participated. There was a high prevalence of CF amongst those who completed the questionnaire and this has generally persisted since the subjects reported to the VMD. Higher CF scores were associated with higher exposure to organophosphate pesticides. CF is very common amongst those who consider their health was affected by pesticides and we have shown there is limited evidence of an association between exposure to organophosphates and CF. Further research is needed to investigate the cause of this syndrome amongst farmers exposed to pesticides.

Agricultural Workers' Diseases↗
PubMed2002

Organic solvent exposure, genes, and risk of neuropsychological impairment.

BACKGROUND: Subtle cognitive and neurological impairments have been found in some workers exposed to organic solvents. Whether these effects occur at or below current legal limits for occupational exposure is controversial. AIM: To determine whether occupational solvent exposure is associated with neuropsychological impairment and whether such risk is modified by polymorphisms in the genes for enzymes involved in detoxification. DESIGN: Retrospective case-control analysis. METHODS: We studied 78 former dockyard painters and 42 community controls. Individual respiratory and dermal exposures to solvents were estimated. Neuropsychological tests were administered, including paper and pencil tests, tests from the Neurobehavioural Evaluation System (NES2), together with a structured neurological examination and genotyping of polymorphic enzymes involved in detoxification: GSTM1, GSTT1, GSTP1, NAT1, NAT2, SOD1 and CYP1A1. RESULTS: While initial case-control analyses failed to identify any significant differences between symptomatic and asymptomatic painters, in regression analyses increasing solvent exposure was associated with increasing risk of cognitive impairment, after adjustment for IQ (or age, where appropriate), smoking and alcohol. There was also an association between exposure and reduction in grip strength. There was limited evidence of risk modification by some enzyme polymorphisms. DISCUSSION: This association between increasing intensity of solvent exposure and neuropsychological impairment may be important at current exposure levels in the UK.

Case-Control Studies↗
PubMed2001

A novel method of assessing the effectiveness of protective gloves--results from a pilot study.

We have devised a novel method for evaluating the effectiveness of protective gloves and have undertaken a small study to assess this approach. Three types of glove were tested in a standardised simulation test with a permethrin-based pesticide. Prewashed cotton gloves were used to collect the samples. One was worn over the protective glove on one hand to measure the potential deposition of pesticide on the hands had the gloves not been worn. A second was placed under the protective glove on the opposite hand to measure the actual deposition of permethrin on the hands when the gloves were worn. This regime was reversed half way through each test in an attempt to prevent bias. Measurable inner glove contamination occurred on 25 out of 30 occasions. Geometric mean protection factors were calculated from the ratio of outer and inner sampling glove contamination, with average protection factors of 470, 200 and 96 being obtained for the two nitrile and PVC gloves, respectively. The PVC gloves were the least effective in preventing inner glove contamination, probably because the glove was thick and fairly inflexible, causing more pesticide to enter the glove around the cuff. Although the tasks were standardised, variability occurred due to worker behaviour and equipment failure. The spray pump failed on five occasions, resulting in higher levels of inner glove contamination and a geometric mean protection factor of 32. On the occasions when the pump worked correctly, the level of protection provided by the gloves rose dramatically with mean protection factors of 220 and 450 being obtained for workers categorised as "messy" and "tidy", respectively.

Analysis of Variance↗
PubMed2001

The development of a prototype database for the voluntary reporting of occupational exposure data on chemicals.

A prototype occupational exposure database was developed as part of a study to retrospectively collect chemical exposure data from U.K. industry. The data dictionary for the database was constructed using existing recommendations on core data elements developed by working groups from the ACGIH and the European Union. The study also made use of existing job and workplace coding schemes. The practicalities of gathering the data by voluntary donation, its storage in a database, and the transfer of suitably anonymised data to the U.K. Health and Safety Executive's National Exposure Database system were investigated and assessed. Prior to the development, several existing exposure database systems were evaluated for their suitability to store the data from the study. Though of high quality, these were found to be insufficiently flexible for the diversity of datasets encountered and so the prototype exposure database was constructed using a leading database development package. The database was successfully used to gather data and forward it in a suitable format to the U.K. Health and Safety Executive. The published recommendations on occupational exposure databases and the associated coding schemes provided a very useful foundation for designing and implementing the prototype database. However, as data collection proceeded it became clear that the existing recommendations often were poorly understood and misinterpreted, or at least interpreted differently, by different database designers, data collectors, and other users of occupational exposure data. It is suggested that several items in the ACGIH and European Union core recommendations are ambiguous and need to be clarified. Once agreed, the improved database design criteria need to be widely promoted to foster a common understanding and to encourage their use by all those involved in collecting occupational exposure data. Beyond this, recommendations for exposure databases should be augmented to facilitate easy exchange of data between organizations.

Databases, Factual↗
PubMed2001

Retrospective collection of exposure data from industry: results from a feasibility study in the United Kingdom.

In the United Kingdom the Health and Safety Executive for some years has stored chemical exposure data in their National Exposure Database. However, it has been difficult to persuade industry and other organizations to contribute to this resource. The aim of this project was to devise a cost-effective method of obtaining occupational exposure data on chemicals from U.K. industry and other sources. Five strategies were used to identify data for three different substances: toluene, acrylonitrile, and ethylene oxide. In total, 810 organizations were contacted and over 45 percent responded. However, only 40 had relevant exposure data. Almost equal numbers of acceptable measurements were identified for toluene and acrylonitrile (2,770 and 2,000 respectively) with lesser ethylene oxide data (800). These measurements were drawn from a wide range of industries and are probably representative of measurements made by U.K. industry, although most of the data were from companies employing more than 100 people. During the second phase of the project, more than 3,000 measurements and associated contextual information were collected (499 for toluene, 1,516 for acrylonitrile, and 17 for ethylene oxide, with a further 1,004 measurements for 1 of 27 substances collected simultaneously with one of the above). The costs of identifying and collecting exposure data ranged from ł7 to ł380 per valid measurement, depending on the source of the data. We suggest that, rather than trying to retrospectively collect data, it is likely to be more cost-effective to enlist a number of occupational hygiene consults and industrial organizations to prospectively provide anonymized exposure measurements for inclusion in the Health and Safety Executives National Exposure Database.

Data Collection↗
PubMed2001

An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry.

OBJECTIVES: To investigate possible relations between respiratory health and past airborne exposure to refractory ceramic fibres (RCFs) and respirable dust in workers at six European factories, studied previously in 1987. METHODS: The target population comprised all current workers associated with RCF production, plus others who had participated in 1987 "leavers". Information was collected on personal characteristics, chest radiographs, lung function, respiratory symptoms, smoking, and full occupational history. Regression analysis was used to study relations between indices of health of individual workers and of cumulative exposure to airborne dust and fibres, and likely past exposure to asbestos. RESULTS AND DISCUSSION: 774 workers participated (90% of current workers, 37% of leavers). Profusion of small opacities in exposed workers (51% 0/1+; 8% 1/0+) was similar to that among an unexposed control group but higher than in new readings of the 1987 study films (11% 0/1+, 2% 1/0+). The large difference between 1987 and recent films may be, at least in part, a reading artefact associated with film appearance. Small opacities of International Labour Organisation (ILO) category 1/0+ were not associated with exposure. An association of borderline significance overall between 0/1+ opacities and exposure to respirable fibres was found for some exposure periods only, the time related pattern being biologically implausible. Pleural changes were related to age and exposure to asbestos, and findings were consistent with an effect of time since first exposure to RCFs. Among men, forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC) were inversely related to exposure to fibres, in current smokers only. FEV(1)/ FVC ratio and transfer factor (TL(CO)) were not related to exposures. The estimated restrictive effect was on average mild. Prevalence of respiratory symptoms was low. Chronic bronchitis and its associated symptoms (cough, phlegm) showed some association with recent exposure to respirable fibres. This could be due to an irritant effect of RCFs.

Adult↗
PubMed2001

Stimulation of IL-8 release from epithelial cells by gas cooker PM(10): a pilot study.

OBJECTIVE: To measure the effect of matter collected by a method that has a 50% efficiency for particles with an aerodynamic diameter of 10 microm (PM10), generated by gas and electric cooking, on A549 epithelial cells with and without nitrogen dioxide (NO2). METHOD: Multiple indoor PM10 samples were collected on Teflon filters during the use of gas or electric cookers. Interleukin-8 (IL-8) concentrations were measured with a sandwich enzyme linked immunosorbent assay (ELISA) system. RESULTS: Treatment of A549 cells with PM10 generated from gas cooking resulted in increased concentrations of IL-8 compared with untreated cells; particles from the electric cooker had no effect. NO2 did not alter the concentration of IL-8. CONCLUSION: PM10 generated by gas cooking has the potential to cause proinflammatory effects in lung cells. This may have implications for susceptible people.

Air Pollution, Indoor↗
PubMed2001

Ultrafine particles and nitrogen oxides generated by gas and electric cooking.

OBJECTIVES: To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens. METHODS: Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NO(x)) were measured by a chemiluminescent ML9841A NO(x) analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm. RESULTS: High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NO(X) were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide. CONCLUSIONS: Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NO(x) might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.

Air Pollution, Indoor↗
PubMed2001

A training exercise in subjectively estimating inhalation exposures.

OBJECTIVES: This study examined whether it is possible to train occupational hygienists to estimate inhalation exposures reliably from limited occupational information using a new method and assessed improvements in the quality of the estimate using the aggregate from multiple assessors. METHODS: Five occupational hygienists estimated inhalation exposure for 40 tasks covering a range of chemical hazards using a recently developed subjective modeling technique supplemented by detailed guidance notes. The measured exposure levels were used to determine the validity of the method. The correlation coefficients of the log-transformed data were used to assess the discriminative power of the method, and the ratio of the mean estimate to measured values was used to measure accuracy. RESULTS: There was good-to-excellent agreement between the assessors' estimates and the measured data, the correlation coefficients ranging from 0.73 to 0.85. There was a tendency for assessors to overestimate the exposure levels by, on the average, two- to fourfold. Aggregating the assessors' estimates helped to improve the correlation coefficient to 0.88, the overestimation being 2.6-fold. Using more than three assessors for aggregate estimates did not improve the reliability of the method. CONCLUSIONS: Overall, the assessors found the method to be useful in generating exposure estimates that correlate well with measured levels. The provision of high-quality guidance information is likely to be important in the generation of reliable exposure estimates. The method is likely to be of use in epidemiologic studies in which limited exposure data are available.

Environmental Monitoring↗