Maternal occupational exposure to electromagnetic fields before, during, and after pregnancy in relation to risks of childhood cancers: findings from the Oxford Survey of Childhood Cancers, 1953-1981 deaths

BACKGROUND

The concern that maternal exposure to electromagnetic fields (EMF) might be related to childhood cancer risks, particularly leukemia risks.

METHODS

Maternal occupational data already collected as part of the Oxford Survey of Childhood Cancers have been reviewed. Information on occupations held before, during, and after the pregnancy was sought for 15,041 children dying of cancer in Great Britain in the period 1953-1981, and for an equal number of matched controls. Each period of working was classified under one of five headings: (1) sewing machinist; (2) textile industry workers (other than sewing machinists) with likely exposures to EMF; (3) other machinists and other jobs with likely "higher" EMF exposure; (4) other jobs with likely exposure to some EMF, and (5) jobs with little potential for EMF exposure.

RESULTS

Relative to risks in the children of mothers who held occupations with little potential for EMF exposure during pregnancy (a category that included housewives), risks of all childhood cancers were close to unity both for the children of sewing machinists (22 case and 31 control mothers, RR 0.72, 95% CI 0.42 to 1.25) and for the children of other machinists with likely "higher" EMF exposures (44 case and 47 control mothers, RR 0.93, 95% CI 0.61 to 1.41). Corresponding risks for all childhood leukemias and for all childhood brain cancers were similarly unexceptional. Simultaneous adjustment for social class, maternal age at birth of child, and sibship position had little effect.

CONCLUSIONS

The study findings did not indicate that maternal occupational exposure to EMF during pregnancy is a risk factor for childhood leukemias, childhood brain cancers, or the generality of all childhood cancers.

1998 and beyond--Legge's legacy to modern occupational health

Thomas Legge achieved much in his professional lifetime. The purpose of this lecture is to highlight some of these achievements in the light of what we have achieved since then. In other words, if Legge was in the audience today, how would he feel we have performed? On 'industrial maladies', progress has been made in reducing poisoning by heavy metals but our success with chrome ulceration and lead depends on surveillance and control. Room for improvements remain. For asbestos related diseases, Legge would be disappointed with our progress. Two areas of particular concern to Legge were upper limb disorders and 'occupational neurosis'. Much remains to be done. As a member of the 1st Committee on Compensatable Diseases, a review of the Scheme to date will focus on the common diseases now being prescribed and on the threats to the Scheme from the Benefits review. For the future, there are many challenges in the newer workplaces and the changing workforces. The HSE initiatives for a new occupational strategy and the Government Green Paper on Public Health provide great opportunities for the occupational health professional to influence the nature and shape of future public health strategy. Above all we must have some of Legge's characteristics to achieve this-vision, passion and commitment.

Retrospective exposure assessment for a cohort study into respiratory effects of acid anhydrides

OBJECTIVES

To estimate past exposure to phthalic (PA), trimellitic (TMA) and maleic anhydride (MA) in three alkyd resin and one cushioned flooring factory to estimate exposure-response relations in a retrospective cohort study.

METHODS

Personal exposure measurements were carried out in 1992 and quantitative and qualitative information on past exposure and production processes were collected. Job titles were ranked by decreasing exposure and amalgamated into job categories and exposure groups. Multiplication factors for back calculating past exposure levels were estimated with past exposure data, or if no such data were available these factors were estimated by a panel of occupational hygienists. Exposure levels were back calculated starting with the exposure levels in 1992.

RESULTS

High exposures to PA were estimated to have occurred among workers operating the PA melting pots in factory 1 (estimated exposure in 1960-9 was 2480 micrograms.m-3). Highest concentrations of TMA were estimated to have occurred among the ink mixers in factory 2 from 1979 to 1986 (554 micrograms.m-3). Exposure in most other job titles was thought to be fairly constant over time for PA, TMA, and MA.

CONCLUSIONS

Exposure to acid anhydride at these factories has fallen during the period covered by the study. However, it is estimated that in only one job in factory 2 did past exposure to acid anhydride exceed the current occupational exposure standard. Accuracy of the estimated exposure is limited by a paucity of reliable past exposure data.

Occupational urothelial tumours: a regional case-control study

OBJECTIVE

To investigate the role of occupational exposures in the risk of developing urothelial cancer.

MATERIALS AND METHODS

Occupational histories, obtained using a self-administered questionnaire, for 803 patients with urothelial cancer (first diagnosed 1991-93) were compared with similar information for 2135 matched controls. Relative risks (RRs) were estimated using conditional logistic regression. Comparisons were also made with historical regional employment information available from the 1971 census.

RESULTS

There were many statistically significant positive associations for urothelial cancer risks and ever being employed in specified occupations (with or without statistical adjustment for smoking status in 1991). Smoking-adjusted RRs of > 2.0 were obtained for seven occupations; manufacture of fire lighters/ patent fuels (RR 4.30, 95% confidence interval 0.78-23.79), rodent extermination (3.71, 1.20-11.48), manufacture of dyestuffs (2.61, 0.98-7.00), leather work (2.51, 1.44-4.35), cable manufacturing industry (2.46, 1.20-5.04), textile printing and dyeing (2.32, 0.98-5.45), and sewage works (2.19, 1.16-4.11). Analyses of the occupations followed in 1971 (thus allowing for 20-year latency) indicated an elevated RR for workers in the plastics industry (5.22, 1.57-17.36).

CONCLUSIONS

The historical legacy of exposure to aromatic amines in the rubber, cable-making, dyestuffs and other industries remains. An important proportion of patients presenting with urothelial tumours are likely to have had occupational exposure to urothelial carcinogens. A review of occupational exposures in the contemporaneous plastic, textile and leather industries is warranted.

Lung cancer mortality in nickel/chromium platers, 1946-95

OBJECTIVES

To investigate mortality from lung cancer in nickel/chromium platers.

METHODS

The mortality experience of a cohort of 1762 chrome workers (812 men, 950 women) from a large electroplating and light engineering plant in the Midlands, United Kingdom, was investigated for the period 1946-95. All subjects were first employed in chrome work at the plant during the period 1946-75, and had at least six months employment in jobs associated with exposure to chromic acid mist (hexavalent chromium). Detailed job histories were abstracted from original company personnel records and individual cumulative durations of employment in three types of chrome work were derived as time dependent variables (chrome bath work, other chrome work, any chrome work). Two analytical approaches were used--indirect standardisation and Poisson regression.

RESULTS

Based on mortalities for the general population of England and Wales, male workers with some period of chrome bath work had higher lung cancer mortalities (observed deaths 40, expected deaths 25.41, standardised mortality ratio (SMR) 157, 95% confidence interval (95% CI) 113 to 214, p < 0.01) than did other male chrome workers (observed 9, expected 13.70, SMR 66, 95% CI 30 to 125). Similar findings were shown for female workers (chrome bath workers: observed 15, expected 8.57, SMR 175, 95% CI 98 to 289, p = 0.06; other chrome workers: observed 1, expected 4.37, SMR 23, 95% CI 1 to 127). Poisson regression was used to investigate risks of lung cancer relative to four categories of cumulative duration of chrome bath work and four categories of cumulative duration of other chrome work (none, < 1 y, 1-4 y, > or = 5 y). After adjusting for sex, age, calendar period, year of starting chrome work, period from first chrome work, and employment status (still employed v left employment), there was a significant positive trend (p < 0.05) between duration of chrome bath work and risks of mortality for lung cancer. Relative to a risk of unity for those chrome workers without any period of chrome bath work, risks were 2.83 (95% CI 1.47 to 5.45), 1.61 (95% CI 0.75 to 3.44), and 4.25 (95% CI 1.83 to 9.87) for the second, third, and fourth exposure categories, respectively. Duration of other chrome work was not a useful predictor of risks of lung cancer. Similar findings for both variables were obtained when adjustment was made for sex and age only. Similar findings for both variables were obtained relative to risk of chrome nasal ulceration.

CONCLUSIONS

The findings are consistent with the hypothesis that soluble hexavalent chromium compounds are potent human lung carcinogens.

Surveillance case definitions for work related upper limb pain syndromes

OBJECTIVES

To establish consensus case definitions for several common work related upper limb pain syndromes for use in surveillance or studies of the aetiology of these conditions.

METHODS

A group of healthcare professionals from the disciplines interested in the prevention and management of upper limb disorders were recruited for a Delphi exercise. A questionnaire was used to establish case definitions from the participants, followed by a consensus conference involving the core group of 29 people. The draft conclusions were recirculated for review.

RESULTS

Consensus case definitions were agreed for carpal tunnel syndrome, tenosynovitis of the wrist, de Quervain's disease of the wrist, epicondylitis, shoulder capsulitis (frozen shoulder), and shoulder tendonitis. The consensus group also identified a condition defined as "non-specific diffuse forearm pain" although this is essentially a diagnosis made by exclusion. The group did not have enough experience of the thoracic outlet syndrome to make recommendations.

CONCLUSIONS

There was enough consensus between several health professionals from different disciplines to establish case definitions suitable for use in the studies of several work related upper limb pain syndromes. The use of these criteria should allow comparability between studies and centres and facilitate research in this field. The criteria may also be useful in surveillance programmes and as aids to case management.

Efficiency of different grouping schemes for dust exposure in the European carbon black respiratory morbidity study

OBJECTIVES

The aim of this study was to assess the theoretical efficiencies of different grouping strategies and its effect on the exposure-response relation in a study of respiratory morbidity associated with exposure to total inhalable and respirable carbon black dust.

METHODS

A large epidemiological study is being undertaken to investigate the respiratory health of employees in the European carbon black manufacturing industry in relation to exposure to carbon black dust. In phase 2 of the study, repeated measurements of total inhalable and respirable dust were taken which enabled estimation of various components of variability in the exposure data (within and between worker variance and within and between group variance). These variance components were used to calculate the contrast in exposure between the groups in various classification schemes and to calculate the theoretical attenuation of the exposure-response relation and the standard error (SE) of the slope.

RESULTS

High contrast in exposure was found when workers were classified according to the combination of their factory and job category as well as when these combinations were amalgamated into five exposure groups. Attenuation was minimal with most grouping schemes; only with the individual based strategy was the attenuation large. The SE of the theoretically attenuated exposure-response slope was smallest for the strategy based on individual people followed by the classification scheme based on factory and job category.

CONCLUSIONS

It was concluded that, although some assumptions for the calculations of the attenuation of the exposure-response slope were not met, the most appropriate classification scheme of the worker seems to be by the combination of factory and job category.

Non-specific symptoms in response to hazard exposure in the workplace

Recent concerns in occupational health have shown a shift in emphasis from the study of diseases with well-established pathology toward the investigation of conditions characterized by a range of nonspecific symptoms. Exposure to potential hazards differing widely in terms of their physical nature or chemical composition, for example, electromagnetic fields, organophosphate-based pesticides, and organic solvents, frequently results in the reporting of a relatively consistent group of symptoms. Furthermore, these symptoms may arise among groups of workers where no specific physical or chemical cause can be implicated; for example, in many cases of sick building syndrome. The role of psychosocial factors in the expression of ill-health has been well-documented in the psychological literature. Important modifying factors include the attitudes and belief systems of the individuals concerned, certain personality and behavior patterns, and the presence of current stress or pre-existing psychological distress. In addition, social processes may be involved in the generation and reinforcement of health concerns at the group level. These include the workers' perceptions of the competence and credibility of managers and professionals, and the influence and involvement of the media, pressure groups, and the legal system. A proper understanding of the association between putative hazards and the reporting of nonspecific symptoms therefore requires consideration not only of the direct physical pathway between hazard and harm, but also an assessment of factors which may modify the relationship between exposure and symptom reporting. The results of such investigations have important implications for determining the focus of any management and control strategies which may subsequently be implemented in the workplace.

Health and safety problems associated with long working hours: a review of the current position

The European Community Directive on Working Time, which should have been implemented in member states of the European Community by November 1996, contains several requirements related to working hours, including the right of employees to refuse to work more than 48 hours a week. The United Kingdom government attempted to oppose the Directive, arguing that there is no convincing evidence that hours of work should be limited on health and safety grounds. Much of the research in this area has focused on the problems of shiftworking and previous reviews have therefore tended to emphasise this aspect of working hours. However, there is much less information about the effects of overtime work, which is a central element of the terms of the Directive. This paper reviews the current evidence relating to the potential effects on health and performance of extensions to the normal working day. Several gaps in the literature are identified. Research to date has been restricted to a limited range of health outcomes--namely, mental health and cardiovascular disorders. Other potential effects which are normally associated with stress--for example, gastrointestinal disorders, musculoskeletal disorders, and problems associated with depression of the immune system, have received little attention. Also, there have been few systematic investigations of performance effects, and little consideration of the implications for occupational exposure limits of extensions to the working day. Existing data relate largely to situations where working hours exceed 50 a week and there is a lack of information on hours below this level, which is of direct relevance to the European Community proposal. Finally, it is clear from investigations relating to shiftwork that a range of modifying factors are likely to influence the level and nature of health and performance outcomes. These include the attitudes and motivation of the people concerned, the job requirements, and other aspects of the organisational and cultural climate. It is concluded that there is currently sufficient evidence to raise concerns about the risks to health and safety of long working hours. However, much more work is required to define the level and nature of those risks.

Occupational exposure to magnetic fields in relation to mortality from brain cancer among electricity generation and transmission workers

OBJECTIVE

To investigate whether the risks of mortality from brain cancer are related to occupational exposure to magnetic fields.

METHODS

A total of 112 cases of primary brain cancer (1972-91) were identified from a cohort of 84,018 male and female employees of the (then) Central Electricity Generating Board and its privatised successor companies. Individual cumulative occupational exposures to magnetic fields were estimated by linking available computerised job history data with magnetic field measurements collected over 675 person-workshifts. Estimated exposure histories of the case workers were compared with those of 654 control workers drawn from the cohort (nested case-control study), by means of conditional logistic regression.

RESULTS

For exposure assessments based on arithmetic means, the risk of mortality from brain cancer for subjects with an estimated cumulative exposure to magnetic fields of 5.4-13.4 microT.y v subjects with lower exposures (0.0-5.3 microT.y) was 1.04 (95% confidence interval (95% CI) 0.60 to 1.80). The corresponding relative risk in subjects with higher exposures (> or = 13.5 microT.y) was 0.95 (95% CI 0.54 to 1.69). There was no indication of a positive trend for cumulative exposure and risk of mortality from brain cancer either when the analysis used exposure assessments based on geometric means or when the analysis was restricted to exposures received within five years of the case diagnosis (or corresponding period for controls).

CONCLUSIONS

Although the exposure categorisation was based solely on recent observations, the study findings do not support the hypothesis that the risk of brain cancer is associated with occupational exposure to magnetic fields.

Research priorities in occupational medicine: a survey of United Kingdom personnel managers

A Delphi survey was carried out in an attempt to identify areas of priority in occupational health that should be targeted by research. Previously 53 occupational physicians identified and ranked these areas. These were then assessed by personel managers. There was considerable agreement on priorities between the two groups with musculoskeletal disorders and stress securing the highest ranking.

Abnormalities on neurological examination among sheep farmers exposed to organophosphorous pesticides

OBJECTIVES

Organophosphates are effective pesticides which are frequently used in several agricultural settings. Although their acute effects are well characterised, it remains unclear whether long term exposure can damage the human nervous system. This study sought to investigate their long term effects by comparing abnormalities on neurological examination between groups of workers exposed to organophosphates and an unexposed group.

METHODS

146 exposed sheep farmers and 143 unexposed quarry workers were recruited into a cross sectional study of symptoms and neuropsychological effects of long term exposure to organophosphates in sheep dip. From a symptom questionnaire given immediately after dipping the 10 most symptomatic and 10 least symptomatic farmers were selected. Several months later each of these, along with 10 of the unexposed quarry workers, underwent a standardised neurological examination similar to that which might be used in clinical practice, at at time as remote as possible from recent exposure to organophosphates so as to exclude any acute effects.

RESULTS

All 30 selected subjects agreed to participate. The components of the examination which showed a significant difference were two point discrimination on the dorsum of the hand (symptomatic farmers 22 mm; asymptomatic farmers 13 mm; quarry workers 8 mm) and the dorsum of the foot (symptomatic farmers 34 mm; asymptomatic farmers 10 mm; quarry workers 11 mm), and mean calf circumference (symptomatic farmers 35.0 cm; asymptomatic farmers 36.3 cm; quarry workers 38.6 cm). Overall the prevalence of neurological abnormalities was low.

CONCLUSIONS

The differences in neurological examination detected between groups were subtle and their clinical significance was unclear. However, they do suggest evidence of an adverse neurological effect from exposure to organophosphates. Further, larger scale studies will be required before it is possible to confirm or refute the differences detected.

Modifiers of non-specific symptoms in occupational and environmental syndromes

Many occupational and environmental health hazards present as an increased reporting of non-specific symptoms such as headache, backache, eye and respiratory irritation, tiredness, memory problems, and poor concentration. The pattern and number of such symptoms is surprisingly constant from hazard to hazard suggesting that common psychological and social factors, not directly related to the exposure may be involved. A recent workshop (see acknowledgements) was held to review the pattern of symptoms in varying hazardous situations and the psychological mechanisms behind the genesis and maintenance of symptoms. The involvement of both direct physicochemical and psychological mechanisms in symptom generation and reporting in any situation was discussed and is reported here. A model that identifies the issues that need to be considered in any epidemiological study based on the incidence or prevalence of non-specific symptoms is proposed.

Occupational exposure to carbon black in its manufacture: data from 1987 to 1992

Carbon black is a very pure form of very finely divided particulate carbon used mainly in the automotive tyre industry. Its carbonaceous nature and submicron size (unpelleted) have raised concerns with regard to its ability to affect respiratory morbidity. This paper describes the exposure to carbon black dust in the first and second phase of a large multi-national epidemiological study investigating the magnitude of these exposure-related effects. In Phase I, 1278 respirable dust samples were taken (SIMPEDS cyclone) which increased to 2941 in Phase II with a similar rise in the number of total inhalable dust samples (IOM head) from 1288 in Phase I to 3433 Phase II. Exposure dropped markedly between the two phases with total inhalable dust showing a bigger reduction (49.9%) than respirable dust (42%), although the mean exposure for certain factories and job categories dropped more than others. The data are presented by the 14 job titles/numbers (21-34). The highest mean exposure in both phases and for both dust fractions is experienced by the warehouse packers and they are also most likely to exceed the OES of 3.5 mg m-3 (35.1% of samples in Phase I and 12.0% in Phase II).

Mortality of copper cadmium alloy workers with special reference to lung cancer and non-malignant diseases of the respiratory system, 1946-92

OBJECTIVES

To identify and quantify any relations between occupational exposure to cadmium oxide fume and mortalities from lung cancer and from chronic non-malignant diseases of the respiratory system.

METHODS

The mortality experience of 347 copper cadmium alloy workers, 624 workers employed in the vicinity of copper cadmium alloy work (vicinity workers), and 521 iron and brass foundry workers (all men) was investigated for the period 1946-92. All subjects were first employed in these types of work in the period 1922-78 and for a minimum period of one year at one of two participating factories. Two analytical approaches were used, indirect standardisation and Poisson regression.

RESULTS

Compared with the general population of England and Wales, mortality from lung cancer among copper cadmium alloy workers was close to expectation (observed deaths 18, expected deaths 17.8, standardised mortality ratio (SMR) 101, 95% confidence interval (95% CI) 60 to 159). A significant excess was shown for lung cancer among vicinity workers but not among iron and brass foundry workers (vicinity workers: observed 55, expected 34.3, SMR 160, 95% CI 121 to 209, P < 0.01; iron and brass foundry workers: observed 19, expected 17.8, SMR 107, 95% CI 64 to 167). Increased SMRs for non-malignant diseases of the respiratory system were shown for each of the three groups (alloy workers: observed 54, expected 23.5, SMR 230, 95% CI 172 to 300, P < 0.001; vicinity workers: observed 71, expected 43.0, SMR 165, 95% CI 129 to 208, P < 0.001; iron and brass foundry workers: observed 34, expected 17.1, SMR 199, 95% CI 137 to 278, P < 0.01). Work histories of the copper cadmium alloy workers were combined with independent assessments of cadmium exposures over time to develop individual estimates of cumulative exposure to cadmium; this being a time dependent variable. Poisson regression was used to investigate risks of lung cancer and risks of chronic non-malignant diseases of the respiratory system in relation to three levels of cumulative cadmium exposure (< 1600, 1600-4799, > or = 4800 micrograms.m-3.y). After adjustment for age, year of starting alloy work, factory, and time from starting alloy work, there was a significant positive trend (P < 0.01) between cumulative exposure to cadmium and risks of mortality from chronic non-malignant diseases of the respiratory system. Relative to a risk of unity for the lowest exposure category, risks were 4.54 (95% CI 1.96 to 10.51) for the middle exposure category and 4.74 (95% CI 1.81 to 12.43) for the highest exposure category. There was a non-significant negative trend between cumulative cadmium exposure and risks of mortality from lung cancer. Relative to a risk of unity for the lowest exposure category, risks were 0.85 (95% CI 0.27 to 2.68) for the middle exposure category and 0.81 (95% CI 0.18 to 3.73) for the highest exposure category. Similar findings were obtained when adjustment was made for age only.

CONCLUSIONS

The findings are consistent with the hypothesis that exposure to cadmium oxide fume increases risks of mortality from chronic non-malignant diseases of the respiratory system. The findings do not support the hypothesis that exposure to cadmium oxide fume increases risks of mortality for lung cancer.

Exposure to acid anhydrides in three resin and one cushioned flooring manufacturing plants

Acid anhydrides are reactive organic chemicals of low molecular weight which cause occupational asthma. No previous research on the relationship between exposure to these chemicals and respiratory sensitization and development of occupational asthma has been reported. A retrospective cohort study was carried out in four factories (three alkyd resin factories and one cushioned flooring factory) to investigate the nature of exposure-response relationships for sensitization to phthalic anhydride (PA), trimellitic anhydride (TMA) and maleic anhydride (MA). This paper describes the results of full-shift and task-specific exposure measurements. Exposure to PA was low in relation to the Occupational Exposure Standard (OES). The highest full-shift PA exposures occurred among resin operators in the resin factory that used solid PA as compared to other resin factories where liquid PA was used. Arithmetic mean exposure levels to TMA and MA in the resin factories were well below their respective OESs. Short-term high exposures occurred during loading of acid anhydrides into the reactors and sampling and testing of the resin. Relatively high full-shift exposure to TMA occurred in the cushioned flooring factory, although no high peak exposures were detected.

Neuropsychological effects of long-term exposure to organophosphates in sheep dip

Organophosphate-based pesticides are widely used throughout the world. The acute effects of over-exposure to such compounds are well known. Concern has also been expressed that long-term exposure may result in damage to the nervous system. In a cross-sectional study, we compared neuropsychological performance in 146 sheep farmers who were exposed to organophosphates in the course of sheep dipping with 143 non-exposed quarry workers (controls). The farmers performed significantly worse than controls in tests to assess sustained attention and speed of information processing. These effects remained after adjustment for covariates. The farmers also showed greater vulnerability to psychiatric disorder than did the controls as measured by the General Health Questionnaire. There were no observed effects on short-term memory and learning. Repeated exposure to organophosphate-based pesticides appears to be associated with subtle changes in the nervous system. Measures should be taken to reduce exposure to organophosphates as far as possible during agricultural operations.

Study of the respiratory health of employees in seven European plants that manufacture ceramic fibres

OBJECTIVES

To study the relation between occupational exposure to ceramic fibres during manufacture and respiratory health.

METHODS

The respiratory health of 628 current employees in the manufacture of ceramic fibres in seven European plants in three countries was studied with a respiratory questionnaire, lung function tests, and chest radiography. Simultaneous plant hygiene surveys measured subjects' current exposure to airborne ceramic fibres from personal samples with optical microscopy fibre counts. The measured exposures were combined with occupational histories to derive estimates of each subject's cumulative exposure to respirable fibres. Symptoms were related to current and cumulative exposure to ceramic fibres and lung function and findings from chest radiographs were related to cumulative exposure.

RESULTS

The mean duration of employment was 10.2 years and mean (range) cumulative exposure was 3.84 (0-22.94) (f.ml-1.y). Eye and skin symptoms were frequent in all plants and increased significantly, as did breathlessness and wheeze, with increasing current exposure. Dry cough and stuffy nose were less common in the least exposed group but did not increase with increasing exposure. After adjustment for the effects of age, sex, height, smoking, and past occupational exposures to respiratory hazards, there was a significant decrease in both forced expiratory volume in one second (FEV1) and forced midexpiratory flow related to cumulative exposure in current smokers (P < 0.05) and in FEV1 in ex-smokers (P < 0.05). Small opacities were found in 13% of the chest radiographs; their prevalence was not related to cumulative exposure to ceramic fibres.

CONCLUSIONS

It is concluded that exposure to ceramic fibres is associated with irritant symptoms similar to those seen in other exposures to man made mineral fibres (MMMFs) and that cumulative exposure to respirable ceramic fibres may cause airways obstruction by promoting the effects of cigarette smoke.

Are the respiratory health effects found in manufacturers of ceramic fibres due to the dust rather than the exposure to fibres?

OBJECTIVES

To determine whether the respiratory symptoms and decrements in lung function found in manufacturers of ceramic fibres are related to exposure to the respirable fibre or inspirable mass constituents of the air in the working environment.

METHODS

Cross sectional survey of all current European primary producers of ceramic fibre was carried out, with measurement of exposure to respiratory fibres by personal samplers that measured inspirable and total mass, together with a health survey with an expanded respiratory questionnaire and standardised measurement of lung function. Odds ratios were calculated for symptoms and current exposure by multiple logistic regression, and multiple linear regression coefficients for lung function related to cumulative exposures controlled for the effects of respirable fibre and inspirable mass separately and together.

RESULTS

Significant effects of current exposure to both inspirable dust and respirable fibres were related to dry cough, stuffy nose, eye and skin irritation and breathlessness. The decrements found in smokers and to some extent in ex-smokers in forced expiratory volume in one second and forced expiratory flow from 25% to 75% of expiratory volume, seem to be related to the respirable fibres rather than the inspirable mass constituents of the environment.

CONCLUSIONS

Current symptoms were related to both current exposure to inspirable dust and respirable fibre. The decrements in lung function were related to the fibre constituent of the exposure.

Retrospective assessment of solvent exposure in paint manufacturing

This paper describes how exposure to solvents at two large paint making sites was assessed in a study carried out to investigate the possibility of neuropsychological effects resulting from long term exposure to organic solvents. A job exposure matrix was constructed by buildings and year. A detailed plant history was taken and this was used to identify uniform exposure periods during which workers' exposure to solvents was not thought to have changed significantly. Exposure monitoring data, collected by the company before the study, was then used to characterise exposure within each uniform exposure period. Estimates were made for periods during which no air monitoring was available. Individual detailed job histories were collected for subjects and controls. The job histories were used to estimate exposure on an individual basis with the job exposure matrix. Exposure was expressed as duration, cumulative dose, and intensity of exposure. Classification of exposure by duration alone was found to result in misclassification of subjects.