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Aim: To quantify the risks of clinically important deficits of FEV1 in coal miners in relation to cumulative and average concentrations of respirable dust. Methods: Data were studied from over 7000 men who had been surveyed in the late 1970s. Linear regression equations for the association between FEV1 and self-reported breathlessness on mild exertion were used to define clinically important levels of FEV1 deficit, and the probabilities that individuals with different dust exposures would experience these deficits were calculated. Results: Levels of FEV1 were lower among breathless men than among others, with a large overlap of the distributions. The relations between standardised FEV1 and breathlessness were constant over all age and smoking groups. A decrease of 100 ml in FEV1 was associated with an increase of 1.12 in the odds of reporting breathlessness. FEV1 deficits of −0.367, −0.627, and −0.993 l (designated as “small”, “medium”, and “large” deficits) were, on average, associated with proportional increases of risks of breathlessness by factors of 1.5, 2.0, and 3.0 respectively. Cumulative respirable dust exposure ranged up to 726 gh/m 3 , mean 136 gh/m 3 (British Medical Research Council measurement convention). An increase of 50 gh/m 3 was associated with an increase of about 2% in the proportion of men with small deficits in FEV1. For medium deficits the increases ranged from 1.5% to 2%, depending on age. A similar pattern was seen for large deficits, but with smaller increases. Conclusions: In the unlikely event of continuous exposure at the proposed new maximum respirable dust limit for British mines of 3 mg/m 3 (ISO-CEN measurement convention) for a working lifetime, the risk of a medium deficit of FEV1 for a non-smoker at age 60 would be estimated to be 34%, compared with 25% for zero dust exposure; for smokers, about 54% compared with 44%.

To help inform the setting of dust control standards in coalmines, this brief review summarises the most recent and reliable exposure-response relations, for damaging respiratory effects, derived from the Pneumoconiosis Field Research (PFR). Collecting data over 38 years in the British coal industry, this was a programme of prospective research on the respiratory health of coal miners, characterised by regular health surveys and detailed measurements of dust and silica concentrations in the workplace. Exposure-response relations are presented for coal workers' simple pneumoconiosis category II, progressive massive fibrosis, defined deficits of lung function (FEV1), and category II silicosis. This simplified overview provides a guide to the most recent and most reliable estimates from the PFR of dust-related risks of substantial pulmonary disease, and to the magnitude of the effects. Control of dust sufficient to prevent category II simple pneumoconiosis should prevent most cases of progressive massive fibrosis and most dust related large lung function deficits. Where the dust contains high proportions of silica, control to low levels is essential, and even quite brief excursions of silica to high levels must be avoided.

OBJECTIVES—To investigate the hypothesis that chronic low level exposure to organophosphates (OPs) in sheep dips is related to clinically detectable measures of polyneuropathy. METHODS—The design was a cross sectional exposure-response study of sheep dippers and other non-exposed groups. The study group consisted of 612 sheep dipping farmers, 53 farmers with no sheep dipping experience, and 107 ceramics workers. Retrospective exposure information was obtained by questionnaire based on stable and easily identifiable features of sheep dipping found during the first phase of the study; in particular, estimates of handling concentrate and splashing with dilute dip. Neurological assessments were based on a standard neuropathy symptoms questionnaire, and thermal and vibration quantitative sensory tests. RESULTS—Adjusted for confounders there was a weak positive association between cumulative exposure to OPs and neurological symptoms, the significance of which was dependent on the inclusion of a few individual workers with extremely high exposure. There was no evidence of an association between cumulative exposure and the thermal or vibration sensory thresholds. However, separating the effects of exposure intensity and duration showed a higher prevalence of symptoms, primarily of a sensory type, among sheep dippers who handled the OP concentrate. There was also evidence that sensory and vibration thresholds were higher among concentrate handlers, the highest exposed group of dippers. CONCLUSIONS—The findings showed a strong association between exposure to OP concentrate and neurological symptoms, but a less consistent association with sensory thresholds. There was only weak evidence of a chronic effect of low dose cumulative exposure to OPs. It is suggested that long term health effects may occur in at least some sheep dippers exposed to OPs over a working life, although the mechanisms are unclear. Keywords: organophosphates; sheep dippers; neuropathy

OBJECTIVES--To design a questionnaire for the identification and assessment of severity of back pain for epidemiological purposes, and gain preliminary experience of its use. METHODS--A group of specialists, experienced in the epidemiology and clinical assessment of back pain, designed the questionnaire, and tested it individually. It was also given cross sectionally by interview to a population of male coal mine workers. RESULTS--The questionnaire comprised a maximum of 12 questions on the presence, radiation, frequency, and severity of back pain with reference to difficulty with specific activities, interference with normal work, and absence from work. 471 coal miners answered the questionnaire (66% of those invited). 56% (265 men) of the responders reported pain or ache in the back during the previous 12 months, and the incidence of first ever attacks during the same period was reported to be 34%. 69% reported having had back pain at some time. The responses to the questionnaire were partially validated by comparison with certified sickness absence for two days or more attributed to back pain. In men who were symptomatic in the previous 12 months, for the question relating to absence from work because of back pain, the sensitivity was 82% and specificity was 84%. CONCLUSION--The questionnaire is easy to administer and generates clear cut data that could be useful for epidemiological or screening purposes. Preliminary, limited, studies of its validity are reasonably encouraging, although further validation is required. It is hoped that researchers will find the questionnaire useful, will extend its validation, and continue to develop it.

The relations of lung function and chest radiographic appearances with exposure to inspirable dust were examined in 634 workers in five wool textile mills in west Yorkshire, randomly selected to represent fully the range of current exposures to wool mill dust. Most of these workers could be categorised into three large sex and ethnic groups; European men, Asian men, and Asian women. Exposures to inspirable dust had been measured at a previous survey and time spent in current job, and in the industry were used as surrogates for lifetime cumulative exposures. Chest radiographs were interpreted on the International Labour Office (ILO) scale by three medically qualified readers, and the results combined. Profusions of small opacities of 0/1 on the ILO scale, or greater, were present in only 6% of the population, and were not positively associated with current exposure to wool mill dust, or duration of exposure. In general, statistically significant relations between exposure and lung function indices were not found, with the exception of an inverse relation between the forced expiratory volume/forced vital capacity ratio and dust concentration in European women. A suggestive but not statistically significant inverse relation between FVC and current dust concentration was seen in Asian men. Substantial differences were found between mills in mean values of lung function variables after adjustment for other factors but these were not apparently related to the differences in dust concentrations between these mills. Dyeworkers and wool scourers (mostly European men in relatively dust free jobs) on average experienced an FEV1 251 ml lower than other workers when age, height, smoking habits, and occupational factors had been taken into account. Twenty four per cent of the workforce responded to intracutaneous application of one or more common allergens (weal diameter at least 4 mm), only 12 (7.9%) of these responding to wool extracts. Atopic subjects did not appear to have an increased susceptibility to the effects of inspirable wool dust on lung function. These studies suggest that exposure to wool mill dust may cause functional impairment in some workers but there is little indication from these data of frequent or severe dust related functional deficits. More detailed estimates of cumulative dust exposure by reconstruction of exposure histories might clarify associations between exposure to dust and lung function. These chest radiographic findings provide no evidence that exposure to wool mill dust is related to lung fibrosis.

Objectives: The UK Ministry of Defence (MoD) controls a biological monitoring programme that includes testing for uranium in personnel who served in the conflict in Iraq in 2003. To help interpret the results, the MoD commissioned this study to quantify a normative reference distribution of urinary uranium concentrations in military personnel who had not served in that conflict. Methods: The study selected and visited various military establishments to recruit a representative mix of ranks, genders and occupational groups (combat, support and auxiliary). A standardised protocol and recruitment questionnaire were used. The 125 ml spot urine samples collected were analysed for uranium and creatinine concentrations and (where possible) for uranium isotope 238 U/ 235 U ratio. Results: Samples from 732 eligible subjects were analysed. Adjusted uranium concentrations ranged up to 556 ng.g −1 creatinine, somewhat higher than reference values quoted for the USA but much lower than recorded in granite areas such as Finland. Isotope ratio measurements were available for 125 samples (17) with the highest concentrations; these all had a natural isotope signature and no evidence of depleted uranium (DU). On average, urinary uranium concentrations were somewhat lower in officers than in other ranks; they differed also across the services, the Navy being lowest and the Army highest. The levels give no concern regarding health risks in the personnel studied. Conclusion: Since even the highest values were from natural sources, we assume the differences represent differences in ingestion of natural uranium. Definition of a reference distribution or normal values will depend on the subpopulation of interest.

To determine whether acquired colour vision deficits in solvent exposed individuals are associated with cognitive impairment.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.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.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.

Aims: To reanalyse exposure-response data from a Scottish colliery to gain a more detailed knowledge of the relations between exposure to quartz and risks of silicosis in coal miners, and hence inform the debate on an appropriate occupational standard for respirable quartz. Methods: Detailed data on working times at different quartz concentrations were combined to produce exposure profiles for miners who had provided a full chest radiograph at a follow up survey. Logistic regression methods were used to model profusion of radiographic abnormalities category 2/1+, and a general exposure index was used to compare different quartz exposure measures in these models. Results: Results in 371 men aged 50–74 indicated that cumulative quartz exposure at higher concentrations resulted in proportionally greater risks of abnormalities. One g.h.m −3 of cumulative exposure at quartz concentrations greater than 2 mg.m −3 was estimated to have equivalent risks to 3 g.h.m −3 at lower concentrations. The timing of exposure relative to follow up appeared less important, although the study had limited power to compare different lag periods between exposure and effect. Conclusions: Quantification of the risks of silicosis should take account of variations in quartz exposure intensity, particularly for exposure to concentrations of greater than 1 or 2 mg.m −3 , even if exposure is for relatively short periods. The risks of silicosis over a working lifetime can rise dramatically with even brief exposure to such high quartz concentrations. Risk estimates are given, to inform choice of control limits.

A sample of men working in the British coal industry in the 1950s has been followed up and examined 22 years later. The relations between lung function and individual cumulative exposure to respirable dust have been studied in 1867 men who were still working in the industry at the time of follow up and 2192 men who had left. Levels of forced expired volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio at follow up were found to be inversely related to exposure to respirable dust after allowing for other factors, even in men without pneumoconiosis. The magnitude of this estimated effect was equivalent to a loss of 228 ml FEV1 in response to an exposure of 300 gh/m3, a moderately high exposure for this group. Ex-miners aged under 65 had worse lung function than miners on average, suggesting that ill health had encouraged some of these men to leave the industry. Whereas a more severe response to dust exposure among ex-miners under 65 was suggested, this difference could easily have arisen by chance. The presence of symptoms of chronic bronchitis was associated with reduced levels of lung function, however, and, additionally, ex-miners under 65 with chronic bronchitis showed a more severe response of the FVC to dust exposure than miners without these symptoms. Among these ex-miners with chronic bronchitis a small group of men who had taken other jobs showed a much more severe effect of dust exposure on their lung function than the average, likely in heavily exposed men to contribute importantly to disability. Men in this group who had given up smoking showed and even more severe effect of dust exposure, equivalent to a loss of 940 ml FEV1 in response to an exposure of 300 gh/m3. These results indicate that exposure to respirable dust can occasionally cause severe respiratory impairment in the absence of progressive massive fibrosis. Dust exposure was related to a parallel reduction of FEV1 and FVC, implying that the pathology of dust induced lung damage differs form that induced by smoking. This pattern of abnormality was shown by some non-smokers, whereas smokers and ex-smokers apparently severely affected by dust showed a classic obstructive pattern of abnormality with pronounced reduction of the FEV1/FVC ratio.

Twenty-five histocompatibility antigens have been measured in 100 coal miners with pneumoconiosis attending a pneumoconiosis medical panel and the results compared with a panel of 200 normal volunteers not exposed to dust. Chest radiographs were read independently by three readers according to the ILO U/C classification. On a combined score, 40 men were thought to have simple pneumoconiosis and 60 men complicated pneumoconiosis. The number of antigens tested and associations between antigens caused difficulties in assessing the statistical significance of differences in prevalence of antigens between groups of men. Using stringent criteria for statistical significance, no significant differences were found in antigen prevalences between miners and controls, or miners with simple or complicated pneumoconiosis. When a less stringent statistical approach was applied, three antigens appeared to have abnormal prevalences in these 100 miners by comparison with the normal volunteers. More detailed examination of these antigen prevalences in relation to radiographic category of pneumoconiosis did not provide any supportive evidence that these slight associations were of statistical or clinical significance. Reports on histocompatibility antigens in miners with pneumoconiosis are reviewed briefly and the results compared. There is no good evidence that any of the histocompatibility antigens so far tested are associated with a clinically important altered risk of simple or complicated pneumoconiosis when dust is inhaled.

A group of 17 738 working miners, medically examined during 1953-8, were followed up from 1974 to 1980. Of the 7118 men re-examined, 2547 were still working miners and 4526 had left the industry (45 were of unrecorded status). The incidence of progressive massive fibrosis (PMF) over an average follow up period of 22 years among men who had remained in the industry was 27 per 1000, but 94 per 1000 among men who had left. This difference was only partly related to the difference in age between the groups; for men without simple pneumoconiosis at the start of the period, and for similar age groups (45-64), the attack rate in miners was 20 per 1000 and in the ex-miners 41 per 1000. In a group of 1902 leavers who did not have PMF at a medical examination conducted at most four years before leaving, 172 had developed PMF by the time of the follow up examination. Of these, 116 had had simple pneumoconiosis at the earlier examination. Cumulative exposure to respirable dust, category of simple pneumoconiosis, and age were each found to influence the probability of developing PMF in a subgroup of the 1902 men. Among the 1902 leavers, there was no overall progression or regression of simple pneumoconiosis.

It is well recognised that exposure to respirable coalmine dust causes a reduction in lung function but it has not been clear whether the impairment of function is sufficient to cause disability, unless progressive massive fibrosis occurs. From a study of 4059 men without progressive massive fibrosis who worked in the coal industry for at least ten years from the 1950s, and who were followed up and re-examined medically more than 20 years later, a subgroup was selected using criteria intended to favour those who may have suffered greater than average effects of dust exposure. These 199 men had left the coal industry before normal retiral age, had taken other jobs, and had reported symptoms of chronic bronchitis at follow up. The inverse relation between dust exposure and FEV1 among these 199 men was much more severe than the average effects previously shown among more representative groups of coalminers. The effect of exposure to respirable dust was estimated conservatively as an impairment of about 2 ml FEV1 per unit of dust exposure (gh/m3). The estimated effect among ex-smokers was more severe. These compare with a previous estimate, based on a less selected population, of 0.6 ml FEV1 per gh/m3. The new estimate in this group of 199 men corresponds to an average loss of 600 ml FEV1 in response to a moderately high dust exposure to 300 gh/m3, with correspondingly higher losses in the ex-smokers. These findings show that among a group of men intentionally selected to include those who may have suffered greater than average effects of dust exposure, the relation between exposure and FEV1 is consistent with the view that in some men even moderately high exposure to dust causes severe impairment of lung function.