The relative importance of whole body vibration and occupational lifting as risk factors for low-back pain.

AIMS: To explore the impact of occupational exposure to whole body vibration (WBV) on low back pain (LBP) in the general population and to estimate the burden of LBP attributable to occupational WBV in comparison with that due to occupational lifting. METHODS: A questionnaire including sections on WBV at work, LBP, and potential risk factors was mailed to a community sample of 22 194 men and women of working age. Sources and durations of exposure to occupational WBV were ascertained for the past week and personal vibration doses (eVDV) were estimated. Analysis was confined to subjects reporting exposures in the past week as typical of their work. Associations of LBP with eVDV, driving industrial vehicles, and occupational lifting were explored by logistic regression and attributable numbers were calculated. RESULTS: Significant associations were found between daily lifting of weights greater than 10 kg at work and LBP, troublesome LBP (which made it difficult to put on hosiery), and sciatica (prevalence ratios 1.3 to 1.7); but the risk of these outcomes in both sexes varied little by eVDV and only weak associations were found with riding on industrial vehicles. Assuming causal associations, the numbers of cases of LBP in Britain attributable to occupational WBV were estimated to be 444 000 in men and 95 000 in women. This compared with an estimated 940 000 male cases and 370 000 female cases of LBP from occupational lifting. CONCLUSIONS: The burden of LBP in Britain from occupational exposure to WBV is smaller than that attributable to lifting at work.

Occupational exposure to noise and the attributable burden of hearing difficulties in Great Britain.

AIMS: To determine the prevalence of self reported hearing difficulties and tinnitus in working aged people from the general population, and to estimate the risks from occupational exposure to noise and the number of attributable cases nationally. METHODS: A questionnaire was mailed to 22 194 adults of working age selected at random from the age-sex registers of 34 British general practices (21 201 subjects) and from the central pay records of the British armed services (993 subjects). Information was collected on years of employment in a noisy job; and whether the respondent wore a hearing aid, had difficulty in hearing conversation, or had experienced persistent tinnitus over the past year. Associations of hearing difficulty and tinnitus with noise exposure were examined by logistic regression, with adjustment for age, sex, smoking habits, and frequent complaints of headaches, tiredness, or stress. The findings were expressed as prevalence ratios (PRs) with associated 95% confidence intervals (CIs). Attributable numbers were calculated from the relevant PRs and an estimate of the prevalence of occupational exposure to noise nationally. RESULTS: Some 2% of subjects reported severe hearing difficulties (wearing a hearing aid or having great difficulty in both ears in hearing conversation in a quiet room). In men, the prevalence of this outcome rose steeply with age, from below 1% in those aged 16-24 years to 8% in those aged 55-64. The pattern was similar in women, but severe hearing loss was only about half as prevalent in the oldest age band. Tinnitus was far more common in subjects with hearing difficulties. In both sexes, after adjustment for age, the risk of severe hearing difficulty and persistent tinnitus rose with years spent in a noisy job. In men older than 35 years with 10 or more years of exposure, the PR for severe hearing difficulty was 3.8 (95% CI 2.4 to 6.2) and that for persistent tinnitus 2.6 (95% CI 2.0 to 3.4) in comparison with those who had never had a noisy job. Nationally, some 153 000 men and 26 000 women aged 35-64 years were estimated to have severe hearing difficulties attributable to noise at work. For persistent tinnitus the corresponding numbers were 266 000 and 84 000. CONCLUSIONS: Significant hearing difficulties and tinnitus are quite common in men from the older working age range. Both are strongly associated with years spent in a noisy occupation--a predominantly male exposure. The national burden of hearing difficulties attributable to noise at work is substantial.

Raynaud's phenomenon, vibration induced white finger, and difficulties in hearing.

BACKGROUND: An association has previously been reported between finger blanching and hearing difficulties, but only in workers with exposure to noise and hand transmitted vibration (HTV). AIMS: To explore the association in a community sample, including cases who lacked occupational exposure to noise or HTV. METHOD: A questionnaire was mailed to 12 606 subjects aged 35-64 years, chosen at random from the age-sex registers of 34 British general practices. Inquiry was made about years of employment in noisy jobs, lifetime exposure to HTV, hearing difficulties and tinnitus, and lifetime history of cold induced finger blanching. Subjects were classed as having severe hearing difficulty if they used a hearing aid or found it difficult or impossible to hear conversation in a quiet room. Associations of finger blanching with hearing difficulties and tinnitus were analysed by logistic regression. RESULTS: Among 8193 respondents were 185 who reported severe hearing difficulty and 1151 who reported finger blanching. After adjustment for age and years of work in noisy jobs, hearing difficulty was about twice as common in men and women who reported finger blanching, including those who had never been importantly exposed to noise and in those never exposed to HTV. CONCLUSIONS: These data support an association between finger blanching and hearing loss, which is not explained by confounding occupational exposure to noise, and suggest that it may extend to causes of blanching other than vibration induced white finger. Further investigations are warranted to confirm the association and explore possible mechanisms, such as sympathetic vasoconstriction in the cochlea.

Exposure to hand-transmitted vibration and pain in the neck and upper limbs.

Workers exposed to hand-transmitted vibration (HTV) often experience aches and pains in the upper limbs, but there have been few studies of the pattern and severity of symptoms, or their relationship to the estimated dose of vibration. As part of a wider survey of vibration, we mailed a questionnaire about exposures to HTV and pain in the neck and upper limbs to a sample of men selected at random from the registration lists of 34 British general practices and the pay records of the armed services. Analysis was confined to the 1856 male respondents who had been employed in manual occupations for a year or more and who reported the last week as being representative of their job. Inquiry was made about pain in the neck, shoulder, elbow and wrist/hand over the past week and past year (including pains that limited normal activity). Subjects were classed according to their lifetime exposure to HTV and their estimated average daily vibration dose [A(8) r.m.s.] in the previous week. A total of 283 men had a minimum estimated A(8) greater than a proposed action level of 2.8 m/s(2), and in this group symptoms were about twice as prevalent as in manual workers who had never used vibratory tools. The excess risk was somewhat higher for distal sites than for proximal ones (e.g. the prevalence ratio for hand/wrist pain in the past week was 2.7 versus 1.8 for neck pain). This accords with the pattern of transmission of HTV to the upper limb, although a confounding effect from other ergonomic risk factors cannot be discounted.

Risk of hand-arm vibration syndrome according to occupation and sources of exposure to hand-transmitted vibration: A national survey.

BACKGROUND: Although some occupational sources of hand-transmitted vibration (HTV) have been extensively investigated, the risks associated with others are poorly characterized. METHODS: A questionnaire was mailed to a community sample of 12,240 men aged 16- 64 years and 906 men from the armed forces. Questions covered current occupation, sources of HTV, numbness or tingling in the fingers in the past week, and finger blanching. In the 5,364 respondents who had been at work in the past week, associations between symptoms and exposures were examined by logistic regression, with odds ratios converted into prevalence ratios (PRs). RESULTS: Altogether, 513 men (10%) reported cold-induced finger blanching and 769 (14%) sensory symptoms in the fingers. The risk of blanching was increased in builders (PR 2.4, 95% CI 1.0-5.2), carpenters and joiners (PR 1.9, 95% CI 1.0-3.4), motor mechanics (PR 2.3, 95% CI 1.1-4.6), and laborers (PR 2.8, 95% CI 1.3-6.0); while the risk of sensory symptoms was elevated in laborers (PR 4.0, 95% CI 2.3-6.6) and plant operatives (PR 3.5, 95% CI 1.9-5.9). Use of hand-guided mowers, concrete breakers, chain saws, and jig saws was significantly associated with symptoms. CONCLUSIONS: Little attention has been paid to the risks of vibration injury in construction workers, woodworkers, motor mechanics, and laborers, or to the risks from mowers, jig saws and several other common vibratory tools. These should be a focus for further investigation and preventive measures.

Prevalence and occupational associations of neck pain in the British population.

OBJECTIVES: This study determined the prevalence of neck pain and its relation to occupation and occupational activities in the general population. METHODS: A questionnaire was mailed to 21 201 subjects aged 16-64 years, randomly selected from the patient registers of general practices in England, Scotland, and Wales, and to 993 subjects randomly selected from pay records of the armed services. Information was collected on occupation, workplace physical activities, neck pain in the past week and year, headaches, and feelings of tiredness or stress. Associations were explored by logistic regression, the resultant odds ratios being converted to prevalence ratios (PR). RESULTS: Among 12907 respondents, 4348 and 2528 reported neck pain in past year (1421 with pain interfering with normal activities) and week, respectively. Symptoms were the most prevalent among male construction workers [past week and year 24% and 38% (pain interfering with activities 11%), respectively], followed by nurses, armed services members, and the unemployed. Generally the age-standardized prevalence of neck pain varied little by occupation. Work with arms above the shoulders for >1 hours/day was associated with a significant excess of symptoms [PR 1.3-1.7 (women) and 1.2-1.4 (men)], but no associations existed for typing, lifting, vibratory tool use, or professional driving. Stronger neck-pain associations were found with frequent headaches (PR 2.3-2.8) and frequent tiredness or stress (PR 2.2-2.5) than with occupational activities. CONCLUSIONS: The data provide evidence against a strong association between neck pain and the examined occupational physical activities. They suggest that psychosocial factors may be more important.

The prevalence of sensorineural symptoms attributable to hand-transmitted vibration in Great Britain: a national postal survey.

BACKGROUND: Exposure to hand-transmitted vibration (HTV) can cause sensorineural symptoms in the upper limb, but its impact has not previously been assessed in the general population. METHODS: To investigate, we mailed a questionnaire about exposures to HTV, finger blanching and sensory symptoms (numbness or tingling) in the upper limbs to a population sample comprising 21,201 working-aged men and women selected at random from the age-sex registers of 34 British general practices, and a further 993 randomly selected from the pay records of the armed services. Associations were explored using multiple logistic regression models to adjust for confounding, with the resultant odds ratios converted into prevalence rate ratios (PRs). RESULTS: Of 12,907 respondents, 2,607 (20.2%) reported sensory symptoms in the upper limb during the past week. Sensory symptoms were more prevalent in those with blanching, and were commonly associated with exposure to HTV, especially in men. In comparison with men who had never been exposed to HTV, the PR in men exposed both at work and in leisure was 2.2 (95% CI 1.9-2.4). Associations were found even in those who had never blanched. CONCLUSIONS: Sensorineural symptoms in the upper limbs are common. HTV is an important risk factor for such complaints in the general population.

Prevalence of Raynaud's phenomenon in Great Britain and its relation to hand transmitted vibration: a national postal survey.

OBJECTIVES: To assess the prevalence of Raynaud's phenomenon in the general population of Great Britain and to estimate the proportion and number of cases attributable to hand transmitted vibration (HTV). METHODS: A questionnaire was posted to a random sample of 22,194 adults of working age. Information was collected on the lifetime prevalence of finger blanching, smoking habits, and occupational and leisure time exposures to HTV. Associations with risk factors were explored by logistic regression, with odds ratios converted into prevalence ratios (PRs). RESULTS: Among the 12 907 respondents, 1835 (14.2%) reported finger blanching at some time, including 1529 (11. 8%) in whom symptoms were induced by cold, and 597 (4.6%) in whom the blanched area was also clearly demarcated. Prevalences were higher in women than men. Around one fifth of cases (2% of respondents) had consulted a doctor about their symptoms. By comparison with men who had never been exposed to HTV, the PR for cold induced blanching in those exposed only at work was 2.0 (95% CI 1.7 to 2.3), and in men exposed both at work and in leisure it was 2. 5 (95% CI 2.1 to 3.1). Higher risks were found in men who consulted a doctor about cold induced blanching, among whom 37.6% of cases were estimated to arise from exposure to HTV. The estimated number of cases attributable to HTV nationally was 222 000 in men who reported extensive blanching (blanching affecting at least eight of the digits or 15 phalanges). Similar patterns of risk were found in women, but the attributable proportion was much lower (5.3% in cases consulting a doctor). CONCLUSIONS: Raynaud's phenomenon is common in the general population. Many cases are attributable to HTV, especially in men, emphasising the public health importance of this common occupational hazard.

Prevalence and pattern of occupational exposure to hand transmitted vibration in Great Britain: findings from a national survey.

OBJECTIVES: To estimate the number of workers in Great Britain with significant occupational exposure to hand transmitted vibration (HTV). Also, to identify the occupations and industries where such exposures arise, and the main sources of exposure. METHODS: A questionnaire was posted to 22,194 men and women aged 16-64, comprising 21,201 subjects selected at random from the age-sex registers of 34 general practices in England, Scotland, and Wales, and a further 993 subjects selected at random from the central pay registers of the three armed services. Among other things, the questionnaire asked about exposure to sources of HTV in current and earlier employment. Responses were assessed by occupation and industry, and prevalence estimates for the country as a whole were derived from census information on occupational and industrial populations nationally. Estimates were also made in exposed workers of the average daily dose of vibration (A(8) root mean squared (rms) for the past week, based on their reported sources and durations of exposure. RESULTS: Usable questionnaires were returned by 12,907 subjects (overall response rate 58%). From these it was estimated that some 4.2 million men and 667 000 women in Great Britain are exposed to HTV at work in a 1 week period, and that personal daily exposures to vibration exceed a suggested action level equivalent to 2.8 ms(-2) for 8 hours (A(8) >2.8 ms(-2) rms) in at least 1.2 million men and 44,000 women. High estimated doses (A(8) >5 ms(-2) rms) arose most often in bricklayers and masons, gardeners and groundsmen, carpenters and joiners, electricians and electrical maintenance fitters, and builders and building contractors. The industries where high A(8) values most often arose were construction, motor vehicle repair and maintenance, manufacture of basic metals, and agriculture. The most common sources of exposure were hammer drills, hand held portable grinders, and jigsaws. CONCLUSIONS: Exposure to HTV is surprisingly prevalent, and preventive measures and health surveillance may be warranted for many men in Britain. Control strategies should focus on prevention at source, with priority accorded to the common sources of exposure and the occupations in which significant exposures tend to arise. Many vibratory tools that are common in Britain have been overlooked in previous surveys, highlighting an important focus for future research.

Prevalence and pattern of occupational exposure to whole body vibration in Great Britain: findings from a national survey.

OBJECTIVES: To estimate the number of workers in Great Britain with significant occupational exposure to whole body vibration (WBV) and to identify the common sources of exposure and the occupations and industries where such exposures arise. METHODS: A postal questionnaire was posted to a random community sample of 22,194 men and women of working age. Among other things, the questionnaire asked about exposure to WBV in the past week, including occupational and common non-occupational sources. Responses were assessed by occupation and industry, and national prevalence estimates were derived from census information. Estimates were also made of the average estimated daily personal dose of vibration (eVDV). RESULTS: From the 12,907 responses it was estimated that 7.2 million men and 1.8 million women in Great Britain are exposed to WBV at work in a 1 week period if the occupational use of cars, vans, buses, trains, and motor cycles is included within the definition of exposure. The eVDV of >374,000 men and 9000 women was estimated to exceed a proposed British Standard action level of 15 ms(-1.75). Occupations in which the estimated exposures most often exceeded 15 ms(-1.75) included forklift truck and mechanical truck drivers, farm owners and managers, farm workers, and drivers of road goods vehicles. These occupations also contributed the largest estimated numbers of workers in Great Britain with such levels of exposure. The highest estimated median occupational eVDVs were found in forklift truck drivers, drivers of road goods vehicles, bus and coach drivers, and technical and wholesale sales representatives, among whom a greater contribution to total dose was received from occupational exposures than from non-occupational ones; but in many other occupations the reverse applied. The most common sources of occupational exposure to WBV are cars, vans, forklift trucks, lorries, tractors, buses, and loaders. CONCLUSIONS: Exposure to whole body vibration is common, but only a small proportion of exposures exceed the action level proposed in British standards, and in many occupations, non-occupational sources are more important than those at work. The commonest occupational sources of WBV and occupations with particularly high exposures have been identified, providing a basis for targeting future control activities.

Occupational exposure to carcinogens in the European Union.

OBJECTIVES: To construct a computer assisted information system for the estimation of the numbers of workers exposed to established and suspected human carcinogens in the member states of the European Union (EU). METHODS: A database called CAREX (carcinogen exposure) was designed to provide selected exposure data and documented estimates of the number of workers exposed to carcinogens by country, carcinogen, and industry. CAREX includes data on agents evaluated by the International Agency for Research on Cancer (IARC) (all agents in groups 1 and 2A as of February 1995, and selected agents in group 2B) and on ionising radiation, displayed across the 55 industrial classes. The 1990-3 occupational exposure was estimated in two phases. Firstly, estimates were generated by the CAREX system on the basis of national labour force data and exposure prevalence estimates from two reference countries (Finland and the United States) which had the most comprehensive data available on exposures to these agents. For selected countries, these estimates were then refined by national experts in view of the perceived exposure patterns in their own countries compared with those of the reference countries. RESULTS: About 32 million workers (23% of those employed) in the EU were exposed to agents covered by CAREX. At least 22 million workers were exposed to IARC group 1 carcinogens. The exposed workers had altogether 42 million exposures (1.3 mean exposures for each exposed worker). The most common exposures were solar radiation (9.1 million workers exposed at least 75% of working time), environmental tobacco smoke (7.5 million workers exposed at least 75% of working time), crystalline silica (3.2 million exposed), diesel exhaust (3.0 million), radon (2.7 million), and wood dust (2.6 million). CONCLUSION: These preliminary estimates indicate that in the early 1990s, a substantial proportion of workers in the EU were exposed to carcinogens.

Are the children of fathers whose jobs involve contact with many people at an increased risk of leukaemia?

OBJECTIVES: To investigate the hypothesis that children of men whose jobs involve contact with many people (particularly children) are at an increased risk of leukaemia. METHODS: A population based dataset obtained from routinely collected death certificates involving 14,168 cancer deaths occurring before the age of 15 years registered in England and Wales between 1959-63 and 1970-90. Associations were assessed with the proportional cancer mortality ratio (PCMR), with all childhood cancer deaths forming the standard for comparison. The PCMRs were adjusted, by stratification, for age and year of death (in 1-year bands) and paternal social class (nine categories). Analyses were performed by estimated level of paternal occupational social contact (high, medium, and low) for all leukaemias, leukaemia subtype, age at death, year of death, and individual occupation. RESULTS: Out of 223 occupations, 36 (16%) were identified as having potentially high levels of social contact, and 27 (12%) as having potentially medium levels of social contact. No associations were found between paternal occupational social contact and death during childhood from leukaemia (high social contact: PCMR 94, 95% confidence interval (95% CI) 87 to 102; medium social contact: 101, 95 to 106). No associations were found when the data were analysed by leukaemia subtype, age at death, year of death, or individual occupation. CONCLUSION: The findings presented here do not support the suggestion that childhood leukaemia is related to the amount of social contact that fathers experience at work.

Women's occupation and cancer: preliminary analysis of cancer registrations in England and Wales, 1971-1990.

BACKGROUND: In recent years increasing attention has been paid to examining the relation between women's health and their own occupation. The findings presented here relate to an analysis of 381,915 cancers in women registered in England and Wales over the 20-year period 1971-1990. METHODS: To explore the value of the data for epidemiological research, five sites (pleura, bladder, stomach, lung, and breast) and two occupations (agriculture and textile) were selected. Associations between cancer and occupation were evaluated using age and social class adjusted proportional registration ratios (PRRs) and 95% confidence intervals (CI). RESULTS: Pleural cancer risk was increased in a range of occupations with a potential for asbestos exposure (e.g., PRR 608, 95% CI 381-921 for craft and other production process workers), and the well-established link between bladder cancer and employment in the rubber industry was confirmed (PRR 303, 95% CI 188-464). Associations between "dusty" occupations and stomach cancer were noted (e.g., PRR 198, 95% CI 126-298 for ceramic decorators and finishers), and possible links with lung cancer and smoke in the work environment were highlighted (e.g., PRR 167, 95% CI 147-189 for publicans). As a group, agricultural workers were found to be at increased risk of non-Hodgkin's lymphoma (PRR 164, 95% CI 126-211), and textile workers at increased risk of pleural cancer (PRR 145, 95% CI 111-185). No evidence for an occupational aetiology for breast cancer was found within these data. CONCLUSIONS: Occupational information collected at cancer registration in the United Kingdom can be reliably used to identify groups that may be at increased risk of disease.

Childhood cancer and paternal employment in agriculture: the role of pesticides.

Previous studies have suggested that the offspring of men potentially exposed to pesticides at work may be at increased risk of kidney cancer (Wilms' tumour), brain tumours, Ewing's bone sarcoma and acute leukaemia. This paper examines the association between potential occupational exposure of fathers to pesticides and offspring's death from cancer in a large national database. Records for 167703 childhood deaths occurring during 1959-63, 1970-78 and 1979-90 in England and Wales have been analysed. Among the offspring of men with potential occupational exposure to pesticides there were 5270 deaths, of which 449 were due to cancer. Associations were assessed using proportional mortality ratios (PMRs), with adjustment for age, year of death and paternal social class. Of the childhood cancers previously linked with potential paternal occupational exposure to pesticides, the only statistically significant excess was for kidney cancer (PMR=1.59, 95% CI=1.18-2.15, based on 42 deaths). Although these results offer some support for the suggestion that paternal occupational exposure to pesticides may be related to the subsequent development of kidney cancer in offspring, other explanations cannot be excluded. In the light of the findings presented here and elsewhere, further, more detailed, research into the nature of this relationship is warranted.

Mortality in employees of a Scottish paper mill.

To assess possible health risks associated with the manufacture of paper, we carried out a retrospective analysis of mortality among 4,242 men and women employed at a Scottish paper mill between 1955 and 1992. During follow-up to 1994, 959 subjects had died giving an SMR of 0.85 (95% CI 0.80-0.90) in comparison with the national population. Mortality from all cancer (SMR 0.77, 95% CI 0.68-0.88) and particularly from lung cancer (SMR 0.64, 95% CI 0.50-0.81) was lower than expected. An excess of lymphatic and hematopoietic cancer (11 deaths, SMR 2.17) was observed in the making department. These findings do not support an occupational hazard of lung cancer as suggested by several earlier studies. The excess of lymphatic and hematopoietic cancer in the making department was unexpected, and may be a chance occurrence.

Validity of a questionnaire for assessing occupational activities.

The objective of this article is to assess the validity of data on occupational activities obtained by a questionnaire. 152 employees from 16 jobs were interviewed independently about activities in their work, using a structured questionnaire. For 11 of the jobs, two further workers were observed during a typical shift, and their activities recorded. The agreement of reporting between subjects doing the same job and with observation was assessed. There was good agreement between subjects and with observation for most of the activities examined when the activities were classified dichotomously. However, frequency of heavy lifting was reported inconsistently. Questionnaires are able to distinguish major differences in physical activity that occur between jobs in the general population, but do not allow more detailed quantification of activities.

Mortality of farmers and farmers' wives in England and Wales 1979-80, 1982-90.

OBJECTIVES: To examine the mortality patterns of male and female farmers and farmers' wives in England and Wales. METHODS: Information on all deaths in England and Wales at ages 20-74 during the periods 1979-80 and 1982-90 was obtained from the Office of Population Censuses and Surveys. Proportional mortality ratios (PMRs) and proportional cancer mortality ratios (PCMRs) were used to compare the mortality of farmers with that of the general working population, and of farmers' wives with wives of all working men. RESULTS: Farmers and farmers' wives had high mortality from accidents and suicide and from certain respiratory diseases. Mortality from hernia was also raised. Deaths from cancer were generally below expectations, but the PMR for prostatic cancer was 112 (95%CI 106-118). The PMRs and PCMRs for oesophageal cancer were significantly increased in male farmers from two counties where cider is produced. CONCLUSIONS: The occupational hazards of farming continue to be associated with excess mortality, and most of the risks extend also to farmers' wives. Action is needed to reduce deaths, particularly from accidents and suicide.

Upper aerodigestive cancer in battery manufacturers and steel workers exposed to mineral acid mists.

OBJECTIVE: To assess the risk of cancer from inhalation of mineral acid mists. METHODS: A cohort study and nested case-control study of upper aerodigestive tumours were carried out in men employed since 1950 at two battery plants and two steel works in Britain. The cohort was identified from personnel records and included 2678 men with definite exposure to acid mists (mainly sulphuric acid), 367 with possible exposure, and 1356 who were unexposed. Mortality was compared with that in the national population by the person-years method. Cases of upper aerodigestive cancer were identified from death certificates and cancer registrations, and their exposure to acids was compared with that of age matched controls (five per case) from the same plant by conditional logistic regression. RESULTS: In follow up to 31 December 1993, 93% of men were traced, including 1277 who had died. Among the men definitely exposed to acid mists, overall mortality was less than in the national population (standardised mortality ratio (SMR) 0.92, 95% confidence interval (95% CI) 0.85-0.98) as was mortality from all cancers (SMR 0.92, 95% CI 0.79-1.05) and specifically from cancer of the larynx (SMR 0.48, 95% CI 0.01-2.70) and lung (SMR 0.98, 95% CI 0.78-1.22). A total of 15 incident or fatal cases of upper aerodigestive cancer were identified during follow up. When these men were compared with controls, risk was moderately increased in those who had worked for at least five years in jobs entailing exposures to sulphuric or hydrochloric acid in excess of 1 mg/m3 (OR 2.0, 95% CI 0.4-10). CONCLUSIONS: These findings are consistent with those from other studies which have indicated a hazard of upper aerodigestive cancer from acid mists. However, they indicate that any risk from exposures to sulphuric and hydrochloric acid below 1 mg/m3 is small.

Mortality pattern among biological research laboratory workers.

A cohort study was conducted to investigate the mortality of individuals employed by biological research institutes in the UK. The inclusion criteria were met by 12,703 individuals, of whom 95% were traced (11,502 alive, 395 deaths, 246 embarkations). All-cause mortality was significantly reduced in men (standardised) mortality ratio (SMR) 55 and women (SMR 52). Mortality was also significantly reduced for circulatory and respiratory diseases, and overall there was low mortality from malignant neoplasms. SMRs exceeded 100, but were not statistically significant, for infective and parasitic diseases. There were no statistically significant raised SMRs for any cancer site. Workers were categorised as ever worked in a laboratory (laboratory workers) and never worked in a laboratory (non-laboratory workers). The all-cause SMR was significantly reduced in both groups, as was mortality from circulatory and respiratory diseases. The SMR for malignant neoplams was also significantly reduced in laboratory workers. On the basis of follow-up to 31 December 1994, there is no evidence of any overall increased risk of mortality in biological research laboratory workers. However, the power of the analysis is limited by the young age of many cohort members and short duration of follow-up. Follow-up is continuing and the data will be reanalysed once more deaths have accumulated.

Mortality from scrotal cancer in metal machinists in England and Wales, 1979-80 and 1982-90.

The hazard of scrotal cancer from cutting oils was first recognized in the 1950s, and led to various control measures including the introduction of solvent refined oils, use of splash guards, provision of protective clothing and washing facilities and education of workers to encourage early detection and treatment of tumours. To assess how effective these controls have been, we have analyzed occupational mortality from scrotal cancer in England and Wales during 1979-80 and 1982-90. Over this 11-year period 85 deaths were attributed to the disease in man aged 20-74. This represents a reduction in mortality from the 1960s. Significantly elevated proportional mortality ratios (PMRs) were found in press and machine tool setters (PMR 1,678, five deaths), centre lathe turners (PMR 1,099, three deaths) and machine tool operators (PMR 303, eight deaths), but all of the metal machinists who died of scrotal cancer had been born before 1930, and could have worked with cutting oils before controls were introduced. These findings are reassuring, but continued monitoring of scrotal cancer incidence and mortality is required.