Silica dust and sarcoidosis in Swedish construction workers

Background

The aetiology of sarcoidosis is not well established. In previous studies, smoking has been negatively associated with sarcoidosis and there are some indications of an association between exposure to silica dust and sarcoidosis.

Aims

To study the risk of sarcoidosis in relation to silica dust exposure.

Methods

A longitudinal cohort of construction workers linked with a registry of Swedish inpatient diagnoses. Workers were designated as exposed or unexposed to silica based on job titles in a job–exposure matrix. The relative risk (RR) was analysed with Poisson regression adjusting for age and smoking.

Results

We identified 371 cases of sarcoidosis among 297 917 male workers. There was an increased risk of sarcoidosis in the medium- to high-exposure group [RR 1.83 (95% confidence interval {CI} 1.14–2.95)]. A stratified analysis according to smoking showed that ever-smoking workers had an increased risk of sarcoidosis if highly exposed to silica dust [RR 2.44 (95% CI 1.37–4.33)] compared to non-exposed ever-smokers. The risk of non-smokers highly exposed to silica was not significantly increased [RR 1.07 (95% CI 0.72–1.58)] compared to non-exposed non-smokers.

Conclusion

The study indicates an increased risk of developing sarcoidosis in ever-smoking men exposed to silica.

Patient-reported signs of dampness at home may be a risk factor for chronic rhinosinusitis: A cross-sectional study

BACKGROUND

An association between dampness at home and respiratory conditions has been convincingly demonstrated in children. Fewer studies have been performed in adults, and data are lacking for chronic rhinosinusitis (CRS). With a prevalence of 10.9% in Europe, CRS imposes a significant burden on quality of life, as well as economy.

OBJECTIVE

Our aim was to study CRS and other respiratory conditions in relation to dampness at home in a representative sample of adults.

METHODS

The Swedish GA² LEN questionnaire was answered by 26 577 adults (16-75 years) and included questions on respiratory symptoms, smoking, education and environmental exposure. CRS was defined according to the EP³ OS criteria. Dampness was defined as reporting water damage, floor dampness or visible moulds in the home during the last 12 months. The dampness score was ranked from 0 to 3, counting the number of signs of dampness reported.

RESULTS

Dampness at home was reported by 11.3% and was independently related to respiratory conditions after adjustment for demographic and socio-economic factors and smoking: CRS odds ratio (OR) 1.71; allergic rhinitis OR 1.24; current asthma OR 1.21; wheeze OR 1.37; nocturnal dyspnoea OR 1.80; nocturnal coughing OR 1.34; and chronic bronchitis OR 1.64. The risk of CRS and most of the other respiratory conditions was further elevated in subjects reporting multiple signs of dampness.

CONCLUSIONS AND CLINICAL RELEVANCE

This study demonstrated an independent association between dampness at home and CRS in adults. The high burden of this and the other respiratory conditions studied is a strong argument in favour of countering indoor dampness by improving building standards.

Symptoms of Musculoskeletal Disorders among Drivers of All-Terrain Vehicles in Northern Sweden

All-terrain vehicles (ATVs) are a group of machines that do not operate on prepared roads. Off-road use of these fast-moving machines results in the driver being exposed to high magnitudes of vibration and shock. It is estimated that there are up to 20,000 people in Sweden that uses ATVs during their work, such as forest machines, snowmobiles, snowgroomers, motorcycles, and three- and four-wheeled vehicles. The aim of this cross-sectional study was to investigate the risk for musculoskeletal symptoms of the neck, shoulders, upper and lower back among professional drivers of ATVs. Data from 215 male drivers of forest machines, 137 drivers of snowmobiles, 79 drivers of snowgroomers and 167 men randomly selected from the general population to act as a control group were collected. All subjects were from the four most northern counties in Sweden. Musculoskeletal symptoms during the previous year were assessed using the standardised Nordic questionnaire. Prevalence rate ratios were adjusted for age, smoking and job strain. Results showed that all driver categories had significantly increased prevalence rate ratios (1.5-2.9) for experiencing symptoms in the neck-shoulder and thoracic regions. Unlike findings from previous epidemiological studies, there was not an increased risk of low back pain among any of the driver categories compared to the control group. The higher prevalence of musculoskeletal problems is thought to be due to long-term exposure to physical factors, such as, whole-body vibration (WBV) and shock, static muscle overload and extreme body postures. The findings in this study highlight the fact that working with ATVs may cause, aggravate or prevent resolution of musculoskeletal symptoms. However, the exact cause of these problems is unclear and the interaction between vibration and body posture is not known. The authors believe however that it is necessary to reduce exposure to WBV and shock to decrease the high prevalence of musculoskeletal symptoms among professional ATV drivers. This may be done by implementing preventative measures, such as selecting the best vehicle model or seat, optimising driving style and minimizing use in rough terrain. Health surveillance seems to be important for people that regularly use ATVs in their work.

Asbestos exposure and the risk of sinonasal cancer

BACKGROUND

While the increased risk of lung cancer and mesothelioma is well established, the relationship between exposure to asbestos dust and sinonasal cancer is less clear.

AIMS

To study the risk of sinonasal cancer in relation to asbestos dust exposure.

METHODS

A retrospective cohort study of construction workers, linked to the Swedish Cancer Registry. Participants were classified into four exposure groups; heavy, medium, low or very low exposure to asbestos, according to the incidence of pleural mesothelioma in their occupational group. Standardized incidence ratios (SIRs) and relative risks (RRs) were analysed, adjusted for age and smoking habits. The risks of adenocarcinoma and squamous cell carcinoma were investigated separately.

RESULTS

Among the 280222 subjects, there was no increased risk of sinonasal cancer compared to the general population [SIR 0.85, 95% confidence interval (CI) 0.68-1.03], or any dose-response relationship with exposure to asbestos. The highest RR was found in the low exposure group (RR 1.25, 95% CI 0.69-2.28) and the lowest RR was found in the group with the highest exposure to asbestos (RR 0.71, 95% CI 0.33-1.53). No significantly increased risk or dose-response association could be found for adenocarcinoma or squamous cell carcinoma when analysed separately.

CONCLUSIONS

This study did not find an increased risk of developing sinonasal cancer after asbestos exposure.

Occupational skin exposure to water: a population-based study

BACKGROUND

Occupational exposure to skin irritants, in particular to water, is an important risk factor for hand eczema.

OBJECTIVES

To assess occupational skin exposure to water in the general population.

METHODS

As part of a public health survey in Stockholm, Sweden, 18,267 gainfully employed individuals aged 18-64 years completed a questionnaire with previously validated questions regarding occupational skin exposure to water.

RESULTS

Altogether 16% reported exposure to water for (1/2) h or more a day, and 13% reported exposure to water more than 10 times a day. Furthermore, 7% reported water exposure of more than 2 h and 6% of more than 20 times a day. Women reported more water exposure than men and many female-dominated occupations were seen to comprise water exposure. Women were also more exposed than men within the same jobs. Young adults were more exposed than older. A total of 18% were employed in high-risk occupations for hand eczema. Fifty-nine per cent of individuals employed in high-risk occupations reported water exposure at work, compared with 11% in low-risk occupations.

CONCLUSIONS

A total of 20% of the population of working age acknowledged occupational skin exposure to water, which was found to be more common in young adults and women. Using job title as a proxy for water exposure gives an underestimation due to misclassification. In assessing occupational skin exposure to water, both exposure time and frequency should be considered.

Incidence of surgically treated osteoarthritis in the hip and knee in male construction workers

OBJECTIVE

Occupational workload has been associated with an increased risk of osteoarthritis. The objective was to further examine the association between workload and occurrence of osteoarthritis and in particular to study whether heavy workload has similar importance as a causative factor for osteoarthritis of the hip and knee.

METHODS

In a cohort study, the authors investigated the incidence of surgically treated osteoarthritis in the hip and knee among men employed in the Swedish construction industry (n = 204 741). Incident cases were found by linkage with the Swedish hospital discharge register between 1987 and 1998. Incidence rates adjusted for age and BMI were compared between different occupational groups.

RESULTS

The incidence rates for osteoarthritis in hip and knee were positively correlated (r = 0.62; p = 0.01). There was a significantly increased risk of surgically treated osteoarthritis in the knee among floor layers, asphalt workers, sheet-metal workers, rock workers, plumbers, brick layers, wood workers and concrete workers. Even if there was a trend towards increased relative risks for osteoarthritis in the hip in floor layers, asphalt workers, wood workers and concrete workers they were not statistically significant. The relative risk for surgically treated osteoarthritis of the knee was 4.7 (95% CI 1.8 to 12.3) among floor layers, indicating an attributable fraction for work factors of 79%.

CONCLUSIONS

This study shows that some work-related factors seem to be risk factors for osteoarthritis both in the knee and hip. However, the risk factors seem to be of greater importance for osteoarthritis in the knee compared with the hip. This study indicates that at least 50% of the cases of severe osteoarthritis of the knee can be prevented through decreasing occupational risk factors in some occupational groups.

Asbestos exposure and differences in occurrence of peritoneal mesothelioma between men and women across countries

OBJECTIVE

In several countries the incidence of peritoneal mesotheliomas among women closely mirrors the pattern among men. The aim was to investigate the role of asbestos exposure in the aetiology of peritoneal mesotheliomas in women and men.

METHODS

All cases of peritoneal mesothelioma were selected from the Swedish and Netherlands Cancer Registers for the period 1989-2003. For both countries incidence rates were calculated and stratified by sex. A linear regression analysis was used to analyse the existence of a trend over time.

RESULTS

Among men the incidence rate of peritoneal mesothelioma in the Netherlands (0.60 per 100 000 persons) was consistently higher than in Sweden with an average ratio of 1.8 (range 1.4-2.8). In both countries no trend over time was observed. During the 15-year period in the Netherlands the incidence rate among men was about 3.3-fold higher than among women. In Sweden the incidence rate among women was slightly higher than in men up to 1999, and thereafter about threefold higher among men. This sudden shift was statistically significant and seemed mainly caused by changes in classification of peritoneal tumours.

CONCLUSION

The absence of a time trend in the incidence rate of peritoneal mesothelioma in the Netherlands and Sweden in the past 15 years may point to a more limited role of occupational exposure to asbestos in the aetiology of peritoneal mesothelioma than for pleural mesothelioma, especially among women. The observed drop around 2000 in annual incidence of peritoneal mesothelioma among Swedish women indicates the presence in the past of a substantial misclassification with other tumours in the peritoneum.

Persistence of respiratory symptoms in ex-underground iron ore miners

AIMS

To assess the persistence of respiratory symptoms in ex-miners after cessation of mining exposure.

METHODS

Population-based cross-sectional study using a postal questionnaire comparing prevalence of symptoms between ex-miners who had stopped mining at least 1 year before the study and referents not occupationally exposed to irritants or dust. Age, smoking and a family history of asthma were considered as possible confounders in the analysis.

RESULTS

A total of 206 ex-miners and 4,560 referents participated. Ex-miners had on average been working as miners for 13 years and had stopped mining 16 years before the study. Chronic productive cough and physician-diagnosed chronic bronchitis were significantly more common among ex-miners (P < 0.05 and <0.01, respectively). Furthermore, there was a trend that other respiratory symptoms were more common in ex-miners.

CONCLUSION

Ex-miners had an increased risk of chronic productive cough and physician-diagnosed chronic bronchitis many years after they had stopped working as a miner.

Vehicle exhaust exposure in an incident case-control study of adult asthma

The objective of this case-control study was to evaluate whether traffic-related air pollution exposure at home increases the risk of asthma in adults and to compare two commonly used exposure variables and differences between urban and rural living. Incident cases of asthma and matched controls of subjects aged 20-60 yrs were recruited in Luleå, Sweden. In total 203 cases and 203 controls were enrolled in the study. Exposure was estimated by traffic flow and measured levels of outdoor nitrogen dioxide (NO2) in the surrounding environment of each home, respectively. The relationship between measured levels of NO2 and traffic flow was studied using linear regression. The results indicated a nonsignificant tendency between living in a home close to a high traffic flow and an increased risk of asthma. The association between asthma and measured NO2 was weak and not significant, but the skin-prick test result acted as an effect modifier with a borderline significant association among positives. The correlation between traffic flow and outdoor NO2 was low. The results suggest that living close to high traffic flows might increase the asthma incidence in adults, while the tendency for nitrogen dioxide was only seen among atopics. Traffic flow and nitrogen dioxide had a lower than expected correlation.

Airway inflammation in iron ore miners exposed to dust and diesel exhaust

The aim of the present study was to investigate if underground miners exposed to dust and diesel exhaust in an iron ore mine would show signs of airway inflammation as reflected in induced sputum. In total, 22 miners were studied, once after a holiday of at least 2 weeks and the second time after 3 months of regular work. Control subjects were 21 "white-collar" workers. All subjects completed a questionnaire regarding medical and occupational history, and underwent lung function testing and induced sputum collection. Total and differential cell counts and analyses of the fluid phase of the induced sputum were performed. Sampling of personal exposure to elemental carbon, nitrogen dioxide and inhalable dust was recorded. The average concentrations of inhalable dust, nitrogen dioxide and elemental carbon were 3.2 mg.m-3, 0.28 mg.m-3 and 27 microg.m-3, respectively. Miners had increased numbers of inflammatory cells, mainly alveolar macrophages and neutrophils, and increased concentrations of fibronectin, metalloproteinase-9 and interleukin-10 in induced sputum compared with controls. In conclusion, miners in an underground iron ore mine demonstrated persistent airway inflammation that was as pronounced after a 4-week holiday as after a 3-month period of work underground in the mine.

Fifteen-year follow-up of hand eczema: persistence and consequences

BACKGROUND

Hand eczema is a skin disease often with a long-lasting and relapsing course. The long-term prognosis in the general population is unknown.

OBJECTIVES

The aims were to examine the extent to which hand eczema had persisted and the medicosocial consequences of the disease.

METHODS

In a 15-year follow-up of hand eczema, patients diagnosed in a previous population-based study were sent a questionnaire with 20 questions concerning the persistence and course of the disease, and its occupational and medicosocial consequences.

RESULTS

Addresses were available for 1115 persons, of whom 868 answered the questionnaire. Sixty-six per cent of the respondents reported periods of hand eczema and 44% reported symptoms during the previous year, with no sex difference. Twelve per cent reported continuous eczema. However, 74% of those reporting symptoms considered that their hand eczema had improved; of these more were women than men (78% vs. 66%, P < 0.01). Twenty people, 3% of those who were gainfully employed in 1983, reported a change to another occupation because of their hand eczema, 15 of these reporting improvement after the job change. A considerable need for medical consultation was reported, as was the influence on psychosocial functions among those who had eczema the previous year, e.g. sleep disturbances (36%) and hampered leisure activities (72%). Job changes related to hand eczema and psychosocial impairment were also reported by individuals who had not sought medical help for their hand eczema.

CONCLUSIONS

This study demonstrates a variable and poor long-term prognosis for hand eczema in the general population. One-third sought medical care during follow-up, while the vast majority with ongoing hand eczema experienced negative psychosocial consequences. For about 5%, the hand eczema gave far-reaching consequences including long sick-leave periods, sick pension and changes of occupation.

Obesity increases the risk of incident asthma among adults

The annual incidence of asthma in adults in northern Sweden has been estimated at 2.3 per thousand population. Risk factors for incident asthma among adults were studied in a case-referent study based on incident cases of asthma during 1995-1999. The healthcare providers reported suspected cases of incident asthma. After clinical examination, 309 (65% female) of 473 reported subjects were included. Inclusion criteria were a history of incident asthma (onset <12 months) and verified bronchial variability. Referents were randomly selected and stratified by age, sex and area of residence. The significant risk factors were hay fever, a family history of asthma, ex-smoking status and elevated body mass index (25.0-29.9 and > or =30). The risk factor pattern was similar for females and males, and increased body mass index was a significant risk factor for both males and females, as well as for allergic and nonallergic subjects. In conclusion, in addition to hay fever, a family history of asthma, allergic sensitisation and ex-smoking status, increased body mass index was a significant risk factor for incident asthma independent of sex and allergic status.

Increased mortality in COPD among construction workers exposed to inorganic dust

The aim of this study was to find out if occupational exposure to dust, fumes or gases, especially among never-smokers, increased the mortality from chronic obstructive pulmonary disease (COPD). A cohort of 317,629 Swedish male construction workers was followed from 1971 to 1999. Exposure to inorganic dust (asbestos, man-made mineral fibres, dust from cement, concrete and quartz), gases and irritants (epoxy resins, isocyanates and organic solvents), fumes (asphalt fumes, diesel exhaust and metal fumes), and wood dust was based on a job-exposure matrix. An internal control group with "unexposed" construction workers was used, and the analyses were adjusted for age and smoking. When all subjects were analysed, there was an increased mortality from COPD among those with any airborne exposure (relative risk 1.12 (95% confidence interval (CI) 1.03-1.22)). In a Poisson regression model, including smoking, age and the major exposure groups, exposure to inorganic dust was associated with an increased risk (hazard ratio (HR) 1.10 (95% CI 1.06-1.14)), especially among never-smokers (HR 2.30 (95% CI 1.07-4.96)). The fraction of COPD among the exposed attributable to any airborne exposure was estimated as 10.7% overall and 52.6% among never-smokers. In conclusion, occupational exposure among construction workers increases mortality due to chronic obstructive pulmonary disease, even among never-smokers.

Risk of fatal industrial accidents and death from other external causes among asphalt workers

The hypothesis that asphalt workers are at increased risk of mortality from industrial accidents and other external causes was tested. Mortality rates for external and violent causes of death in a cohort of asphalt industry employees from seven European countries and Israel were compared to that of the general population. There was no evidence that mortality from external causes was increased among long term employees in asphalt application and mixing. There was an increased risk for mortality due to external causes among short term workers. However, none of the fatal accidents among short term workers appear to have occurred during employment in the studied asphalt companies. Overall, no evidence was found supporting the hypothesis that asphalt workers are at increased risk of fatal industrial or road accidents. Mortality from other external causes did not increase in this population as a whole, but increased risks among short term workers deserve further attention.

Exposure assessment of monoterpenes and styrene: a comparison of air sampling and biomonitoring

BACKGROUND

Within- and between-worker variance components have seldom been reported for both environmental and biological data collected from the same persons.

AIMS

To estimate these variance components and their ratio for air contaminants and urinary metabolites in two different work environments and to predict the attenuation of exposure-response relationships based on these measures.

METHODS

Parallel measurements of air and urine were performed among workers exposed to monoterpenes in sawmills (urinary metabolite: verbenol) and styrene in reinforced plastics factories (urinary metabolite: mandelic acid).

RESULTS

Among the sawmill workers, variance components of the air and urinary verbenol results were similar; for the reinforced plastics workers the estimated between-worker variance component was greater for styrene in air than mandelic acid in urine. This suggests that attenuation bias would be about equal if air or biological monitoring were employed for monoterpene exposures, but would be greater if urinary mandelic acid were used instead of airborne styrene in an investigation of styrene exposure.

CONCLUSIONS

Personal air samplers provide data with similar or superior quality to urinary metabolites as measures of exposure to these monoterpenes in sawmills and styrene in reinforced plastics factories.

Lung cancer in heavy equipment operators and truck drivers with diesel exhaust exposure in the construction industry

BACKGROUND

Several studies indicate that truck drivers have an increased risk of lung cancer, but few studies have examined lung cancer risk in heavy equipment operators. Workers in both occupations are exposed to diesel exhaust.

AIMS

To examine the incidence and mortality from lung cancer among truck drivers and among drivers of heavy vehicles.

METHODS

A computerised register of Swedish construction workers participating in health examinations between 1971 and 1992 was used. Male truck drivers (n = 6364) and drivers of heavy construction vehicles (n = 14 364) were selected as index groups; carpenters/electricians constituted the reference group (n = 119 984).

RESULTS

Operators of heavy construction equipment experienced no increased risk of lung cancer compared to risk among the carpenter/electrician referents (61 cases v 70.1 expected). However, a significant inverse trend risk with increasing use of cabins was apparent. Truck drivers had increased risks of cancer of the lung (61 cases v 47.3 expected) and prostate (124 cases v 99.7 expected), although only mortality for lung cancer was significantly increased. Comparisons with the general population showed similar results.

CONCLUSION

Results are consistent with those of previous studies suggesting that heavy equipment operators with potential exposure to diesel exhaust may have little or no increased risk of lung cancer, although the use of cabins seemed to decrease the risk of lung cancer. The results for truck drivers are also consistent with previous reports of increased lung cancer risk among truck drivers exposed to diesel exhaust, as well as recent reports linking diesel exhaust exposure to prostate cancer.

Hand eczema in 45 bakers - a clinical study

The skin of bakers is heavily exposed to dough, spices, water and detergents. This is follow-up of a previous Swedish questionnaire study showing bakers to have a 3-fold increased risk of hand eczema. The aims were to establish diagnoses and to study consequences of hand eczema. From a cohort study of 2226 bakers, a random sample among bakers reporting hand eczema was examined. Of 60 randomly selected bakers reporting a history of hand eczema, 52 attended an examination comprising a standardized interview, documentation of clinical skin signs, patch testing and prick testing with standard and bakery series, and serum analyses. In all, 45 bakers confirmed a history of hand eczema, for which 11 (24%) had been on sick leave, with a median duration of 14 weeks. 13 (29%) had changed their occupation due to skin disease, 19 had positive patch test reactions to standard contact allergens - and 5 to bakery contact allergens. 16 bakers had positive prick tests to standard allergens, 10 to bakery allergens, of whom 9 reacted to flours. Since considerable medical and social consequences of hand eczema are seen, thorough diagnosis of contact allergy and IgE-mediated allergy in bakers, as well as preventive measures, are essential.

Suicide mortality among electricians in the Swedish construction industry

OBJECTIVES

To investigate the risk of suicide in Swedish electricians employed in the construction industry. A few studies have indicated an increased risk of suicide for electricians in the construction industry and electricians exposed to electromagnetic fields.

METHODS

This is a cohort study. Electricians were identified through a computerised register of construction workers who had participated in health examinations in 1971-92. In this register, 33,719 male electricians were identified together with a reference group consisting of 72,653 male glass or woodworkers. Through a linkage with the Swedish Death Register, the cause of death was identified to the end of 1997. Mortality as a result of suicide was also compared with the general population with adjustments for sex, age, and period.

RESULTS

The risk of mortality from suicide was decreased for electricians (standardised mortality ratio (SMR) 0.58, 95% confidence interval (95% CI) 0.47 to 0.71) and for the reference group of construction workers (SMR 0.81, 95% CI 0.72 to 0.91) compared with the general population.

CONCLUSION

Contrary to some other studies, risk of suicide was not increased among electricians in the construction industry.

[An observational study requires careful consideration by the reader]

The observational study has its merits when randomized controlled studies are impossible to perform. This review discusses its merits and weaknesses for a reader of such studies. The reader has to consider the internal and external validity of the study and its role in the establishment of causal relationships and estimations of risks. The reader is recommended to primarily evaluate the quality of study design, confounding and measurement bias, rather than to try to understand if an advanced statistical analysis is correct. The possibilities of misleading results are discussed.

Incidence of lung cancer in a large cohort of non-smoking men from Sweden

Valid data on the occurrence of lung cancer among non-smokers are sparse and refer mainly to North American populations. The objective of our study is to provide an estimate of the incidence of lung cancer among non-smokers in a large European population. Proceeding from a nation-wide health care program among Swedish construction workers, we estimated the incidence of lung cancer among 143,998 males who reported to be never smokers at 1 or several physical check-ups (average, 2.9 visits) during 1971-92. Cancer incidence data for 1971-95 were obtained through linkage with the virtually complete national cancer registry. Cohort members contributed over 2 million person-years of observation, during which 101 lung cancers occurred. The age-standardized rate was 3.7/100,000 (95% confidence interval [CI] 2.8-4.6). There was a suggestion of a calendar period effect, with rates increasing from 1.5/100,000 in 1976-80 to 5.4/100,000 in 1991-95. A birth cohort effect was also suggested. Rates estimated in this population are comparable to those from North American studies. The increasing rate during the study period might be due to non-smokers who took up the habit, but it might also reflect temporal changes in the effect of other risk factors of lung cancer in non-smokers.

Dampness in buildings and health. Nordic interdisciplinary review of the scientific evidence on associations between exposure to "dampness" in buildings and health effects (NORDDAMP)

Several epidemiological investigations concerning indoor environments have indicated that "dampness" in buildings is associated to health effects such as respiratory symptoms, asthma and allergy. The aim of the present interdisciplinary review is to evaluate this association as shown in the epidemiological literature. A literature search identified 590 peer-reviewed articles of which 61 have been the foundation for this review. The review shows that "dampness" in buildings appears to increase the risk for health effects in the airways, such as cough, wheeze and asthma. Relative risks are in the range of OR 1.4-2.2. There also seems to be an association between "dampness" and other symptoms such as tiredness, headache and airways infections. It is concluded that the evidence for a causal association between "dampness" and health effects is strong. However, the mechanisms are unknown. Several definitions of dampness have been used in the studies, but all seems to be associated with health problems. Sensitisation to mites may be one but obviously not the only mechanism. Even if the mechanisms are unknown, there is sufficient evidence to take preventive measures against dampness in buildings.

Obesity, hypertension, and the risk of kidney cancer in men

BACKGROUND

Obesity and hypertension have been implicated as risk factors for the development of renal-cell cancer.

METHODS

We examined the health records of 363,992 Swedish men who underwent at least one physical examination from 1971 to 1992 and were followed until death or the end of 1995. Men with cancer (renal-cell cancer in 759 and renal-pelvis cancer in 136) were identified by cross-linkage of data with the nationwide Swedish Cancer Registry. Poisson regression analysis was used to estimate relative risks, with adjustments for age, smoking status, body-mass index, and diastolic blood pressure.

RESULTS

As compared with men in the lowest three eighths of the cohort for body-mass index, men in the middle three eighths had a 30 to 60 percent greater risk of renal-cell cancer, and men in the highest two eighths had nearly double the risk (P for trend, <0.001). There was also a direct association between higher blood pressures and a higher risk of renal-cell cancer (P for trend, <0.001 for diastolic pressure; P for trend, 0.007 for systolic pressure). After the first five years of follow-up had been excluded to reduce possible effects of preclinical disease, the risk of renal-cell cancer was still consistently higher in men with a higher body-mass index or higher blood pressure. At the sixth-year follow-up, the risk rose further with increasing blood pressures and decreased with decreasing blood pressures, after adjustment for base-line measurements. Men who were current or former smokers had a greater risk of both renal-cell cancer and renal-pelvis cancer than men who were not smokers. There was no relation between body-mass index or blood pressure and the risk of renal-pelvis cancer.

CONCLUSIONS

Higher body-mass index and elevated blood pressure independently increase the long-term risk of renal-cell cancer in men. A reduction in blood pressure lowers the risk.

Obesity, hypertension, and the risk of kidney cancer in men

BACKGROUND

Obesity and hypertension have been implicated as risk factors for the development of renal-cell cancer.

METHODS

We examined the health records of 363,992 Swedish men who underwent at least one physical examination from 1971 to 1992 and were followed until death or the end of 1995. Men with cancer (renal-cell cancer in 759 and renal-pelvis cancer in 136) were identified by cross-linkage of data with the nationwide Swedish Cancer Registry. Poisson regression analysis was used to estimate relative risks, with adjustments for age, smoking status, body-mass index, and diastolic blood pressure.

RESULTS

As compared with men in the lowest three eighths of the cohort for body-mass index, men in the middle three eighths had a 30 to 60 percent greater risk of renal-cell cancer, and men in the highest two eighths had nearly double the risk (P for trend, <0.001). There was also a direct association between higher blood pressures and a higher risk of renal-cell cancer (P for trend, <0.001 for diastolic pressure; P for trend, 0.007 for systolic pressure). After the first five years of follow-up had been excluded to reduce possible effects of preclinical disease, the risk of renal-cell cancer was still consistently higher in men with a higher body-mass index or higher blood pressure. At the sixth-year follow-up, the risk rose further with increasing blood pressures and decreased with decreasing blood pressures, after adjustment for base-line measurements. Men who were current or former smokers had a greater risk of both renal-cell cancer and renal-pelvis cancer than men who were not smokers. There was no relation between body-mass index or blood pressure and the risk of renal-pelvis cancer.

CONCLUSIONS

Higher body-mass index and elevated blood pressure independently increase the long-term risk of renal-cell cancer in men. A reduction in blood pressure lowers the risk.

Onset and remission of allergic rhinitis and asthma and the relationship with atopic sensitization and smoking

The aim of this study was to assess the influence of some risk factors for onset and remission of allergic rhinitis and asthma in Swedish adults. A random sample of 1,370 subjects, age 20 to 44 yr was investigated by means of postal questionnaires in 1990 and 1993. Skin prick tests were conducted in 1991-1992. The association between risk factors and onset or remission of allergic rhinitis and asthma was estimated using multivariate logistic regression analysis. Onset of allergic rhinitis was associated with sensitization to birch (odds ratio [OR] = 6.5), Parietaria (OR = 7.4); and pets (OR = 3.0) and with female sex (OR = 1.9). Onset of asthma was associated with allergic rhinitis (OR = 4.9), sensitization to pets (OR = 2.4); and with smoking (OR = 3.0). Onset of asthma was strongly associated with allergic rhinitis among atopics (OR = 5.7), but onset of asthma and rhinitis also tended to be related among nonatopics (OR = 3.5). A strong association between smoking and onset of asthma was found among nonatopics (OR = 5.7). In conclusion, sensitization to pollens and pets were risk factors for onset of allergic rhinitis, whereas allergic rhinitis, sensitization to pets, and smoking were risk factors for onset of asthma.

Natural organic fibers--health effects

OBJECTIVES

Natural organic fibers are used in large quantities in the production of paper products and textiles. They are also constituents of food and added to food to promote health. The objective of this review is to evaluate the health effects of natural organic fibers. The health effects of dietary fibers are excluded from the review.

METHODS

This is a literature review.

RESULTS

Exposure to these fibers in industry is usually not characterized as fibers but as dust. Rather dusty conditions have been reported in both paper and textile industries with concentrations up to and above 30 mg/m3. Both in the paper and textile industry inorganic fibers may occur making it hard to evaluate health effects of natural organic fibers from studies of workers in the paper and textile industry. There seems to be no increased risk of mesothelioma, lung cancer or lung fibrosis in workers exposed to natural organic fibers in contrast to workers exposed to inorganic crystalline fibers as asbestos. However, workers with a heavy exposure to paper dust or textile dust seem to have an increased risk of obstructive lung disease and bronchitis. These effects have not been causally linked to the fibrous shape of the particles but rather to the dust, chemicals absorbed on the dust or microorganisms occurring together with the dust. There is some indication that work in the textile industry may increase the risk of sinonasal cancer, but the etiological agents are unknown.

CONCLUSION

Natural organic fibers are not causally linked with the well-known effects of some inorganic fibers, i.e. mesothelioma, lung cancer, lung fibrosis or some pleural diseases. The health effects of natural organic fibers, e.g. irritative effects, seem not to be linked to their fibrous shape.

Exposure-response relations for self reported asthma and rhinitis in bakers

OBJECTIVES

To explore relations between two estimates of exposure to inhalable flour dust, and the incidence rates (IRs) of asthma and rhinitis in bakers.

METHODS

This was a retrospective cohort study among 2923 bakers. A posted questionnaire registered the disease and work history. For every year, each baker was assigned an estimate of the exposure concentration to inhalable flour dust derived from reported job-tasks and dust measurements. Exposure at onset of disease was expressed as current dust exposure concentration, and as cumulative dose of exposure to dust. A multiple Poisson regression analysis assessed the impacts of the exposure estimates on the IRs of asthma and rhinitis.

RESULTS

IRs of asthma and rhinitis increased by dust concentration at onset of disease. The IR of asthma for the bakers with highest exposure (dough makers) was 7. 3/1000 person-years in men and 6.5 in women and for rhinitis 43.4 and 38.5, respectively. There was a significant association between the dust concentration at onset of disease and the risk for asthma or rhinitis, but not of the cumulative exposure.

CONCLUSION

The risk of asthma seemed to be increased at inhalable dust concentrations >/=3 mg/m(3) (dough making or bread forming), whereas the risk of rhinitis was increased at all concentrations >/=1 mg/m(3), indicating an increased risk in all bakery job-tasks. The risks seemed to be less dependent on the cumulative exposure dust than the inhalable dust concentrations.

Cancers in concrete workers: results of a cohort study of 33,668 workers

OBJECTIVES

To study cancer morbidity patterns in concrete workers.

METHODS

A cohort of 33,503 concrete workers was enrolled in the study from 1971-86. The average duration of follow up was 19.4 years (582,225 person-years). The workers' cancer morbidity was compared with the morbidity of the general population.

RESULTS

A total of 3572 incident cancers were observed. Significantly increased standardised incidence ratios (SIRs) were found for all malignant neoplasms (SIR 107; 95% confidence interval (95%CI) 103 to 110), cancer of the lip (SIR 179; 95%CI 134 to 234), cancer of the stomach (SIR 139; 95%CI 122 to 158), cancer of the lung (SIR 125; 95%CI 114 to 137), and cancer of the prostate (SIR 108; 95%CI 101 to 116). Reduced risk was found for cancer of the large intestine (SIR 80; 95%CI 69 to 93) and cancer of the testis (SIR 50; 95%CI 26 to 87). Smoking was more prevalent among the concrete workers than in the general population (50% v 35%).

CONCLUSION

The study has shown a slightly increased overall risk of cancer among concrete workers. The increased risk of lung cancer could entirely be due to differences in smoking habits between concrete workers and the general population. There is a possibility that the smoking also has contributed to the increased risks of stomach cancer and lip cancer, but occupational factors may have contributed to these cancer sites.

Perceived pain before and after three exercise programs--a controlled clinical trial of women with work-related trapezius myalgia

The effect of exercise on neck-shoulder pain was studied in 103 women with work-related trapezius myalgia randomized into three exercise groups and a control group. One group trained strength, the second muscular endurance and the third co-ordination. The exercise groups met three times weekly for 10 weeks. Pain assessment was made on three visual analogue scales, indicating pain at present, pain in general and pain at worst. Pain thresholds were measured in the trapezius muscle with a pressure algometer. A pain drawing was completed. The rated pain decreased significantly (P<0.05) on the VAS describing pain at worst in the strength and endurance groups. Pressure sensitivity decreased significantly (P<0.05) in four triggerpoints in the exercise groups. No changes were seen in the extent of painful body area in any group. Comparison of exercisers (n=82) and controls (n=21) showed significantly larger pain reductions on VAS pain at present and VAS pain at worst among exercisers. All three exercise programs showed similar decreases of pain which indicates that the type of exercise is of less importance to achieve pain reduction.

Adult-onset asthma and occupational exposures

OBJECTIVES

This study examined certain occupational exposures and the risk for adult-onset asthma.

METHODS

A nested case-referent study of adult-onset asthma was performed on a random population sample (N=15813), aged 21 to 51 years. Cases for the study included 2 groups: subjects reporting "physician-diagnosed" asthma (N=251) and a broader "asthma" group (N=362). The "asthma" group consisted of subjects with "physician-diagnosed" asthma (N=251) and subjects reporting asthma-like symptoms without having "physician-diagnosed" asthma (N=111). The referents (N=2044) were randomly selected from the whole population sample. The case-referent sample was investigated with a comprehensive questionnaire about occupational exposures, asthma, respiratory symptoms, smoking, and atopy. Odds ratios were calculated with stratification for gender, year of diagnosis, and birth year.

RESULTS

The highest odds ratio for "physician-diagnosed" asthma was associated with exposure to flour dust [odds ratio (OR) 2.8, 95% confidence interval (95% CI) 1.5-5.2] and the occupational handling of resin-based paints (isocyanates) (OR 3.0, 95% CI 1.6-5.9). Exposure to welding fumes, textile dust, and work with glues containing acrylates was also associated with an increased odds ratio for "physician-diagnosed" asthma. Including persons with asthma-like symptoms (ie, the asthma group) showed similar results.

CONCLUSION

This population-based case-referent study from Sweden indicates that occupational exposure to acrylate-based compounds and welding fumes is associated with increased risk for adult-onset asthma.

Adult asthmatics sensitized to cats and dogs: symptoms, severity, and bronchial hyperresponsiveness in patients with furred animals at home and patients without these animals

BACKGROUND

Domestic furred animals are important sources of allergens in asthma, but few clinical studies have investigated the effects of exposure to or elimination of these allergens. The objective of this study was to investigate whether pet-sensitized asthmatics with pets at home have worsened asthma, compared with similar asthmatics without pets.

METHODS

In a cross-sectional epidemiologic study, 129 adult asthmatics sensitized to cats or dogs were investigated by interviews, skin prick tests, specific IgE, eosinophil counts, and bronchial methacholine challenge tests. Patients with a cat or dog at home (n=39) were compared with subjects without pets (n=90).

RESULTS

More subjects with pets had symptoms, inhaled or oral steroids, abnormal peak-flow records, higher eosinophil counts, and a higher degree of bronchial hyperresponsiveness than subjects without pets. Asthmatics with pets more frequently ascribed their symptoms to their home environment, but fewer of them reported that their symptoms were elicited by contact with cats or dogs.

CONCLUSIONS

This study strongly indicates that living with a cat or a dog aggravates symptoms and biomarkers of airway inflammation in asthmatics sensitized to cats or dogs. The study indicates that avoidance of these allergens may be an important measure in the treatment of sensitized asthmatics.

Association between atopic sensitization and asthma and bronchial hyperresponsiveness in swedish adults: pets, and not mites, are the most important allergens

BACKGROUND

Atopic sensitization is a well-known risk factor for asthma and bronchial hyperresponsiveness (BHR). Mites have been regarded as the most important allergens, but the prevalence of sensitization to mites is relatively low in Sweden.

OBJECTIVE

The aim of the study was to investigate possible associations between sensitization to various allergens and asthma and BHR in adults.

METHODS

A random sample of 1859 subjects, aged 20 to 46 years, was investigated in a cross-sectional study by using a questionnaire, skin prick tests (SPTs), specific and total IgE measurements, and methacholine bronchial challenge tests. Possible associations were analyzed univariately and by using multivariate logistic regression analysis and proportional hazard regression analysis.

RESULTS

Positive SPT and specific IgE results were more common in subjects with asthma and BHR than in subjects without these conditions for all allergens. The independent associations between positive SPT responses and asthma and BHR are given as adjusted prevalence ratios (PRRs): pets and asthma, PRR = 3.6; pets and BHR, PRR = 2.0; grass and asthma, PRR = 2.0; grass and BHR, PRR = 1.7; mites and asthma, PRR = 1.4; and mites and BHR, PRR = 1.2. The use of specific IgE measurements instead of SPTs showed essentially similar results.

CONCLUSION

Cats and dogs were the sensitizing allergens most closely associated with asthma and BHR. The relationships with sensitization to grass and mites were less pronounced.

Exposure to polycyclic aromatic hydrocarbons and genotoxic effects on nonsmoking Swedish road pavement workers

OBJECTIVES

The objective of this study was to investigate exposure to polycyclic aromatic hydrocarbons (PAH) from asphalt fumes among Swedish road pavement workers and determine whether any effects could be detected with genotoxic tests.

METHODS

The study included 28 nonsmoking road pavers and 30 nonsmoking referents. The concentration of PAH was determined in the breathing zone of the road pavers. 1-Hydroxypyrene was analyzed before and after shifts of asphalt work and during the afternoon for referents. Sister chromatid exchanges (SCE) and micronuclei (MN) were determined in peripheral lymphocytes.

RESULTS

Several 3- or 4-ring PAH were found, and the analysis indicated that they occurred in bitumen fumes rather than in traffic fumes. The average total concentration of PAH was 2.3 (range 0.2-23.8) microg/m3. The concentration of 1-hydroxypyrene in urine was higher for the road pavers than for the referents, but there was no significant difference between the pre- and postshift values of the road pavers. The road pavers had no significant increase in SCE or MN.

CONCLUSIONS

The study showed that Swedish road pavers have an increased exposure to PAH from bitumen fumes, but no genotoxic effects could be detected by SCE or MN tests.

Bakery work, atopy and the incidence of self-reported hay fever and rhinitis

The aims of this study were to estimate the risk to bakers of developing hay fever and rhinitis, to assess the modifying effect of atopy and to estimate the occurrence of job change due to nasal symptoms. A retrospective cohort study was performed among bakers trained in Swedish trade schools from 1961 to 1989 (n=2,923). School control subjects (n=1,258) comprised students in other programmes in the trade schools and population controls (n=1,258) were randomly selected from the general population. A questionnaire on hay fever, rhinitis, the year of onset of these diseases, change of work due to nasal symptoms and work history was mailed to all participants. The atopic state of the responders was assessed by questions on allergic diseases in childhood and among next of kin. Incidence rates for hay fever and other rhinitis were calculated. The relative risk (RR) for hay fever when working as a baker compared with all control subjects combined was increased in males (RR=1.9, 95% confidence interval (CI) 1.2-2.9). The RR for rhinitis in male bakers compared with combined control subjects was 2.8 (95% CI 2.3-3.4) and for female bakers 2.0 (1.6-2.7). Of the bakers, 6.1% had changed job due to nasal symptoms, significantly more than the controls. A history of respiratory atopy increased the incidence rates of hay fever and rhinitis, with a synergistic effect between atopy and bakery work in males. In conclusion, Swedish bakers, mainly working in the 1970s and 1980s, had an approximately doubled risk of developing rhinitis. Male bakers also had an increased risk for hay fever. There was a synergistic effect of bakery work and atopy such as a family history of hay fever. Bakers also changed job due to nasal symptoms more often than control subjects.

Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos

OBJECTIVE

To investigate if the preventive measures taken to reduce the occupational exposure to asbestos have resulted in a decreased incidence of pleural mesothelioma in Sweden.

METHODS

The incidence of pleural mesothelioma between 1958 and 1995 for birth cohorts born between 1885 and 1964 was investigated. The cases of pleural mesothelioma were identified through the Swedish Cancer Register.

RESULTS

In 1995, around 80 cases of pleural mesothelioma could be attributed to occupational exposure to asbestos. There is an increasing incidence in more recent birth cohorts in men. The incidence was considerably higher in the male cohort born between 1935 and 1944 than in men born earlier.

CONCLUSIONS

The annual incidence of pleural mesothelioma attributable to occupational exposure to asbestos is today larger than all fatal occupational accidents in Sweden. The first asbestos regulation was adopted in 1964 and in the mid 1970s imports of raw asbestos decreased drastically. Yet there is no obvious indication that the preventive measures have decreased the risk of pleural mesothelioma. The long latency indicates that the effects of preventive measures in the 1970s could first be evaluated around 2005.

The association between epidemiological measures of the occurrence of asthma

SETTING

The prevalence of asthma is useful for studying the causes of asthma.

OBJECTIVE

To ascertain whether there is a relationship between the prevalence and incidence of asthma.

DESIGN

The association between age and the occurrence of asthma was analysed in an epidemiological study of 15,813 persons.

RESULTS

Different conclusions were reached depending on whether the point prevalence, cumulative prevalence or the incidence rates were studied. The relation between the incidence and prevalence of asthma is described in two epidemiological models, and none of the models seem to fit empirical data. Furthermore, it is shown that estimating incidence rates by prospectively measuring the point prevalences may introduce a considerable bias if the reliability of the diagnosis of asthma is around or below an agreement of 99%, which is probably usually the case. Including asthmatic symptoms during the last year in the definition of point prevalence means that there is no simple relation between incidence rates and point prevalences.

CONCLUSION

The point prevalence may be a biased measure in the study of the etiology of asthma, as there is no simple relationship between the incidence and prevalence of asthma.

Occurrence of self reported hand eczema in Swedish bakers

OBJECTIVES

To estimate the risk of bakers developing hand eczema. The importance of atopy was studied as well as change of job due to hand eczema.

METHODS

A retrospective cohort study was performed among bakers trained in Swedish trade schools in 1961-89 (n = 2923). School referents followed other programmes (n = 1258); population controls were randomly selected from the general population (n = 1258). A questionnaire on self reported hand eczema, year of onset of hand eczema, change of work due to hand eczema, childhood eczema, family atopy, and work history was posted to all participants.

RESULTS

The incidence of hand eczema among male controls was 4.4-5.4 cases/1,000 person-years compared with 16.7 for bakery work. The corresponding figures for women were 11.3-14.1 compared with 34.4. The relative risk for male bakers was 3.5 (95% confidence interval (95% CI) 2.8 to 4.5) and for female bakers 2.8 (2.2 to 3.6). Skin atopy increased the incidence about threefold and a synergistic effect of atopy and exposure was indicated. Also, bakers had changed job significantly more often than controls.

CONCLUSIONS

Swedish bakers, mainly working during the 1970s and 1980s, have about a threefold increased risk of hand eczema. There seems to be a synergistic effect of atopy and occupational exposure.

Lung cancer and mesothelioma in the pleura and peritoneum among Swedish insulation workers

OBJECTIVES

To estimate the risk of cancer and death in Swedish insulation workers some years after their exposure to asbestos had stopped. One hypothesis was that the risk of lung cancer would tend to decrease some years after the exposure had ended.

METHODS

In a cohort study the cancer morbidity and cause of death was investigated in 248 insulation workers and compared with the corresponding morbidity and mortality in the general population. Due to stringent regulations, exposure to asbestos of all types had almost ended in Sweden in the mid-1970s. Through a questionnaire, surviving insulation workers were asked about their exposure to asbestos and their smoking habits.

RESULTS

Between 1970 and 1994 there were 86 deaths compared with the 46.0 expected (standardised incidence ratio (SIR) 1.9; 95% confidence interval (95% CI) 1.5 to 2.3), the increase was mainly due to an increased cancer mortality. The morbidity was increased for lung cancer (11 cases v 2.5 expected (SIR 4.4; 95% CI 2.2 to 7.9)), peritoneal mesothelioma (seven cases; no expected incidence could be calculated as the occurrence is too rare in the general population), cancer in pancreas (five cases v 0.7 expected (SIR 7.1; 95% CI 2.3 to 16.7)). No cases of pleural mesothelioma were found. The risk of lung cancer did not tend to approach that of the general population after the exposure to asbestos decreased.

CONCLUSIONS

In the 1980s and the early 1990s, Swedish insulation workers still have a highly increased risk of diseases related to asbestos. The attributable risk for death and cancer was about 50%. The study also confirms the previous finding that mesothelioma in insulation workers seems to be situated in the peritoneum more often than in the pleura.

Leukaemia, lymphoma, and multiple myeloma in seamen on tankers

OBJECTIVES

To investigate the risk of lymphatic and haematopoietic malignancies in deck crew on tankers exposed to cargo vapours.

METHODS

The study design was as a nested case-referent study in two cohorts of male Swedish seamen 20-64 years of age at the national census 1960 (n 13,449) and 1970 (n 11,290), respectively. Cases were detected by record linkage with the Swedish Cancer Register 1961-79 and 1971-87, respectively. For each case, three to five age matched referents from the population were selected. Exposure was assessed from data in the Swedish Registry of Seamen and from a register of Swedish ships.

RESULTS

Seamen in the 1970 cohort, who had been exposed to cargo vapours for at least one month on chemical or product tankers, had an increased risk of lymphatic and haematopoietic malignancies (Mantel-Haenszel odds ratio (OR) 2.6, 95% confidence interval (95% CI) 1.1 to 5.9)) with a significant exposure-response relation (conditional logistic regression analysis, p = 0.04). The ORs were increased for both lymphoma (3.2), multiple myeloma (4.0), and leukaemia (1.6), but the increase was only significant for non-Hodgkin's lymphoma (OR 3.3, 95% CI 1.1 to 10.6). There were no significantly increased risks for the 1960 cohort or for seamen exposed only on crude oil tankers, but these groups had few exposed cases and low cumulative exposure to benzene and other light petroleum products.

CONCLUSIONS

Seamen exposed to cargo vapours from gasoline and other light petroleum products on chemical or product tankers had an increased incidence of lymphatic and haematopoietic malignancies. One possible cause is exposure to benzene during loading, unloading, and tank cleaning operations.

Variability in the skin exposure of machine operators exposed to cutting fluids

OBJECTIVE

This study describes a new technique for measuring skin exposure to cutting fluids and evaluates the variability of skin exposure among machine operators performing cyclic (repetitive) work.

METHODS

The technique is based on video recording and subsequent analysis of the video tape by means of computer-synchronized video equipment. The time intervals at which the machine operator's hand was exposed to fluid were registered, and the total wet time of the skin was calculated by assuming different evaporation times for the fluid. The exposure of 12 operators with different work methods was analyzed in 6 different workshops, which included a range of machine types, from highly automated metal cutting machines (ie, actual cutting and chip removal machines) requiring operator supervision to conventional metal cutting machines, where the operator was required to maneuver the machine and manually exchange products.

RESULTS

The relative wet time varied between 0% and 100%. A significant association between short cycle time and high relative wet time was noted. However, there was no relationship between the degree of automatization of the metal cutting machines and wet time.

CONCLUSIONS

The study shows that skin exposure to cutting fluids can vary considerably between machine operators involved in manufacturing processes using different types of metal cutting machines. The machine type was not associated with dermal wetness. The technique appears to give objective information about dermal wetness.

Late skin-prick-test reactions to malted wheat. Clinical observations and immunohistochemical characterization

This study reports late skin-prick-test (SPT) reactions in seven bakers and seven control subjects to malted wheat appearing after 6-10 h, and not preceded by an immediate-phase reaction. Two subjects in each group had a history of atopic symptoms and were Phadiatope positive. Serologic IgE analysis (RAST) of normal wheat flour and of malted wheat grain was negative in all subjects. Skin biopsy specimens were obtained 16-18 h after SPT to malted wheat grain and to histamine and from untested skin. The late SPT reactions in all participants had an urticarial appearance, clinically and in routine histology. Immunohistologically mild to moderate perivascular dermal cell infiltrates were observed in both groups, consisting mainly of CD4+ and HLA-DR+ cells. The number of CD1a+ epidermal cells was statistically significantly higher (P < 0.01) in the bakers' prick-tested skin compared to that of the controls, a fact which might reflect preparedness to react upon challenge. There were no statistical differences between the two groups in IgE+ epidermal cells or epidermal cells expressing the high-affinity IgE receptor (Fc epsilon RI). However, there was a correlation between serum-IgE levels and the number of IgE+ epidermal cells. The late skin reactions observed in both bakers and controls were probably more of an irritant or toxic than immune-mediated nature, but they raise the question of whether skin contact with malted flour contributes to an unfavorable prognosis of hand eczema in bakers.

Cancer incidence of workers in the Swedish petroleum industry

OBJECTIVES

To estimate the risk of cancer due to occupational exposure to petroleum products in the Swedish transport and refinery industries.

METHODS

In a retrospective cohort study the cancer incidence in 4128 men and 191 women, who had worked for at least one year in the petroleum industry, was compared with the incidence in the general population. The job titles and employment times for each person were found in personal files in the industries. The men had on average worked in jobs exposed to petroleum for 11.6 years at the end of the observation period. The cases of cancer were identified by record linkage with the Swedish cancer register.

RESULTS

In total there were 146 cases of cancer v 157.6 expected (standardised mortality ratio (SMR) 0.93 90% confidence interval (90% CI) 0.80 to 1.1). Operators at refineries had an increased risk of leukaemia (6 cases v 1.7 expected, 90% CI of relative risk (RR) 1.5 to 7.0). Five of the six cases had started to work at the refineries in the 1950s or later. No other significantly increased risk of cancer was found. Distribution workers had a decreased incidence of lung cancer (no cases, 90% CI of RR 0 to 0.4).

CONCLUSIONS

Operators at Swedish refineries had an increased risk of leukaemia. A possible cause is exposure to benzene. There was no increased risk of leukaemia in distribution workers. Distribution workers had a decreased risk of lung cancer.

Successful use of a selective serotonin reuptake inhibitor in a patient with multiple chemical sensitivities

A 53-year-old man with multiple chemical sensitivities (MCS) received the selective serotonin reuptake inhibitor (SSRI) citalopram for treatment of depression. The treatment was successful and, in parallel to the remission of the depressive symptoms, all MCS symptoms vanished. This suggests that a subgroup of MCS patients may have an atypical depression, that they should be psychiatrically evaluated, and that antidepressive pharmacological treatment may be considered in cases of MCS.

Relative risk and excess rate models in exposure-response analysis

The cumulative dose of an environmental exposure and age are usually correlated. It is shown that if an excess rate model is the true relationship, a relative risk model based on standardized mortality ratios (SMR) may show a biased and even contradictory dose-response relationship if the incidence rate in the reference population increases rapidly by age. The choice of model should be based on biological plausibility rather than on available software, and in many cases it may be reasonable to analyze the data both according to a relative and to an excess risk model as the prior knowledge rarely favors one of these models. In a review of a volume of this journal, there were eight cohort studies analyzing dose-response relationship by comparing SMRs without reporting or analyzing excess rates. Thus, there seems to be some lack of awareness of the possible bias in analyzing exposure-disease associations by SMRs.

Symptoms, lung and liver function, blood counts, and genotoxic effects in coastal tanker crews

OBJECTIVE

The deck crew on tankers can be exposed to high concentrations of benzene and other chemicals during loading, unloading and tank-cleaning operations. The objective of this study was to investigate whether genotoxic or other early health effects of cargo vapour exposure could be detected in coastal tanker crews.

METHODS

The association between exposure to cargo vapours and clinical symptoms and signs, spirometry, blood cell count, blood test for liver function, and the frequency of micronuclei and sister chromatid exchanges in peripheral lymphocytes was studied in a cross-sectional investigation of 107 male crew members (66 deck crew and 41 others) on ten coastal tankers.

RESULTS

Seven of the tankers had automatic cargo level gauging systems but some of the ships still had open hatches during loading and unloading operations. Acute symptoms such as headache, nausea, vertigo, fatigue and dizziness after loading or tank-cleaning operations were reported by 56 of the 66 deck crew members (85%). Irritation of the mucous membrane in eyes and upper respiratory tract by cargo vapours were also common in this group. Obstructive symptoms were more common in the group with the highest exposure to cargo vapours but persistent effects on lung function (vital capacity and forced expiratory volume in 1 s), nervous system, liver enzymes or blood counts were not found. The frequency of micronuclei after mitotic stimulation with phytohaemagglutinin was higher among the deck crew (mean 4.2 SEM 0.40) than in other crew members (mean 3.6, SEM 0.35). although the difference was not statistically significant. We found no association between exposure and the frequency of sister chromatid exchanges or micronuclei after stimulation with pokeweed mitogen.

CONCLUSION

This study indicates that exposure to cargo vapours in coastal tanker crews may cause symptoms in the respiratory and nervous systems.