Annika Gustavsson

Recent time trends in acute myocardial infarction in Stockholm, Sweden

AIMS The purpose of this study was to analyse time trends in first acute myocardial infarction (AMI) incidence in Stockholm County during 1984-1996. METHODS AND RESULTS The study base consisted of the population of Stockholm County 30-89 years old 1984-1996. New cases of first AMI in the study base were identified by combining information regarding hospital discharges and deaths. The diagnostic quality was evaluated for 2403 First-AMI cases 45-70 years old that occurred during 1992-1994. The evaluation indicated a very high agreement with diagnostic criteria of AMI among hospital treated cases. Among fatal cases outside hospital, the autopsy rate was nearly 70%. The incidence of first AMI declined during the study period for both men and women. In men, the age-adjusted incidence of first AMI was 18% lower in 1994-1996 than in 1984-1987 and in women it was 13% lower. The average yearly decline was 2% for men and 1.4% for women. CONCLUSION The results of this study suggest a continued decline in AMI incidence in Stockholm. A reduction in the proportion of regular smokers has probably contributed to this decline. Future trends in AMI incidence are difficult to predict in view of diverging trends in risk factors.

Environmental tobacco smoke and myocardial infarction among never-smokers in the Stockholm Heart Epidemiology Program (SHEEP)

An increased risk for myocardial infarction (MI) related to environmental tobacco smoke (ETS) exposure has previously been reported, but several aspects of the association are still uncertain. We studied the MI risk associated with ETS exposure among 334 nonfatal never-smoking MI cases and 677 population controls, 45–70 years of age, in Stockholm County. A postal questionnaire with a telephone follow-up provided information on ETS exposure and other potential risk factors for MI. After adjustment for age, gender, hospital catchment area, body mass index, socioeconomic status, job strain, hypertension, diet, and diabetes mellitus, the odds ratio for MI was 1.58 (95% confidence interval = 0.97–2.56) for an average daily exposure of 20 cigarettes or more from the spouse. Combined exposure from spouse and work showed an increasing odds ratio for MI, up to 1.55 (95% confidence interval = 1.02–2.34) in the highest category of weighted duration, that is, more than 90 “hour-years” of exposure (1 “hour-year” = 365 hours, or 1 hour per day for 1 year). In addition, more recent exposure appeared to convey a higher risk. Our data confirm an increased risk of MI from exposure to ETS and suggest that intensity of spousal exposure, combined exposure from spouse and work, and time since last exposure are important.

Occupational magnetic field exposure and myocardial infarction incidence.

Background: Studies on healthy volunteers have seen reduced heart rate variability after exposure to extremely low-frequency electric and magnetic fields (EMF). Because reduced heart rate variability has been linked to cardiovascular disease risk, it has been hypothesized that exposure to EMF might increase the risk of cardiovascular disease. One epidemiologic study has shown increased mortality from cardiovascular conditions in utility workers with elevated exposure to magnetic fields, but several other epidemiologic studies have failed to confirm this result. We tested the hypothesis that occupational EMF exposure increases the risk of myocardial infarction in a large population-based case-control study of myocardial infarction, with detailed information on potential confounders. Methods: We used data from the SHEEP study, which is a population-based case-control study of acute myocardial infarction in Stockholm. Occupational EMF exposure was based on job titles 1, 5, and 10 years before diagnosis. We used 2 approaches to classify exposure: first, specific individual job titles with presumed elevated EMF exposure, and second, classification of subjects according to a job-exposure matrix. Results: We found no increased risk of myocardial infarction in subjects classified as having elevated EMF exposure. For the highest exposure category of ≥0.3 μT according to the job-exposure matrix, the adjusted relative risk was = 0.57 (95% confidence interval = 0.36–0.89). Conclusions: The results of this study do not support the hypothesis that occupational EMF exposure increases the risk of myocardial infarction.

Excess mortality among Swedish chimney sweeps.

In a cohort study of 5464 union organised Swedish chimney sweeps employed at any time between 1918 and 1980 mortality was studied from 1951 to 1982 with national statistics used as a reference. Follow up was possible for 98.6% of the individuals: 717 deaths were observed against 540 expected. There was an increased mortality from coronary heart disease, respiratory diseases, and several types of malignant tumours. Lung cancer mortality was significantly increased and positively correlated to the number of years employed. A fivefold risk increase for oesophageal cancer and liver cancer was found. The increased mortality could be attributed to exposure to combustion products in the work environment but not to smoking habits.

Diagnoses of alcohol abuse and other neuropsychiatric disorders among house painters compared with house carpenters.

The incidence of alcoholism and the incidence of other neuropsychiatric diagnoses were compared between the 767 house painters and the 1212 house carpenters, born in 1925 or later, who were members of the Stockholm branches of their respective trade unions in 1965 and who had been members for at least 10 years before 1970. Four different outcome registers were used: (1) the alcohol crime register, which contained all persons who had broken any law regulating the handling and consumption of alcohol (follow up period 1972-6). (2) The register of diagnoses at early retirement (follow up period 1971-84). (3) The register of diagnoses at discharge from inpatient psychiatric care (follow up period 1968-83). (4) The register of causes of death (follow up period 1965-86). Exposures to solvents and consumption of alcohol were evaluated by interviews with samples of the cohorts. A high average cumulative exposure to solvents was found among the painters. The mean consumption of alcohol was similar in the two cohorts. The incidence of diagnoses of neuropsychiatric disorders was higher in painters than in carpenters in all registers. Alcoholism was the most common neuropsychiatric disorder diagnosed and showed the highest relative risk. The excess of alcoholism among the painters was, however, due singularly to painters who had several registrations in the alcohol crime register or diagnoses of alcoholism in multiple registers. Thus the study implies that excessive alcohol consumption or severe damage due to alcohol, or both, but not less severe problems, were more common in painters than in carpenters. This suggests an interaction between exposure to solvents and intake of alcohol causing an increase in diagnosis of alcoholism among painters.

Mortality among Welders Exposed to High and to Low Levels of Hexavalent Chromium and Followed for More Than 20 Years

Hexavalent chromium particles are generated in the welding of stainless steel. A cohort consisting of 233 welders working on stainless steel and exposed to high levels of chromium was selected. According to an earlier survey, the hexavalent chromium exposures of such welders are often above 20 µg/m(3). Another cohort consisting of 208 railway track welders exposed to low levels of chromium was also selected. The participants of both cohorts had welded for at least five years between 1950 and 1965 and were followed for mortality until December 1992. Among the welders exposed to high levels of chromium, six deaths due to pulmonary tumors occurred. This number is higher than the two deaths that occurred among the welders exposed to low levels of chromium and the corresponding mortality of the general population, but not significantly higher. Thus, exposure to stainless steel welding fumes might increase the incidence of pulmonary tumors.

Cancer incidence in female laboratory employees: extended follow-up of a Swedish cohort study

Objectives Work in chemical laboratories is associated with exposure to chemicals, of which some are known or suspected carcinogens. A cohort study of laboratory workers in Stockholm followed until 1992 showed an excess of hematolymphatic malignancies in chemical laboratories and an excess of breast cancer among women working for more than 10 years in such laboratories. The follow-up of this cohort has now been extended by 20 years. Methods The cohort comprised 2245 female laboratory workers who are employed for >1 year from 1950 to 1989. Information on employment periods and type of laboratory (‘chemical’ or ‘non-chemical’) was obtained from employee registers. Cancer diagnoses from 1958 to 2012 were obtained from the Swedish Cancer Registry. Results There were 383 cases of cancer (SIR=0.93 (95% CI 0.84 to 1.02)). The risk of breast cancer was elevated, of borderline statistical significance, among those who had worked for at least 10 years in chemical laboratories (SIR=1.41 (95% CI 0.99 to 1.95) 36 cases). The breast cancer risk was especially high in women who had worked for more than 10 years in chemical labs before 1970 (SIR=3.76 (95% CI 1.72 to 7.14), nine cases). There was no excess of breast cancer in non-chemical labs (SIR=0.77 (95% CI 0.54 to 1.07), 35 cases). The number of hematolymphatic cancer was no longer significantly elevated. Conclusions The increased risk of breast cancer, as well as the earlier noted excess of hematolymphatic malignancies, may be related to exposure to carcinogenic chemicals/organic solvents (eg, benzene) used in chemical laboratories, especially during earlier periods.

0360 Occupational exposure to respirable silica dust in men and women and risk for acute myocardial infarction

Respirable silica dust is a common and serious occupational hazard to workers´ health. Inhalation causes inflammation which is a risk factor for cardiovascular disease, but few studies have confirmed a relationship. In the present study, we have investigated the risk of myocardial infarction in workers exposed to respirable silica dust, as well as differences in sensitivity based on gender. The cohort consists of manual workers in the Swedish National Census in 1980 with information on demography and occupation (1960–1990). Information on hospital admissions for acute myocardial infarction and cause of death were obtained from nation-wide registers. A job-exposure matrix was used to assess lifetime occupational exposure. No smoking data was available. Among manual workers ever exposed to respirable silica dust, the hazard ratio (HR) for acute myocardial infarction was 1.29 (95% Confidence Interval (CI) 1.15–1.46) for women, and 1.02 (95% CI 1.00–1.04) for men, respectively. In the highest quartile of cumulative exposure the HR was 1.66 (95% CI 1.27–2.18) for women, and 1.06 (95% CI 1.03–1.10) for men, respectively. We found a dose-response relationship between exposure and disease. The population etiologic fraction of disease for women was 11%. In absolute numbers this corresponds to 7 extra cases/10000 person years among exposed women in the highest exposed group. In conclusion, occupational exposure to respirable silica dust was in this study related to an increased risk for acute myocardial infarction in women, indicating a slightly increased sensitivity of the exposed women.

0322 Cancer incidence in firefighters in sweden – preliminary findings from an updated cohort study

Objectives Firefighters are potentially exposed to carcinogens during work, such as benzene, benso(a)pyrene, arsenic, asbestos and silica dust. There are previous studies indicating an increased cancer risk among firefighters. The aim was to study risk of cancer in Swedish firefighters. Methods We updated a previous cohort study of firefighters in Stockholm, comprising 1 080 men who worked at least 1 year as a firefighter during 1931–1983. They were followed regarding cancer incidence (in the National Cancer Register) from 1958–2012, adding 26 years of follow-up compared to the previous study. We also updated the information of employment duration, by annual records at the fire stations. We calculated standardised incidence ratios (SIR) with the male population in Stockholm as reference. Results The overall cancer incidence was low (SIR=0.81, 95% CI=0.71–0.91), but there was a trend of increasing cancer incidence with increasing employment duration (p=0.03). There was an increased incidence of stomach cancer (SIR=1.89, 95% CI=1.25–2.75). The risk was significantly low for prostate cancer (SIR=0.68, 95% CI=0.52–0.87) and for malignant melanoma of the skin (SIR=0.30, 95% CI=0.06–0.88). Conclusions We found no increased cancer incidence overall in Swedish firefighters, although the increasing incidence with increasing work duration indicates a possible carcinogenic effect of exposures at work. The cause of the increased incidence of stomach cancer is uncertain but could possibly be due to exposure to asbestos or silica dust, although this is quite speculative.

O14-1 Cancer incidence in laboratory technicians – extended follow-up of a swedish cohort study

Work in chemical laboratories may potentially be associated with exposure to carcinogenic chemicals. A previous cohort study of laboratory technicians in Stockholm followed until 1992 showed an excess of hematolymphatic malignancies among workers in chemical laboratories and an excess of breast cancer among women working for more than 10 years in such laboratories. The cohort comprised laboratory technicians employed 1950–1989 at “chemical” (e.g. chemistry, cytology, pathology) or “non-chemical” (e.g. physiology, haematology, fertility) laboratories at Karolinska Hospital and Karolinska Institutet in Stockholm. Follow-up of the 2 247 women in the cohort was extended by 20 years to include the period 1958–2012. Information on employment times and types of laboratory work was obtained from employee registers. Cancer incidence data was obtained from the the Swedish Cancer Registry. There were 389 cases of cancer in the cohort, SIR = 0.94 (95% CI: 0.85–1.04). The risk of breast cancer was increased among those who had worked for at least 10 years in chemical laboratories, SIR = 1.49 (1.05–2.05), 38 cases. There was no excess of breast cancer among those who had worked in non-chemical labs (SIR = 0.77 (0.54–1.07), 35 cases. The number of hematolymphatic cancers was not significantly increased. The increased risk of breast cancer among women who had worked for at least 10 years in chemical labs may be related to exposure to cancerogenic chemicals used in these laboratories. The absence of risk among those working in non-chemical labs makes it less likely that the excess would be caused by diagnostic bias resulting from a higher participation in mammography screening among health care workers, or late or no child-births due to longer education, since these factors would be expected to be similar between chemical and non-chemical labs. Night work, a well-recognised risk factor for breast cancer, is uncommon for lab workers.