Association between occupational psychosocial factors and waist circumference is modified by diet among men.

BACKGROUND/OBJECTIVES: Occupational psychosocial stress has been identified as a risk factor for obesity, whereas dietary habits have a key role in weight control. We examined whether dietary habits modify the association between occupational psychosocial factors and waist circumference. SUBJECTS/METHODS: Data comprised 31-year-old men (n=2222) and women (n=2053) in the Northern Finland Birth Cohort 1966. Waist circumference was measured and data on occupational psychosocial factors (demands, control and social support) and other characteristics were obtained through questionnaires. Healthy and unhealthy diet indices were constructed according to the current dietary guidelines. Associations were examined using analysis of variance adjusted for body mass index at age 14, basic education level, leisure-time physical activity, alcohol consumption, smoking, stress-related eating behaviour and parity. RESULTS: Among men, high job demands and high job control were associated with greater waist circumferences, and there were interactions between unhealthy diet and job demands (P=0.043) and job control (P=0.036) in relation to waist circumference. The waist of men with high demands or high control and low consumption of unhealthy foods (red/processed meat, hamburgers and pizzas, fried potatoes, sugar-sweetened soft drinks and white bread) was smaller than that of men with high demands or high control and high consumption of such foods. No associations were found among women. CONCLUSIONS: A diet based on the current dietary guidelines seems to cancel out the adverse effects of occupational psychosocial factors on waist circumference among young men. Longitudinal studies are needed to assess the risks for obesity-related diseases arising from psychosocial work environments and dietary habits.

Early retirement and non-employment after breast cancer.

OBJECTIVE: This study examined whether workplace support, sociodemographic factors and co-morbidity are associated with early retirement or non-employment due to other reasons among breast cancer survivors. We also compared quality of life and chronic symptoms (pain, fatigue, anxiety and depression) among employed, retired and other non-employed breast cancer survivors. METHODS: We identified breast cancer survivors diagnosed between 1997 and 2002 from either a hospital or a cancer registry in Denmark, Finland, Iceland and Norway (NOCWO study). All patients had been treated with curative intent. Information on employment, co-morbidity and support was collected via a questionnaire. The sample included 1111 working-aged cancer-free survivors who had been employed at the time of diagnosis. We used multinomial logistic regression models to analyse the association of various determinants with early retirement and other non-employment (due to unemployment, subsidized employment or being a homemaker). RESULTS: Low education, low physical quality of life, co-morbidity and pain were associated with both early retirement and other non-employment after cancer. Other non-employed survivors also rated their mental quality of life as lower and experienced anxiety and fatigue more often than all the other survivors. Moreover, they reported a lower level of supervisor support after their diagnosis than the employed survivors. Retired survivors more often reported weak support from colleagues. CONCLUSIONS: Differences in ill health and functional status between various groups of non-employed cancer survivors need to be considered when planning policy measures for improving the labour market participation of this population and preventing their early withdrawal from working life.

Work ability of survivors of breast, prostate, and testicular cancer in Nordic countries: a NOCWO study.

INTRODUCTION: Cancer can cause adverse effects on survivors' work ability. We compared the self-assessed work ability of breast, testicular, and prostate cancer survivors to that of people without cancer. We also investigated the association of disease-related and socio-demographic factors and job-related resources (organizational climate, social support, and avoidance behavior) with work ability and looked at whether these associations were different for the survivors and reference subjects. METHODS: Working aged cancer patients diagnosed between 1997 and 2002 were identified from hospital or cancer registries in Denmark, Finland, Iceland, and Norway (Nordic Study on Cancer and Work). A cancer-free reference group was selected from population registries. We collected information on work ability and other factors from 1,490 employed survivors and 2,796 reference subjects via a questionnaire. RESULTS: The adjusted mean value of work ability was slightly lower among the breast and prostate cancer survivors compared to the cancer-free population. Co-morbidity, chemotherapy, low workplace support, and low organizational commitment were associated with reduced work ability. Avoidance behavior from supervisors or colleagues was only related to work ability among the cancer survivors. CONCLUSIONS AND IMPLICATIONS: More attention should be paid to assisting cancer survivors in work life, particularly those who have chronic diseases or have undergone chemotherapy. Although most factors affecting the work ability of the survivors and reference subjects were the same, survivors' work ability seemed to be particularly sensitive to avoidance behavior. The results suggest that there is a need to improve communication at the workplace and develop supportive leadership practices in order to avoid isolating behavior towards cancer survivors.

Cancer as the cause of changes in work situation (a NOCWO study).

OBJECTIVE: To investigate the frequency of changes in work situation due to cancer and to analyze the association of physically demanding work, social support from supervisors, colleagues or occupational health services, and disease-related factors, with changing employers due to cancer. METHODS: Working-aged patients with breast, testicular or prostate cancer, or lymphoma with a good prognosis between 1997 and 2002 were identified from a hospital or cancer registry in four Nordic countries. The registers provided data on the disease-related factors. Information on changes in work situation, received support, and other work-related factors was collected using a questionnaire (response rate 72%). The frequency of changes in work situation was evaluated among a total of 2030 survivors. Further analyses were carried out among 688 survivors using a multivariable logistic regression model, to investigate factors affecting the risk of changing employers due to cancer. RESULTS: Altogether, 5-10% of cancer survivors had changed employers, occupations or work tasks, 5% had been unemployed, and 9% had retired due to cancer. The physical demands of previous work were the most important reason behind changing employers after cancer. Among women, weak support from supervisors and occupational health personnel increased the risk of changing employers because of cancer. CONCLUSIONS: A minority of cancer survivors changed employers, occupations, or work tasks because of cancer. Supervisors' support in the form of lightening physically demanding jobs and taking illness into consideration when planning work tasks, and health-care workers' advice on coping at work may help survivors to maintain their jobs.

Factors affecting cancer survivors' employment and work ability.

PURPOSE: Due to the improved prognosis of many forms of cancer, an increasing number of cancer survivors are both willing and able to return to work after their treatment. This has increased interest in studying work and cancer-related issues. The purpose of this paper is to give an overview of research on the impact of cancer on employment and work ability, on the effect of psychosocial factors on survivors' well-being, and to indicate research needs for the future. RESULTS: Studies have shown that the majority of cancer survivors are able to continue working. There is, however, a group of cancer survivors who suffer from impaired health as a result of their illness, and this impairment sometimes leads to a decreased ability to work, or even disability. Employment and impaired work ability has most commonly been found to be associated with cancer type, type of treatment, health status, education and physical workload. The few studies that have focused on the effects of psychosocial factors in work life suggest that social support from occupational health services, and workplace accommodations for illness affect cancer survivors' return to work. CONCLUSIONS: More research is needed on the impact of social factors at work, which seem to play an important role in cancer survivors' ability to continue working.

Time To Pregnancy and occupational lead exposure.

BACKGROUND: Lead exposure is known to be harmful to the male reproductive system, including impairment of fertility. However, it is unclear whether currently existing low levels of exposure have this effect. AIMS: To study retrospectively current workers in lead using industries (battery manufacture, smelting, etc), and in non-lead using control industries, in four European countries, with Time To Pregnancy as the outcome variable, as part of the EU funded Asclepios Project. METHODS: Exposure assessment was mainly by blood lead values, which were available from the late 1970s, supplemented by imputed values where necessary. Three exposure models were studied: (1) short term (recent) exposure; (2) total duration of work in a lead using industry; and (3) cumulative exposure. A Cox proportional hazards model with discrete ties was used for the statistical analysis, with covariates for both partners. RESULTS: A total of 1104 subjects took part, of whom 638 were occupationally exposed to lead at the relevant time. Blood lead levels were mainly less than 50 microg/dl. No consistent association of Time To Pregnancy with lead exposure was found in any of the exposure models, although reduced fertility was observed in one category each in models (2) and (3). CONCLUSIONS: This basically negative result is unlikely to be due to the misclassification of key variables, to insufficient statistical power, or to bias, for example, response bias. If any impairment of male reproductive function exists at the levels of occupational lead exposure now current, it does not appear to reduce biological fertility.

Time to pregnancy among the wives of men occupationally exposed to lead.

We conducted a retrospective study on time to pregnancy among the wives of men biologically monitored for lead to assess whether paternal occupational exposure to inorganic lead is associated with decreased fertility. After three mailings, 554 (72.2%) wives of the monitored men participated. The final study population consisted of 502 couples who did not use contraception at the beginning of the pregnancy. We assessed lead exposure from blood lead measurements and from questionnaires completed by the men. We calculated the relative fecundability density ratios with discrete proportional hazards regression. The fecundability density ratios, adjusted for potential confounders, were 0.92 [95% confidence interval (95% CI) = 0.73-1.16], 0.89 (95% CI = 0.66-1.20), 0.58 (95% CI = 0.33-0.96), and 0.83 (95% CI = 0.50-1.32) for blood lead categories 0.5-0.9, 1.0-1.4, 1.5-1.8, and > or =1.9 micromol/L, respectively, as compared with <0.5 micromol/L. The findings provide limited support for the hypothesis that paternal exposure to lead is associated with decreased fertility.

Paternal exposure to lead and infertility.

To assess whether paternal exposure to lead is associated with infertility, we performed a register-based study among married men biologically monitored for exposure to inorganic lead. We obtained information about the marriages and the wives of the men from the Finnish Central Population Register. Data on pregnancies were obtained from medical records. Paternal exposure to lead was assessed on the basis of blood lead measurements. We estimated the risk of infertility, defined as nonoccurrence of a marital pregnancy, by applying binomial regression. For the blood lead categories of 0.5-0.9, 1.0-1.4, 1.5-1.9, 2.0-2.4, and > or =2.5 micromol/L the relative risk of infertility, compared with the risk in the lowest exposure category (<0.5 micromol/L), was 1.27 (95% confidence interval 1.08-1.51), 1.35 (1.12-1.63), 1.37 (1.08-1.72), 1.50 (1.08-2.02), and 1.90 (1.30-2.59), respectively. The findings support the hypothesis that paternal exposure to lead increases the risk of infertility at low occupational exposure levels. We applied proportional hazards regression to the analysis of pregnancy delay. A delay was observed among the wives of men exposed to lead. Exposure to lead was not clearly associated with delayed pregnancy, however, when the analysis was restricted to couples with at least one pregnancy. This finding suggests that the restriction of the study on time to pregnancy to fertile couples may introduce a bias toward no association.

Spontaneous abortions among veterinarians.

OBJECTIVES: The objective of the study was to determine whether female veterinarians have an increased risk of spontaneous abortion and whether the potential risk is related to the type of work veterinarians do. METHODS: The investigation was a retrospective cohort study among all the female members of the Finnish Veterinary Association (N=549). Information on pregnancies was obtained from hospital records from 1973-1990. The risk of spontaneous abortion among the veterinarians was compared with that of all other Finnish women and other upper-level employees. Odds ratios from logistic regression analyses were used as the estimates of the risk ratios. RESULTS: The risk of spontaneous abortion was 10.5% for the veterinarians. In the 1970s, practicing veterinarians had an increased risk of spontaneous abortion as compared with other Finnish women (adjusted odds ratio 1.8, 95% confidence interval 1.0-3.1) or other upper-level employees (adjusted odds ratio 2.0, 95% confidence interval 1.1-3.4). In the 1980s, the risk fell below that of other Finnish women. No essential differences were observed in the risk between the veterinarians employed in different occupational categories. CONCLUSIONS: The results suggest that the veterinarians had an increased risk of spontaneous abortion in the 1970s, but not in the 1980s. Factors which might have contributed to this decrease in risk include decreases in the prevalence and level of exposure to harmful agents, improvements in the occupational hygiene of the work environment, and an increased awareness of reproductive hazards and the use of sick leave during pregnancy.

Spontaneous abortions among Finnish flight attendants.

We conducted a retrospective cohort study to investigate whether work as a cabin attendant is related to an increased risk for spontaneous abortion. Data on female cabin crew members were linked to medical records on pregnancies. There were 1751 eligible pregnancies for the final analysis. Flight attendants who worked during early pregnancy had a slightly elevated risk of spontaneous abortion, as compared with attendants who were pregnant outside a time span of active flying (odds ratio [OR] = 1.3; 95% confidence interval [CI], 0.9 to 1.8). During the earliest years of the study period (1973 through 1977), the risk seemed to be decreased (OR = 0.4; 95% CI, 0.2 to 1.1), whereas during the later years (1978 through 1994) the risk was increased (OR = 1.6; 95% CI, 1.1 to 2.4). The results are in agreement with earlier studies, showing suggestive evidence of a slightly increased risk of spontaneous abortion among female cabin crew members.

Women's reproductive health: some recent developments in occupational epidemiology.

Epidemiological research on occupational hazards and reproductive health is an expanding and strongly developing area. This article focuses on some recent areas of occupational reproductive epidemiology that are or seem to be important for the future. Interest in the research on fertility has increased during the past decade, and time to pregnancy has proved to be a useful measure of fertility. The research on menstrual function or early fetal loss is still limited, and further research is desirable. It is important to chart the advantages and disadvantages of various methods for measuring these outcomes. Recently developed methods of exposure assessment provide new possibilities to improve the validity of exposure data. Biological exposure markers can also provide useful dosimeters for reproductive studies. Research on the reproductive effects of job stress and individual susceptibility to reproductive toxicants is also gaining in importance.

Reduced fertility among female wood workers exposed to formaldehyde.

BACKGROUND: The aim of the study was to investigate whether exposure to formaldehyde, organic solvents or other chemicals in the wood-processing industry affects the fertility of women. METHODS: For this purpose, a retrospective study on time to pregnancy was conducted among female wood workers who had given birth during 1985-1995. Data on pregnancy history, time to pregnancy, occupational exposures, and potential confounders were collected by a questionnaire; 64% (699/1,094) participated. The exposure assessment was conducted by an occupational hygienist. The data on time to pregnancy were analyzed with the discrete proportional hazards regression. RESULTS: Exposure to formaldehyde was significantly associated with delayed conception: adjusted fecundability density ratio, FDR, was 0.64 (95% CI 0.43-0.92). At high exposure if no gloves were used, the FDR was 0.51 (% CI 0.28-0.92). Exposure to phenols, dusts, wood dusts, or organic solvents was not related to the time to pregnancy. Additionally, an association was observed between exposure to formaldehyde and an increased risk of spontaneous abortion (concerning previous spontaneous abortions, reported by the women). Associations between exposure to formaldehyde or to organic solvents and endometriosis, and between exposure to organic solvents or to dusts and salpingo-oophoritis were also suggested. CONCLUSIONS: The study suggests that a woman's occupational exposure to formaldehyde has an adverse effect on fertility.

Time to pregnancy among the wives of men exposed to organic solvents.

OBJECTIVES: To assess whether paternal exposure to organic solvents is associated with decreased fertility. METHODS: A retrospective time to pregnancy study was conducted among men biologically monitored for organic solvents. The workers were classified into exposure categories on the basis of work description and the use of solvents as reported in the questionnaires, and on biological exposure measurements. The relative fecundability density ratios (FDR--an analogue of incidence density ratio of clinically recognised pregnancies) were calculated with discrete proportional hazards regression. RESULTS: After three mailings 316 (72.1%) wives of the monitored men participated. The final study population consisted of 282 couples who did not use contraception at the beginning of pregnancy. The FDRs, adjusted for potential confounders, were 0.80 (95% confidence interval (95% CI) 0.57 to 1.11) and 0.74 (95% CI 0.51 to 1.06) for high or frequent and low or intermediate exposure, respectively. High or frequent and low or intermediate exposure were related to decreased fecundability among primigravida (FDRs 0.36; 95% CI 0.19 to 0.66 and 0.53; 95% CI 0.27 to 1.04) but not among couples with at least one previous pregnancy (FDRs 0.96; 95% CI 0.62 to 1.49 and 0.77; 95% CI 0.47 to 1.24). CONCLUSIONS: The findings of the study provide limited support for the hypothesis that paternal exposure to organic solvents might be associated with decreased fertility. Further studies with careful design are warranted.

Validity aspects of exposure and outcome data in reproductive studies.

Some validity aspects related to various sources on pregnancy outcome and exposure are discussed. Register-based data on outcome and exposure are compared with workers' own reports. The problems in the use of personal interview data on pregnancies are related to the possible selection in recognition and reporting the pregnancy outcome. The best way of avoiding misclassification of outcome is to resort to medical records whenever possible. Misclassification of exposure is most likely a common reason for discrepancies in results in reproductive studies. The misclassification of exposure deflates the power of the study to detect the true difference between exposed and nonexposed subjects, particularly when the prevalence of exposure is low. It is of great importance to confirm, if possible, the exposure status by using two or more independent sources of data.

Effects of parental exposure to solvents on pregnancy outcome.

The findings and methodological issues of epidemiologic studies on adverse developmental effects of parental occupational exposure to organic solvents are reviewed. The studies on maternal effects suggest that high exposure to solvents may increase the risk of spontaneous abortion, but the findings on congenital malformations are inconsistent. Suggestive associations of spontaneous abortions have also been observed with some particular solvents. The evidence appears to be most adequate for toluene. Evidence on the effects of paternal exposure to solvents on pregnancy outcome is limited and inconsistent. Suggestive results link paternal exposure to spontaneous abortion, congenital malformation, and low birth weight or preterm birth. A common methodological weakness in these studies is the inaccurate data on exposure. Positive findings encourage further studies with an improved study design and methods, particularly with improved assessment of exposure.

Time to pregnancy among women occupationally exposed to lead.

A retrospective time-to-pregnancy study was conducted among women biologically monitored for exposure to lead. The women were participants of a previous study on spontaneous abortion. They were classified into exposure categories on the basis of questionnaire information, and individual blood lead (B-Pb) measurements. The adjusted incidence density ratios (IDR) of clinically recognized pregnancies were .93 (95% confidence interval [CI] .56 to 1.57) for very low (B-Pb < .5 mumol/L), .84 (CI .48 to 1.45) for low (B-Pb .5 to .9 mumol/L), and .80 (CI 0.42 to 1.54) for higher (B-Pb > or = 1.0 mumol/L) exposure compared with no exposure, in the discrete proportional hazards analysis. Exposure to inorganic lead was not associated with fecundability at current, low-exposure levels. The suggestive finding among the eight most heavily exposed women (B-Pb 1.4 to 2.4 mumol/L, IDR .53; CI .19 to 1.52) should be confirmed or refuted in a larger study.

Magnetic fields of video display terminals and pregnancy outcome.

The magnetic fields emitted by video display terminals (VDTs) and their potential association with pregnancy outcome are discussed. The majority of the epidemiologic studies suggest that VDT work is not related to adverse pregnancy outcome. The exposure to magnetic fields from modern VDTs is usually even lower than that from other sources in the office environment, such as printers and photocopying machines. There are, however, some indications of an increased risk of adverse pregnancy outcome among women exposed to high levels of extremely low-frequency magnetic fields of VDTs or electric appliances at home. Because the present evidence is not sufficient to allow the drawing of final conclusions, it would be important to examine the effects of exposure to higher fields existing at industrial work places.