Geographical variation of sporadic Legionnaires' disease analysed in a grid model.

The aim was to analyse variation in incidence of sporadic Legionnaires' disease in a geographical information system in three time periods (1990-2005) by the application of a grid model and to assess the model's validity by analysing variation according to grid position. Coordinates of the addresses at time of disease of 606 confirmed cases with Legionnaires' disease were obtained. The incidence was calculated in cells of 10 x 10 km in 25 different grids superimposed on a map of Denmark. A 95% and 99% threshold was applied to identify cells with excess incidence representing potential clusters. Four cells had excess incidence in all three time periods. The analysis in 25 different grid positions indicated a low risk of overlooking cells with excess incidence in a random grid. The coefficient of variation ranged from 0.08 to 0.11 independent of the threshold. By application of a random grid model we demonstrated that it was possible to detect small areas with excess incidence that were not detected in the present surveillance system.

Legionella antibodies in a Danish hospital staff with known occupational exposure.

Although legionnaires' disease frequently is acquired in health care institutions, little is known about the occupational risk of Legionella infection among health care workers. The aim of the present cross-sectional study was to analyse antibody levels among exposed hospital workers and to determine the correlation between antibodies to Legionella and self-reported symptoms. The study included 258 hospital employees and a reference group of 708 healthy blood donors. Hospital workers had a higher prevalence of Legionella antibody titres (>/=1 : 128) than blood donors (odds ratio 3.4; 95% CI 2.4-4.8). Antibody levels were not higher among staff members at risk of frequent aerosol exposure than among less exposed employees. There was no consistent association between a history of influenza-like symptom complex and the presence of antibodies. The results indicate that hospital workers have a higher risk of Legionella infections than the general population. However, since no excess morbidity was associated with seropositivity, most Legionella infections may be asymptomatic.

Mortality among anesthesiologists in Denmark, 1973-95.

BACKGROUND: Preliminary data from Sweden indicating that anesthesiologists have a high mortality risk has caused a lot of concern in Denmark. The aim of this study therefore was to compare mortality between consultant anesthesiologists and other consultants in Denmark. METHODS: A historical prospective cohort study based on the membership register of the Danish Medical Association from 1973 to 1992. The study population consisted of 6854 consultants who were members of the Association of Medical Specialists, 406 of whom were anesthesiologists. The all-cause mortality between the two groups was compared during the period 1972-95 using Cox's proportional hazard regression model. RESULTS: The study covered approximately 86000 person-years. A total of 1205 deaths occurred within the period studied, 41 of whom were anesthesiologists. The relative risk for all-cause mortality among the anesthesiologists compared with all the other consultants was 1.0 (95% confidence limit: 0.7-1.4). CONCLUSION: In Denmark there is no evidence of a high mortality risk in consultant anesthesiologists compared with other consultants.

Improvement in semen quality associated with decreasing occupational lead exposure.

BACKGROUND: Cross-sectional studies have suggested that occupational lead exposure may adversely affect sperm quality. METHODS: Sperm quality changes were prospectively assessed in 19 men employed at a car battery plant where efforts were made to decrease the exposure level. The participants delivered monthly samples of semen and venous blood during their employment at the factory. The factory then closed, and additional samples were obtained from 16 of the men. RESULTS: Average blood-lead concentrations decreased from 2.03 mumol/l to 0.96 mumol/l during the observation period. Concomitantly, significant improvements were seen in the proportion of motile cells both at sample delivery and after 24 hr, and in penetration. However, the sperm cell concentration and the proportion of morphological abnormalities did not change. CONCLUSIONS: These results support the notion that occupational lead exposure at currently acceptable levels has a small adverse effect on sperm quality, especially sperm motility, and that this effect is at least partially reversible.

[Pregnancy and occupational environment. Counseling of pregnant women in the department of occupational medicine during the period 4 January--31 December 1992]. / Graviditet og arbejdsmilijø. De arbejdsmedicinske afdelingers rådgivning af gravide i perioden 1.4.--31.12.1992.

Since the new Sickness and Maternity Benefit Act was introduced in Denmark 1981, it has been possible to provide maintenance allowance for pregnant women working under conditions that might be harmful to the unborn child. The assessment of the risk is primarily undertaken by the general practitioner, but in cases of doubt, the pregnant women can be referred to the Department of Occupational Medicine. The assessment at the Department of Occupational Medicine is made one or two weeks after referral. It consists of a careful work history, which includes characterization of exposure, both qualitatively and quantitatively and a decision whether the exposure entails a risk to the foetus and which steps should be taken for the rest of the pregnancy. The purpose of this study was to describe the practice of risk assessment at the Department of Occupational Medicine in Denmark. Over a period of nine months all cases of pregnant women referred to 12 out of 14 departments were reviewed. Out of 60,000 births per year only 250 pregnant women were referred, which is less than 1%. Main risk factors in the assessment were of chemical (80%) or ergonomic (17%) origin. Forty-three percent were advised to leave work on maintenance allowance and 15% were advised to stay at work, on condition that the work environment was changed or they could be moved to a job without risk exposure. The study revealed big differences in referral incidence between the different counties as well as differences in risk assessment practice. It is concluded, that the best way to secure pregnant women and their foetus is by primary prophylactic measures at the workplace. Hopefully the new EU Directive 92/85 will be a step in that direction.

Communication Concerning the Risks of Occupational Exposures in Pregnancy.

The health professional who is involved in communicating information about reproductive risks from occupational hazards needs to consider several important aspects. Uncertainties in risk assessment, timing of exposure in relation to pregnancy, and the consequences of different preventive measures for the woman (family), as well as for the employer and other persons at the workplace are examples of such aspects. The basis for the pregnant woman's perception of risk must be recognized. The risk-communication goal is that the persons concerned fully understand the risk and its possible consequences, so that they will be able to make informed decisions about how to act. More attention should be given to risk communication in the training of health professionals.

Temporal and interindividual variation in erythrocyte zinc-protoporphyrin in lead exposed workers.

Nineteen male workers from a factory making lead batteries participated in monthly blood tests to follow the effects of decreasing exposures to lead. The overall average blood lead (B Pb) concentration was 1.95 mumol/l (40 micrograms/100 ml), but a significant decrease was seen over the one year study period. The relation to erythrocyte zinc-protoporphyrin (ZPP) concentration showed considerable scatter and only marginal improvement of the relation was obtained when each ZPP result was compared with the average B Pb concentration during the previous four months. On an individual basis, five men showed a considerable decline in ZPP following decreases in B Pb concentration. In five other subjects with similar decreases in B Pb, no change in ZPP concentration was seen. These two groups were similar with regard to haemoglobin concentration, initial B Pb concentration, and age, but differed in duration of exposure. A longer exposure time and presumably, therefore, larger body burdens of lead seemed to prevent the expected decrease in erythrocyte ZPP.

[The work environment and male reproduction]. / Arbejdsmiljø og mandlig reproduktion.

This review is focused on the connection between environmental factors in the workplace and male reproduction. Infertility is a problem for 10-15 per cent of Danish couples, and little is known about how large a part is played by environmental factors. It is now accepted that exposure by environmental hazards may result in partial or total infertility. The classic examples are exposure to lead, heat and radioactivity. Recent investigations have shown that occupational exposure to chemical substances such as dibromochloropropane and ethylene dibromide may interfere with spermiogenesis. In Denmark studies have been initiated concerning the connection between welding, lead and organic solvents, and the sperm-specimens. The findings of these studies support the hypothesis that, at levels currently accepted at workplaces, lead interferes especially with the sperm-cell concentration. In a few studies exposure to welding fumes have been found to have an adverse effect on sperm cell concentrations. All the investigations cited are marred by methodological problems. Despite these problems, it is internationally recognised that further studies are urgently needed, as are further epidemiological and methodological investigations in this field.