Cluster management and the role of concerned communities and the media.

Public health services often have to deal with reported clusters of adverse health events. An important characteristic of disease clusters is that the involved community often is concerned about environmental factors influencing health. To facilitate cluster investigations, a stepwise protocol was developed in the Netherlands, based on international literature. Essential is the two-way approach, consisting of a disease-track and an environment-track. Attention to potential environmental exposures is as important as attention to the reported diseases, not only because environmental pollution often is the reason of public concern and thus relevant for risk communication, but also for deciding about the boundaries of the population at risk. Moreover, environmental information is necessary for judgement of the plausibility of a causal relation and for advising measures to prevent exposure. Within this two-way approach, three stages are distinguished: orientation stage, verification stage and quantification stage. Only if an increased risk as well as an elevated exposure is verified, under certain conditions a case-control study may be useful to study causality between exposure and adverse health events. During all stages of the investigation, good risk communication strategies have to be taken into account. However, even then it might be difficult to prevent conflicts, because of the differing interests between experts and the community involved. One of the most important aspects that determine judgements about risks by threatened people, is controllability; that is why community participation is essential. Therefore it can be concluded that cluster management is a mutual endeavour for experts, public and media, where experts are judged on three characteristics: expertise, credibility and empathy.

Chronic respiratory symptoms in children and adults living along streets with high traffic density.

OBJECTIVES: To investigate if the population living along streets with high traffic density has a higher prevalence of chronic respiratory symptoms. METHODS: A sample of 673 adults and 106 children (0-15 years), living along busy traffic streets in the city of Haarlem was compared with a control sample of 812 adults and 185 children living along quiet streets. Exposed and control streets were selected on the basis of model calculations of NO2 concentrations. A postal questionnaire containing questions about respiratory symptoms and several potential confounders was used to collect information from the study subjects. RESULTS: After adjustment for potential confounders, children living along busy streets were found to have a higher prevalence of most respiratory symptoms than children living along quiet streets. Adjusted odds ratios were significant for wheeze and for respiratory medication used. Risk ratios were higher for girls than for boys, with significant adjusted odds ratios between 2.9 and 15.8 for girls. In adults, only mild dyspnoea was more often reported by subjects living along streets with high traffic density. CONCLUSIONS: The results suggest that living along busy streets increases the risk of developing chronic respiratory symptoms in children.

Case-control study on the association between a cluster of childhood haematopoietic malignancies and local environmental factors in Aalsmeer, The Netherlands.

STUDY OBJECTIVE AND DESIGN: In Aalsmeer, a horticultural community near the main international airport in The Netherlands, a more than fourfold increase in the incidence of haematopoietic malignancies in young people was observed between 1980 and 1985. In a population based case-control study, the association with local environmental factors was investigated. PARTICIPANTS: For each patient younger than 40 years of age (n = 14) diagnosed between 1975 and 1989, four age and sex matched controls were selected via local general practitioners. METHODS: All parents of patients and controls completed a questionnaire on their lifestyle, living conditions, and health, for several years preceding each individual diagnosis. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated, matched, and, if necessary, stratified for neighbourhood. MAIN RESULTS: Increased ORs were recorded for intensive use of petroleum products and pesticides by the patients themselves and their fathers: OR petroleum products: 8.0 (95% CI 2.2, 129.9) and 9.0 (1.0, 66.1) respectively; OR pesticides: 6.0 (0.6, 49.3) and 3.2 (1.0, 10.1) respectively. Swimming in a local pond was also significantly associated with the disease: OR = 5.3 (1.3, 17.4). In the 1970s this pond had been polluted by petroleum products and pesticides. CONCLUSIONS: The increased incidence of childhood haematopoietic malignancies in Aalsmeer may have been associated with several specific local environmental factors. Interpretation of the results, however, should take into account the fact that confidence intervals were wide because of the limited number of cases.

[Case control study of the relationship between local environmental factors and hematopoietic malignancies in young subjects in Aalsmeer]. / Patiënt-controle-onderzoek naar het verband tussen lokale milieufactoren en hematopoëtische maligniteiten bij jongeren in Aalsmeer.

In Aalsmeer, a horticultural community near the main international airport in the Netherlands, an incidence of haematopoietic malignancies in young people over four times the national mean was observed in the period 1980-1985. A population based case-control study investigated the association with local environmental factors. For each case younger than 40 years of age (n = 14), diagnosed between 1975 and 1989, four controls, matched for age and gender, were selected via local general practitioners. All parents of patients and controls completed a questionnaire on their life style, living conditions and health for several years preceding each individual diagnosis. Odds ratios (ORs) were calculated, matched and--if necessary--stratified for neighbourhood. Increased ORs were recorded for intensive use of petroleum products and pesticides, by the patients themselves and their fathers (OR petroleum products: 8.0, resp. 9.0; OR pesticides: 6.0, resp. 3.2). Most of these increases were statistically significant. Swimming in a local pond was also significantly associated with the disease (OR = 5.3); in the seventies this pond had been polluted by accidents with petroleum products and pesticides. contributed to the increase of the disease: ORs for several indirect exposure parameters were all above 2. It can be concluded that the increased incidence of childhood haematopoietic malignancies in Aalsmeer may have been associated with several specific local environmental factors. However, interpretation of the results should take into account that confidence intervals were wide, due to the necessarily limited number of cases.

"John Henryism" and blood pressure in a Dutch population.

In a stratified, random sample of 100 men and 100 women, aged 20-59 years, residing in Zutphen, the Netherlands, the hypothesis was tested that high scores on "John Henryism," a strong behavioral predisposition to cope actively with psychosocial environmental stressors, would be associated with higher blood pressure, especially among persons of lower education. In univariate analyses higher scores on John Henryism were strongly associated with higher blood pressures in men. Among women there was only an association of John Henryism and systolic blood pressure, but this association was no longer statistically significant after adjustment for potential confounders such as age, alcohol consumption, physical activity, Quetelet Index, and education. Among men, however, the association between John Henryism and systolic blood pressure remained statistically significant after adjustment for potential confounders. The association between John Henryism and blood pressure was more pronounced for men of low educational background.

Serum cholesterol and 25-year incidence of and mortality from myocardial infarction and cancer. The Zutphen Study.

In the Zutphen Study, cholesterol determinations were carried out in 1960 in serum of 829 middle-aged men. Between 1960 and 1985, detailed information was collected on morbidity and mortality in these men. During 25 years of follow-up, 179 men developed myocardial infarctions and 203 developed cancer. During this period, 110 men died of myocardial infarction, 144 of cancer, and 410 of all causes. Survival analysis showed that the serum cholesterol level in 1960 was independently related to the 25-year incidence of myocardial infarction. This long-term relation was mainly due to the strong association between serum cholesterol level and 15-year incidence of myocardial infarction. Similar but less pronounced relations were found between serum cholesterol level and 15- and 25-year mortality from myocardial infarction. Serum cholesterol level was related neither to long-term incidence of and mortality from cancer nor to mortality from all causes.

Determinants of polychlorinated biphenyls (PCBs) in human milk.

In a longitudinal pilot study on the course of the PCB concentration in human milk during six months of lactation, some important PCB determinants could be studied in 23 women and their infants. PCB values were within the range of those found in the literature. Pearson correlation coefficients were calculated to investigate the association of the mean PCB concentration over the first half year of lactation with maternal parameters, such as age, height, weight, previous lactation period, education, occupation, residence, smoking, drinking and dietary habits as well as the infant parameters gestational age, birthweight and weight gain in the first six months of life. Since the PCB concentration on fat basis and the fat content of the milk were strongly inversely related, statistical analyses were carried out both on fat and on milk basis. In univariate analyses the PCB concentration on fat basis was most strongly associated with pre- versus post-pregnancy weight gain, age and occupation. After multiple regression analysis PCB concentration on fat basis remained significantly associated with weight gain changes and remained borderline (p less than 0.10) significantly related with occupation. The pre-pregnancy Quetelet Index of the mother (height/weight) and the estimated PCB content of the diet (primarily fish) were strongly correlated with the PCB concentration on milk basis. Only the Quetelet Index remained significantly related after multiple regression analysis.