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Introduction: The aim of this study was to evaluate the registration of childhood CNS tumours in the Danish Cancer Registry (CR) from 1980 to 1996, based on completeness and validity., Materials and Methods: The completeness of the CR was estimated by examination of the Danish National Hospital Register and an independent hospital registry. To determine the validity of the CR, 640 cases of childhood CNS tumours identified in the CR were compared with the corresponding medical record, with regard to cancer morphology and date of diagnosis., Results: The completeness of the CR was 98-99%. For 82% of all cases, the morphology registered in the CR was identical with that in the medical record. The validity of the morphological diagnosis was 84% for astrocytomas, 88% for ependymomas, 95% for medulloblastomas, 47% for other gliomas and 76% for miscellaneous intracranial and intraspinal neoplasms. In a further 7% of all cases, the morphological diagnosis in the CR was incorrect with respect to details but correct within these main diagnostic groups, 6% were tumours of another main diagnostic group than that registered in the CR and 5% were not tumours, were tumours outside the study criteria or were registered in the hospital journal as suspected tumours. The date of diagnosis in the CR and that in the medical records were concordant in 88% of the evaluated cases., Conclusion: Registration of childhood CNS tumours in the CR was highly complete, while the validity of the morphological diagnosis differed among the main diagnostic groups. The relatively low validity might be explained by the anatomic location of CNS tumours, which makes tissue sampling for histological verification and therefore diagnosis difficult.

Epidemiological studies have consistently shown relation between exposure to particulate matter in urban air and cardiovascular and pulmonary morbidity and mortality. Some recent population studies suggest that the ultrafine fraction of particulate matter generated by motorised vehicles is particularly damaging. Animal studies and cell culture experiments support this hypothesis and address the possible mechanisms of action. Inhalation of particulate matter, especially ultrafine particles, causes oxidative stress and inflammation in lung tissue, which affects the lung cells per se, as well as the cardiovascular system.

Introduction: Ambient air pollution is a risk factor for mortality and morbidity. The aim of this study was to quantify the health effects related to particulate matter (PM10) in Denmark., Materials and Methods: We used relative risk estimates in relation to PM10 based on the epidemiological literature. Population exposure to PM10 was calculated. Cases attributable to PM10 were estimated for mortality, cardiovascular and respiratory hospital admissions, chronic bronchitis, acute bronchitis, restricted activity days, and asthma attacks. Moreover, we attempted to estimate health-related gains from equipping all heavy-duty vehicles in Denmark with particle filters., Results: We estimated the average population PM10 exposure to be about 22 micrograms/m3, about one third of which can be attributed to natural (not man-made) PM10. The number of cases per year attributable to the estimated exposure included about 5,000 deaths, about 5,000 hospital admissions, about 5,000 cases of chronic bronchitis, about 17,000 cases of acute bronchitis, about 200,000 asthma attacks, and about three million restricted activity days. The health-related gains from installing particle filters on all heavy-duty vehicles in Denmark are uncertain; the estimates for mortality ranged from 22 to 1,250, depending on the assumptions., Discussion: Although air pollution constitutes only a minor risk factor on the individual level, it seems to be a major public health problem. The particle characteristics responsible for the estimated health effects are not well understood. The ultrafine particle fraction may cause a much greater impact on health than indicated by the mass.

Introduction: The hypothesis that exposure to traffic-related air pollution increases the risk of cancer developing during childhood was investigated., Materials and Methods: We enrolled 1,989 children notified to the Danish Cancer Registry with a diagnosis of leukaemia, tumour of the central nervous system (CNS), or malignant lymphoma during 1968-1991, and 5,506 control children selected at random from the entire childhood population. The residential histories of the children were traced from nine months before birth up to the time of diagnosis, as was a similar period for the controls. Information on traffic and the configuration of streets and buildings was collected for each of the 18,440 identified addresses. Concentrations of benzene and nitrogen dioxide (indicators of traffic-related air pollution) were calculated for the relevant residential periods, and combined into exposures to air pollution during pregnancy and childhood, respectively., Results: The risks of leukaemia, CNS tumours, and all selected cancers combined were not related to exposure to benzene or nitrogen dioxide during either period. The risk of lymphomas increased by 25% (p for trend = 0.06) and 51% (p for trend = 0.05) for a doubling of the concentration of benzene and nitrogen dioxide, respectively, during the pregnancy. The association was restricted to Hodgkin's disease., Discussion: On the basis of a low potential for selection bias, information bias, and confounding factors, we conclude that traffic-related air pollution at the residence of children is not linked to the risk of leukaemia or CNS tumour, which are the two major types of childhood cancer. The results indicated a possible association between air pollution and the risk of Hodgkin's disease, but the evidence allows of no firm conclusion at present.