Work-related asthma in aluminium potroom workers, is reviewed and discussed, mainly on the basis of own investigations. The occurrence of work-related asthma has been shown to be associated with the duration of potroom employment, although the prevalence of asthmatic symptoms is not significantly different from that of the general population. Typical manifestations of occupational asthma are described in potroom workers, and a close relationship between the levels of fluoride exposure and work-related asthmatic symptoms has been observed. The existence of occupational asthma in aluminium potroom workers has been confirmed by characteristic patterns of repeated peak flow measurements, supported by changes in methacholine responsiveness in workers with suspected work-related asthma. However, no immunological test is available to establish the diagnosis. Methacholine challenge appears to be inappropriate for screening aluminium potroom workers in order to detect work-related asthma. Current smoking, but not self-reported allergy, is a risk factor for potroom asthma. A family history of asthma and previous occupational exposure may have some effect on the risk of developing symptoms. The prognosis of potroom asthma seems to depend on early replacement to unexposed work. The pathogenetic mechanisms are unknown, although some studies indirectly imply a hypersensitivity reaction. Future studies involving specific bronchial challenge appear to be necessary to find the causal agent(s) of aluminium potroom asthma.
An increased risk of cervical intra-epithelial neoplasia grade II-III among human papillomavirus positive patients with the HLA-DQA1*0102-DQB1*0602 haplotype: a population-based case-control study of Norwegian women.
Several recent studies have reported different associations between HLA specificities and human papillomavirus (HPV)-associated disease of the cervix. We report the distribution of DQA1 and DQB1 genes and HPV infection in a population-based case-control study including 92 patients with histologically verified cervical intraepithelial neoplasia grade II-III (CIN II-III) (thus including moderate and severe dysplasia and carcinoma in situ) and 225 control subjects. We found an overrepresentation of the DQA1*0102-DQB1*0602 haplotype among HPV-positive cases compared with controls. The association was even stronger when comparing HPV-16-positive cases with HPV-16-positive controls. In addition, among HPV-16-positive individuals, we observed a decreased frequency of DQA1*0102-DQB1*0604 in cases compared with controls. We were not able to detect any association between CIN II-III and DQB1*03. Compared with previous findings in cervical cancer, our data indicate that carrying the DQA1*0102-DQB1*0602 haplotype gives an increased risk of developing CIN when infected with HPV-16, without influencing progression to cancer.
The occurrence of anencephalus as reported to the Norwegian Medical Birth Registry has fallen from 4.9 per 10,000 births in 1967-71 to 2.7 in 1987-90. The decrease is particularly noticeable for births with a gestational length of 28 weeks or more. On the other hand, there has been a significant increase in the number of cases of anencephalus with a gestational age less than 28 weeks. The occurrence of meningomyelocele has remained relatively stable throughout the same period. Ascertainment error could explain these contrasting trends, since cases of anencephalus detected on ultrasound screening may lead to early termination of pregnancy without notification to the Medical Birth Registry. Better routines for notification of malformations are needed to improve the basis for surveillance in Norway.
BACKGROUND. This study examines whether the association between maternal educational level and postneonatal death has changed over time. METHODS. All single survivors of the neonatal period in Norway in three periods, 1968-1971, 1978-1981 and 1989-1991 were studied. There were 582 046 births and 1717 postneonatal deaths. Logistic regression analyses were applied. RESULTS. There has been an increasing inverse relationship between maternal educational level and postneonatal mortality in recent years. There was no statistically significant association between educational level and postneonatal mortality in the late 1960s. In the second period (1978-1981) the association is statistically significant for first-born children. In the third period (1989-1991) postneonatal mortality for first-born and later-born children was associated with maternal educational level, with adjusted odds ratios of 2.5 and 2.1 respectively. The overall level of education has increased tremendously, and the proportion of women with the lowest level of education has decreased from 56.3 to 10.7% in the period under study. CONCLUSIONS. The underlying causes of changes in the impact of educational level are hard to determine and are indicative of the complexity of using maternal educational level as an indicator of social status over time. Possible mechanisms by which certain variables may covary with educational level, and thus have an adverse effect on postneonatal mortality, are discussed. The fact that the inverse association between educational level and postneonatal mortality has increased over time should be a matter for concern. It may indicate that the growth of the welfare state has not reached all segments of the population.
Data on parental consanguinity have been recorded for all births in Norway since 1967. Pregnancy outcome for offspring of 848 women mated to their first cousins were compared with offspring of 1,696 control women. The stillbirth rate was 23.6 per thousand for cases and 13.4 for controls. The neonatal death rate was 34.9 per thousand for cases and 14.3 for controls. The recurrence risk for sibs for early death was 9.4% for cases and 4.2% for controls. The mean offspring birth weight was significantly lower (3377 g vs. 3491 g), and the variance in birth weight was slightly larger for cases than controls. The percentage of children with malformations detected shortly after birth was 4.6% for cases and 2.2% for controls. The differences may be attributed to the increased homozygosity in offspring of first cousins. The results have relevance for genetic counselling to consanguineous couples, as well as for the understanding of the etiology of adverse pregnancy outcome and for elucidating the causes of variation in birth weight.
The increase in birth weight with parity was studied in sibships of 2, 3, and 4 children using large samples from the Norwegian Birth Registry. Families with full sibs were compared to families with maternal half-sibs. The sensitization hypothesis of Warburton and Naylor predicts no increase in birth weight with parity when the mother changes mate. The hypothesis was not supported by the data, since similar increases in birth weight with parity were found in both types of families. A small effect of the sex of the first child on the birth weight of the later born children was observed.
The concentration of particulate matter in outdoor air, as indicated by daily measures of particulate matter 10 microm in diameter (PM10) in many cities, has been found to be associated with the daily number of deaths and hospital admissions in these cities. To understand this association better, we studied the daily number of hospital admissions for respiratory diseases and the concentrations of eight pollutants in ambient air, during a period of 38 months, in an area with cold winters and air pollution that comes mainly from motor vehicles. We estimated the changes in risk of hospitalization by interquartile increases in pollutant concentrations by Poisson regression analyses. Controlling for periodic trends and weather, the relative risk of hospitalization associated with an interquartile increase of PM10 was 1.038 [95% confidence interval (CI) = 0.991-1.087]. In contrast, the relative risk associated with benzene was 1.105 (95% CI = 1.047-1.166). In a two-pollutant model, the relative risk estimates were 1.014 (95% CI = 0.966-1.063) for PM10 and 1.090 (95% CI = 1.031-1.153) for benzene. We evaluated other two- and three-pollutant models and concluded that pollutants other than PM10 are more strongly associated with hospital admissions for respiratory diseases.
To estimate the extent of meningococcal carriage in the Norwegian population and to investigate the relationship of several characteristics of the population to the carrier state, 1,500 individuals living in rural and small-town areas near Oslo were selected at random from the Norwegian National Population Registry. These persons were asked to complete a questionnaire and to volunteer for a bacteriological tonsillopharyngeal swab sampling. Sixty-three percent of the selected persons participated in the survey. Ninety-one (9.6%) of the volunteers harbored Neisseria meningitidis. The isolates were serogrouped, serotyped, tested for antibiotic resistance, and analyzed by multilocus enzyme electrophoresis. Eight (8.8%) of the 91 isolates represented clones of the two clone complexes that have been responsible for most of the systemic meningococal disease in Norway in the 1980s. Age between 15 and 24, male sex, and active and passive smoking were found to be independently associated with meningococcal carriage in logistic regression analyses. Working outside the home and having an occupation in transportation or industry also increased the risk for meningococcal carriage in individuals older than 17, when corrections for gender and smoking were made. Assuming that our sample is representative of the Norwegian population, we estimated that about 40,000 individuals in Norway are asymptomatic carriers of isolates with epidemic potential. Thus, carriage eradication among close contacts of persons with systemic disease is unlikely to have a significant impact on the overall epidemiological situation.
The median AIDS survival for all AIDS patients was estimated as 11 months (95% confidence interval (Cl): 8-13 months). For the group of AIDS patients who were asymptomatic when HIV seropositivity was established, the median AIDS survival was 20 months (95% Cl: 13-23 months). For the group with symptomatic HIV infection or those who already had AIDS when HIV seropositivity was established, survival was estimated to 5 months (95% Cl: 1-15 months) and 4.5 months (95% Cl: 2-8 months), respectively. By using a Cox proportional hazard model it was found that being asymptomatic when HIV seropositivity was established or having Pneumocystis carinii pneumonia as the initial AIDS-related disease were associated with long AIDS survival. Being HIV infected by transfusion was associated with short survival. Long AIDS survival in the asymptomatic group may be explained by a positive selection of slow disease progressors. Differences in diagnostic routines may also cause systematic differences in the estimated AIDS survival.