The study presents empirical evidence of accident risk during and following rain events in the cities of Calgary and Edmonton, Canada. The matched sample approach is used to examine data for 169 rain events and over 15,000 accidents that occurred during the years 1979-1983. The overall accident risk during rainfall conditions was found to be 70% higher than normal. The data suggest that accident risk returns to normal as soon as the rainfall has ended, despite the lingering effects of wet road conditions.
The risk of breast cancer associated with delivering a twin birth was examined in a population-based nested case-control study of nearly 4800 Swedish women with breast cancer and 47000 age-matched control subjects. All were aged less than 50 years and parous. After adjustment for age at first birth and parity, a 29% reduction in breast cancer risk was observed in mothers of twins relative to those who were not (odds ratio = 0.71, 95% confidence interval 0.55-0.91). These results provide evidence that women who bear twins are at reduced risk of breast cancer, one explanation for which may be their unusual levels of hormonal exposure.
Many studies have shown that unilateral breast cancer is more frequent in the left breast than in the right. This has been investigated in the Icelandic Cancer Registry. Information on all but 18 female breast cancer cases diagnosed in the forty-year-period from 1948 to 1987, a total of 2139 cases, was used. Of these 2011 were unilateral, 1069 were in the left breast, an excess of 13%. Primary breast cancer in both breasts was diagnosed in 81 women, 35 in the left breast first, and 46 in the right breast first. The excess risk of developing cancer remains for the left breast also for women who have already lost one breast because of cancer. Information on whether their relatives had developed breast cancer existed for 1197 of these women. Patients with an affected first degree relative were of 2.54 fold risk of developing contralateral primary breast cancer, but women with no affected relative were at a reduced risk (not significant). Patients with right sided breast cancer are more likely to have a relative with breast cancer. The breast cancer status of the relatives did not influence the risk of death, so a better survival of familial cases could not be shown.
To examine the prevalence and associated factors of bidi and hookah use among Canadian youth.
Data from 41,886 grade 7 to 12 youth were used to examine factors associated with bidi and hookah use.
Youth who are current or former cigarette smokers, have tried marijuana or alcohol, were more likely to use bidi or hookah.
Results suggest bidi and hookah use may be an emerging issue in tobacco control among youth. Findings also support an integrated approach where future prevention efforts should address multiple risk behaviors.
We aimed to determine if the risk of Multiple Sclerosis (MS) is associated with month of birth in Norway and to explore a possible latitudinal gradient.
All patients with MS born between 1930 and 1979 registered in the Norwegian MS Registry or ascertained in Norwegian prevalence studies were included (n = 6649). The latitude gradient was divided in Southern, Middle and Northern Norway, according to the estimated regional yearly mean vitamin D effective UV dose.
Risk of MS was 11% higher for those born in April (p = 0.045), and 5% higher for those born in May (p = 0.229), 5% lower for those born in November (p = 0.302) and 12% lower for those born in February (p = 0.053) compared with the corresponding population, unaffected mothers and siblings. In Southern Norway the odds ratio of MS births in April and May was 1.05 (0.98-1.24), in Middle Norway 1.11 (0.97-1.27) and in Northern Norway 1.28 (1.0-1.63) compared with the other months.
This study confirms previous reports of increased MS births in spring and decreased MS births in the winter months. This could support the role of decreased sunlight exposure during pregnancy and vitamin D deficiency in prenatal life in MS.
The regional pattern of insulin-dependent diabetes mellitus (IDDM) incidence among children in Finland was analysed applying several methods attempting to describe the geographical variation in occurrence of IDDM. From 1987 to 1991 the number of newly diagnosed cases aged 14 years or less at diagnosis was 1728. The incidence, the incidence rate ratio and the Bayes relative risk (RR) for IDDM were calculated by municipality, by functional area (an urban centre with a subordinated surrounding area) and by area with a population of equal size at risk employing the Geographical Information Systems. The association of IDDM incidence with the degree of urbanization was assessed using the population density as a criterion for the degree of urbanization. The overall mean of the IDDM incidence was 35 per 100000 persons per year. Between municipalities the incidence varied from 4 to 245 per 100000 persons per year, whereas a clear regional pattern was seen among the functional areas and the incidence varied from 26 to 43 per 100000 persons per year. The RR for IDDM among the municipalities ranged from 0.82 to 1.34 and from 0.73 to 1.27 among the functional areas. The incidence determined in four zones with the same size of population was the highest in the middle part of the country. There was a strong inverse correlation between population density and the incidence of IDDM and this also applied to the relationship between child population density and incidence.