Incidence of Pediatric Inflammatory Bowel Disease in Finland: An Environmental Study.

OBJECTIVES: The aim of this study was to explore possible environmental factors behind the regional differences in the incidence of pediatric inflammatory bowel disease (IBD). METHODS: All of the patients diagnosed with IBD who were aged 0 to 14 years in Finland between 1987 and 2003 were identified from the Social Insurance Institution database. Finland was divided into squares of 250 × 250 m, and spatial variations of incidence rates were evaluated accordingly. The role of the environmental determinants (pediatric population density, agricultural industry, chemical contaminants of tap water and proximity to the sea or paper mills) in the geographic variations of the incidence rates was evaluated. RESULTS: During the study period, the overall incidence of pediatric IBD was 6.5 of 100,000 (95% confidence interval [CI] 6.1-6.9). The incidence in very sparsely populated areas (≤10 person-years per 250 × 250 m) was 9.2 of 100,000 (95% CI 6.3-13.1) and 5.6 of 100,000 (95% CI 4.8-6.4) in the districts with the highest population density (>800 person-years per 250 × 250 m). A nonsignificant trend toward the same direction was also seen for ulcerative colitis (trend P = 0.09). Chemical contaminant concentrations of tap water, residence near the seaside, or proximity to paper mills were not associated with the incidence of pediatric IBD. CONCLUSIONS: Our findings suggest higher incidence rates of pediatric IBD in the districts with low compared with high density of child population, but the differences cannot be explained by variations in the environmental exposures evaluated here.

Chernobyl fallout and cancer incidence in Finland.

Twenty-five years have passed since the Chernobyl accident, but its health consequences remain to be well established. Finland was one of the most heavily affected countries by the radioactive fallout outside the former Soviet Union. We analyzed the relation of the estimated external radiation exposure from the fallout to cancer incidence in Finland in 1988-2007. The study cohort comprised all ∼ 3.8 million Finns who had lived in the same dwelling for 12 months following the accident (May 1986-April 1987). Radiation exposure was estimated using data from an extensive mobile dose rate survey. Cancer incidence data were obtained for the cohort divided into four exposure categories (the lowest with the first-year committed dose <0.1 mSv and the highest ≥ 0.5 mSv) allowing for a latency of 5 years for leukemia and thyroid cancer, and 10 years for other cancers. Of the eight predefined cancer sites regarded as radiation-related from earlier studies, only colon cancer among women showed an association with exposure from fallout [excess rate ratio per increment in exposure category 0.06, 95% confidence interval (CI) 0.02-0.11]. No such effect was observed for men, or other cancer sites. Our analysis of a large cohort over two decades did not reveal an increase in cancer incidence following the Chernobyl accident, with the possible exception of colon cancer among women. The largely null findings are consistent with extrapolation from previous studies suggesting that the effect is likely to remain too small to be empirically detectable and of little public health impact.

Fallout from the Chernobyl accident and overall cancer incidence in Finland.

AIM: We studied whether incidence of all cancer sites combined was associated with the radiation exposure due to fallout from the Chernobyl accident in Finland. An emphasis was on the first decade after the accident to assess the suggested "promotion effect". METHODS: The segment of Finnish population with a stable residence in the first post-Chernobyl year (2 million people) was studied. The analyses were based on a 250m × 250m grid squares covering all of Finland and all cancer cases except cancers of the breast, prostate and lung. Cancer incidence in four exposure areas (based on first-year dose due to external exposure <0.1 mSv, 0.1-1.3, 0.3-0.5, or ≥ 0.5 mSv) was compared before the Chernobyl accident (1981-1985) and after it (1988-2007) taking into account cancer incidence trends for a longer period prior to the accident (since 1966). RESULTS: There were no systematic differences in the cancer incidence in relation to radiation exposure in any calendar period, or any subgroup by sex or age at accident. CONCLUSION: The current large and comprehensive cohort analysis of the relatively low levels of the Chernobyl fallout in Finland did not observe a cancer promotion effect.

Mortality among population with exposure to industrial air pollution containing nickel and other toxic metals.

OBJECTIVE: To assess disease mortality among people with exposure to metal-rich particulate air pollution. METHODS: We conducted a cohort study on mortality from 1981 to 2005 among 33,573 people living near a nickel/copper smelter in Harjavalta, Finland. Nickel concentration in soil humus was selected as an indicator for long-term exposure. Relative risks--adjusted for age, socioeconomic status, and calendar period--were calculated for three exposure zones. RESULTS: The relative risks for diseases of the circulatory system by increasing exposure were 0.93 (95% confidence interval = 0.79 to 1.09), 1.20 (1.04 to 1.39), and 1.18 (1.00 to 1.39) among men and 1.01 (0.88 to 1.17), 1.20 (1.04 to 1.38), and 1.14 (0.97 to 1.33) among women. Exclusion of smelter workers from the cohort did not materially change the results. CONCLUSIONS: Long-term environmental exposure to metal-rich air pollution was associated with increased mortality from circulatory diseases.

Odor annoyance near waste treatment centers: a population-based study in Finland.

Decomposition of biodegradable waste in municipal waste centers may produce odor emissions and subsequently cause discomfort to nearby residents. The public health importance of the resulting nuisance has not been sufficiently characterized. The aim of this study was to study the perception and annoyance of waste odor among residents in relation to distance from the large-scale source. In 2006, 1142 randomly selected residents living within 5 km from the boundaries of five waste treatment centers were interviewed by telephone. These centers were landfilling municipal waste and composting source-separated biowaste and/or sludge. The questionnaire consisted of 102 items containing questions on perceived environmental nuisance. Odds ratios (ORs) and confidence intervals (CIs) were calculated adjusting for sex and age. The proportion of respondents perceiving odor varied by center and distance (< 1.5 km: 66-100%; 1.5 to < 3 km: 13-84%; 3 to < 5 km: 2-64%). The pooled OR for odor annoyance was 6.1 (95% CI 3.7-10) in the intermediate and 19 (95% CI 12-32) in the innermost zone compared with residents in the outermost zone. Intensity of odor characterized as very strong or fairly strong affected odor annoyance more than weekly or more frequently perceived odor. The high level of odor perception and annoyance in residents living near waste treatment centers draws attention to the need to prevent odor nuisance constricting emission peaks and frequent emissions. Because odors may affect fairly distant (even 1.5 to < 3 km) residential areas, planning of the locations of waste treatment operations is essential.

Cancer incidence in the vicinity of Finnish nuclear power plants: an emphasis on childhood leukemia.

The objective of this paper was to study cancer incidence, especially leukemia in children (<15 years), in the vicinity of Finnish nuclear power plants (NPPs). We used three different approaches: ecological analysis at municipality level, residential cohorts defined from census data, and case-control analysis with individual residential histories. The standardized incidence ratio of childhood leukemia for the seven municipalities in the vicinity of NPPs was 1.0 (95% CI 0.6, 1.6) compared to the rest of Finland. The two cohorts defined by censuses of 1980 and 1990 gave rate ratios of 1.0 (95% CI 0.3, 2.6) and 0.9 (95% CI 0.2, 2.7), respectively, for childhood leukemia in the population residing within 15 km from the NPPs compared to the 15-50 km zone. The case-control analysis with 16 cases of childhood leukemia and 64 matched population-based controls gave an odds ratio for average distance between residence and NPP in the closest 5-9.9 km zone of 0.7 (95% CI 0.1, 10.4) compared to > or =30 km zone. Our results do not indicate an increase in childhood leukemia and other cancers in the vicinity of Finnish NPPs though the small sample size limits the strength of conclusions. The conclusion was the same for adults.

Geographic distribution of cervical cancer-associated human leucocyte antigens and cervical cancer incidence in Finland.

Cervical cancer (CxCa) is a long-term sequelae caused by persistent human papillomavirus (HPV) infection. Genetic susceptibility to the persistent infection and CxCa is associated with certain human leucocyte antigen (HLA) types. The same susceptibility genes may also determine whether a woman will be protected against the persistent infection and against CxCa by HPV vaccination or not. A systematic review of literature identified following HLAs to be associated with CxCa: A11 (odds ratio [OR] = 1.4, 95% confidence interval [CI] 1.1-2.0); B7 (1.5, 1.1-2.0); B15 (0.6, 0.4-0.8); DR2 (1.2, 1.1-1.4) and DR6 (0.6, 0.5-0.8). In the Caucasian population, HLA-B7 and DR6, and DR2 and B15 antigens showed at least borderline associations. In view of a bone marrow donor registry at the Finnish Red Cross and the Finnish Cancer Registry, we created geographic distribution maps of index HLA frequencies and CxCa incidence in the fertile-aged Finnish population. Increased incidence of CxCa was found in a region of western coastal Finland, where frequency of two CxCa susceptibility genes (HLA-DR2 and B7) was increased, and frequency of one CxCa resistance gene (HLA-B15) was decreased. Whether or not HLA type determines also regional susceptibility to persistent HPV infection, and the success of HPV vaccination in preventing both the persistent infection and CxCa warrants further investigation.

Seroprevalence atlas of infections with oncogenic and non-oncogenic human papillomaviruses in Finland in the 1980s and 1990s.

Vaccines against high-risk (hr) human papillomaviruses (HPVs) causing cervical cancer may soon be licensed. Thus, nature of HPV epidemics needs to be studied now. Random sampling for studies on HPV epidemiology was done from all 230,998 women belonging to the population-based Finnish Maternity Cohort and having a minimum of 2 pregnancies between 1983 and 1994. First pregnancy serum specimens were retrieved for 7,805 subjects, and were analyzed for antibodies to HPV6/11, 16 and 18 with standard ELISAs. HPV16 seroprevalence almost doubled from the 1980s to the 1990s, and the epidemic spread to new areas in 23-31 year olds, i.e. the bulk of pregnant female population in the southwest part of the country. The HPV16 epidemic in the 14-22 year olds in 1983-1988 (1961-1974 birth cohorts) and in the 23-31 year olds in 1989-1994 (1958-1971 birth cohorts) overlapped with strong clustering of HPV16 and HPV18 infections in the latter (odds ratio 8.0, 95% confidence interval 6.6-9.7). Similar clustering of HPV16 and HPV6/11 infections was not found. The epidemic and the clustering may be due to high transmission probability of the hrHPV types and increase in sexual activity of the index birth cohorts.