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.

Cancer incidence in a cohort with high fish consumption.

PURPOSE: Evidence suggests that fish-derived omega-3 polyunsaturated fatty acids inhibit cancer promotion and progression. On the other hand, fish may contain endocrine-disrupting and potentially carcinogenic environmental contaminants. Our objective was to describe cancer incidence among the Finnish professional fishermen and their wives who are presumed to eat a lot of fish, partly from the contaminated Baltic Sea. Additionally, we wanted to see whether occupational characteristics are reflected in the fishermen's cancer pattern. METHODS: All Finnish fishermen during 1980-2002 were identified from the Professional Fishermen Register (n = 6,410) and their wives from the National Population Information System (n = 4,260). The cohort was linked with the Finnish Cancer Registry data until 2011, and the standardized incidence ratios (SIR) were calculated based on national incidence rates. RESULTS: The total cancer incidence among the fishermen and their wives was the same as in the Finnish general population. Among the fishermen, the incidence was increased for lip (SIR 2.17, 95 % confidence interval 1.26-3.47) and testis (2.51, 1.15-4.75) and decreased for colon (0.72, 0.52-0.98) cancers. CONCLUSIONS: We cannot exclude the possibility that the observed excess in testis cancer among the fishermen could reflect life-long high exposure to environmental contaminants. An excess in lip cancer has been repeatedly observed among outdoor workers due to high exposure to ultraviolet radiation, whereas high physical activity during fishing is the most likely explanation for the deficit in colon cancer.

Fish consumption in relation to other foods in the diet.

Our aim was to investigate whether fish consumption is associated with the consumption of other healthy foods. The study population consisted of 2605 men and 3199 women from the nationally representative Health 2000 survey and 114 professional fishermen and 114 fishermen's wives (the Fishermen substudy) in Finland. Dietary data were collected using a calibrated (i.e. determined to have relative validity) FFQ. Model-adjusted means for food consumption and P values for linear trend were calculated across fish consumption tertiles. Those with the highest fish consumption had the highest consumption of vegetables, fruit and berries, potatoes, oil and wine even after adjusting for other food groups. The consumption of red meat and sausages had a tendency to decrease across fish consumption tertiles but the associations were inconsistent in the study populations. In conclusion, fish consumption had a positive linear association with the consumption of some other healthy foods such as vegetables, fruit, berries, and oil both in the general population of Finland and in a population with high fish consumption. Additional adjustment for other food groups had a clear effect on some of the studied associations. Therefore, when evaluating the health effects of fish consumption, confounding by other foods characterising a healthy diet needs to be considered.

Odour annoyance and physical symptoms among residents living near waste treatment centres.

Waste treatment processes produce odours and biological emissions to the environment, but their health effects are controversial. The aim of our study was to assess odour-associated self-reported physical symptoms among residents living near waste treatment centres. The study was conducted in the surroundings of five large-scale Finnish waste treatment centres with composting plants. In 2006, 1142 randomly selected residents living within 1.5, 3.0 and 5.0 km of these centres were interviewed by telephone. A questionnaire with 102 items asked about respondent's personal characteristics, odour exposure and symptoms during the preceding 12 months. Physical symptoms were analysed by distance to the waste treatment centre and by the respondent's perception and annoyance of waste treatment odour. The residents who were classified as "annoyed of the odour" reported following physical symptoms more than the others did: unusual shortness of breath (OR 1.5, 95% CI 1.0-2.2), eye irritation (1.5, 1.1-2.1), hoarseness/dry throat (1.5, 1.1-2.0), toothache (1.4, 1.0-2.1), unusual tiredness (1.5, 1.1-2.0), fever/shivering (1.7, 1.1-2.5), joint pain (1.5, 1.1-2.1) and muscular pain (1.5, 1.1-2.0). Moreover, the ORs for almost all other physical symptoms were elevated among the annoyed respondents. Reported odour annoyance near the waste treatment centres showed an association with many physical symptoms among residents living in the neighbouring areas.

Blood concentration of methylmercury in relation to food consumption.

OBJECTIVE: Dietary fish is the main source of methylmercury (MeHg) for man, and fish consumption has been used as a measure of MeHg exposure. However, other dietary sources of exposure exist and MeHg metabolism may also be modified by nutritional factors. The aim of the present study was to examine the association between blood MeHg concentration and consumption of different foods in a Finnish population with high fish consumption. DESIGN: Blood samples, a detailed FFQ and additional frequency data on fish consumption were collected. MeHg was analysed from whole blood by the isotope dilution method with high-resolution MS. The consumption of different foods was calculated by MeHg quartiles and tested for linear trend. SETTING: Finnish southern and south-western coast of the Baltic Sea. SUBJECTS: Two hundred and ninety-nine professional fishermen, their spouses and other family members. RESULTS: Mean (range) blood MeHg concentration was 4·6 (0·21-22) µg/l among men and 2·8 (<0·15-20) µg/l among women. Fish had the strongest positive association with MeHg (P for linear trend <0·001 among both men and women). Among men, positive associations were also observed for fruit vegetables, wheat and wine. Among women, positive associations were observed for root vegetables, legumes, potato and game, but adjustment for fish consumption attenuated these trends. CONCLUSIONS: The study shows that, besides fish, MeHg may have other dietary sources that should be taken into account in risk assessment studies. Due to the observed high blood MeHg concentration, a thorough exposure assessment among the general Finnish population is recommended.

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.

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.

Development and field trial of a household surface lead loading rate sampling device in a lead-contaminated community of southern Thailand.

A new dust-collecting device was developed to assess surface lead loading rates in houses in communities contaminated with lead oxide dust used for caulking in nearby boat-repair yards. The device consists of two small glass sheets with total area of 1,200 cm(2) placed in two plastic trays suspended from the ceiling in the house for 3 months before wiping and sending the dust specimen for determination of lead content using flame atomic absorption spectrophotometry. After a pilot trial in four households, further data were collected from 43 matched pairs of boat-caulkers' and neighboring control households. All devices were retained in the house for 3 months without any complaint. Static measurements of lead dust levels were also assessed in all households. The values significantly discriminated high from low lead exposure households (p = 0.015) and provided good correlations with floor lead loading (Spearman rank correlation coefficient, r = 0.39 to 0.62) and dust lead content (r = 0.53 to 0.64). This sampling method is an alternative to others which consume more household space or require a longer collection period.

A decision framework for possible remediation of contaminated sediments in the River Kymijoki, Finland.

BACKGROUND, AIM, AND SCOPE: The paper describes the spatial contamination of the River Kymijoki, South-Eastern Finland, and the coastal region of the Gulf of Finland with PCDD/Fs and mercury. The findings of ecotoxicologial and human health studies are also reported, including environmental and human risk assessments. Sediments from the River Kymijoki, draining into the Gulf of Finland, have been heavily polluted by the pulp and paper industry and by chemical industries. A wood preservative, known as Ky-5, was manufactured in the upper reaches of the river between 1940 and 1984 causing severe pollution of river sediments with polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF). Moreover, the sediments have been polluted with mercury (Hg) from chlor-alkali production and the use of Hg as a slimicide in pulp and paper manufacturing. MATERIALS AND METHODS: An extensive sediment survey was conducted as well as sediment transport modeling, toxicity screening of sediment invertebrates, and a survey of contaminant bioaccumulation in invertebrates and fish. Studies on human exposure to PCDD/Fs and the possible effects on hypermineralization of teeth as well as an epidemiological study to reveal increased cancer risk were also conducted. An assessment of the ecological and human health risks with a null hypothesis (no remediation) was undertaken. RESULTS: The sediment survey revealed severe contamination of river and coastal sediments with PCDD/Fs and Hg. The total volume of contaminated sediments was estimated to reach 5x10(6) m3 and hot spots with extremely high concentrations (max 292,000 ng g(-1) or 1,060 ng I-TEQ g(-1) d.w.) were located immediately downstream from the pollution source (approximately 90,000 m3). Sediment contamination was accompanied by changes in benthic assemblages, but direct effects were masked by many factors. The fish showed only slightly elevated PCDD/F levels in muscle, but orders of magnitude higher in the liver compared with reference freshwater sites and the Baltic Sea. The concentrations in human fat did not reveal high human exposure in the Kymijoki area in general and was lower than in sea fishermen. The relative risk for total cancer among farmers was marginally higher (RR=1.13) among those living close to the river, compared with farmers living further away, and the possibility of increased cancer risk cannot be ruled out. A conservative risk assessment revealed that the present probability of exceeding the WHO upper exposure limit of 4 pg WHO-TEQ kg(-1) d(-1) for PCDD/Fs and DL-PCBs was 6%. The probability of exceeding the WHO limit value of 0.23 mug kg(-1) d(-1) for methyl mercury was estimated to be notably higher at 62%. Based on these studies and the estimated risks connected with different remediation techniques a general remediation plan with cost benefit analysis was generated for several sub-regions in the river. Dredging, on-site treatment, and a close disposal of the most contaminated sediments (90,000 m3) was suggested as the first phase of the remediation. The decision regarding the start of remediation will be made during autumn 2008. CONCLUSIONS: The sediments in the River Kymijoki are heavily polluted with PCDD/Fs and mercury from earlier chlorophenol, chlor-alkali, and pulp and paper manufacturing. A continuous transport of contaminants is taking place to the Gulf of Finland in the Baltic Sea. The highly increased PCDD/F and Hg levels in river sediments pose an ecotoxicological risk to benthic fauna, to fish-eating predators and probably to human health. The risks posed by mercury exceed those from PCDD/Fs and need to be evaluated for (former) chlor-alkali sites and other mercury releasing industries as one basis for remediation decision making. RECOMMENDATIONS AND PERSPECTIVES: The studies form the basis of a risk management strategy and a plan for possible remediation of contaminated sediments currently under consideration in the Southeast Finland Regional Environment Centre. It is recommended that a detailed restoration plan for the most seriously contaminated areas should be undertaken. Based on current knowledge, the restoration of the whole river is not feasible, considering the current risk caused by the contaminated sediment in the river and the costs of an extensive restoration project. The experiences gained in the present case should be utilized in the evaluation of PCDD/F- and mercury-contaminated sites in other countries. The case demonstrates that the historic reservoirs are of contemporary relevance and should be addressed, e.g., in the national implementation plans of the Stockholm Convention.

Blood levels of organotin compounds and their relation to fish consumption in Finland.

The objective of this study was to measure the concentrations of organotin compounds in the whole blood of Finnish male fishermen (n=133), their wives (n=94), and other family members (n=73), and to investigate their associations with background variables. The concentrations were generally low, less than the limit of quantification (LOQ) for the vast majority of compounds and samples. Of the organotin compounds (mono-, di-, and tributyltin, mono-, di-, and triphenyltin, and dioctyltin), only triphenyltin was detected in more than just a few samples (in 37 of 300 samples, LOQ=0.04 ng/ml). These were mainly the samples of fishermen (26/37) and their wives (10/37). For statistical analysis, concentrations of triphenyltin were divided into two categories, LOQ. Of the different background variables, age and fish consumption contributed the most to the triphenyltin concentrations. When age and fish consumption (g/day) were divided into three categories, odds ratios comparing the highest with the lowest category were 3.88 for age (95% CI 1.36-11.09) and 3.48 for fish consumption (1.36-8.94), respectively. Compared with females, males had an odds ratio of 1.51 of having the concentration of triphenyltin >LOQ (0.72-3.14). To the best of our knowledge, this study confirmed for the first time with human samples that fish consumption can be associated with triphenyltin concentration in whole blood.

Sleep duration and breast cancer: a prospective cohort study.

Breast cancer incidence has increased during recent decades for reasons that are only partly understood. Prevalence of sleeping difficulties and sleepiness has increased, whereas sleeping duration per night has decreased. We hypothesized that there is an inverse association between sleep duration and breast cancer risk, possibly due to greater overall melatonin production in longer sleepers. This population-based study includes information from women born in Finland before 1958. Sleep duration, other sleep variables, and breast cancer risk factors were assessed by self-administered questionnaires given in 1975 and in 1981. Breast cancer incidence data for 1976 to 1996 was obtained from the Finnish Cancer Registry. Hazard ratios (HR) and 95% confidence intervals (CI) were obtained from Cox proportional hazards models adjusting for potential confounders. Altogether, 242 cases of breast cancer occurred over the study period among the 12,222 women with sleep duration data in 1975. For these women, the HRs for breast cancer in the short (< or =6 hours), average (7-8 hours), and long sleep (> or =9 hours) duration groups were 0.85 (CI, 0.54-1.34), 1.0 (referent), and 0.69 (CI, 0.45-1.06), respectively. Analysis restricted to the 7,396 women (146 cases) whose sleep duration in 1975 and 1981 were in the same duration group (stable sleepers) yielded HRs of 1.10 (CI, 0.59-2.05), 1.0, and 0.28 (CI, 0.09-0.88), with a decreasing trend (P = 0.03). This study provides some support for a decreased risk of breast cancer in long sleepers.

Risk factors for breast cancer at young ages in twins: an international population-based study.

BACKGROUND: Breast cancer etiology in women may relate to exposures early in life as well as in adulthood, but it has been difficult to gain information on childhood variables, and evidence on their effects is very limited. Comparison of risk factor levels between affected probands and unaffected twins in twin pairs can provide a unique method to investigate risk factors that act in early life. METHODS: We conducted four population-based case-control studies of breast cancer risk in twins in Denmark, England and Wales, Finland, and Sweden and pooled the data from these studies. The case patients were 400 women with incident breast cancer before the age of 50 years, and the control subjects were their twin sisters who had not had breast cancer by that time. Data on risk factors (e.g., demographic and anthropomorphic variables, reproductive history, and family history) were collected by interview and by a mailed questionnaire and were analyzed by calculating matched odds ratios [ORs]. All statistical tests were two-sided. RESULTS: The risk of breast cancer was increased for women who were less obese (OR = 1.44, 95% confidence interval [CI] = 1.08 to 1.91) or taller (OR = 1.27, 95% CI = 0.95 to 1.70) than their co-twin at age 10 years, for women who developed breasts earlier than their co-twin (OR = 1.53, 95% CI = 1.14 to 2.06), and for women who had a smaller waist-to-hip ratio at age 20 years than their co-twin (OR = 1.79, 95% CI = 1.00 to 3.21). Analysis according to family history of breast cancer showed that the associations of childhood height and weight with risk of breast cancer were only apparent in women without a family history of breast cancer. CONCLUSIONS: Childhood growth before puberty may affect the risk of premenopausal breast cancer, at least in women without a family history of breast cancer. The distribution of body fat in young adulthood may also be related to breast cancer risk.

Cancer risk near a polluted river in Finland.

The River Kymijoki in southern Finland is heavily polluted with polychlorinated dibenzo-p-dioxins and dibenzofurans and may pose a health threat to local residents, especially farmers. In this study we investigated cancer risk in people living near the river (less than 20.0 km) in 1980. We used a geographic information system, which stores registry data, in 500 m times 500 m grid squares, from the Population Register Centre, Statistics Finland, and Finnish Cancer Registry. From 1981 to 2000, cancer incidence in all people (N = 188884) and in farmers (n = 11132) residing in the study area was at the level expected based on national rates. Relative risks for total cancer and 27 cancer subtypes were calculated by distance of individuals to the river in 1980 (reference: 5.0-19.9 km, 1.0-4.9 km, less than 1.0 km), adjusting for sex, age, time period, socioeconomic status, and distance of individuals to the sea. The respective relative risks for total cancer were 1.00, 1.09 [95% confidence interval (CI), 1.04-1.13], and 1.04 (95% CI, 0.99-1.09) among all residents, and 1.00, 0.99 (95% CI, 0.85-1.15), and 1.13 (95% CI, 0.97-1.32) among farmers. A statistically significant increase was observed for basal cell carcinoma of the skin (not included in total cancers) in all residents less than 5.0 km. Several other common cancers, including cancers of the breast, uterine cervix, gallbladder, and nervous system, showed slightly elevated risk estimates at less than 5.0 km from the river. Despite the limitations of exposure assessment, we cannot exclude the possibility that residence near the river may have contributed to a small increase in cancer risk, especially among farmers.

Improving the efficiency of nested case-control studies of interaction by selecting controls using counter matching on exposure.

BACKGROUND: Studies of the effect of exposure to a risk factor measured in an entire cohort may be augmented by nested case-control subsets to investigate confounding or effect modification by additional factors not practically assessed on all cohort members. We compared three control-selection strategies-matching on exposure, counter matching on exposure, and random sampling-to determine which was most efficient in a situation where exposure is a known, continuous variable and high doses are rare. METHODS: We estimated the power to detect interaction using four control-to-case ratios (1:1, 2:1, 4:1, and 8:1) in a planned case-control study of the joint effect of atomic bomb radiation exposure and serum oestradiol levels on breast cancer. Radiation dose is measured in the entire cohort, but because neither serum oestradiol level nor the true degree of interaction was known, we simulated values of oestradiol and hypothetical levels of oestradiol-radiation interaction. RESULTS: Compared with random sampling, power to detect interaction was similarly higher with either matching or counter matching with two or more controls. CONCLUSIONS: Because counter matching is generally at least as efficient as random sampling, whereas matching on exposure can result in loss of efficiency and precludes estimation of exposure risk, we recommend counter matching for selecting controls in nested case-control studies of the joint effects of multiple risk factors when one is previously measured in the full cohort.

Relative contribution of potential modes of surface dust lead contamination in the homes of boatyard caulkers.

OBJECTIVES: The aim of this study was to quantify the relative contributions to surface lead contamination of boat-caulkers' houses of three contamination modes, namely "take-home" lead from the caulker, "natural" spatial dispersal from boatyard to household and "redistribution" of accumulated lead-laden dust within the house. METHODS: Boat-caulkers' houses situated in areas surrounding boat repair yards were recruited. Caulkers' houses that were located close together were divided into location-matched pairs, within which one was randomly assigned to be given a cleaning and designated a CL house, and the other was to be left uncleaned and designated a NCL house. Geographically isolated caulker's houses were randomly assigned to one of the two categories. The nearest non-boatyard worker's house (NB) was additionally recruited for each set. The surface lead loading rate (SLLR), defined as the mass of lead deposited in dust per unit area of surface per unit time, was measured over a period of 3 mo in all houses, and the data were modeled using linear mixed effects regression. RESULTS: Adjusted values of SLLR differed only slightly between CL and NCL houses (0.96 to 1.02 times) but were between 1.65 and 2.03 times higher in CL and NCL houses than in NB houses depending on proximity to the boatyard and between 2.12 and 2.61 times higher in houses within one km of a boatyard than in more distant houses depending on category of house. CONCLUSIONS: Newly deposited dust lead likely resulted from the take-home and spatial dispersion modes. The contribution of redistribution is very small.

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.

Stress and survival after cancer: a prospective study of a Finnish population-based cohort.

Stress has been suggested to reduce survival after cancer, but the results of previous studies have been contradictory. We investigated the hypothesis in a national cohort of adults in Finland. Of those who completed the Stressful Life Events scale and the Stress of Daily Activities scale, 1470 and 1882, respectively, later had cancer and were included in the analysis, covering 23 years of follow-up between 1982 and 2004. In Cox regression analysis, the multivariate hazard ratio (HR) was 0.99 (95% confidence interval [CI], 0.96-1.01) for total number of life events and the HR for the life change score was 0.99 (95% CI, 0.95-1.03). Further, the HR was 0.92 (95% CI, 0.69-1.22) for severe daily stress. Overall, the results of the current study do not support the hypothesis that stress reduces cancer survival.

Fish consumption and omega-3 polyunsaturated fatty acids in relation to depressive episodes: a cross-sectional analysis.

High fish consumption and omega-3 polyunsaturated fatty acid (PUFA) intake are suggested to benefit mental well-being but the current evidence is conflicting. Our aim was to evaluate whether a higher level of fish consumption, a higher intake of omega-3 PUFAs, and a higher serum concentration of omega-3 PUFAs link to a lower 12-month prevalence of depressive episodes.We used data from the nationwide Health 2000 Survey (n = 5492) and the Fishermen Study on Finnish professional fishermen and their family members (n = 1265). Data were based on questionnaires, interviews, health examinations, and blood samples. Depressive episodes were assessed with the M-CIDI (the Munich version of the Composite International Diagnostic Interview) and a self-report of two CIDI probe questions, respectively. Fish consumption was measured by a food frequency questionnaire (g/day) and independent frequency questions (times/month). Dietary intake (g/day) and serum concentrations (% from fatty acids) of PUFAs were determined. Fish consumption was associated with prevalence of depressive episodes in men but not in women. The prevalence of depressive episodes decreased from 9% to 5% across the quartiles of fish consumption (g/day) in men of the Health 2000 Survey (p for linear trend = 0.01), and from17% to 3% across the quartiles of fish consumption (times/month) in men of the Fishermen Study (p for linear trend = 0.05). This association was modified by lifestyle; in the Health 2000 Survey a higher level of fish consumption was related to a lower prevalence of depressive episodes in men who consumed the most alcohol, were occasional or former smokers, or had intermediate physical activity. The associations between depressive episodes and the intake or serum concentrations of omega-3 PUFAs were not consistent.In men, fish consumption appears as a surrogate for underlying but unidentified lifestyle factors that protect against depression.

Fish consumption and polyunsaturated fatty acids in relation to psychological distress.

BACKGROUND: It has been suggested that high fish consumption improves mental well-being. The aim of this study was to assess whether high fish consumption or omega-3 polyunsaturated fatty acid (PUFA) intake was associated with reduced self-reported psychological distress. METHODS: We used three cross-sectional data sets, the nationwide Health 2000 Survey (n = 5840), the Fishermen Study on Finnish fishermen and their family members (n = 1282) and the Finntwin16 Study on young adults (n = 4986). Data were based on self-administered questionnaires, interviews, health examinations and blood samples. Psychological distress was measured using the 12-item and 21-item General Health Questionnaires (GHQs). Fish consumption was measured by a food frequency questionnaire (FFQ, g/day) and independent frequency questions (times/month). Dietary intake (g/day) and serum concentrations (% from fatty acids) of PUFAs were determined. Relationships were analysed using regression analysis. RESULTS: Regardless of the measure, fish consumption and omega-3 PUFA dietary intake were not associated with distress in any of the data sets. In contrast to the hypothesis, high serum docosahexaenoic acid was associated with high distress in the Fisherman Study men. Some non-linear associations were detected between serum omega-3 PUFAs or fish consumption (times/month) and distress. In the Fishermen Study, the associations were modified by alcohol consumption, smoking and physical activity. CONCLUSIONS: Our results do not support the hypothesis that fish consumption or omega-3 PUFA intake are associated with reduced psychological distress in the general population or in a population with high fish consumption.