To investigate attrition of subjects in a longitudinal study of caries.
A radiographic study of caries and caries-associated factors was carried out in subjects, initially aged 14 years, and followed-up for six years. Attrition of subjects occurred at the last stage of the study.
A nationwide survey of subjects living in fishing, rural farming, and urban communities in Iceland.
A sub-sample of the nationwide random sample comprising 150 subjects was investigated using bitewing radiographs and a structured questionnaire to determine caries-risk factors. Subjects were re-examined at 16 years and 20 years using the same methods.
Mean caries increment from 14-16 years was 3.0 lesions (1.5 lesions/subject/year) but reduced to 2.6 lesions (0.7 lesions/subject/ year) by 20y. The proportion of subjects found to be caries-free at 14 years, 16 years and 20 years, was 29%, 17% and 10%, respectively. "Dropouts" from this study occurred mostly after 16 years. Analysis of subjects dropping out showed that they were least likely to be from the rural farming community but most likely from the fishing community. Those dropping out attended their dentist less frequently, had a higher consumption of carbonated drinks and a higher prevalence and incidence of caries by 16 years.
Subjects with high-risk behaviours, or residents in a fishing community were more likely to drop out of the study. Recognised advantages of conducting longitudinal studies of caries may, therefore, be lost.
On the basis of some epidemiological criteria, the work gives grounds for distinguishing the category of "new settlers" among the whole number of "newcomers". The time necessary for the social adaptation of new settlers is estimated, which makes it possible to take them into account together with permanent residents. The scheme of the division of the population according to the duration of their residence in the endemic area is proposed.
Commercial fishing is one of the most dangerous occupations in the United States. During 1992-2008, an annual average of 58 reported deaths occurred (128 deaths per 100,000 workers), compared with an average of 5,894 deaths (four per 100,000 workers) among all U.S. workers. During the 1990s, safety interventions addressing specific hazards identified in Alaska resulted in a significant decline in the state's commercial fishing fatality rate. During 2007-2010, CDC expanded surveillance of commercial fishing fatalities to the rest of the country's fishing areas. To review the hazards and risk factors for occupational mortality in the U.S. commercial fishing industry, and to explore how hazards and risk factors differ among fisheries and locations, CDC collected and analyzed data on each fatality reported during 2000-2009. This report summarizes the results, which showed that, among the 504 U.S. commercial fishing deaths, the majority occurred after a vessel disaster (261 deaths, 52%) or a fall overboard (155 deaths, 31%). By region, 133 (26%) deaths occurred off the coast of Alaska, 124 (25%) in the Northeast, 116 (23%) in the Gulf of Mexico, 83 (16%) off the West Coast, and 41 (8%) in the Mid- and South Atlantic. Type of fishing was known in 478 deaths; shellfish (226, 47%) was the most common, followed by groundfish (144, 30%) and pelagic fish (97, 20%). To reduce fatalities in this industry, additional prevention measures tailored to specific high-risk fisheries and focusing on prevention of vessel disasters and falls overboard are needed.
Individuals migrate to exploit heterogeneities between spatially separated environments to modulate growth, survival, or reproduction. We devised a bioenergetics model to investigate the evolution of migration distance and its dependence on individual states. Atlantic cod Gadus morhua ranges from sedentary populations to stocks that migrate several thousand kilometers annually. We focused on the Northeast Arctic cod stock, which migrates south to spawn. A linear relationship between migration distance and the expected survival of offspring was assumed, here understood as the prospects for future survival and development that a fertilized egg faces at a particular spawning location. Reasons for why it may increase southward include warmer water that increases development rates, and thereby survival, along the pelagic drift trajectory. In the model, ingested energy can either be allocated to growth or stored for migration and reproduction. When migrating, individuals forgo foraging opportunities and expend energy. Optimal energy allocation and migration strategies were found using state-dependent optimization, with body length, age, condition, and current food availability as individual states. For both a historical and contemporary fishing regime we modeled two behaviors: (1) homing cod returning to the same spawning site each year and (2) roaming cod with no such constraints. The model predicted distinct regions of locally high spawning stock biomass. Large individuals in good condition migrated farthest, and these also tended to mature later in life. The roaming cod spread farther south as they grew larger and older. Homing cod did not have this freedom, and spawning was generally concentrated along a narrower stretch of the coastline. Under contemporary fishing, individuals matured earlier at a smaller size, had shorter migrations, spawned over a contracted geographical range, and tended to be in poorer condition. The effects were most pronounced for the homing behavior.
To investigate whether fatal accidents, including drownings, have decreased among Icelandic fishermen and seamen.
Historical prospective study. The study population was record linked with the National Register and the Register of Deceased to get information on water transport accidents (ICD-7, E850-E858) during the period 1966-86. The number of persons in each calendar year and the number of days at sea registered at the pension fund were both used as denominator to find annual mortalities.
27,884 seamen who were members of the Seamen's Pension Fund. The cohort included both fishermen and seamen from the merchant fleet.
Changes in mortality from all accidents and drownings from 1966-86.
The mortality for all fatal accidents was 89.4 per 10(5) person-years and did not change appreciably during the study period. The mortality for drowning was unchanged at 73.2 per 10(5) person-years. The greatest number of drownings were among those 20-24 years of age but the mortality for drowning was highest among those 45-54 years of age.
Mortality because of fatal accidents and drownings among these seamen was high and did not conclusively decrease during the study period. Further preventive measures are needed.
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Fishery is a hazardous occupation and fatigue may contribute to the observed risks. This study aims to investigate the association between workload and fatigue among Danish fishermen.
The cross-sectional survey of demographic characteristics and self-reported exposure and health data was performed on a random sample of 270 active fishermen. We applied the validated Multidimensional Fatigue Inventory (MFI-20) to assess the degrees of the different dimensions of perceived fatigue. We estimated physical workload using questions regarding the frequency of seven physical work activities and analysed the association between fatigue and workload using multiple linear regressions.
The mean fatigue scores were 9.18 (SD 3.58) for general fatigue, 9.05 (SD 3.36) for physical fatigue, 7.57 (SD 3.03) for reduced activity and 7.16 (SD 3.07) for mental fatigue. Highest levels of fatigue were observed among fishermen at Danish seiners (mean 10.21), and fatigue scores decreased with more days at sea. However, none of these results were significant. Adjusted analyses showed that physical workload was significantly related to general fatigue (b = 0.20, 95% CI: 0.12-0.28), physical fatigue (b = 0.10, 95% CI: 0.04-0.16) and mental fatigue (b = 0.09, 95% CI: 0.01-0.16). Reduced activity was unrelated to work exposures.
General fatigue was the dominant fatigue dimension among Danish fishermen and it is mostly associated with physical workload. Physical workload was additionally significantly associated to the levels of physical and mental fatigue. Fishermen had a lower average score for all fatigue dimensions compared to those seen in general Danish working population. Prospective studies are required to assess whether the identified associations are causal.
The purpose of the study was to assess the incidence and relative risk of hepatitis A and B and tuberculosis among Danish merchant seamen. We also assessed the occurrence of malaria. The study was based on record linkage of a research database containing data on 24,132 Danish male seamen and the Registry for Notifiable Infectious Diseases in Denmark, supplemented by data from other sources. The standardized incidence ratio (SIR) for hepatitis A for male seamen was 1.77 (0.91-3.10) as compared with the incidence in the general population. The incidence was 0.9 notified cases/10,000 years. The SIR for hepatitis B for male seamen was 3.02 (1.79-4.78), the main risk factors being intravenous drug use and casual sex abroad. Tuberculosis was not more common among seamen than in non-seamen. The results have implications for vaccination strategies in this occupational group. Malaria occurred frequently in the seamen, especially among those involved in West African trade. Irregular use of malaria prophylaxis and probably chloroquine resistance were of importance in some cases. To detect further cases of hepatitis A and B and malaria, other sources were reviewed. Only a few extra cases were identified. The registry of notifiable infectious diseases was thus found to be rather complete.
From a prospective epidemiological and radiological study of peptic ulcer disease in the northern part of Norway, relations between occupation and the occurrence of new peptic ulcers are presented. Over a 3-year period 1861 patients with dyspeptic complaints, 557 women and 1304 men belonging to 12 different occupational groups, were studied. Special attention was paid to the fishing population, constituting 2488 men and only 55 women. In the period studied 87 gastric ulcers and 118 duodenal ulcers were found. A statistically significantly higher incidence of both gastric and duodenal ulcers was found in fishermen than in the other groups. Furthermore, significantly higher incidences of duodenal ulcers were found in men occupied in 'land or water transport'. Compared with the total male population at risk in the area studied, significantly higher incidences were found for duodenal ulcer in fishermen. The present study confirms prior reports both from Scotland and from North Norway, showing an increased incidence of peptic ulcers in the fishing population.