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PubMed2001

The geographical distribution of primary biliary cirrhosis in a well-defined cohort.

The incidence of primary biliary cirrhosis (PBC) varies widely between regions. However, little is known about variation within regions and the degree to which this may reflect environmental risk factors. The aim of this study was to describe the spatial distribution of cases of PBC in a defined region of Northeast England over a defined period, and to assess the magnitude of any departure from random spatial distribution. Seven hundred seventy patients with established PBC were identified in a previous comprehensive case finding study. A total of 3,044 control locations were randomly selected from postcode (zip code) data weighted for number of drop off points per postcode. Geographical analysis was performed by testing both for spatial variation in risk and local clustering by using previously described point process methods. Both tests used the same null hypothesis that risk of disease does not vary spatially and cases occur independently of each other. Statistically significant spatial variations in risk were found in the whole study region (P <.001) and in the major urban area within the region (P <.004). Risk was higher in the urban area of Tyneside than in the surrounding rural area. Within the rural area, spatial variation in risk was equivocal (P =.012), but there was significant (P =.001) clustering of cases (estimated average cluster effect approximately 10 excess cases within a 7-km radius). PBC occurred to a density of 10.7 cases/km(2) in the highest risk areas. In conclusion, PBC is unevenly distributed in Northeast England. This may reflect one or more environmental risk factors in its etiology.

Cluster Analysis↗
PubMed2005

Using passive air samplers to assess urban-rural trends for persistent organic pollutants and polycyclic aromatic hydrocarbons. 2. Seasonal trends for PAHs, PCBs, and organochlorine pesticides.

This is the second of two papers demonstrating the feasibility of using passive air samplers to investigate persistent organic pollutants along an urban-rural transect in Toronto. The first paper investigated spatial trends for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). This second paper investigates the seasonality of air concentrations for polycyclic aromatic hydrocarbons (PAHs), PCBs, and OCPs along this transect. Air samplers, consisting of polyurethane foam (PUF) disks housed in stainless steel domed chambers, were deployed for three 4-month integration periods from June 2000 to July 2001. The seasonal variations of derived air concentrations for PAHs, PCBs, and OCPs reflected the different source characteristics for these compounds. PAHs showed a strong urban-rural gradient with maximum concentrations at urban sites during the summer period (July-October). These high summer values in Toronto were attributed to increases in evaporative emissions from petroleum products such as asphalt. PCBs also exhibited a strong urban-rural gradient with maximum air concentrations (approximately 2-3 times higher) during the spring period (April-June). This was attributed to increased surface-air exchange of PCBs that had accumulated in the surface layer over the winter. alpha-HCH was fairly uniformly distributed, spatially and temporally, as expected. This pattern and the derived air concentration of approximately 35 to approximately 100 pg m(-3) agreed well with high volume air data from this region, adding confidence to the operation of the passive samplers and showing that site-to-site differences in sampling rates was not an issue. For other OCPs, highest concentrations were observed during the spring period. This was associated with either (i) their local and/or regional application (gamma-HCH, endosulfan) and (ii) their revolatilization (chlordanes, DDT isomers, dieldrin, and toxaphene). Principal component analysis resulted in clusters for the different target chemicals according to their chemical class/source type. The results of this study demonstrate how such a simple sampling technique can provide both spatial and seasonal information. These data, integrated over seasons, can be used to evaluate contaminant trends and the potential role of large urban centers as sources of some semivolatile compounds to the regional environment, including the Great Lakes ecosystem.

Air↗
PubMed1990

Metropolitan America: beyond the transition.

Americans have always gravitated toward cities, and for most of this century, urban growth has continued at a fast pace. During the 1970s, however, nonmetropolitan area grew at the expense of many large metropolitan areas, especially those in the industrial Northeast and Midwest. New patterns of population distribution appeared to be emerging. This Bulletin analyzes the trends of the 1970s, the shifting patterns of the 1980s, and likely prospects for future growth in metropolitan areas. The "rural renaissance" resulted from a combination of forces, including improved infrastructure in nonmetropolitan area, growing demand for retirement and recreation spots, the entrance of the large baby-boom cohort into the labor force, and the economic situation both at home and abroad. Some of these same forces have shifted settlement patterns in the 1980s, helping create "World Cities," like New York and San Francisco, and regional "Command and Control Centers" such as Atlanta and Minneapolis-St. Paul, that will continue to gain in both population and influence. Yet nonmetropolitan areas still attract retirees and other former urbanites. The distribution of minority groups among metropolitan populations is also undergoing significant change. The heavy immigration of Hispanics and Asians in the 1980s has increased the proportion of these groups, particularly in metropolitan areas in the South and West. More black Americans are moving to the suburbs formerly dominated by whites. Yet large pockets of poverty--of both black and whites--remain in both suburban and central city areas.

Black or African American↗
PubMed1994

Selected aspects of the population health status in ecological hazard areas in comparison with ecologically "clean" area. II. Assessment of spatial distribution of mortality.

On the basis of age adjusted rates of mortality from all diseases and from diseases of the circulatory system in female and male populations living in ecological hazard areas and in ecologically "clean" area, the distributions of the rate values were assessed. In the regions under consideration, urban and rural regions were distinguished. The goodness of fit of the empirical distribution to the normal one was assessed using the following statistical parameters: arithmetic mean, mode, median, standard deviation, coefficient of variation, coefficient of asymmetry, difference between the third and the first quartiles, as well as the Chi2 and lambda-Kolmogorow-Smirnow tests, maximum difference between cumulative distribution functions and standard deviation of differences between empirical and theoretical frequencies. A differentiation in the mean values of age adjusted rates of mortality from both groups of diseases in ecological hazard areas and in "clean" area was indicated particularly in urban female and male populations.

Cardiovascular Diseases↗
PubMed1993

Africa: rapid population increase retards development.

The Organization of African Unity (OAU), the African Development Bank (ADB) and the UN Economic Commission for Africa (ECA) have criticized African governments for not taking the problem of unchecked population growth seriously enough. "Until recently most African governments did not view rapid population growth as a matter for concern," said the OAU assistant secretary-general for political affairs, Machivenyika Mapuranga, at a seminar on 'population and development'. The OAU estimates that an annual average population increase of 3.1% far outstrips Africa's economic growth, which in 1992 was less than 1%. Mapuranga acknowledged that cutting the population increase is an uphill struggle, especially among rural communities. African agriculture is largely labor intensive, sustained by smallholders, which encourages farmers to have more children. Like other wage earners, African farmers look to support from their family when they grow old and, for that reason, the number of children also counts. But with agricultural production growing at an average annual rate of 2.5%, self-sufficiency in food remains an elusive goal. Cities in sub-Saharan Africa are growing much faster than the overall rate of population increase of 3.1% per year. Between 1980 and 1988 the region's urban population increased at the rate of 6.9% a year. Urban areas now account for nearly 30% of the sub-Saharan Africa population, currently put at 680 million. By 2025, approximately 700 million people are expected to live in urban areas. Despite migration to towns, the rural population is expected to rise more than 68%, reaching over 590 million.

Africa↗
PubMed2004

[Scarlet fever in Poland in 2002].

Following the last epidemic in 1995 the scarlet fever incidence in Poland has been gradually decreasing, on average 20% per year. The downward trend continued in 2002, the overall incidence rate being 10.6 per 100,000. It was the lowest incidence registered in Poland since the introduction of mandatory reporting of scarlet fever in 1918 (the lowest so far registered incidence rates were 15.2 in 2001 and 17.5 in 1918). Spatial distribution of cases was relatively even--incidence ranged from 5.0 per 100,000 in łódzkie voivodeship to 25.1 in opolskie voivodeship. As observed previously incidence in the urban areas (12.0) was significantly higher then in the rural areas (8.4) and the incidence in men (11.7) exceeded the incidence in women (9.6). The majority of cases occurred in children and adolescents younger then 15 years (mode--6 years). Two percent of cases were hospitalized. There were no deaths due to scarlet fever reported in 2002.

Adolescent↗
PubMed2003

Random spatial distribution of Schistosoma mansoni and hookworm infections among school children within a single village.

Schistosomes and soil-transmitted helminths currently infect a third of the world's human population. An important feature of these parasitic infections is their focal distribution, which has significant implications for control. Only a few studies have been carried out at the microepidemiological scale, comparing infection levels among individuals or households within a single village. In this study, data are presented from a cross-sectional survey, examining all children attending a primary school in rural Côte d'Ivoire over several consecutive days for Schistosoma mansoni, soil-transmitted helminths, and intestinal protozoa. All houses in the main village were mapped, and school children were linked to these households for small-area spatial analyses. Comparison between the 260 school children who live within the main village and the 89 children who reside in nearby settlements revealed significant differences in the overall prevalence and intensity of infections with S. mansoni and hookworm, confirming the focal nature of these 2 parasites. On the other hand, S. mansoni and hookworm infections exhibited random spatial patterns within the main village. The validity of these results is discussed in the context of this epidemiological setting, drawing attention to the issue of scale. Our findings have direct implications for intervention because they call for a uniform, community-wide approach to control schistosomiasis and soil-transmitted helminthiasis. Implementation can be relatively straightforward, and the proposed control approach might be cost-effective and prove sustainable.

Adolescent↗
PubMed2006

Spatial and temporal trends of volatile organic compounds (VOC) in a rural area of northern Spain.

Ambient concentrations of volatile organic compounds (VOCs) were measured at 40 rural sampling points in Navarre (northern Spain). Air samples were collected by means of sorbent passive sampling and analyzed by thermal desorption (TD) and gas chromatography/mass-selective detector (GC/MSD). A total of 140 VOCs were identified during the study, which was carried out between May to October 2004 for a total of a 10 biweekly sampling campaigns. Concentrations of benzene, toluene, ethylbenzene, m/p-xylenes, o-xylene (BTEX) and 1,3,5-trimethylbenzene were determined in order to investigate their temporal and spatial distributions. Geostatistical analysis pointed to traffic as the main emission source of these compounds. Supporting this idea, BTEX and nitrogen oxides concentrations were found to be highly significantly correlated (r = 0.495, P = 0.001), whereas a strong negative correlation between BTEX and ozone was also observed (r = -0.355, P = 0.025). The concentrations for the BTEX group were similar to the values that have been previously reported for other rural areas.

Air↗
PubMed1982

Social-demographic development of Vologda Oblast during the intercensal period 1970-79.

"Demographic trends in Vologda Oblast are analyzed on the basis of 1979 census results as a case study of an oblast involved in the [development] program for the Nonchernozem Zone of the RSFSR. The trend in the 1970-79 intercensal period was for continuing growth of urban population, especially in the two major urban centers of Vologda and the iron and steel city of Cherepovets, and depopulation of rural areas. The age-sex structure is distinguished by a strong aging trend and sex imbalance, especially in rural areas. Despite the proclaimed aim of fostering abandonment of tiny rural places (with 25 residents or less), the number of places in that size class actually increased during the intercensal period (from 40% of all rural places in 1970 to 52 percent in 1979)."

Age Distribution↗