What's driving an epidemic? The spread of syphilis along an interstate highway in rural North Carolina.
OBJECTIVES: The purpose of this study was to determine whether county syphilis rates were increased along Interstate Highway 95 (I-95) in North Carolina during a recent epidemic. METHODS: Ecological data on syphilis cases demographic data, highway data, and drug activity data were used to conduct a cross-sectional and longitudinal study of North Carolina countries from 1985 to 1994. Crude and adjusted incidence rate ratios (IRRs) were determined by means of standard and longitudinal Poisson regression models adjusted for sociodemographic factors and drug use. RESULTS: Ten-year syphilis rates in I-95 counties greatly exceeded rates in non-I-95 counties (38 vs 16 cases per 100,000 persons) and remained higher after adjustment for race, age, sex, poverty, large cities, and drug activity (adjusted IRR = 2.05, 95% confidence interval [CI] = 1.84, 2.28). Syphilis rates were stable until 1989, when rates increased sharply in I-95 counties but remained stable in non-I-95 counties. Increased drug activity in I-95 counties preceded the rise in syphilis cases. CONCLUSIONS: A better understanding of the relationship between high-ways and the spread of sexually transmitted diseases may guide future prevention interventions. (+info
Exposure to polycyclic aromatic hydrocarbons and genotoxic effects on nonsmoking Swedish road pavement workers.
OBJECTIVES: The objective of this study was to investigate exposure to polycyclic aromatic hydrocarbons (PAH) from asphalt fumes among Swedish road pavement workers and determine whether any effects could be detected with genotoxic tests. METHODS: The study included 28 nonsmoking road pavers and 30 nonsmoking referents. The concentration of PAH was determined in the breathing zone of the road pavers. 1-Hydroxypyrene was analyzed before and after shifts of asphalt work and during the afternoon for referents. Sister chromatid exchanges (SCE) and micronuclei (MN) were determined in peripheral lymphocytes. RESULTS: Several 3- or 4-ring PAH were found, and the analysis indicated that they occurred in bitumen fumes rather than in traffic fumes. The average total concentration of PAH was 2.3 (range 0.2-23.8) microg/m3. The concentration of 1-hydroxypyrene in urine was higher for the road pavers than for the referents, but there was no significant difference between the pre- and postshift values of the road pavers. The road pavers had no significant increase in SCE or MN. CONCLUSIONS: The study showed that Swedish road pavers have an increased exposure to PAH from bitumen fumes, but no genotoxic effects could be detected by SCE or MN tests. (+info
Socio-economic consequences of rheumatoid arthritis in the first years of the disease.
OBJECTIVE: Few data have been presented to document the impact of rheumatoid arthritis (RA) on socio-economic well-being. In this study, exact figures on socio-economic consequences were assessed. METHODS: The socio-economic consequences were studied in an inception cohort (186 early RA patients, mean disease duration 3 yr) by measuring the change in work capability, income, rest during the daytime, leisure time activity, transport mobility, housing and social support occurring in the first years of the disease. RESULTS: For 89% of the patients, RA had an impact on one of the socio-economic items; for 58%, at least three of these items were affected simultaneously. Work disability appeared to be 4-15 times higher than in the general population. After 3 yr, 42% of the patients were registered as work disabled. Nearly a quarter of the patients experienced income reduction. Over 40% of the patients claimed extra rest during the daytime. Leisure activity changed towards activities with a lower joint load. There was a decline in transport mobility for 52% of the patients. Social support increased strongly. CONCLUSIONS: Socio-economic change already presents in the first years of RA and appears to be influenced by age, gender, marital status and work disability. Furthermore, physical limitation appeared to be predictive for work-related income reduction, reduced transport mobility and development of social dependency. (+info
Racial discrimination and alcohol-related behavior in urban transit operators: findings from the San Francisco Muni Health and Safety Study.
OBJECTIVE: A growing body of literature is documenting the health effects of racial discrimination. The authors investigated the association between racial discrimination and alcohol-related behavior in a sample of urban transit operators. METHODS: Using data from a 1993-1995 cross-sectional study of transit operators in San Francisco, California, the authors analyzed responses to two sets of questions about racial discrimination; the first set focused on reaction to unfair treatment and the second on arenas, or domains, of discrimination. Alcohol-related variables were: number of drinks per month, heavy drinking, alcohol dependence, and negative consequences of alcohol consumption. RESULTS: Operators who reported five or more domains of discrimination drank an average of 13.4 more drinks per month than those who reported no domains of discrimination (P = 0.01). Similarly, they were more likely to be heavy drinkers (adjusted odds ratio [OR] = 2.16; 95% confidence interval [CI] 1.14, 4.09) and dependent on alcohol (adjusted OR = 2.02; 95% CI 1.08, 3.79) than operators who reported no domains of discrimination. The number of domains in which operators reported having experienced discrimination was not related to sex, age, household income, job seniority, or marital status, but varied significantly by educational level and race/ethnicity. CONCLUSIONS: Data from a sample of urban transit operators showed an association between the number of domains of discrimination and some alcohol-related outcomes, but not others. (+info
Transport and temperature effects on measurement of serum and plasma potassium.
Transport of blood samples from general practice to a central laboratory can result in spuriously high or low potassium concentrations. The importance of this phenomenon was studied in a general practice serving a population of 15,000 patients, 27 km from the pathology laboratory that routinely measured serum potassium. The design involved comparison of potassium levels between control serum (plain gel-separation serum tubes centrifuged in the surgery), routine serum (plain gel-separation tubes centrifuged in the laboratory) and routine plasma samples (lithium-heparin tubes centrifuged in the laboratory). Complete triple sets of data were obtained for 371 samples. Altman and Bland plots for the control serum vs routine serum samples showed a mean difference of +0.1 mmol/L with limits of agreement (+/- 2SD) +0.6 mmol/L, -0.4 mmol/L and for control serum vs routine plasma a mean difference of +0.2 mmol/L with limits of agreement +0.8 mmol/L, -0.4 mmol/L. There was a negative association between mean weekly routine plasma potassium levels with mean weekly temperatures achieved. Regression analysis indicated that both maximum temperature achieved and time to centrifugation significantly contributed to differences observed in the routine plasma samples, but not with the routine serum samples. For plasma samples exposed to high temperatures a clinically significant lowering of potassium concentrations can arise. These results confirm that spurious lowering of potassium concentrations occurs in plasma samples collected in a primary care setting. The preferred method is to centrifuge samples soon after venepuncture. Where this is not possible, collection into plain gel-separation tubes (serum) ensures less variation due to temperature and time to centrifugation than does collection into lithium-heparin tubes (plasma). (+info
Stability of plasma human immunodeficiency virus load in VACUTAINER PPT plasma preparation tubes during overnight shipment.
VACUTAINER PPT plasma preparation tubes were evaluated to determine the effects of various handling and shipping conditions on plasma human immunodeficiency virus (HIV) load determinations. Plasmas obtained from PPT tubes stored and shipped under nine different conditions were compared to conventional EDTA tube plasmas stored at -70 degrees C within 2 h after phlebotomy. Compared to viral loads in frozen EDTA plasma, those in PPT tube plasma that was frozen immediately and either separated or shipped in situ were not significantly different. Viral loads in PPT tube plasma after storage for 6 h at either room temperature or 4 degrees C, followed by shipment at ambient temperature or on wet or dry ice, were not significantly different from baseline viral loads in EDTA or PPT plasma. The results of this study indicate that the HIV load in PPT tube plasma is equivalent to that in standard EDTA plasma. Plasma viral load is not affected by storage or shipment temperature when plasma is collected in PPT tubes. Furthermore, plasmas can be shipped in spun PPT tubes, and the tubes provide a safer and more convenient method for sample collection and transport than regular EDTA tubes. (+info
Analysis of incidence of childhood cancer in the West Midlands of the United Kingdom in relation to proximity to main roads and petrol stations.
OBJECTIVES: To investigate whether there is an excess of leukaemias in 0-15 year old children among those living in close proximity (within 100 m) of a main road or petrol station. METHODS: Data for 0-15 year old children diagnosed between 1990 and 1994 in the United Kingdom West Midlands were used. Postcode addresses were used to locate the point of residence which was compared with proximity to main roads and petrol stations separately, and to both together. Odds ratios (ORs) were calculated with solid tumours as a control, and incidence ratios (IRs) with population density as a control. RESULTS: The method based on solid tumours as a control showed ORs of 1.61 (95% confidence interval (95% CI) 0.90 to 2.87) and 1.99 (95% CI 0.73 to 5.43), for those living within 100 m of a main road or petrol station respectively. When population was used as a control, the estimated IRs for leukaemia were 1.16 (95% CI 0.74 to 1.72) and 1.48 (95% CI 0.65 to 2.93) for residence within 100 m of a main road or petrol station respectively, but neither reached significance at the 95% level. Results for residence in close proximity to both a main road and petrol station were inconsistent, but there were few. The influence of socioeconomic factors as represented by the Townsend deprivation index on leukaemia incidence was not significant and the results were not explicable on the basis of impact of social class. CONCLUSIONS: The results are suggestive of a small increase in risk of childhood leukaemia, but not solid tumours, for those living in close proximity to a main road or petrol station. This increase in risk is not, however, significant and a larger study is warranted to establish the true risk and causes of any increase in risk. (+info
HIV heterogeneity and proximity of homestead to roads in rural South Africa: an exploration using a geographical information system.
objective To describe heterogeneity of HIV prevalence among pregnant women in Hlabisa health district, South Africa and to correlate this with proximity of homestead to roads. methods HIV prevalence measured through anonymous surveillance among pregnant women and stratified by local village clinic. Polygons were created around each clinic, assuming women attend the clinic nearest their home. A geographical information system (GIS) calculated the mean distance from homesteads in each clinic catchment to nearest primary (1 degrees ) and to nearest primary or secondary (2 degrees ) road. results We found marked HIV heterogeneity by clinic catchment (range 19-31% (P < 0.001). A polygon plot demonstrated lower HIV prevalence in catchments remote from 1 degrees roads. Mean distance from homesteads to nearest 1 degrees or 2 degrees road varied by clinic catchment from 1623 to 7569 m. The mean distance from homesteads to a 1 degrees or 2 degrees road for each clinic catchment was strongly correlated with HIV prevalence (r = 0.66; P = 0.002). conclusions The substantial HIV heterogeneity in this district is closely correlated with proximity to a 1 degrees or 2 degrees road. GIS is a powerful tool to demonstrate and to start to analyse this observation. Further research is needed to better understand this relationship both at ecological and individual levels, and to develop interventions to reduce the spread of HIV infection. (+info