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At least 307 records · Page 17Linked to original sources

PubMed2006

Residential exposure to petrochemicals and the risk of leukemia: using geographic information system tools to estimate individual-level residential exposure.

The authors conducted a population-based, case-control study in Kaohsiung, southern Taiwan, Republic of China, to investigate the association between residential petrochemical exposure and leukemia risk among subjects 29 years of age and younger. Between November 1997 and June 2003, 171 cases and 410 controls matched for age and sex were recruited. Since assessment of petrochemical impacts depends on accurate exposure estimates, the authors developed a procedure using geographic information system tools to assign subjects' exposure. The resulting individual-level exposure estimates (the exposure opportunity score) are an integrated exposure measure that accounts for subjects' mobility, length of stay at each residence, distance to petrochemical plant(s), monthly prevailing wind direction, and multiple petrochemical pollution sources. Different conditional logistic regression models were fitted for subjects aged 0-19 and 20-29 years to evaluate separately childhood versus adulthood leukemia. No overall association was observed for the younger age group. However, residential petrochemical exposure was a significant risk factor for leukemia for the older age group. For one unit of increase in the log-transformed exposure opportunity score, the adjusted odds ratio was 1.54 (95 percent confidence interval: 1.14, 2.09). This study illustrates the utility of geographic information system tools for providing refined exposure estimates for residential exposure to petrochemical pollution.

Adolescent↗

PubMed2006

Mercury contamination of biota from Acadia National Park, Maine: a review.

We reviewed literature reporting both total and methylmercury from biota from Acadia National Park, Maine, USA. Our review of existing data indicates that 1) mercury contamination is widespread throughout the Park's various aquatic ecosystems; 2) mercury pollution likely represents a moderate to high risk to biota inhabiting the Park; and 3) biota at all trophic levels possess elevated concentrations of both total and methylmercury. Watershed fire history and the resulting post-fire forest succession patterns are an important landscape attribute governing mercury cycling at Acadia National Park. Therefore, park service personnel should consider these factors when planning and implementing Hg biomonitoring efforts. Additional baseline funding from the National Park Service for Hg research and biomonitoring will likely be required in order to further evaluate the spatial and temporal patterns of mercury contamination in the park's biota.

Animals↗

PubMed2000

Simulated effects on dairy cattle health of extending the voluntary waiting period with recombinant bovine somatotropin.

We simulated the effect of extending the voluntary wait period by 100 days on disorder-frequency measures that were based on cow-years (from lactations completed during the 4-year simulation horizon), metric tons of milk yield, and lactational incidence risks. A dynamic stochastic discrete-event simulation model that focuses on clinical and subclinical intramammary infections (IMI), plus clinical metabolic (left-displaced abomasum, ketosis, milk fever) and reproductive (cystic ovarian disease, dystocia, retained placenta, twinning, uterine infection) disorders in dairy herds was used. Although the voluntary wait period was increased by 100 days (50 vs. 150), the predicted difference in simulated days to conception was only 89 days for the extended voluntary wait-period group (which we attributed to higher fertility later in lactation). Herds that had a voluntary wait period of 150 days (compared to the control herds' voluntary wait period of 50 days) were predicted to have significantly lower rates of metabolic and reproductive disorders and clinical mastitis on both cow-year and milk-yield bases. Simulated control herds, on average, produced 8539 kg of milk in an average lactation of 325 days and simulated herds with a 150-day voluntary wait period 10893 kg of milk in an average lactation of 409 days. There was a significantly lower predicted rate and risk of culling for reproductive failure in the extended voluntary wait period group. The predicted lactational incidence risks for subclinical IMI were 18% higher for the extended voluntary wait period group - but extending the voluntary wait period by 100 days was predicted not to increase the risk of any of the other 10 disorders.

Algorithms↗

PubMed2000

Perceived risk of cocaine use and experience with cocaine: do they cluster within US neighborhoods and cities?

This study investigates whether experience with cocaine and the perception of risk associated with cocaine use might tend to cluster within neighborhoods and cities in the US. Population-based data from six years of the National Household Surveys on Drug Abuse public use files are employed. The alternating logistic regressions model is used to quantify the extent of geographic concentration. Perceptions of the harm associated with cocaine use and actual experience with cocaine tend to cluster within neighborhoods; once within-neighborhood concentration is taken into account, there is little evidence of residual concentration within cities.

Adolescent↗

PubMed2003

Estimation of demographic toxicity through the double bootstrap.

Toxicity to organisms is usually expressed in terms of an observable effect on individuals from which a summary endpoint (such as the NOEC or ECx) is derived for risk assessment and environmental quality standards. However, toxicity evaluated in terms of a demographic endpoint may be more relevant to such regulatory applications. In this paper the effect of toxicity on population growth rate r is explored in tandem with a 'double bootstrap' to incorporate uncertainty. Exemplifying the approach with a set of individualized life table response data obtained for Daphnia magna exposed to zinc sulphate solution, the influence of increasing concentrations is assessed. A demographic-based metric for r, the ErCx (effect on r concentration percentage), is defined to permit alternative population level estimation of a 'safe effect' concentration.

Animals↗

PubMedDate not supplied

Enumerating lepidopteran species associated with maize as a first step in risk assessment in the USA.

Pest management can have substantial impacts on non-target species both within and outside the units being managed. Assessment of these impacts is hampered by the lack of even the most basic checklist of the species present in most systems. The maize agroecosytem is of particular interest because of the large area covered and the intensity of widely varying forms of pest management. In this study a database of lepidopteran species that occur within the maize agroecosystem in the United States was compiled. The process was initiated by developing a list of plants present in maize using published sources and the first-hand knowledge of "weed" experts. This list of plant species associated with maize was then cross-listed with lepidopteran host feeding records using published sources. Finally, phenological profiles and conservation rankings were added. Although our list is not exhaustive, we found 132 plant species in 33 families associated with maize, and 229 lepidopteran species in 21 families that feed on these plants. The database of plants and lepidopteran species can be a starting point for assessment of risk to non-target Lepidoptera in maize from chemical control, biological control, and the use of transgenic Bt maize. The lepidopteran species associated with maize were found to be significantly less imperiled, as measured by their conservation rankings, than lepidopteran species as a whole in all habitats. This finding suggests that rare or endangered lepidopteran species are unlikely to be impacted by pest management in maize. Based on the likely lack of impact of pest management in maize on individual species, future studies should focus on potential impacts on the ecological services that lepidopteran species provide.

Agriculture↗

PubMed2001

Urbanisation and coronary heart disease risk factors in South Asian children.

BACKGROUND: Coronary Heart Disease (CHD) and other Non Communicable Diseases (NCDs) are increasing globally. Comparison of various sections of the South Asian populations living at different levels of urbanization can help in understanding the role of demographic transition in the increased prevalence of these diseases in urbanized populations. OBJECTIVE: To compare the prevalence of certain CHD risk factors in 10-12 year old school children living at different levels of urbanization. METHOD: Differences in height, Body Mass Index (BMI), Waist Hip Ratio (WHR), Fasting Blood Glucose (FBG) and Total Blood Cholesterol (TBC) were studied. SUBJECTS: Anthropometric and biochemical measurements of six groups of 10-12 year old children, representing various urbanization categories, were studied. Three groups of children were recruited from Punjab, Pakistan: rural, middle income urban and high income urban and they were assigned urbanization rank (UR) 1, 2 and 3. Another three groups of children were recruited from Slough, UK: British Pakistani, British Indian, and British Caucasian and they were assigned urbanization rank 4, 5 and 6 respectively. RESULTS: Proportion of children having high CHD risk increased with urbanization rank. Increase in BMI and TBC with urbanization status was steadier than the increase in FBG and WHR. Stunting which have been found to have a positive association with obesity and increased risk of CHD was higher among the less urbanized groups. BMI and TBC of the urbanized South Asian groups were lower, but FBG was higher than the British Caucasian, who served as controls. CONCLUSION: These findings support the hypothesis that high CHD death rate among South Asians in UK may have its origin in the genetic predisposition to diabetes but are not likely to be solely due to this factor. The environmental factors like under nourishment in early life, adoption of urbanized life style or a combination of both could be the major determinants of CHD morbidity and mortality.

Anthropometry↗

PubMedDate not supplied

[Individualization of the "presumptive risk" of hypertensive crisis using fractals interpolation of the 24-hour arterial pressure. Study of patients with essential hypertension].

PURPOSE: The present study applies the "fractal interpolation" (FI) to blood pressure that was nonivasively and ambulatorily monitored over a day-night period in essential hypertensives. The purpose is the identification of cases who are at a "presumptive risk" (PR) for hypertensive crisis. MATERIALS AND METHODS: The investigation was performed on 380 ascertained cases of essential hypertension, who underwent a non-invasive ambulatory monitoring of 24-h blood pressure. The FI was applied to the ambulatory mean arterial pressure. RESULTS: The FI showed that the PR of hypertensive crisis can be found in 14% of the investigated essential hypertensive patients. Such a risk is not significantly higher in dippers as compared to non-dippers, and in those who showed a significant blood pressure circadian rhythm as compared to those who showed the blood pressure circadian rhythm to be abolished. Furthermore, no significant difference was found between the cases "at risk" and "not at risk" as far as the spectrum of harmonic formants of the 24-h blood pressure pattern is concerned. CONCLUSIONS: The PR of hypertensive crisis is not correlated to the dipping/nondipping condition, circadian rhythmicity and complex harmonic structure of 24-h blood pressure pattern. Its occurrence depends essentially from the disorder that is detectable in 24-h blood pressure pattern. Therefore, such a PR in essential hypertensives may be attributed to the mechanisms, likely neurovegetative, which confer a non-linear chaotic variability to 24-h blood pressure values.

Adult↗

PubMed1993

Estimation of early childhood mortality using preceding birth technique in a community-based setting.

The preceding birth technique, an indirect method for estimating early childhood mortality based on ascertaining the survival of previous children, was applied in rural Ethiopia within a system of demographic surveillance. Trained community health workers acted as interviewers and transmission flow of the routine health information system was used for data reporting. Data were collected for a median 12 month period from 39 sampled villages of Ticho district in Arsi region. From 1064 mothers having at least a second birth, the proportion dead of the last birth was 0.138 (95% CI 0.117-0.150), corresponding approximately to the probability of dying between birth and age two. It approximates to an infant mortality rate of about 100 x 1000 live-births. From 974 mothers having at least a higher-order birth, the proportion dead of the second to last birth was 0.203 (95% CI 0.178-0.228), equivalent to the risk of dying between 0 and age 5. In spite of the progressive migration of the surveyed population, the process and the outcome of the study suggest that PBT may well be inserted into a primary health care information system run by trained community health workers.

Birth Order↗

PubMed2004

Fractal meta-analysis and 'causality' embedded in complexity: advanced understanding of disease etiology.

Epidemiologists have gradually come to realize that repeated testing of 'causal' hypotheses normally results in inconsistent outcomes. Contradictory results pop up often enough to arouse suspicion that central epidemiological paradigms may be invalid. In this paper, we introduce complexity to explain inconsistency. Linear models produce inconsistency simply because they are not sufficiently rooted in the complex nature of living things. We design a meta-analysis consisting of (a) fractal investigation, used in this paper to reveal the possibly fractal nature of ordered series of relative risks (RR) and their possible Self-Organized Criticality (SOC); (b) disclosure of complexity-bound associations (DCBA) analysis which is used to disclose law-like and chaos-like associations of exposure and risk of disease within the series. We use (a) and (b) to reanalyze three published meta-studies, one of which investigates the possible association of oral contraceptives and female breast cancer. We demonstrate that the OR-series of the latter is fractal and in a state of SOC and conclude, contrary to the authors of the original meta-study, that there is no law-like association of oral contraceptives and breast cancer in this series. We achieve similar results for the other two meta-studies, results that are highly relevant for the clinical recommendations given by the authors.

Breast Neoplasms↗

PubMed2005

Population survivorship index for fish and amphibians: application to criterion development and risk assessment.

Criterion development currently focuses on physiological responses when determining permitted chemical concentrations in environmental media. Losses of biodiversity attributed to chemical pollution may be related not only to physiological sensitivity but also to inherent population characteristics that are not included in risk assessment or criterion development. In the present study, we proposed a process and a tool for summarizing population- and species-level information that contributes to long-term survivorship. We investigated the influences of life-history strategies of fish and amphibians that contribute to variations in population sensitivity or resiliency. A life-history survivorship index for application in criterion development and risk assessment was developed to help identify which species in a study system possess life-history strategies inherently sensitive to chemical stressors. It includes life-history characteristics of fecundity, number of spawning events, life stages, parental care, attrition rates, time to reproductive maturity, and other factors. Survivorship index values may be used as multipliers to permitting criteria, resulting in toxicological-ecological guidelines that incorporate toxicological information with regional ecological and population characteristics for local or regional application. We intended the procedure to serve as a step toward incorporating population and ecological information into regulatory procedures with the goal of protecting biodiversity from chronic toxic impacts.

Adaptation, Physiological↗

PubMed1995

Neuroangiographic assessment of aneurysm stability and impending rupture based on a non-linear biomathematical model.

The probability or risk of aneurysm rupture is assessed using conventional angiography by applying the aneurysm radius and systolic blood pressure obtained at examination to a non-linear biomathematical model of an aneurysm. A non-linear biomathematical model was developed based on Laplace's law to represent the viscoelastic relation between the wall tension and the radius. A differential expression of this relation was used to derive the critical radius: Rc = [2Et/P]2At/P where E is the elastic modulus of the aneurysm, t is the wall thickness, P is the pressure, and A is the elastic modulus of collagen. Using average values of E, A, and t, the risk of aneurysm rupture is defined as the area of integration under the curve defined by the minimum value of pressure (50 mmHg) and the patient pressure recorded at examination. This area was normalized by the area of integration defined by the pressure limits: 50 to 300 mmHg. This method of risk assessment was applied to four previously published case studies of patients with documented aneurysm rupture in which both the aneurysm size at rupture and the patient systolic blood pressure were reported. Two additional parameters were calculated to further evaluate aneurysm stability: (1) a ratio given as (Rexp/Rth) where Rexp is the radius of aneurysm rupture measured from angiography and Rth is the critical radius based on the model; and (2) chi 2 analysis defined by chi 2 = (O - E)2/E where O and E are the observed (Rexp) and expected (Rth) variables, respectively. The average systolic blood pressure and radius of aneurysm rupture was 147.2 mmHg and 3.95 mm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Ruptured↗

PubMed2003

Determining public health priorities for an ageing population: the value of a disability survey.

In order to determine which diseases and health problems were most strongly associated with long-term disability among the Thai elderly and to determine their public health priority, a national cross-sectional multistage random sampling survey was conducted in 1997. Four thousand and forty-eight Thai older persons aged 60 years and over were recruited and interviewed by trained interviewers. Overall, 769 (19%) people reported having a long-term disability. Participants with long-term disability (LD) reported having between one and 21 long-term diseases or health problems. Eighteen of these problems were independently associated with LD in logistic regression analysis. Nearly half of the cases with LD (46.4%) suffered from two or more health problems. The odds of LD increased with the number of problems suffered. The problems contributing most to the population burden of disease as assessed by population attributable risk fractions were hemiparesis, arthritis, accidents (unintentional injuries), blindness and other eye diseases, kyphosis, weakness of limbs, deafness, and hypertension. This ranking of public health priority differs from conventional approaches using mortality statistics and disability adjusted life years (DALYs). In conclusion, national disability surveys provide a valuable means of assessing the population burden of disability and determining the underlying causes of disability. These methods provide a direct assessment of disability prevalence and disease priorities for rapidly ageing transitional countries where death certification may be incomplete or inaccurate.

Aged↗

PubMed2003

Spills of fuel oil #6 and Orimulsion can have indistinguishable effects on the benthic meiofauna.

Fuel oil #6 is used for the production of electrical power in the United States. Orimulsion is being considered as an alternative fuel, but its value and risk compared to fuel oil #6 need to be assessed. Our study examined the relative impact of accidental spills of the two hydrocarbons on the meiofaunal community. To do so, we maintained microcosms of the shallow, sandy, subtidal environment for three months. Treatment microcosms received a single application of hydrocarbon-coated sand. As indicators of effect, we used copepod and nematode abundance and copepod species diversity, sex ratio, fecundity, age structure, and neutral-lipid content. A comparison of the hydrocarbon treatments showed no significant differences. The tests had adequate power to detect ecologically significant changes. Our results indicate that a spill of Orimulsion would have approximately the same impact as a spill of fuel oil #6 on the meiofauna.

Animals↗

PubMedDate not supplied

Impact of genetically modified crops on soil- and plant-associated microbial communities.

Transgenic or genetically modified plants possess novel genes that impart beneficial characteristics such as herbicide resistance. One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil- and plant-associated microbial communities. The potential for interaction between transgenic plants and plant residues and the soil microbial community is not well understood. The recognition that these interactions could change microbial biodiversity and affect ecosystem functioning has initiated a limited number of studies in the area. At this time, studies have shown the possibility that transgenes can be transferred to native soil microorganisms through horizontal gene transfer, although there is not evidence of this occurring in the soil. Furthermore, novel proteins have been shown to be released from transgenic plants into the soil ecosystem, and their presence can influence the biodiversity of the microbial community by selectively stimulating the growth of organisms that can use them. Microbial diversity can be altered when associated with transgenic plants; however, these effects are both variable and transient. Soil- and plant-associated microbial communities are influenced not only by plant species and transgene insertion but also by environmental factors such as field site and sampling date. Minor alterations in the diversity of the microbial community could affect soil health and ecosystem functioning, and therefore, the impact that plant variety may have on the dynamics of the rhizosphere microbial populations and in turn plant growth and health and ecosystem sustainability, requires further study.

Bacteria↗

PubMed2004

Projecting rates of spread for invasive species.

All else being equal, the faster an invading species spreads, the more dangerous its invasion. The projection of spread rate therefore ought to be a central part of the determination of invasion risk. Originally formulated in the 1970s to describe the spatial spread of advantageous alleles, integrodifference equation (IDE) models have since been co-opted by population biologists to describe the spread of populations. More recently, they have been modified to include population structure and environmental variability. We review how IDE models are formulated, how they are parameterized, and how they can be analyzed to project spread rates and the sensitivity of those rates to changes in model parameters. For illustrative purposes, we apply these models to Cytisus scoparius, a large shrub in the legume family that is considered a noxious invasive species in eastern and western North America, Chile, Australia, and New Zealand.

Algorithms↗

PubMed2006

The impact of imperfect vaccines on the evolution of HIV virulence.

A theoretical framework is proposed on which some hypotheses related to the impact of imperfect vaccines on the evolution of HIV virulence can be tested. For this, a linear increase of risk behaviour with vaccine efficacy is assumed. This is based on the hypothesis that people are prone to relax preventive measures by knowing that they and their partners are vaccinated and that this effect is more intense the more effective the vaccine is known to be. An additional, and perhaps more important hypothesis is related to the theoretical possibility that increased risk behaviour of some vaccinated individuals in partially protected populations could act as a selective pressure toward more virulent HIV strains. Those hypotheses were tested by a mathematical model that considers three different HIV strains competing against each other in a population partially protected by imperfect vaccines of distinct efficacies. Simulations of the model demonstrated that, under the above hypotheses, there is a shift in HIV virulence towards more aggressive strains with increase in vaccine efficacy, associated with a marked reduction in the total amount of transmission and, consequently, in the prevalence of HIV. Potential ways for further testing the theory/model and the implications of the results are discussed.

AIDS Vaccines↗

PubMed2004

Using ecological risk assessment to identify the major anthropogenic stressor in the Waquoit Bay Watershed, Cape Cod, Massachusetts.

The Waquoit Bay Watershed ecological risk assessment was performed by an interdisciplinary and interagency workgroup. This paper focuses on the steps taken to formulate the analysis plan for this watershed assessment. The workgroup initially conducted a series of meetings with the general public and local and state managers to determine environmental management objectives for the watershed. The workgroup then decided that more information was needed on the impacts of six stressors: nutrient enrichment, physical alteration of habitat, altered freshwater flow, toxic chemicals, pathogens, and fisheries harvesting. Assessment endpoints were selected to establish the link between environmental management objectives, impacts of stressors, and scientifically measurable endpoints. The following assessment end-points were selected: estuarine eelgrass cover, scallop abundance, finfish diversity and abundance, wetland bird distribution and abundance, piping plover distribution and abundance, tissue contaminant levels, and brook trout distribution and abundance in streams. A conceptual model was developed to show the pathways between human activities, stressors, and ecological effects. The workgroup analyzed comparative risks, by first ranking stressors in terms of their potential risk to biotic resources in the watershed. Then stressors were evaluated by considering the components of stressors (e.g., the stressor chemical pollution included both heavy metals and chlorinated solvents components) in terms of intensity and extensiveness. The workgroup identified nutrient enrichment as the major stressor. Nutrient enrichment comprised both phosphorus enrichment in freshwater ponds and nitrogen enrichment within estuaries. Because phosphorus impacts were being analyzed and mitigated by the Air Force Center for Environmental Excellence, this assessment focused on nitrogen. The process followed to identify the predominant stressor and focus the analyses on nitrogen impacts on eelgrass and scallops will serve as an example of how to increase the use of the findings of a watershed assessment in decision making.

Animals↗