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Results for “environmental variability”

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PubMed1996

The behavioral and emotional well-being of school-age children with different birth weights.

OBJECTIVE: To describe the mental and emotional well-being of children born at different birth weights assessed at school age and to identify neonatal, intervening health, and sociodemographic and environmental factors associated with mental and emotional well-being. METHODS: To address this issue, we used a prospective cohort study involving two previously studied cohorts, which were recontacted at 8 to 10 years of age to provide a multisite sample of 247 children weighing 1000 g or less at birth, 364 weighing 1001 to 1500 g, 724 weighing 1501 to 2500 g, and 533 weighing more than 2500 g. Maternal reports were obtained on three standardized measures of mental and emotional well-being (the Rand General Well-being Scale, the Behavior Problem Index, and the Harter Scale of Child Competence) and on intervening health, sociodemographic, and environmental variables. Neonatal variables were derived from records at birth. Statistical techniques included analysis of variance and ordinary least squares multiple regression. RESULTS: Lower birth weight children did not differ on the General Well-being Scale but were more likely to have behavior problems and to be considered less competent. Other important correlates of mental and emotional well-being included childhood illness, maternal mental health, home environment score, and exposure to household cigarette smoking. CONCLUSION: Although lower birth weight children have poorer mental and emotional well-being, a substantial portion of this adverse outcome reflects modifiable environmental factors.

Analysis of Variance↗
PubMed2006

Diet and capture of Hypostomus strigaticeps (Siluriformes, Loricariidae) in a small Brazilian stream: relationship with limnological aspects.

The purpose of this study is to ascertain whether variations in the limnological parameters of the Corumbataí river resulting from the discharge of a variety of wastes into its waters may be responsible for spatial shifts in the diet and capture of the armored catfish Hypostomus strigaticeps (Regan, 1907). Individuals were collected over a period of two years from two sites with similar physical, albeit distinct limnological characteristics. As a whole, the environmental variables (temperature, pH, dissolved oxygen, electrical conductivity, and total coliforms and fecal coliforms) of the two sites were found to vary significantly. The food items found in the guts of these armored catfish (sediments, diatoms, fungi hyphae, chlorophytes, cyanophytes and non-identified material) ranked differently in samples from the two sites. In the more polluted (site B), diatoms and chlorophytes ranked higher in the diet than in that of individuals caught in the more preserved location (site A). This fact may be related to the greater amount of organic material found at site B, which provides favorable environmental conditions for such algae and, consequently, for algivorous fishes. Even so, fewer fish were captured at site B than at site A, suggesting that although food is more abundant in the more polluted site, its limnological conditions appear, on the whole, to be less beneficial than the conditions at site A.

Animals↗
PubMed1997

The limits of life on Earth and searching for life on Mars.

Considerations of basic properties of bacteria such as size, structure, and metabolic versatility allow one to understand how these remarkable life-forms are so adaptable to environments previously thought to be uninhabitable. It is now appreciated that bacteria on Earth can utilize almost any redox couple that yields energy, taking advantage of this energy, while transforming the elements during metabolism. The ability to grow at the expense of inorganic redox couples allows the microbes to occupy niches not available to the more metabolically constrained eukaryotes. Furthermore, the simplicity of the bacterial structure allows them considerably more resistance to environmental variables (pH, salinity, temperature) that are toxic or lethal to more complex organisms. This information can be used to explain the predominance of prokaryotes in extreme environments on Earth, and to speculate as to simple types of metabolism and biogeochemical cycles that may exist on this planet, Mars, and perhaps other non-Earth environments.

Adenosine Triphosphate↗
PubMedDate not supplied

2D mapping by Kohonen networks of the air quality data from a large city.

The 15-variable environmental data (7 concentrations: CO, SO2, O3, NOx, NO, NO2, particulate matter smaller than 10 micron (PM10), and 8 weather data: cloudiness, rainfall, insolation factor (Isfi), temperature, pressure at two locations, and wind intensity with direction) in a period of 45 days with 1-h intervals were extracted from a larger database of concentrations recorded in minute intervals for the same time period. The monitoring site was located in the City of Buenos Aires in a relatively heavy traffic crossroad of two avenues. The data required special pretreatment where the hourly content of rain, wind intensity, wind velocity, and cloudiness were concerned. The new variable named insolation factor (relative UV radiation) calculated on the basis of the general meteorological data, the geographic position of the monitoring site, cloudiness, date, and the time of the recording was composed. The relative intensity of UV radiation was modeled by a Gaussian function, multiplied by a cloudiness factor. Based on the 14-variable input and the 1-variable output (ozone) data, first, the clustering of all 980 data records was made. The top map clustering showing the ozone concentration was related to the maps of all 14 variables. The link between O3 clusters, NO2, and Isfi weight levels is shown and discussed. As a preliminary result of this study some of the most interesting correlations between the maps and remaining variables are given.

Journal Article↗
PubMed1999

Fitness of wild-caught Drosophila melanogaster females: allozyme variants of GPDH, ADH, PGM, and EST.

We have collected several hundred Drosophila melanogaster flies (near Davis, California), isolated them individually, without anesthesia, at the collecting site, and estimated the fitness components of the wild-caught females under different environmental conditions. The fitness parameters measured are fecundity, oviposition rate, and productivity (egg-to-adult viability, development rate, and number of progeny). The environmental variables are two temperatures (22 degrees C and 28 degrees C) and two densities ('scant' and 'crowded'). After the fitness measurements are completed for each individual female, its genotype is determined at four loci encoding enzymes: GPDH and ADH, located on chromosome II; and PGM and EST-C, located on chromosome III. Density has a large significant effect on productivity; temperature has significant effects on fecundity, oviposition rate, and development rate. The experiments show that allozyme polymorphisms are associated with selection effects. Fitness differences between allozyme genotypes occur for all fitness components, except oviposition rate. But which genotype is superior depends on the environmental conditions; heterozygotes exhibit higher fitness than homozygotes in a number of cases, but inferior in others. A unique feature of the present experiments is that the experimental flies are wild-caught females rather than laboratory-bred individuals.

Alcohol Dehydrogenase↗
PubMed2004

Climate and habitat barriers to dispersal in the highly mobile grey wolf.

We reanalysed published data to evaluate whether climate and habitat are barriers to dispersal in one of the most mobile and widely distributed mammals, the grey wolf (Canis lupus). Distance-based redundancy analysis (dbRDA) was used to examine the amount of variation in genetic distances that could be explained by an array of environmental factors, including geographical distance. Patterns in genetic variation were also examined using MDS plots among populations and relationships between genetic structure and individual environmental variables were further explored using the BIOENV procedure. We found that, contrary to a previous report, a pattern of isolation with distance is evident on a continental scale in the North American wolf population. This pattern is apparently related to climate and habitat. Specifically, vegetation types appear to play a role in the genetic dissimilarities among populations. When we controlled for the effect of spatial variation, climate was still associated with genetic distance. Further, partitioning of geographical distances into latitudinal and longitudinal axes revealed that the east-west gradient had the strongest relationship with genetic distance. We suggest two possible mechanisms by which environmental conditions may influence the dispersal decisions made by wolves.

Animals↗
PubMed1989

Involvement of DNA repair in cancer and aging.

The theory of aging which proposes that DNA repair capacity declines with age and/or DNA damage accumulates with age, resulting in increasingly aberrant gene expression, is attractive but still unproven. Most results that do not support the theory are at least neutral. We propose that much of the ambiguity produced by work so far is due to (a) the difficulty of controlling all relevant variables, including particularly the proliferation state of the cells used and the location and nature of the damage being repaired, and (b) the existence of multiple and overlapping DNA repair pathways. A better knowledge of the critical, rate-limiting events in DNA repair in vivo, and the application of more sophisticated approaches for studying these events, may ultimately resolve the ambiguities. The causal relationship between DNA damage and cancer seems more secure. Declining DNA repair capacity with age would be expected to accelerate the increased incidence of cancer with age, but it is not known how important this is compared to other genetic and environmental variables. Results with genetic diseases generally support this view. Diseases characterized by DNA repair deficiencies are accompanied by phenomena that are also characteristic of normal aging, but a causal relationship has not been established. However, some of these diseases do constitute a strong risk factor for cancer. Even less convincing is a causal link between DNA repair deficiencies and aging in the so-called premature aging syndromes.

Aging↗
PubMed2001

The standardized fish bioassay procedure for detecting and culturing actively toxic Pfiesteria, used by two reference laboratories for atlantic and gulf coast states.

In the absence of purified standards of toxins from Pfiesteria species, appropriately conducted fish bioassays are the "gold standard" that must be used to detect toxic strains of Pfiesteria spp. from natural estuarine water or sediment samples and to culture actively toxic Pfiesteria. In this article, we describe the standardized steps of our fish bioassay as an abbreviated term for a procedure that includes two sets of trials with fish, following the Henle-Koch postulates modified for toxic rather than infectious agents. This procedure was developed in 1991, and has been refined over more than 12 years of experience in research with toxic Pfiesteria. The steps involve isolating toxic strains of Pfiesteria (or other potentially, as-yet-undetected, toxic Pfiesteria or Pfiesteria-like species) from fish-killing bioassays with natural samples; growing the clones with axenic algal prey; and retesting the isolates in a second set of fish bioassays. The specific environmental conditions used (e.g., temperature, salinity, light, other factors) must remain flexible, given the wide range of conditions from which natural estuarine samples are derived. We present a comparison of information provided for fish culture conditions, reported in international science journals in which such research is routinely published, and we provide information from more than 2,000 fish bioassays with toxic Pfiesteria, along with recommendations for suitable ranges and frequency of monitoring of environmental variables. We present data demonstrating that algal assays, unlike these standardized fish bioassays, should not be used to detect toxic strains of Pfiesteria spp. Finally, we recommend how quality control/assurance can be most rapidly advanced among laboratories engaged in studies that require research-quality isolates of toxic Pfiesteria spp.

Animals↗
PubMed2002

Heavy equipment maintenance wastes and environmental management in the mining industry.

Maintenance wastes, if not managed properly, represent significant environmental issues for mining operations. Petroleum hydrocarbon liquid wastes were studied at an Australian site and a review of the literature and technology vendors was carried out to identify oil/water separation technologies. Treatment technologies and practices for managing oily wastewater, used across the broader mining industry in the Asia-Pacific region, were also identified. Key findings from the study were: (1) primary treatment is required to remove grease oil contamination and to protect secondary oily wastewater treatment systems from being overloaded; (2) selection of an effective secondary treatment system is dependent on influent oil droplet size and concentration, suspended solids concentration, flow rates (and their variability), environmental conditions, maintenance schedules and effectiveness, treatment targets and costs; and (3) oily wastewater treatment systems, based on mechanical separation, are favoured over those that are chemically based, as they simplify operational requirements. Source reduction, through housekeeping, equipment and reagent modifications, and segregation and/or consolidation of hydrocarbon waste streams, minimizes treatment costs, safety and environmental impact.

Costs and Cost Analysis↗
PubMed1993

Concentrations of zinc and chromium in aquatic macrophytes from the sudbury and muskoka regions of Ontario, Canada.

Root and shoot samples of Eriocaulon septangulare, Nuphar variegatum, Nymphaea odorata and Pontederia cordata were collected from 15 lakes in central Ontario during the summer of 1988 to investigate possible relationships between zinc and chromium levels in aquatic macrophytes and water and sediment variables. Although concentrations of zinc and chromium differed greatly among the four species, both metals were consistently higher in Eriocaulon. Generally, root and rhizome tissue contained higher zinc and chromium than shoot tissues of the same species and site. Zinc concentrations (dry weight) ranged from 6.3 microg g(-1) in Nuphar shoots to 87.7 microg g(-1) in whole Eriocaulon. Chromium ranged from 0.23 microg g(-1) in Pontederia shoots to 23.9 microg g(-1) in whole Eriocaulon. No significant trends were detected throughout the growing season in macrophyte or sediment concentrations of either metal. Results of multiple linear regression analyses of several water quality and environmental variables on Eriocaulon indicated that sediment zinc was the best predictor of plant zinc, and sediment chromium and calcium were the best predictors of plant chromium.

Journal Article↗
PubMed1983

Effects of particulate air pollution on asthmatics.

Twenty-four asthmatic subjects in Denver were followed from January through March 1979, a three-month period in which Denver air pollution levels are generally high and variable. Dichotomous, virtual impactor samplers provided daily measurements (micrograms/m3) of inhaled particulate matter (total mass, sulfates, and nitrates) for coarse (2.5--15 micrograms in aerodynamic diameter) and fine fractions (less than 2.5 micrometers). Carbon monoxide, sulfur dioxide, ozone, temperature, and barometric pressure were also measured. Twice daily measurements of each subject's peak expiratory flow rates, use of as-needed aerosolized bronchodilators, and report of airways obstruction symptoms characteristic of asthma were tested for relationships to air pollutants using a random effects model across subjects. During the time actually observed, there were very few days in which high levels of suspended particulates were recorded. Of the environmental variables studied, only fine nitrates were associated with increased symptom reports and increased aerosolized bronchodilator usage.

Adult↗
PubMed1984

Improved methodology for field validation of industrial hygiene monitoring methods.

During the development and validation of industrial hygiene monitoring methods in the laboratory, various parameters of collection, storage, and analysis are studied. It is not feasible, however, to study all the environmental variables in the laboratory, so field validation is necessary to detect problems which are specific to the actual work site. A statistical procedure to evaluate the field validation experiment is described together with the methodology necessary to perform these experiments and the equipment to facilitate these experiments. These procedures are demonstrated in an experiment measuring acrylonitrile in the workplace.

Acrylonitrile↗
PubMed1985

Residential formaldehyde sampling--current and recommended practices.

The usefulness of test results in assessing the health hazard potential of residential formaldehyde exposures depends in great measure on the accuracy and reliability of sampling/analysis methods employed, the protocol used in collecting samples, sampling objectives, and an understanding of residential formaldehyde dynamics and their relationship to environmental variables. Active sampling and analysis methods including detector tubes, the impinger/chromotropic acid method, the impinger/pararosaniline method, and the CEA continuous monitor are reviewed as to advantages and limitations for residential sampling. Passive dosimeter methods including the Dupont Pro-Tec Badge, 3M Monitor, Air Quality Research, Inc. Passive Formaldehyde Kit, and Envirotech, Inc. Dosimeter are also reviewed. Sampling considerations for one-time formaldehyde sampling using the impinger/chromotropic acid method are discussed in detail, including pre-sampling closure of residences, maintenance of a standard indoor temperature both before and during sampling, the undesirability of sampling during cold, dry winter weather, sample number, sampling location, height and duration, environmental measurements during sampling, source identification and sample storage. A model formaldehyde sampling protocol based on the impinger/chromotropic acid method is described.

Air Pollutants↗
PubMed2006

Spectral and landscape characterization of filarious and non-filarious villages in Egypt.

Filarial disease is endemic in Egypt in some villages of Nile Delta governorates where it is transmitted by Culex pipiens female. GIS functions are used to identify environmental indicators of high-risk village as indicated by mosquito density, human infection rate, vector species composition, mean life expectancy "e(o)" & environmental variables (geology, hydrology, soil types, etc) as well as meteorological factors (temperature, RH and rainfall) in relation to filaria transmission risk. Remote-sensing technology was used to distinguish between the two studied villages as high and non-infected, as defined by microfilarial prevalence. The results indicate that filaria transmission risk is higher at an area characterized by highly productive aquifers, silt clay soil, receiving little amount of rain with low relative humidity (RH). The results indicate that the most important landscape elements associated with prevalence are water and different vegetation. This work showed that the integration between GIS and remote sensing technologies to analyze and identify the environmental factors, associated with the disease, did not only allow mapping icurrent spatial patterns, but also predicting its distribution under expected future developmental and environmental changes.

Animals↗
PubMedDate not supplied

Geographic Information System mapping of snakebite incidence in northern Ghana and Nigeria using environmental indicators: a preliminary study.

Snakebite is an important health problem in many parts of rural West Africa where the carpet or sawscaled viper, Echis ocellatus, is responsible for most of the morbidity and mortality. Marked seasonal and geographical variation in the incidence of snakebite suggests an association with environmental factors that could potentially identify high-risk areas and inform health care decision making. This preliminary investigation describes a Geographic Information System (GIS) approach to risk mapping that identifies environmental variables potentially associated with variation in snakebite incidence rates at a number of health facilities in northern Ghana and Nigeria and which has been used to create a preliminary risk map of the potential probability of high snakebite incidence for West Africa. Detailed and extensive further studies will enable the more reliable estimation of snakebite incidence at a local level across the region.

Environmental Health↗
PubMed2004

Evaluation of environmental risk factors for leptospirosis in dogs: 36 cases (1997-2002).

OBJECTIVE: To identify environmental risk factors for leptospirosis. DESIGN: Retrospective study. ANIMALS: 36 dogs with leptospirosis and 138 dogs seronegative for leptospirosis as determined by microscopic agglutination test for antibodies against Leptospira spp. PROCEDURES: Medical records of dogs evaluated for leptospirosis from 1997 though 2002 were identified. Owner address was used to geocode locations of dogs, and location-specific environmental risk factor data were obtained by use of a geographic information system. Risk of leptospirosis was estimated by odds ratios, controlling for potential confounding by dog age, sex, and breed. RESULTS: Leptospirosis in 19 of the 30 dogs in which an infecting Leptospira serovar could be identified was associated with Leptospira kirschneri serovar grippotyphosa infection. Dogs in which a diagnosis of leptospirosis was made, and dogs with leptospirosis caused by L kirschneri serovar grippotyphosa, were more likely to have addresses located in areas classified as rural in 1990 but urban in 2000. By use of information on recent urbanization and a logistic regression model, the status of 81.6% and 89.8% of dogs with leptospirosis and leptospirosis caused by serovar grippotyphosa, respectively, were correctly classified. Other environmental variables (proximity to streams, recreational areas, farmland, wetlands, areas subject to flooding, and areas with poor drainage; annual rainfall; and county cattle or pig population) did not significantly improve accuracy of classification. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs in periurban areas are at greater risk of leptospirosis. Vaccination of dogs in these areas to protect against leptospirosis should be considered.

Animals↗
PubMed2004

Effects of alcohol and drug use on inpatient and residential treatment among youth with severe emotional disturbance in Medicaid-funded behavioral health care plans.

This study examined the use of alcohol and recreational drugs among 875 youth with severe emotional disturbance (SED) enrolled in Medicaid-funded behavioral health care plans, and whether co-occurring SED and substance use affected the subsequent likelihood of receiving inpatient and/or residential treatment. Youth at five sites nationwide were interviewed about their use of drugs and alcohol, while interviews with their caregivers elicited information about youths' service utilization, degree of functional impairment, and a series of demographic and environmental variables. Results indicated that half of the youth (52%) reported lifetime use of alcohol, street drugs, or over-the-counter medications for recreational purposes, while 18% reported use in the past 30 days. Among those reporting recent use, 32% reported using drugs only, 34% alcohol only, and 33% reported use of both drugs and alcohol. In multivariate logistic regression analyses, the effect of recent use was stronger than that of lifetime use; however, the largest effect occurred for those reporting recent use of both drugs and alcohol, versus either alone, or none. Differences remained significant when controlling for managed care versus fee for service enrollment as well as child, family, and environmental characteristics including study site. These results mirror those of prior studies that found an association between substance use and greater likelihood of inpatient services, even in managed care settings.

Adolescent↗
PubMed1997

Community structure and dynamics in desert ecosystems: potential implications for insecticide risk assessment.

Insecticides are increasingly being used in hot arid ecosystems. The evaluation of the ecological risk these insecticides may pose, however, is based largely on data derived from temperate organisms and ecosystems. The major differences in the composition, structure, and functioning of desert animal communities when compared to temperate terrestrial ecosystems are discussed. Desert communities are characterized by a high fraction of ectotherms (both vertebrates and invertebrates);rodents and insectivores appear to dominate the mammalian fauna; and detritivores make up a very large part of the arthropod fauna. Presently available toxicity data cover these groups only to a very limited extent. It is not known if the ranges of insecticide susceptibility observed in temperate species are representative of those in arid organisms. Thus, it is not certain that ecotoxicological assessments based on such data sets adequately protect desert animal communities. It is shown that food web connectance is higher in desert ecosystems than in temperate grasslands or forests. This may to a large extent be due to the high degree of omnivory among desert organisms. Population regulation between predators and prey appears to be weaker in deserts. The same is often, though not always, the case for competition among desert organisms. It is argued that such characteristics will reduce the chance that strong indirect effects of insecticide perturbations will occur. In spite of the fact that many desert organisms are well adapted to cope with high temporal and spatial environmental variability, there is no reason to believe that they will always recover more rapidly from population perturbations caused by insecticides. The relatively large physiological and life-history plasticity encountered in many desert animals may increase tolerance to insecticide stress. Food chains are longer in deserts than in temperate grasslands and forests. The implications of this observation for the risk of biomagnification of contaminants are discussed.

Agriculture↗