Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 21
Filter
1.
Indoor Air ; 27(3): 631-641, 2017 05.
Article in English | MEDLINE | ID: mdl-27555567

ABSTRACT

Uptake kinetics of semi-volatile organic compounds (SVOCs) present indoors, namely phthalates and halogenated flame retardants (HFRs), were characterized for cellulose-based cotton and rayon fabrics. Cotton and rayon showed similar accumulation of gas- and particle-phase SVOCs, when normalized to planar surface area. Accumulation was 3-10 times greater by rayon than cotton, when normalized to Brunauer-Emmett-Teller (BET) specific surface area which suggests that cotton could have a longer linear uptake phase than rayon. Linear uptake rates of eight consistently detected HFRs over 56 days of 0.35-0.92 m3 /day.dm2 planar surface area and mass transfer coefficients of 1.5-3.8 m/h were statistically similar for cotton and rayon and similar to those for uptake to passive air sampling media. These results suggest air-side controlled uptake and that, on average, 2 m2 of clothing typically worn by a person would sequester the equivalent of the chemical content in 100 m3 of air per day. Distribution coefficients between fabric and air (K') ranged from 6.5 to 7.7 (log K') and were within the range of partition coefficients measured for selected phthalates as reported in the literature. The distribution coefficients were similar for low molecular weight HFRs, and up to two orders of magnitude lower than the equilibrium partition coefficients estimated using the COSMO-RS model. Based on the COSMO-RS model, time to reach 95% of equilibrium for PBDEs between fabric and gas-phase compounds ranged from 0.1 to >10 years for low to high molecular weight HFRs.


Subject(s)
Air Pollution, Indoor/analysis , Cellulose/chemistry , Cotton Fiber , Flame Retardants/analysis , Phthalic Acids/analysis , Clothing , Ontario , Textiles , Volatile Organic Compounds
2.
Brain Behav Immun ; 45: 253-62, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25555531

ABSTRACT

Traumatic brain injury (TBI) results in a significant inflammatory burden that perpetuates the production of inflammatory mediators and biomarkers. Interleukin-6 (IL-6) is a pro-inflammatory cytokine known to be elevated after trauma, and a major contributor to the inflammatory response following TBI. Previous studies have investigated associations between IL-6 and outcome following TBI, but to date, studies have been inconsistent in their conclusions. We hypothesized that cohort heterogeneity, temporal inflammatory profiles, and concurrent inflammatory marker associations are critical to characterize when targeting subpopulations for anti-inflammatory therapies. Toward this objective, we used serial cerebrospinal fluid (CSF) samples to generate temporal acute IL-6 trajectory (TRAJ) profiles in a prospective cohort of adults with severe TBI (n=114). We examined the impact of injury type on IL-6 profiles, and how IL-6 profiles impact sub-acute (2weeks-3months) serum inflammatory marker load and long-term global outcome 6-12months post-injury. There were two distinct acute CSF IL-6 profiles, a high and low TRAJ group. Individuals in the high TRAJ had increased odds of unfavorable Glasgow Outcome Scale (GOS) scores at 6months (adjusted OR=3.436, 95% CI: 1.259, 9.380). Individuals in the high TRAJ also had higher mean acute CSF inflammatory load compared to individuals in the low TRAJ (p⩽0.05). The two groups did not differ with respect acute serum profiles; however, individuals in the high CSF IL-6 TRAJ also had higher mean sub-acute serum IL-1ß and IL-6 levels compared with the low TRAJ group (p⩽0.05). Lastly, injury type (isolated TBI vs. TBI+polytrauma) was associated with IL-6 TRAJ group (χ(2)=5.31, p=0.02). Specifically, there was 70% concordance between those with TBI+polytrauma and the low TRAJ; in contrast, isolated TBI was similarly distributed between TRAJ groups. These data provide evidence that sustained, elevated levels of CSF IL-6 are associated with an increased inflammatory load, and these increases are associated with increased odds for unfavorable global outcomes in the first year following TBI. Future studies should explore additional factors contributing to IL-6 elevations, and therapies to mitigate its detrimental effects on outcome.


Subject(s)
Brain Injuries/cerebrospinal fluid , Cytokines/cerebrospinal fluid , Interleukin-6/cerebrospinal fluid , Multiple Trauma/cerebrospinal fluid , Adult , Brain Injuries/immunology , Brain Injuries/rehabilitation , Cohort Studies , Cytokines/immunology , Disease Progression , Female , Glasgow Outcome Scale , Humans , Injury Severity Score , Interleukin-1beta/immunology , Interleukin-6/immunology , Logistic Models , Male , Multiple Trauma/immunology , Prognosis , Prospective Studies
3.
Ecotoxicol Environ Saf ; 73(3): 222-30, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20036006

ABSTRACT

Contaminant loadings to the Venice Lagoon peaked from 1950s-1980s and although they have since declined, contaminant concentrations remain elevated in sediment and seafood. In order to identify the relative importance of contaminant sources, inter-media exchange and removal pathways, a modified 10-segment fugacity/aquivalence-based model was developed for octachlorodibenzodioxin/furan (OCDD/F), PCB-180, Pb and Cu in the Venice Lagoon. Results showed that in-place pollution nearby the industrial area, current industrial discharges, and tributary loadings were the main sources of contaminants to the lagoon, with negligible contributions from the atmosphere. The fate of these contaminants was governed by sediment-water exchange with simultaneous advective transport by water circulation. Contaminants circulated amongst the northern and central basins with a small fraction reaching the far southern basin and the Chioggia inlet. As a consequence, we estimated limited contaminant transfer to the Adriatic Sea, trapping the majority of contaminants in the sediment in this "average" circulation scenario which does not account for periodic flooding events.


Subject(s)
Environmental Monitoring/methods , Models, Theoretical , Water Movements , Water Pollutants, Chemical/analysis , Finite Element Analysis , Furans/analysis , Italy , Mediterranean Sea , Metals, Heavy/analysis , Polychlorinated Biphenyls/analysis , Polychlorinated Dibenzodioxins/analogs & derivatives , Polychlorinated Dibenzodioxins/analysis , Seawater/chemistry
4.
Ecotoxicol Environ Saf ; 73(3): 231-9, 2010 Mar.
Article in English | MEDLINE | ID: mdl-19493571

ABSTRACT

A Monte Carlo analysis is used to quantify environmental parametric uncertainty in a multi-segment, multi-chemical model of the Venice Lagoon. Scientific knowledge, expert judgment and observational data are used to formulate prior probability distributions that characterize the uncertainty pertaining to 43 environmental system parameters. The propagation of this uncertainty through the model is then assessed by a comparative analysis of the moments (central tendency, dispersion) of the model output distributions. We also apply principal component analysis in combination with correlation analysis to identify the most influential parameters, thereby gaining mechanistic insights into the ecosystem functioning. We found that modeled concentrations of Cu, Pb, OCDD/F and PCB-180 varied by up to an order of magnitude, exhibiting both contaminant- and site-specific variability. These distributions generally overlapped with the measured concentration ranges. We also found that the uncertainty of the contaminant concentrations in the Venice Lagoon was characterized by two modes of spatial variability, mainly driven by the local hydrodynamic regime, which separate the northern and central parts of the lagoon and the more isolated southern basin. While spatial contaminant gradients in the lagoon were primarily shaped by hydrology, our analysis also shows that the interplay amongst the in-place historical pollution in the central lagoon, the local suspended sediment concentrations and the sediment burial rates exerts significant control on the variability of the contaminant concentrations. We conclude that the probabilistic analysis presented herein is valuable for quantifying uncertainty and probing its cause in over-parameterized models, while some of our results can be used to dictate where additional data collection efforts should focus on and the directions that future model refinement should follow.


Subject(s)
Environmental Monitoring/methods , Models, Theoretical , Seawater/chemistry , Water Movements , Water Pollutants, Chemical/analysis , Environmental Monitoring/statistics & numerical data , Geologic Sediments/chemistry , Italy , Mediterranean Sea , Monte Carlo Method , Principal Component Analysis , Uncertainty
5.
Chemosphere ; 74(3): 404-11, 2009 Jan.
Article in English | MEDLINE | ID: mdl-19022474

ABSTRACT

Surface soils and sediments were collected in Toronto, Canada to investigate the concentrations and enantiomeric signatures of urban versus rural locations. Samples were analyzed for polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and organochlorine pesticides (OCs). In soils, the sum of 10 PCB congeners (Sigma PCB 28, 52, 95, 101, 118, 136, 138, 149, 153, 180) and 15 PAHs (Sigma PAHs) ranged from 0.76-58 to 58-3200 ng g(-1), respectively. The most abundant OCs detected were DDTs, followed by chlordanes and endosulfans. Sigma PAHs exhibited an urban-rural gradient of up to 60 times but a gradient was not observed for Sigma PCBs and OCs which may reflect local sources of these chemicals. In sediments, Sigma PCBs and Sigma PAHs ranged from 0.03-23 ng g(-1) to 42-3300 ng g(-1), respectively. Sigma PCBs, Sigma PAHs, chlordanes and DDTs exhibited weak urban-rural gradients. Chiral signatures of PCB 95, 136, 149, trans-chlordane (TC), cis-chlordane (CC) and o,p-DDT were characterized to study the enantiomeric degradation in urban versus rural areas and its relation to contaminant levels. Supplementary to these data, we also report on the chiral signatures of PCBs in UK lake sediments from a variety of urban and rural locations. The extent of enantiomeric degradation was expressed as the enantiomeric excess (EE%) which is defined as 100x(E1-E2)/(E1+E2), where E1 is always the most abundant enantiomer and E2 is the least abundant enantiomer. The EE% of PCB 149 in the UK sediments was negatively correlated (p<0.05) with Sigma PAHs suggesting either more recent emissions of this PCB congener in the more contaminated urban locations and hence a more racemic signature or less enantiomeric degradation of the congener in more contaminated urban soils. However, no significant correlation was observed between EE% of any of the chiral chemicals and contaminant levels in the Toronto soils.


Subject(s)
Cities , Environmental Monitoring , Geologic Sediments/analysis , Hydrocarbons, Chlorinated/analysis , Pesticides/analysis , Soil Pollutants/analysis , Canada , Chlordan/analysis , Chlordan/chemistry , DDT/analysis , DDT/chemistry , Geologic Sediments/chemistry , Hydrocarbons, Chlorinated/chemistry , Pesticides/chemistry , Polychlorinated Biphenyls/analysis , Polychlorinated Biphenyls/chemistry , Soil Pollutants/chemistry , Stereoisomerism , United Kingdom
6.
Qual Life Res ; 12(8): 953-61, 2003 Dec.
Article in English | MEDLINE | ID: mdl-14651414

ABSTRACT

BACKGROUND: Headache impact test (HIT) is a precise, practical tool that quantifies the impact of headache on respondents' lives. It is the first widely-available dynamic health assessment (DynHA). Applications of this brief, precise survey include population based screening for disabling headaches, tracking of individual patient scores over time, disease management programs and others. We use data from Internet HIT assessments during the fall of 2000 to (1) evaluate characteristics of respondents and assessments, (2) assess the utility of joint administration of HIT and the SF-8 Health Survey (SF-8) to screen for migraine and depression, and (3) explore associations between HIT scores and subsequent healthcare-related attitudes and behaviors. METHODS: We analyzed Internet HIT surveys completed between 9/1 and 11/30/2000 (n = 19,195). Subsamples include respondents who also completed (1) a 12-item Internet survey assessing severity, frequency, cause and management of headaches; (2) an e-mail survey measuring healthcare-related behaviors; (3) the SF-8; or (4) the website registration process, providing age and gender data. We used analysis of variance (ANOVA) to evaluate HIT score differences associated with age, gender, headache severity or frequency, and healthcare-related behaviors and attitudes and chi2 tests to assess the prevalence and comorbidity of migraine and depression. RESULTS: Three-quarters of respondents achieved a precise HIT score in < or = 5 items. Most had moderate/severe headaches; 65% had headaches at least monthly. HIT scores were directly related to headache severity and frequency. Most respondents were females, with significantly higher HIT scores than males. Most HIT respondents were between ages 25 and 54 (HIT scores were higher for younger respondents). Sixty four percent screened positive for migraine; 20% for depression. Both conditions were more prevalent among females than males. Comorbid migraine and depression was 50% more prevalent among females and increased with age until age 50. Patients with worse headache impact were more likely to seek care, discuss headaches with their providers and find HIT useful. CONCLUSIONS: It is feasible to use Internet-based dynamic assessments to measure health status. These data complement previous results showing that HIT differentiates respondents according to headache characteristics (severity and frequency). HIT plus SF-8 yields a practical screen for migraine and depression in headache patients and may lead to more effective treatment for patients with these conditions. Preliminary findings suggest that the experience of taking HIT on the Internet may motivate headache patients to seek care and discuss headaches with their providers.


Subject(s)
Headache/physiopathology , Internet , Sickness Impact Profile , Surveys and Questionnaires , Adolescent , Adult , Aged , Computer Systems , Feasibility Studies , Female , Humans , Male , Middle Aged , Psychometrics , Quality of Life
7.
Arch Environ Contam Toxicol ; 44(4): 421-9, 2003 May.
Article in English | MEDLINE | ID: mdl-12712271

ABSTRACT

A novel environmentally derived mixture that integrates exposure to atmospherically derived gas- and particle-phase compounds in urban areas-namely, the organic film that develops as a thin layer on urban impervious surfaces-was investigated for its ability to induce gene expression via the aryl hydrocarbon receptor (AhR). The organic film on window glass from 21 sites in downtown Toronto (Ontario, Canada) was found to contain a complex mixture of environmental contaminants typical of urban environments, notably PAHs, n-alkanes, PCBs, organochlorine (OC) pesticides, and polar constituents. Using a stably transfected reporter cell line, we found that the crude extract of organic film induces AhR-dependent gene expression in a dose-dependent fashion. Three subfractions of the crude extract induced significant luciferase expression: nonpolar aromatic > polar aromatic > nonpolar aliphatic. Recombination of the fractions did not lead to recovery of the full activity of the crude extract, which may indicate that some of the compounds lost during fractionation were significant contributors to the induction observed with the crude extract. The interactions between a tonic dose of B[ a]P (10(-7) M) and each of the aromatic fractions were determined to be antagonistic following analysis by the method of isoboles. Our results suggest that organic film makes up a diverse array of compounds active at the AhR and that these compounds may not interact in a strictly additive manner.


Subject(s)
Air Pollutants/toxicity , Gene Expression/drug effects , Glass/chemistry , Organic Chemicals/toxicity , Receptors, Aryl Hydrocarbon/genetics , Animals , Cities , Dose-Response Relationship, Drug , Drug Interactions , Genes, Reporter/genetics , Luciferases/genetics , Mice , Ontario , Surface Properties , Tumor Cells, Cultured
8.
Environ Sci Technol ; 35(20): 4031-7, 2001 Oct 15.
Article in English | MEDLINE | ID: mdl-11686363

ABSTRACT

Atmospherically derived organic films have been found on an impervious surface along an urban-rural gradient in the Toronto, Ontario, Canada area. Film thickness and concentrations, expressed on an aerial basis, of sigman-alkanes, sigmaPCB, sigmaPAH, and sigmaOC (organochlorine) pesticides decrease along this gradient, coincident with lower atmospheric emissions (PCB and PAH) and less accumulation in thinner rural films (OC pesticides). For PCBs and some OC pesticides, patterns of chemical abundance also shift, indicating a "fresh" pattern near emission sources (downtown) versus aged patterns at rural locations that are indicative of atmospheric transport. Plant-derived n-alkane concentrations were greater at urban than rural sites, and we hypothesize greater urban plant wax production and erosion due to air pollution. As expected, along the urban-rural gradient the concentration of particle-phase PAH decreased more rapidly than that of gas-phase compounds, but unexpectedly the contribution of alkylated PAH increased from urban to rural locations. Distances over which concentrations decline by 63% vary from 50 km for persistent gas-phase compounds (e.g., P1,2CB) to 10-20 km for reactive gas-phase compounds (e.g., naphthalene, fluoranthene) to <5-10 km for particle-phase compounds (e.g., P6-10CB, benzo[b]fluoranthene, benzo[e]pyrene).


Subject(s)
Environmental Pollutants/analysis , Insecticides/analysis , Polychlorinated Biphenyls/analysis , Polycyclic Aromatic Hydrocarbons/analysis , Air Pollutants/analysis , Cities , Environmental Monitoring , Gases , Industry , Particle Size
9.
Chemosphere ; 44(7): 1655-67, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11545531

ABSTRACT

A multimedia model has been developed to account for the movement of semi-volatile organic compounds (SOCs) in an urban environment. The model, based on a Level III fugacity model of D. Mackay (Multimedia Environmental Models: The Fugacity Approach, Lewis Publishers, Boca Raton, FL, 1991), consists of six compartments: air, surface water, sediment, soil, vegetation, and an organic film that coats impervious surfaces. The latter is a newly identified compartment into which gas-phase SOCs partition and particle-phase SOCs are believed to be efficiently captured (M.L. Diamond, S.E. Gingrich, K. Fertuck, B.E. McCarry, G.A. Stern, B. Billeck, B. Grift, D. Brooker, T.D. Yager, Environ. Sci. Technol., 34 (2000a), 2900-2908). The model, parameterized for downtown Toronto, Ontario, Canada, and run with an illustrative emission rate for selected polycyclic aromatic hydrocarbons and homologues of polychlorinated dibenzodioxins, indicates that the film achieves the highest concentrations among media but that soils are the greatest sink for all but the least hydrophobic chemicals. The film "reflects" the more volatile chemicals into air, facilitates removal to surface waters by wash-off, and provides a surface on which photolytic degradation can occur. As such, the film is a transient sink that increases chemical mobility in urban areas by increasing air concentrations and the cycling of these compounds between air and urban surfaces and increasing water concentrations. Vegetation also accumulates SOCs, a portion of which is transferred to soil that reduces chemical mobility.


Subject(s)
Cities , Environmental Pollutants , Models, Chemical , Multimedia , Polycyclic Aromatic Hydrocarbons , Air Movements , Forecasting , Organic Chemicals , Photolysis , Plants , Volatilization , Water Movements
10.
Headache ; 41(7): 638-45, 2001.
Article in English | MEDLINE | ID: mdl-11554951

ABSTRACT

OBJECTIVE: A population-based survey was conducted in 1999 to describe the patterns of migraine diagnosis and medication use in a representative sample of the US population and to compare results with a methodologically identical study conducted 10 years earlier. METHODS: A survey mailed to a panel of 20 000 US households identified 3577 individuals with severe headache meeting a case definition for migraine based on the International Headache Society (IHS) criteria. Those with severe headache answered questions regarding physician diagnosis and use of medications for headache as well as headache-related disability. RESULTS: A physician diagnosis of migraine was reported by 48% of survey participants who met IHS criteria for migraine in 1999, compared with 38% in 1989. A total of 41% of IHS-defined migraineurs used prescription drugs for headaches in 1999, compared with 37% in 1989. The proportion of IHS-defined migraineurs using only over-the-counter medications to treat their headaches was 57% in 1999, compared with 59% in 1989. In 1999, 37% of diagnosed and 21% of undiagnosed migraineurs reported 1 to 2 days of activity restriction per episode (P<.001); 38% of diagnosed and 24% of undiagnosed migraineurs missed at least 1 day of work or school in the previous 3 months (P<.001); 57% of diagnosed and 45% of undiagnosed migraineurs experienced at least a 50% reduction in work/school productivity (P<.001). CONCLUSIONS: Diagnosis of migraine has increased over the past decade. Nonetheless, approximately half of migraineurs remain undiagnosed, and the increased rates of diagnosis of migraine have been accompanied by only a modest increase in the proportion using prescription medicines. Migraine continues to cause significant disability whether or not there has been a physician diagnosis. Given the availability of effective treatments, public health initiatives to improve patterns of care are warranted.


Subject(s)
Migraine Disorders/diagnosis , Migraine Disorders/drug therapy , Adolescent , Adult , Child , Disability Evaluation , Female , Health Surveys , Humans , Male , Middle Aged , United States
11.
Headache ; 41(7): 646-57, 2001.
Article in English | MEDLINE | ID: mdl-11554952

ABSTRACT

OBJECTIVE: To describe the prevalence, sociodemographic profile, and the burden of migraine in the United States in 1999 and to compare results with the original American Migraine Study, a 1989 population-based study employing identical methods. METHODS: A validated, self-administered questionnaire was mailed to a sample of 20 000 households in the United States. Each household member with severe headache was asked to respond to questions about symptoms, frequency, and severity of headaches and about headache-related disability. Diagnostic criteria for migraine were based on those of the International Headache Society. This report is restricted to individuals 12 years and older. RESULTS: Of the 43 527 age-eligible individuals, 29 727 responded to the questionnaire for a 68.3% response rate. The prevalence of migraine was 18.2% among females and 6.5% among males. Approximately 23% of households contained at least one member suffering from migraine. Migraine prevalence was higher in whites than in blacks and was inversely related to household income. Prevalence increased from aged 12 years to about aged 40 years and declined thereafter in both sexes. Fifty-three percent of respondents reported that their severe headaches caused substantial impairment in activities or required bed rest. Approximately 31% missed at least 1 day of work or school in the previous 3 months because of migraine; 51% reported that work or school productivity was reduced by at least 50%. CONCLUSIONS: Two methodologically identical national surveys in the United States conducted 10 years apart show that the prevalence and distribution of migraine have remained stable over the last decade. Migraine-associated disability remains substantial and pervasive. The number of migraineurs has increased from 23.6 million in 1989 to 27.9 million in 1999 commensurate with the growth of the population. Migraine is an important target for public health interventions because it is highly prevalent and disabling.


Subject(s)
Cost of Illness , Migraine Disorders/epidemiology , Migraine Disorders/physiopathology , Adolescent , Adult , Child , Disability Evaluation , Female , Humans , Male , Middle Aged , Prevalence , Surveys and Questionnaires , United States
13.
Headache ; 41(3): 271-8, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11264687

ABSTRACT

OBJECTIVE: The purpose of this study was to assess the safety and efficacy of divalproex sodium in the long-term treatment of chronic daily headache. Correlations between treatment variables were assessed. BACKGROUND: Controlled and open-label trials of divalproex sodium have previously demonstrated its efficacy and safety in the treatment of migraine and chronic daily headaches. These data were primarily short-term and did not examine interaction between treatment variables. METHODS: Retrospective chart review with data extraction was conducted from headache diaries of 642 current patients under treatment with divalproex sodium for chronic daily headaches. One hundred thirty-eight of the patients were treated with only divalproex sodium. Demographic variables including age, sex, initial and final body weights, adverse events, dose of divalproex sodium, duration of treatment, and the ability to differentiate their chronic daily headache into its migraine and tension-type headache components were analyzed. Baseline and end of study headache frequency indices were obtained. RESULTS: The mean improvement was 47%, with an improvement in migraine of about 65%. At least a 50% reduction in headache frequency was reported by 93 of the 138 patients receiving treatment with only divalproex sodium. No correlation between response and age, sex, duration of treatment, and the prescribed dose of divalproex sodium was demonstrated. Adverse events occurred in approximately 35% of the patients. None were severe. Women were more likely to experience adverse effects than men. Weight gain, however, occurred less commonly in women (mean, 1.9 lbs) than in men (mean, 7 lbs). Initial body weight and age did not correlate with the weight change. CONCLUSIONS: Divalproex sodium can be used for a prolonged period as a sole agent for the successful treatment of chronic daily headache. Nearly 75% of the patients had at least a 50% reduction in headache frequency, and adverse effects occurred in approximately one third. Weight gain was negligible and hepatotoxicity did not occur during treatment periods of up to 6 years.


Subject(s)
Headache Disorders/prevention & control , Migraine Disorders/prevention & control , Valproic Acid/therapeutic use , Adult , Body Weight/drug effects , Female , Headache Disorders/etiology , Humans , Male , Migraine Disorders/complications , Retrospective Studies , Tension-Type Headache/complications , Tension-Type Headache/prevention & control , Time Factors , Treatment Outcome
14.
Environ Toxicol Chem ; 20(12): 2690-8, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11764150

ABSTRACT

Concentrations of (alpha- and gamma-hexachlorocyclohexane (HCH), alpha/gamma-HCH ratios, and enantiomer ratios (ER) of alpha-HCH were measured in lakes in the arctic, subarctic, Great Lakes, Canada, and temperate regions, and temperate and arctic wetlands and streams. The highest concentrations of alpha-HCH were found in cold, large, and oligotrophic lakes such as those in the arctic, subarctic, and the upper Great Lakes, which is attributed to greater inputs from atmospheric deposition and slower loss rates relative to warmer, temperate lakes. High alpha/gamma-HCH ratios in northern systems indicate aged HCH that has undergone long-range transport to high latitude areas, whereas low ratios in the lower Great Lakes and small temperate systems indicate recent gamma-HCH usage and residual alpha-HCH concentrations. Enantioselective degradation (ERs ranged from 0.31 to 0.7) was greatest in small, high arctic lakes and streams and in large lakes in the subarctic in which alpha-HCH concentrations and contact time between chemical and sediments are highest and nutrient concentrations are lowest. Low ERs were found in wetlands and streams in which contact between chemical and sediments was greatest. Conversely, minimal enantioselective degradation occurred in temperate small lakes and wetlands (ERs ranging from 0.77 to 1.06), despite the warmer temperatures, greater microbial populations, and nutrient availability. The results suggest that enantioselective degradation is optimized by maximal contact between chemical and sediment substrates in nutrient-poor waters in which, it is hypothesized, oligotrophic bacteria may act as biofilms.


Subject(s)
Hexachlorocyclohexane/chemistry , Insecticides/chemistry , Water Pollutants, Chemical/analysis , Biodegradation, Environmental , Climate , Ecosystem , Hexachlorocyclohexane/metabolism , Insecticides/metabolism , Isomerism , Water Microbiology , Water Pollutants, Chemical/metabolism
15.
Sci Total Environ ; 254(2-3): 93-234, 2000 Jun 01.
Article in English | MEDLINE | ID: mdl-10885446

ABSTRACT

Recent studies of contaminants under the Canadian Northern Contaminants Program (NCP) have substantially enhanced our understanding of the pathways by which contaminants enter Canada's Arctic and move through terrestrial and marine ecosystems there. Building on a previous review (Barrie et al., Arctic contaminants: sources, occurrence and pathways. Sci Total Environ 1992:1-74), we highlight new knowledge developed under the NCP on the sources, occurrence and pathways of contaminants (organochlorines, Hg, Pb and Cd, PAHs, artificial radionuclides). Starting from the global scale, we examine emission histories and sources for selected contaminants focussing especially on the organochlorines. Physical and chemical properties, transport processes in the environment (e.g. winds, currents, partitioning), and models are then used to identify, understand and illustrate the connection between the contaminant sources in industrial and agricultural regions to the south and the eventual arrival of contaminants in remote regions of the Arctic. Within the Arctic, we examine how contaminants impinge on marine and terrestrial pathways and how they are subsequently either removed to sinks or remain where they can enter the biosphere. As a way to focus this synthesis on key concerns of northern residents, a number of special topics are examined including: a mass balance for HCH and toxaphene (CHBs) in the Arctic Ocean; a comparison of PCB sources within Canada's Arctic (Dew Line Sites) with PCBs imported through long-range transport; an evaluation of concerns posed by three priority metals--Hg, Pb and Cd; an evaluation of the risks from artificial radionuclides in the ocean; a review of what is known about new-generation pesticides that are replacing the organochlorines; and a comparison of natural vs. anthropogenic sources of PAH in the Arctic. The research and syntheses provide compelling evidence for close connectivity between the global emission of contaminants from industrial and agricultural activities and the Arctic. For semi-volatile compounds that partition strongly into cold water (e.g. HCH) we have seen an inevitable loading of Arctic aquatic reservoirs. Drastic HCH emission reductions have been rapidly followed by reduced atmospheric burdens with the result that the major reservoir and transport agent has become the ocean. In the Arctic, it will take decades for the upper ocean to clear itself of HCH. For compounds that partition strongly onto particles, and for which the soil reservoir is most important (e.g. PCBs), we have seen a delay in their arrival in the Arctic and some fractionation toward more volatile compounds (e.g. lower-chlorinated PCBs). Despite banning the production of PCB in the 1970s, and despite decreases of PCBs in environmental compartments in temperate regions, the Arctic presently shows little evidence of reduced PCB loadings. We anticipate a delay in PCB reductions in the Arctic and environmental lifetimes measured in decades. Although artificial radionuclides have caused great concern due to their direct disposal on Russian Shelves, they are found to pose little threat to Canadian waters and, indeed, much of the radionuclide inventory can be explained as remnant global fallout, which was sharply curtailed in the 1960s, and waste emissions released under license by the European reprocessing plants. Although Cd poses a human dietary concern both for terrestrial and marine mammals, we find little evidence that Cd in marine systems has been impacted by human activities. There is evidence of contaminant Pb in the Arctic, but loadings appear presently to be decreasing due to source controls (e.g. removal of Pb from gasoline) in Europe and North America. Of the metals, Hg provokes the greatest concern; loadings appear to be increasing in the Arctic due to global human activities, but such loadings are not evenly distributed nor are the pathways by which they enter and move within the Arctic well understood.


Subject(s)
Environmental Pollutants/analysis , Environmental Pollution , Animals , Arctic Regions , Canada , Ecosystem , Environmental Pollutants/metabolism , Humans , Hydrocarbons, Chlorinated/analysis , Pesticides/analysis , Polycyclic Aromatic Hydrocarbons/analysis , Radioisotopes/analysis
17.
Clin Cornerstone ; 1(6): 45-54, 1999.
Article in English | MEDLINE | ID: mdl-10682187

ABSTRACT

Headache is a common complaint of patients seeking care at an emergency department (ED). A survey of more than 16,755 walk-in patients at an ED showed that 323 (1.9%) had a chief complaint of migraine (1). Almost one sixth of these patients had used the ED more than once. In fact, migraineurs used the ED and other health care providers 2 to 5 times more than nonmigraineurs (2). Fortunately, headaches associated with significant morbidity and mortality occur infrequently (3). The ED physician must be able to address the patient's need for pain management and establish the correct diagnosis for the headache while also ruling out any possibility of organic disease or life-threatening illness. Potential problems include ensuring appropriate follow-up and avoidance of narcotic habituation.


Subject(s)
Brain Neoplasms/complications , Giant Cell Arteritis/complications , Headache/etiology , Meningitis/complications , Subarachnoid Hemorrhage/complications , Acute Disease , Brain Neoplasms/diagnosis , Diagnosis, Differential , Giant Cell Arteritis/classification , Giant Cell Arteritis/diagnosis , Headache/classification , Headache/diagnosis , Humans , Meningitis/classification , Meningitis/diagnosis , Migraine Disorders/diagnosis , Subarachnoid Hemorrhage/diagnosis
18.
Neurology ; 51(1): 274-6, 1998 Jul.
Article in English | MEDLINE | ID: mdl-9674820

ABSTRACT

With the use of the newer antidepressants beyond the traditional tricyclics and monoamine oxidase inhibitors, newer options in headache prophylaxis are provided as well as the potential for undesirable and even potentially life-threatening interactions between medications. In this article, four patient reports of a specific interaction--the serotonin syndrome--are presented. These events resulted from transitioning headache patients from an older antidepressant (phenelzine) to a newer antidepressant (venlafaxine).


Subject(s)
Central Nervous System Diseases/chemically induced , Cyclohexanols/adverse effects , Migraine Disorders/drug therapy , Monoamine Oxidase Inhibitors/adverse effects , Phenelzine/adverse effects , Selective Serotonin Reuptake Inhibitors/adverse effects , Serotonin/metabolism , Adult , Drug Interactions , Female , Humans , Male , Middle Aged , Venlafaxine Hydrochloride
19.
Postgrad Med ; 101(1): 169-72, 175-6, 179, 1997 Jan.
Article in English | MEDLINE | ID: mdl-9008695

ABSTRACT

The physician confronted with a headache patient in acute distress must establish the diagnosis before initiating therapy. Although the typical treatment in the emergency department has been to rely on narcotic analgesics, many safer alternatives are available. With all these therapeutic options to choose from, fewer patients should run the risk of narcotic addiction because of migraine attacks. To prevent a patient from becoming a frequent emergency department visitor, referral for prophylactic treatment is essential.


Subject(s)
Migraine Disorders/drug therapy , Acute Disease , Analgesics/therapeutic use , Diagnosis, Differential , Emergency Service, Hospital , Ergotamine/therapeutic use , Humans , Migraine Disorders/diagnosis , Serotonin Receptor Agonists/therapeutic use , Sumatriptan/therapeutic use
SELECTION OF CITATIONS
SEARCH DETAIL
...