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PubMed2001

Characterization of the B12- and iron-sulfur-containing reductive dehalogenase from Desulfitobacterium chlororespirans.

The United Nations and the U.S. Environmental Protection Agency have identified a variety of chlorinated aromatics that constitute a significant health and environmental risk as "priority organic pollutants," the so-called "dirty dozen." Microbes have evolved the ability to utilize chlorinated aromatics as terminal electron acceptors in an energy-generating process called dehalorespiration. In this process, a reductive dehalogenase (CprA), couples the oxidation of an electron donor to the reductive elimination of chloride. We have characterized the B12 and iron-sulfur cluster-containing 3-chloro-4-hydroxybenzoate reductive dehalogenase from Desulfitobacterium chlororespirans. By defining the substrate and inhibitor specificity for the dehalogenase, the enzyme was found to require an hydroxyl group ortho to the halide. Inhibition studies indicate that the hydroxyl group is required for substrate binding. The carboxyl group can be replaced by other functionalities, e.g. acetyl or halide groups, ortho or meta to the chloride to be eliminated. The purified D. chlororespirans enzyme could dechlorinate an hydroxylated PCB (3,3',5,5'-tetrachloro-4,4'-biphenyldiol) at a rate about 1% of that with 3-chloro-4-hydroxybenzoate. Solvent deuterium isotope effect studies indicate that transfer of a single proton is partially rate-limiting in the dehalogenation reaction.

Amino Acid Sequence↗
PubMed2000

Patterns and concentrations of PM10 in a mountainous basin region.

In this study, continuous data of PM10 (particles with aerodynamic diameter < 10 microns) concentration measurements for a 4-yr period were analyzed. These measurements have been carried out in the Eordea Basin, an industrial area in the northwestern mountainous region of Greece. The annual, monthly, and diurnal patterns are presented and investigated regarding the prevailing meteorological conditions and atmospheric processes that affect the ambient concentrations of PM10. The effect of wind on controlling PM10 concentration is also discussed. Based on the data analysis, an attempt is made to provide useful information about air quality levels, taking into account U.S. Environmental Protection Agency air quality standards.

Air Pollution↗
PubMed1992

A model for radon gas adsorption on charcoal for open-faced canisters in an active environment.

It was previously suggested that the calibration factor (CF) relating the detected activity (A) of the radon decay products 214Bi and 214Pb within a charcoal canister to the radon concentration (CR) in air be defined as CF = A/(E x DF x CR), where E is the counting efficiency of the detector for 214Bi and 214Pb gamma rays, and DF is a factor accounting for decay during the time (tD) from the end of the exposure until the canister is counted; i.e., DF = exp(-lambda RPtD), where lambda RP is the physical decay constant for radon. With CF defined as above, a kinetic model for the adsorption of radon gas on charcoal in humid air predicts that CF (in m3) can be written for CR in Bq m-3, A in cpm, and E in cpm Bq-1 as CF = alpha[1-exp(-delta t)] + beta[1 - exp(-delta t)]M(t), where alpha, beta, and delta are free parameters, t is the canister exposure time in hours, and M(t) is the canister water mass gain in grams in time t. For CF data for the U.S. Environmental Protection Agency's open-faced canisters in an active (with respect to air flow) environmental chamber, delta = (0.046 +/- 0.002)h-1, and exp(-delta t) much less than 1 for t greater than or equal to 3 d. Also, alpha = (0.342 +/- 0.002)m3, and beta = -(0.0123 +/- 0.0001)m3g-1.

Adsorption↗
PubMed2006

Modeling radiological dose in non-human species: principles, computerization, and application.

Due to the increasing interest in environmental protection against ionizing radiation on the international scene, the need for operational tools for radiological environmental risk assessment is becoming critical. Within this framework, this paper puts forward a fast and user-friendly computerized method to allow the transformation from exposure (expressed in Bq per unit of mass or volume) to dose (i.e., the energy deposited in the organism, expressed in Gy) received from any radionuclide by any non-human species, for a unit of time and a unit of "concentration" of radionuclide in the radiation source. The calculation principles used to determine this dose coefficient, expressed in Gy/unit of time per Bq/unit of volume or mass, are described for gamma, beta, and alpha radiation. Both internal and external exposure situations are considered. The domain of validity of the proposed model is specified, as is the way in which it has been computerized. The paper concludes by verifying the numerical accuracy of the tool and making initial comparisons between results from the described method and those developed at the European level.

Algorithms↗
PubMed1992

[Organization of the public health services in Latin America and the Caribbean].

The organisation of veterinary public health (VPH) services in countries of Latin America and the Caribbean has resulted from an historical process which has consolidated the structure of these services and the concept of VPH. This concept comprises five principal plans of action: promotion of animal health in order to increase the production of protein of animal origin; protection of foods for human consumption; vigilance, prevention, control and eradication of zoonoses; promotion of environmental protection, together with the development of biomedical models. These plans of action serve the purpose of improving human health and well-being, which is essential for the socioeconomic development of populations. Within this context, the authors describe the organisation of VPH services for health and agriculture, which have a part to play in intersectorial collaboration and in social participation. Finally, an account is given of progress in the control of rabies, brucellosis and tuberculosis, and the organisation of integrated programmes for food protection and also the control and eradication of foot and mouth disease. Technical cooperation with the Pan American Health Organisation (PAHO) assists these activities and intersectorial coordination, principally between health and agriculture.

Agriculture↗
PubMed1988

[Modifying effect of environmental chemical factors on the metabolic activation of carcinogens].

Current investigations of modifications of metabolic activation of carcinogens by the environmental chemical factors which are able to induce or inhibit the metabolic activation are reviewed. From the standpoint of ecological oncology the most promising are the following trends: 1) modelling under experimental conditions of integral ecosystems including the complex of living organisms, environmental carcinogens, and factors which modify their biotransformation; 2) study of the imprinting effectors of metabolism modifiers; 3) detection in the environment of modifiers of metabolic activation of carcinogens. The comprehensive oncological-ecological studies of chemicals which influence different pathways of carcinogen metabolism are very important for both primary prevention of cancer and the environmental protection.

Animals↗
PubMed1997

Media dissemination of and public response to the Ultraviolet Index--United States, 1994-1995.

Exposure to the ultraviolet component of sunlight may be associated with an increased risk for some skin cancers. The Ultraviolet Index (UVI) links a rating by the National Weather Service (NWS) of solar ultraviolet intensity (on a scale of 0 [minimal] to 10+ [very high]) to recommendations for appropriate sun-protection behaviors. During the summers of 1994 and 1995, the NWS, in collaboration with the Environmental Protection Agency (EPA), the American Academy of Dermatology, the National Association of Physicians for the Environment, and CDC, disseminated UVI forecasts to selected major television stations and newspapers in the United States. In 1995, the Boston University School of Medicine conducted three surveys to evaluate how widely the UVI was televised, printed in newspapers, and used by adults (aged > or = 18 years) to modify their behaviors to reduce exposure to ultraviolet light. This report summarizes the findings of the elevation, which indicate generally high rates of television broadcast and public awareness of the UVI.

Adult↗
PubMed1999

Subclinical health effects of environmental pesticide contamination in a developing country: cholinesterase depression in children.

The effect of exposure to pesticides among children in a Nicaraguan community in the path of rain water runoff from a large crop-dusting airport was evaluated by measuring plasma cholinesterase. Mean cholinesterase activity in 17 children in the path of runoff was 2.4 international units/ml blood/min, lower than the 2.9 IU/ml/min measured in a group of 43 children from an unexposed community (difference=0.49 IU/ml/min; 95% C.I. 0.24, 0.76). Six (35%) of the 17 exposed children had abnormally low cholinesterase levels. A possible explanation for this physiological effect of exposure to pesticides is the dermal absorption which may have occurred among children playing barefoot in puddles grossly contaminated by runoff from the airport. Drinking water from a well in the exposed community demonstrated low level residues of cholinesterase-inhibiting pesticides, although contamination with toxaphene (not a cholinesterase inhibitor) exceeded by over 8-fold the United States Environmental Protection Agency maximum permissible concentration in drinking water. The difficulty in measuring health effects resulting from environmental pesticide contamination, and in controlling exposure resulting from the rapidly increasing use of pesticides, is a growing problem for developing countries like Nicaragua.

Child↗
PubMed1992

A comparison of human toxics exposure and environmental contamination by census division.

National Human Adipose Tissue Survey (NHATS) data and U.S. Environmental Protection Agency (U.S. EPA) STORET data were used to test for relationships between human exposure and environmental contamination according to census division. Regions were ranked according to the mean concentration of 43 toxic substances (pesticides, polychlorinated biphenyls, semi-volatiles, and volatiles) in human adipose tissue and environmental media (sediment, fish tissue, and groundwater). Correlation analyses between regional human and environmental ranks indicated that fish tissue data were good predictors of regional pesticide exposure, sediment data were good predictors of PCB exposure, and groundwater data were good predictors of exposure to semi-volatile compounds. None of the environmental data used were good predictors of exposure to volatile chemical compounds. Groundwater appeared to be a better predictor of overall regional toxics exposure than other types of environmental data.

Animals↗
PubMed1993

The Jülich Environmental Specimen Bank.

The environmental specimen bank of the Federal Republic of Germany represents the modern form of a systematically designed archive for the preservative storage of selected environmental specimens. Major aims of environmental specimen banks are: (i) retrospective identification and quantification of environmental chemicals including those not known at the time of storage; (ii) retrospective replicate analysis of samples stored under preservative conditions for the determination of inorganic elements or organic compounds already examined; and (iii) retrospective control of the success of legislative environmental protection measures in handling chemicals regarded as hazardous for man and the environment. Results of the environmental specimen bank at Jülich by the Institute of Applied Physical Chemistry, Research Centre Jülich, KFA, obtaining the initiated legislative regulations providing environmental pollution, are already proved for various compartments.

Animals↗
PubMedDate not supplied

Addressing residual risk issues at anthrax cleanups: how clean is safe?

Since the 2001 attacks in which Bacillus anthracisspores were mailed to various media offices and two U.S. Senators, considerable interest has focused on developing estimates of the risk of contracting inhalational anthrax from exposure to such spores. Credible risk estimates would have significant utility in establishing future cleanup goals for contaminated sites. To perform a meaningful risk assessment, one needs sufficient data to identify the hazards, conduct dose-response assessment, and assess exposure. This report reviews the existing data on mortality produced by Bacillus anthracisspores in laboratory animals and humans. In particular, it focuses on the 11 cases of inhalational anthrax resulting from the 2001 attacks and their impact on hazard identification activities. It also addresses factors that may contribute to increased risk among exposed populations and the sources of uncertainty in dose response analysis. The article examines the state of the science for assessing exposure levels to Bacillus anthracis spores and concludes that significant challenges exist to performing robust assessments of risk. This conclusion supports the policy position of the U.S. Environmental Protection Agency (EPA) that there should be no growth of Bacillus anthracis spores from all postremediation environmental samples, for the cleanup of a site to be judged effective and for that site to be considered safe for reoccupancy. This has been the ultimate criterion for efficacy of cleanups performed in response to the 2001 anthrax attacks.

Animals↗
PubMed1990

Organochlorine compounds in human adipose tissue from north Texas.

This paper reports a preliminary study that was conducted to determine the concentrations of organochlorine compounds in the adipose tissue of residents of North Texas. Thirty-five human adipose tissue samples were obtained during autopsy between 1987 and 1988 from persons who had no known occupational exposure to organochlorine pesticides. These samples were analyzed by electron-capture gas chromatographic methods for the presence of beta-benzene hexachloride, o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT, dieldrin, oxychlordane, and heptachlor epoxide. The findings indicate greater than 97% occurrence for each compound with the exception of o,p'-DDE and o,p'-DDT, each of which occurred in 54% of the population sampled. Statistical analyses of the data showed strong positive correlations between adipose tissue concentrations and age for oxychlordane, heptachlor epoxide, p,p'-DDT, p,p'-DDE, and total DDT (the normalized sum of DDT and its analogues) (p less than or equal to .05). Statistically significant differences (p less than or equal to .05) in geometric mean concentrations between all age groups were found for total DDT and p,p'-DDE. However, the group means comparison test was only significantly different between the 41-60 yr and 61 and over age groups for p,p'-DDT, oxychlordane, and heptachlor epoxide. No statistically significant difference was found between sexes in this study. The geometric means of pesticide concentrations in adipose tissue were compared with those reported in previous U.S. Environmental Protection Agency surveys for the general population. This comparison clearly indicates a declining temporal trend in environmental exposure for banned DDT analogues; however, a consistent temporal trend exists for oxychlordane and heptachlor epoxide--pesticides whose uses are currently restricted but not proscribed.

Adipose Tissue↗
PubMed1999

Reducing uncertainty in the derivation and application of health guidance values in public health practice. Dioxin as a case study.

We were requested by the U.S. Environmental Protection Agency (EPA) to clarify the relationships among the minimal risk level (MRL), action level, and environmental media evaluation guide (EMEG) for dioxin established by the Agency for Toxic Substances and Disease Registry (ATSDR). In response we developed a document entitled "Dioxin and Dioxin-Like Compounds in Soil, Part I: ATSDR Interim Policy Guideline"; and a supporting document entitled "Dioxin and Dioxin-Like Compounds in Soil, Part II: Technical Support Document". In these documents, we evaluated the key assumptions underlying the development and use of the ATSDR action level, MRL, and EMEG for dioxin. We described the chronology of events outlining these different health guidance values for dioxin and identified the areas of uncertainty surrounding these values. Four scientific assumptions were found to have had a great impact on this process; these were: (1) the specific uncertainty factors used, (2) the toxicity equivalent (TEQ) approach, (3) the fractional exposure from different pathways, and (4) the use of body burdens in the absence of exposure data. This information was subsequently used to develop a framework for reducing the uncertainties in public health risk assessment associated with exposure to other chemical contaminants in the environment. Within this framework are a number of future directions for reducing uncertainty, including physiologically based pharmacokinetic modeling (PBPK), benchmark dose modeling (BMD), functional toxicology, and the assessment of chemical mixture interactions.

Benchmarking↗
PubMed1991

[Air pollution in East Germany--state and requirements].

The GDR is the country with the highest degree of air pollution in Europe. The oil crisis and the subsequent substitution of oil, coal and gas by lignite has led to an enormous increase of SO2-emissions. The highest air pollution concentrations are found in the industrial centres of Halle and Leipzig. The end of the socialist system in the GDR and the financial, economical and social union with the FRG is also the beginning of fundamental changes in the field of environmental protection, -regulations and -management. In June the Volkskammer passed a law for the assimilation of GDR environmental regulations to FRG-right presented by the common environmental commission. Subsequently, the old structure of the Hygiene Inspectorates has to be reorganised to ensure an efficient environmental control. The development of environmental epidemiology, the investigation of diseases caused by environmental pollutions should play an important role in environmental research.

Air Pollutants↗
PubMed1993

Passive smoking and lung cancer.

The findings of a multicenter national study of lung cancer in lifetime-never smokers are reported. An increased lung cancer risk of approximately 30% was found among women whose husbands smoked. Elevated risks of 40% to 60% were also found associated with workplace exposures and other exposures outside the home. The findings of this study have been included in the recent Environmental Protection Agency assessment of the health effects of passive smoking, and have implications for regulation of environmental tobacco smoke exposure in Louisiana.

Adenocarcinoma↗
PubMed1996

[Education in environmental medicine: practical aspects].

Rarely physicians educated in environmental medicine will be able to work as independent specialists. Most probably they will fulfill their mission besides a main job, usually in general medical care. On one hand this additional education may be applied in daily practice (diagnosis and investigation of environmentally induced diseases and disturbances) on the other hand by presentations in schools, courses, public meetings. Of special importance are political activities such as counselling, discussions with authorities of the environmental protection agency and other authorities, official statements etc. aiming at general medical prevention. Different topics of environmental medicine are outlined and the special importance of interdisciplinarity in thinking and research is stressed. Finally some informations for the practitioner concerning postgraduate education and literature-search are given.

Curriculum↗
PubMed1999

The international program on plant bioassays and the report of the follow-up study after the hands-on workshop in China.

Among the seven plant bioassays reviewed by the US Environmental Protection Agency (EPA) Gene-Tox program in 1980, the Allium/Vicia root tip chromosome aberration assay and the Tradescantia stamen hair mutation and micronucleus assays were adopted by the International Program on Plant Bioassays (IPPB) for monitoring or testing environmental pollutants. These assays are highly sensitive and capable of detecting mutagens, clastogens and carcinogens from the environment. They are effective in situ monitors. These bioassays were validated and their protocols were standardized through a program under the International Program on Chemical Safety (IPPB), the precursor of the IPPB program which currently is in operation under the auspices of the United Nations Environment Program (UNEP). Six different categories of environmental studies, ranging from wastewater, surface or ground water, soil samples, ambient air, pesticides, and radiation, were carried out and are reported in this special issue. The mission of the IPPB/UNEP is to use these bioassays to monitor or test environmental mutagens and clastogens in the air, water, and soil to safeguard the quality of these essential elements in life and to use these simple and clear indicators of pollution damage as the tool for environmental education for the general public. The published reports of the monitoring and testing results will establish the database for environmental conditions in a number of locations around the world. An international monitoring network for the detection of genotoxicity of environmental pollutants is being established under the auspices of UNEP to protect the global environment.

Biological Assay↗
PubMed2002

Surveillance for waterborne-disease outbreaks--United States, 1999-2000.

PROBLEM/CONDITION: Since 1971, CDC, the U.S. Environmental Protection Agency (EPA), and the Council of State and Territorial Epidemiologists (CSTE) have maintained a collaborative surveillance system for the occurrences and causes of waterborne-disease outbreaks (WBDOs).This surveillance system is the primary source of data concerning the scope and effects of waterborne diseases on persons in the United States. REPORTING PERIOD COVERED: This summary includes data regarding outbreaks occurring during January 1999-December 2000 and previously unreported outbreaks occurring in 1995 and 1997. DESCRIPTION OF THE SYSTEM: The surveillance system includes data for outbreaks associated with drinking water and recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. The unit of analysis for the WBDO surveillance system is an outbreak, not an individual case of a waterborne disease. Two criteria must be met for an event to be defined as a WBDO. First, > or = 2 persons must have experienced a similar illness after either ingestion of drinking water or exposure to water encountered in recreational or occupational settings. This criterion is waived for single cases of laboratory-confirmed primary amebic meningoencephalitis and for single cases of chemical poisoning if water-quality data indicate contamination by the chemical. Second, epidemiologic evidence must implicate water as the probable source of the illness. RESULTS: During 1999-2000, a total of 39 outbreaks associated with drinking water was reported by 25 states. Included among these 39 outbreaks was one outbreak that spanned 10 states. These 39 outbreaks caused illness among an estimated 2,068 persons and were linked to two deaths. The microbe or chemical that caused the outbreak was identified for 22 (56.4%) of the 39 outbreaks; 20 of the 22 identified outbreaks were associated with pathogens, and two were associated with chemical poisoning. Of the 17 outbreaks involving acute gastroenteritis of unknown etiology, one was a suspected chemical poisoning, and the remaining 16 were suspected as having an infectious cause. Twenty-eight (71.8%) of 39 outbreaks were linked to groundwater sources; 18 (64.3%) of these 28 groundwater outbreaks were associated with private or noncommunity wells that were not regulated by EPA. Fifty-nine outbreaks from 23 states were attributed to recreational water exposure and affected an estimated 2,093 persons. Thirty-six (61.0%) of the 59 were outbreaks involving gastroenteritis. The etiologic agent was identified in 30 (83.3%) of 36 outbreaks involving gastroenteritis. Twenty-two (61.1%) of 36 gastroenteritis-related outbreaks were associated with pools or interactive fountains. Four (6.8%) of the 59 recreational water outbreaks were attributed to single cases of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri. All four cases were fatal. Fifteen (25.4%) of the 59 outbreaks were associated with dermatitis; 12 (80.0%) of 15 were associated with hot tubs or pools. In addition, recreational water outbreaks of leptospirosis, Pontiac fever, and chemical keratitis, as well as two outbreaks of leptospirosis and Pontiac fever associated with occupational exposure were also reported to CDC. INTERPRETATION: The proportion of drinking water outbreaks associated with surface water increased from 11.8% during 1997-1998 to 17.9% in 1999-2000. The proportion of outbreaks (28) associated with groundwater sources increased 87% from the previous reporting period (15 outbreaks), and these outbreaks were primarily associated (60.7%) with consumption of untreated groundwater. Recreational water outbreaks involving gastroenteritis doubled (36 outbreaks) from the number of outbreaks reported in the previous reporting period (18 outbreaks). These outbreaks were most frequently associated with Cryptosporidium parvum (68.2%) in treated water venues (e.g., swimming pools or interactive fountains) and by Escherichia coli O157:H7 (21.4%) in freshwater venues. The increase in the number of outbreaks probably reflects improved surveillance and reporting at the local and state level as well as a true increase in the number of WBDOs. PUBLIC HEALTH ACTION: CDC and others have used surveillance data to identify the types of water systems, their deficiencies, and the etiologic agents associated with outbreaks and evaluated current technologies for providing safe drinking water and safe recreational water. Surveillance data are used also to establish research priorities, which can lead to improved water-quality regulations. Only the groundwater systems under the influence of surface water are required to disinfect their water supplies, but EPA is developing a groundwater rule that specifies when corrective action (including disinfection) is required. CDC and EPA are conducting epidemiologic studies to assess the level of waterborne illness attributable to municipal drinking water in nonoutbreak conditions. Rules under development by EPA--the Ground Water Rule (GWR), the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), and Stage 2 Disinfection Byproduct Rules (DBPR)--are expected to further protect the public from contaminants and disinfection byproducts in drinking water. Efforts by EPA under the Beaches Environmental Assessment, Closure, and Health (BEACH) program are aimed at reducing the risks for infection attributed to ambient recreational water by strengthening beach standards and testing; providing faster laboratory test methods; predicting pollution; investing in health and methods research; and improving public access to information regarding both the quality of the water at beaches and information concerning health risks associated with swimming in polluted water. EPA's Beach Watch (available at http://www.epa.gov/waterscience/beaches) provides online information regarding water quality at U.S. beaches, local protection programs, and other beach-related programs. CDC partnered with a consortium of local and national pool associations to develop a series of health communication materials for the general public who attend treated recreational water venues and to staff who work at those venues. CDC has also developed a recreational water outbreak investigation toolkit that can be used by public health professionals. All of the CDC materials are accessible at the CDC Healthy Swimming website (http://www.cdc.gov/healthyswimming).

Communicable Diseases↗