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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↗
PubMed2005

Development of a United States-Mexico Emissions Inventory for the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study.

The Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study was commissioned to investigate the sources of haze at Big Bend National Park in southwest Texas. The modeling domain of the BRAVO Study includes most of the continental United States and Mexico. The BRAVO emissions inventory was constructed from the 1999 National Emission Inventory for the United States, modified to include finer-resolution data for Texas and 13 U.S. states in close proximity. The first regional-scale Mexican emissions inventory designed for air-quality modeling applications was developed for 10 northern Mexican states, the Tula Industrial Park in the state of Hidalgo, and the Popocatépetl volcano in the state of Puebla. Emissions data were compiled from numerous sources, including the U.S. Environmental Protection Agency (EPA), the Texas Natural Resources Conservation Commission (now Texas Commission on Environmental Quality), the Eastern Research Group, the Minerals Management Service, the Instituto Nacional de Ecología, and the Instituto Nacional de Estadistica Geografía y Informática. The inventory includes emissions for CO, nitrogen oxides, sulfur dioxide, volatile organic compounds (VOCs), ammonia, particulate matter (PM) < 10 microm in aerodynamic diameter, and PM < 2.5 microm in aerodynamic diameter. Wind-blown dust and biomass burning were not included in the inventory, although high concentrations of dust and organic PM attributed to biomass burning have been observed at Big Bend National Park. The SMOKE modeling system was used to generate gridded emissions fields for use with the Regional Modeling System for Aerosols and Deposition (REMSAD) and the Community Multiscale Air Quality model modified with the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (CMAQ-MADRID). The compilation of the inventory, supporting model input data, and issues encountered during the development of the inventory are documented. A comparison of the BRAVO emissions inventory for Mexico with other emerging Mexican emission inventories illustrates their uncertainty.

Aerosols↗
PubMed2005

Disinfectants' effect on mercury release from amalgam.

BACKGROUND: Mercury environmental discharge is under increased scrutiny by the U.S. Environmental Protection Agency (EPA). Dental amalgam should be processed properly to prevent an additional environmental burden. Some processing agencies require that submitted amalgam be noninfectious. Investigations have demonstrated that oxidizing disinfectants mobilize mercury from amalgam into solution and add mercury to the environmental burden if it is disposed of improperly. The authors conducted a study to evaluate the effect of representative disinfectants on amalgam mercury release. METHODS: The authors sized a high-copper spherical amalgam alloy to match that typically found in dental unit suction traps. They exposed 20 grams of the alloy to several disinfectant solutions and evaluated the filtered supernatant solution for mercury content. RESULTS: Chlorine disinfectant materials discharged the most mercury ions, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. The quaternary ammonium compound did not discharge mercury ions above the detection limit (0.2 parts per billion) into solution. CONCLUSIONS: A quaternary ammonium compound did not mobilize mercury ions into solution when used as a disinfectant agent for amalgam. Chlorine disinfectants mobilized mercury ions the most, followed by bromide, iodophor, peroxide/peracetic acid and phenolic disinfectants. CLINICAL IMPLICATIONS: Dentists are obligated to be good environmental stewards and should follow practices that reduce environmental mercury release. Dental personnel should be aware that oxidizing disinfectants mobilize mercury ions into solution, which will be added to the environment if they are processed improperly. If required by processing, dental personnel should consider the different oxidizing effects of commonly used disinfectants.

Anti-Infective Agents, Local↗
PubMedDate not supplied

Methylmercury: a new look at the risks.

In the US, exposure to methylmercury, a neurotoxin, occurs primarily through consumption of fish. Data from recent studies assessing the health impact of methylmercury exposure due to consumption of fish and other sources in the aquatic food web (shellfish, crustacea, and marine mammals) suggest adverse effects at levels previously considered safe. There is substantial variation in human methylmercury exposure based on differences in the frequency and amount of fish consumed and in the fish's mercury concentration. Although virtually all fish and other seafood contain at least trace amounts of methylmercury, large predatory fish species have the highest concentrations. Concerns have been expressed about mercury exposure levels in the US, particularly among sensitive populations, and discussions are underway about the standards used by various federal agencies to protect the public. In the 1997 Mercury Study Report to Congress, the US Environmental Protection Agency summarized the current state of knowledge on methylmercury's effects on the health of humans and wildlife; sources of mercury; and how mercury is distributed in the environment. This article summarizes some of the major findings in the Report to Congress and identifies issues of concern to the public health community.

Adolescent↗
PubMed2002

Assessment of cancer risk and environmental levels of arsenic in New Hampshire.

The Agency for Toxic Substances and Disease Registry (ATSDR) and the United States (US) Environmental Protection Agency (EPA) Office of Solid Waste and Emergency Response (OSWER) list arsenic as a major concern for Superfund sites and the environment at large. Arsenic is clearly linked to skin, bladder, and lung cancer occurrence in populations highly exposed to arsenic occupationally, medicinally, or through contaminated drinking water (Agency for Toxic Substances and Disease Registry, 1999; IARC, 1987). While these studies have identified important adverse health effects, they cannot provide risk information at lower levels of exposure such as those commonly found in the US. Additionally, precise measurement of exposure is critical to assessing risk in populations consuming relatively trace amounts of arsenic. In New Hampshire, domestic wells serve roughly 40% of the population, and about 10% of these contain arsenic concentrations in the controversial range of 10 to 50 micrograms/l. New Hampshire, along with other states in New England, has among the highest bladder cancer mortality rates in the country. Therefore, we are conducting a population-based epidemiologic study in New Hampshire (1) to assess the risk of skin and bladder cancer associated with arsenic exposure in a US population, (2) to evaluate methods of quantifying individual exposure to arsenic at low to moderate levels, and (3) to explore alternative models of determining the dose-response relationship at the lower end of exposure. Our findings to date indicate that toenail arsenic concentrations are a reliable, long-term biomarker of total arsenic exposure and reflect arsenic intake by drinking water containing 1 microgram/l or more. We found that urinary arsenic cannot be detected consistently in a population for which drinking water arsenic is primarily below 50 micrograms/l. Lastly, our data suggest that use of a biologic marker along with alternative statistical approaches may aid detection of the levels at which arsenic may affect cancer occurrence in the US.

Adult↗
PubMed1997

Human exposure to PCBS: modeling and assessment of environmental concentrations on the Akwesasne reservation.

The Mohawk Nation at Akwesasne, comprised of approximately 10,000 people, is located along the St. Lawrence River in upstate New York. The Akwesasne reservation has been contaminated by local industries, which are located on the St. Lawrence River and its tributaries, and by upstream sources on the Great Lakes. The closest known source of contamination to the reservation is General Motors (GM) Foundry, which is located less than 100 feet from the reservation's border. This facility is listed on the Environmental Protection Agency's National Priority List and the New York State's Department of Environmental Conservation's (NYSDEC) inactive hazardous waste disposal site list. Contamination to the reservation arising from discharge and secondary transport mechanisms has caused concern to the Mohawk people of Akwesasne. The characterization of the environment at Akwesasne required a historical review of existing environmental data, generation of a database, review of existing data, sampling to augment existing data, data analysis, data modeling and data generation based on a chosen model for all environmental pathways of interest. The objectives this work were to: 1) assess the quality of existing data, 2) create a database which will manage the over 6000 samples recorded taken from the local area, 3) augment the existing data with additional sampling, 4) determine the degradation or attenuation of PCBs and specific congeners in various environmental media over time, and 5) create a model that estimates environmental concentrations of PCBs retro- and pro-spectively for times that sampling had not occurred. The results of this process yielded concentrations of PCBs, congener specific and total, in several environmental medium. Modeling of environmental concentrations through a thirteen-year time period was performed for a fish, wildlife and surface soil. Other media were not modeled due to limited information or non-detectable concentrations reported in past work. Additionally, the study participants activity, consumption and residential information was considered when limiting this modeling effort. The results of this work were used to estimate environmental concentrations through time and space. The results of this work were extremely valuable when determining areas of concern and provided the basis for a detailed exposure assessment of 97 women who reside at the Reservation.

Animals↗
PubMedDate not supplied

Airborne manganese particulates and methylcyclopentadienyl manganese tricarbonyl (MMT) at selected outdoor sites in Montreal.

This study aims to assess the atmospheric concentrations of methylcyclopentadienyl manganese tricarbonyl (MMT), respirable manganese (MNR) and total manganese (MnT) in certain specific microenvironments and to provide an estimation of human exposure to MnR. Sampling was carried out in five microenvironments: a gas station, an underground car park, downtown Montreal, near an expressway and near an oil refinery. The samples were collected using Gil-Air portable pumps during three days and were analyzed by instrumental neutron activation analysis (INAA). The mean concentrations of MnR, MnT and MMT were 0.036 microgram m-3, 0.103 microgram m-3 and 0.005 microgram m-3 respectively. The MnR/MnT ratios vary from 25% to 43% (mean 35%) while the MMT/MnT ratios averaged about 5%. Furthermore, the mean concentration of the MnR measured near the expressway (0.053 microgram m-3) is similar to the United States Environmental Protection Agency (U.S. EPA) reference concentration (RfC = 0.05 microgram m-3). The average daily environmental exposure dose to MNR is estimated at 0.010 microgram kg-1 d-1 and its contribution to the multimedia exposure (air, food and water) is low. The overall results show a lack of potential exposure to MMT and substantial concentrations of MnR near an expressway.

Air Pollutants↗
PubMed2003

Recycling of wastewater-derived phosphorus in Swedish agriculture--a proposal.

In 2001 the Swedish Government commissioned the Swedish Environmental Protection Agency (Swedish EPA) (i) to examine the need for stricter human health and environmental regulations governing the agricultural use of sewage sludge and (ii) to propose national targets for the agricultural recycling of phosphorus (P) originating from wastewater. The Swedish EPA may propose: (i) stricter regulations on sludge treatment to limit the risk of spreading pathogens in the environment and transmission of infectious diseases; (ii) recycling of 20-30% of wastewater-P to agriculture by 2015 and recycling of 35-50% of wastewater-P to agriculture by 2025.

Agriculture↗
PubMed1980

Overview of human exposure to dieldrin residues in the environment and current trends of residue levels in tissue.

An overview of available literature indicates that dieldrin residues are still found routinely in soil, air, water, and food, despite the 1974 U.S. Environmental Protection Agency ban on the use of aldrin and dieldrin. Dieldrin residue levels in environmental substrates, which are indicative of aldrin or dieldrin use, have decreased significantly since the mid-1960s, the peak usage years. However, human tissue studies do not show a corresponding decline in dieldrin residue levels. Thirteen studies, conducted between 1963 and 1976, show that average dieldrin levels in human adipose tissue and human milk fat remain between 0.160 ppm and 0.220 ppm. Other studies suggest that an equilibrium exists in the distribution of dieldrin among various tissues in humans, including blood, fat, brain, and liver. This relationship indicates that the concentration of dieldrin in any tissue may be used as an index of total body burden. Thus it appears that the concentration of dieldrin in the human body has reached a constant level at which the amount ingested and absorbed equals the amount metabolized and excreted. The mechanism of the stable concentrations is unknown, as are the possible health effects of chronic, low-level exposure to dieldrin.

Adipose Tissue↗
PubMed2005

Flared gases and other pollutants associated with air quality in industrial areas of Nigeria: an overview.

Nigeria, like any other developing nation, is faced with the twin problem of development without destruction. Industrialization, though an important component of development, has had a large share in the despoilation of air quality in the country by the release of high amounts of pollutants into the atmosphere. Petroleum hydrocarbons from refineries, flared gases, dusts, and fumes of metal-smelting and cement works, odorous gases of chemical and allied industries, carbon monoxide and oxides of sulfur and nitrogen of internal combustion engines, the charred particulates and sulfur dioxide emissions of the steel industries etc., all constitute pollutants or co-pollutants of the Nigerian atmosphere. This review article gives an insight into the phenomenal concentrations of some of these pollutants in the Nigerian atmosphere, which point to their unsafe levels and concomitant health risks. It is against this background that there should be continuous but sound monitoring exercise of the Nigerian environment, devoid of the peculiar mix of politics and science, in order to properly audit the quality of air, especially in areas of heavy industrial pollution. Such checks and balances would provide empirical data to assess the various trade-offs of atmospheric pollution in industrial areas of the country such as the Niger Delta region where oil and gas are produced. There should also be enforcement, thereof, of all existing and/or revised standards or regulations such as the compliance limits of the Department of Petroleum Resources (DPR) or the erstwhile Federal Environmental Protection Agency (FEPA).

Air Pollutants↗
PubMed2001

Changing environmental strategies over time: an empirical study of the steel industry in the United States.

This study investigates how environmental strategies change over time. We submit evidence from the US steel industry that firms have modified their strategies over time. We offer that US industry passed through three stages--cost minimization, cost-effective compliance, and beneficial environmental controls. We compare typologies of environmental strategies and choose that of C. Oliver as the most appropriate. We investigate how environmental strategies in the steel industry changed over time a 4-year period. We offer that a further understanding of Oliver's strategies may increase understanding of the relationship between business and government on environmental issues. One over-arching problem in our field is the need to adequately operationalize how firms change strategies and pass through different stages. We hope that our study will help future researchers and practitioners better articulate the concepts of environmental strategies over time. Our study focused on the steel industry in the United States. We chose the US steel industry as one of the major environmental actors in the United States. The United States Environmental Protection Agency ranks the iron and steel industry as the largest industrial source of toxic environmental contamination. We encourage researchers to evaluate and test our methodology and findings in other contexts--both in other nations and different industries.

Conservation of Natural Resources↗
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↗
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↗
PubMed2003

Environmental water-quality zones for streams: a regional classification scheme.

Various approaches have been used to classify large geographical areas into smaller regions of similar water quality or extrapolate water-quality data from a few streams to other unmonitored streams. A combination of some of the strengths of existing techniques is used to develop a new approach for these purposes. In this new approach, referred to here as SPARTA (SPAtial Regression-Tree Analysis), environmental characteristics for each monitored stream are first quantified using a Geographic Information System (GIS) and then regression-tree analysis is used to determine which characteristics are most statistically important in describing the distribution of a specific water-quality constituent. GIS coverages of only the most statistically significant environmental characteristics are then used to subdivide the area of interest into relatively homogeneous environmental water-quality zones. Results from the regression-tree analysis not only define the most important environmental characteristics, but also describe how to subdivide the coverage of the specific characteristic (for example, areas with <26% or >or=26% soil clay content). The resulting regionalization scheme is customized for each water-quality constituent based on the environmental characteristics most statistically related to that constituent. SPARTA was used to delineate areas of similar phosphorus, nitrogen, and sediment concentrations (by including land-use characteristics) and areas of similar potential water quality (by excluding land-use characteristics). The SPARTA approach reduced the variability in water-quality concentrations (phosphorus, total nitrogen, Kjeldahl nitrogen, and suspended sediment) within similarly classified zones from that obtained using the US Environmental Protection Agency's nutrient ecoregions.

Agriculture↗
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↗
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↗