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PubMedDate not supplied

Comparative performance studies of water lettuce, duckweed, and algal-based stabilization ponds using low-strength sewage.

A bench-scale continuous-flow wastewater treatment system comprising three parallel lines using duckweed (Spirodela polyrhiza), water lettuce (Pistia stratiotes), and algae (natural colonization) as treatment agents was set up to determine environmental conditions, fecal coliform profiles and general treatment performance. Each line consisted of four ponds connected in series fed by diluted sewage. Influent and effluent parameters measured included environmental conditions, turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, nitrite, ammonia, total phosphorus, fecal coliforms, mosquito larvae, and sludge accumulations. Environmental conditions and fecal coliforms profiles were determined in the sediments (0.63 m), suspensions (0.35 m), and surfaces (0.1 m) of each pond. Acidic conditions were observed in the pistia ponds, neutral conditions in duckweed ponds, and alkaline conditions in algal ponds. Fecal coliforms log removals of 6, 4, and 3 were observed in algal, duckweed, and pistia ponds, respectively, in the final effluents, with die-off rates per pond of 2.7, 2.0, and 1.6. Sedimentation accounted for over 99% fecal coliform removal in most of the algal and pistia ponds. BOD removal was highest in the duckweed system, followed by pistia and algae at 95%, 93%, and 25%, respectively. COD removals were 65% and 59%, respectively, for duckweed and pistia, while COD increased in algal ponds by 56%. Nitrate removals were 72%, 70%, and 36%, respectively for duckweed, pistia, and algal ponds. Total phosphorus removals were 33% and 9% for pistia and duckweed systems, while an increase of 19% was observed in the algal treatment system. Ammonia removals were 95% in both pistia and duckweed and 93% in algal systems. Removals of total dissolved solids (TDS) were 70% for pistia, 15% for duckweed, and 9% for algae. Mosquito populations of 11,175/m(2), 3516/m(2), and 96/m(2) were counted in pistia, algal, and duckweed ponds, respectively. Low turbidity and low sludge accumulation characterized the macrophyte ponds. Performance in the removal of fecal coliforms in the algal-based treatment system and organic load removal in both macrophytes and algal-based treatment systems met the Ghana Environmental Protection Agency guideline values.

Animals↗
PubMed2001

UV doses of Americans.

The UV doses of Americans were never measured, but are needed for assessing the risks of UV-related health effects. We calculated these doses using a novel approach. The Environmental Protection Agency's (EPA) National Human Activity Pattern Survey (NHAPS) recorded the activity profiles of 9386 Americans over 24 months to assess their exposure to environmental pollutants, one of which is UV radiation. NHAPS used randomized telephone interviews to get their previous day's minute-by-minute activities. From NHAPS we extracted only the outdoor-daylight data of the northern and southern indoor workers (95%), stratifying by season, sex and age (0-21, 22-40, 41-59 and 60+ years) to find the average time Americans spend outdoors. Knowing the total daylight time and that while outdoors Americans are exposed to about 30% of the available solar UV (on a horizontal plane), we calculated their percent ambients. The average American's percent ambients are 2.6 and 2.5% for northern and southern females, respectively, and 3.5 and 3.6% for northern and southern males, respectively. Men over 40 years of age have the highest ambients (4%). From their ambients we calculated their annual doses using seasonal averages of UV measurements taken daily for over 2 years by EPA Brewer spectrophotometers located in four quadrants of the United States: Atlanta, GA; Boston, MA; Bozeman, MT and Riverside, CA. The average erythemal UV doses of Americans are about 25,000 J/m2/year, 22,000 for females and 28,000 for males, or 33,000 J/m2/year including a conservative continental U.S. vacation (7800 J/m2). Thus, we can now assess the risks of UV-related health effects for Americans.

Adolescent↗
PubMed2001

Selected mechanisms of genotoxic effects of inorganic arsenic compounds.

Chronic exposure to inorganic arsenic compounds is responsible for the prevalance of various tumors, as well as of other diseases. A major problem is the exposure to inorganic arsenic (i-As) in drinking water that affects millions of people, primarily in Asia and South America. In these regions, the concentration of arsenic in drinking water amounts to several thousand microg/l and considerably exceeds the standard of 50 microg/l, recommended by the US Environmental Protection Agency. It is interesting that not all populations are equally sensitive to i-As. Therefore, the existing standard should be verified and the environmentally safe i-As concentration should be established. Bearing this in mind, it would be helpful to know the mechanisms of toxicity of inorganic arsenic compounds. In vitro and in vivo studies and examination of people exposed to high concentrations of i-As in drinking water show its genotoxicity. Inorganic As increases the frequency of micronuclei, chromosome aberrations and sister chromatid exchanges both in humans and in animals, but it does not induce point mutations. If arsenic does not affect DNA directly, then what is the mechanism of its toxicity? The results of various studies suggest that it may intensify toxic effects of other physical and chemical agents, especially by DNA repair inhibition. Besides, it is believed that inorganic arsenic compounds may cause changes in the cell redox potential and alter DNA methylation and phosphorylation of cell-cycle control proteins. Some data also suggest that i-As increases celluar proliferation and apoptosis. The purpose of this work is to present some views on cytotoxic mechanisms of inorganic arsenic compounds.

Animals↗
PubMedDate not supplied

Meta-analytic approaches to dose-response relationships, with application in studies of lung cancer and exposure to environmental tobacco smoke.

This paper outlines several meta-analytic approaches to the assessment of quantal dose-response relationships; that is, to the evaluation of an increase in the level of exposure to an agent and the associated relative risk of a disease when this is investigated over a number of different studies. Analysis is developed at two levels: first, a consistent method of evaluating the dose-response relationship is applied to each study, and second, an overall picture is obtained by comparing and combining these relationships. At the first stage, for an individual study, dose-response assessment involves choices of model and appropriate tests for trend, which are influenced by such issues as dose measurement and use of the unexposed group. At the second stage, different methods for pooling results across studies must be considered. These depend on the choices made in the first stage of analysis, with additional attention paid to heterogeneity, and possible bias due to studies included in meta-analysis. We describe these meta-analytic approaches for three methods of evaluating dose response. The approaches are illustrated by evaluating the relationship between lung cancer and levels of exposure to environmental tobacco smoke (ETS). The strength of this relationship has been a point of debate in recent assessment of evidence for an overall carcinogenic effect of ETS exposure. We find little indication of a consistent dose response, a result explained in terms of recent models for cancer and passive smoking developed by Darby and Pike, the current meta-analysis results of overall risk-ratios of current studies in Tweedie and Mengersen, and misclassification models developed by the United States Environmental Protection Agency (EPA).

Case-Control Studies↗
PubMed2000

Separation of acidic solutes by nonaqueous capillary electrophoresis in acetonitrile-based media. Combined effects of deprotonation and heteroconjugation.

Nonaqueous capillary electrophoresis (NACE) is a chemical separation technique that has grown in popularity over the past few years. In this report, we focus on the combination of heteroconjugation and deprotonation in the NACE separation of phenols using acetonitrile (ACN) as the buffer solvent. By preparing various dilute buffers consisting of carboxylic acids and tetrabutylammonium hydroxide in ACN, selectivity may be manipulated based on a solute's dissociation constant as well as its ability to form heterogeneous ions with the buffer components. ACN's low viscosity, coupled with its ability to allow for heteroconjugation, often leads to rapid and efficient separations that are not possible in aqueous media. In this report, equations are derived showing the dependence of mobility on various factors, including the pKa of the analyte, the pH and concentration of the buffer, and the analyte-buffer heteroconjugation constant (Kf). The validity of these equations is tested as several nitrophenols are separated at different pH values and concentrations. Using nonlinear regression, the Kf values for the heteroconjugate formation between the nitrophenols and several carboxylate anions are calculated. Also presented in this report are the NACE separations of the 19 chlorophenol congeners and the 11 priority pollutant phenols (used in US Environmental Protection Agency methods 604, 625/1625 and 8270B).

Acetonitriles↗
PubMed2000

Microbiological water purification without the use of chemical disinfection.

OBJECTIVE: Point-of-use (POU) water treatment systems are self-contained units that can be used by recreational enthusiasts who normally obtain drinking water from untreated sources (i.e., rivers, lakes, etc). Microbiological water purifier units are capable of removing all waterborne pathogens. The purpose of this study was to evaluate a new technology (Structured Matrix) capable of micro-biologically purifying the water without the use of chemical disinfectants or an external power requirement. METHODS: Each of 3 identical portable water filtration units were evaluated for their ability to remove Klebsiella terrigena, poliovirus type 1, rotavirus SA-11, and Cryptosporidium parvum oocysts. Units were operated according to the manufacturer's instructions to process 378 L of water. Each unit was challenged with test organisms after 0, 94, 190, 227, 284, 340, and 378 L had passed through it. For the 227-L and 284-L challenges, a "worst-case" water quality (4 degrees C, pH 9, and turbidity 30 NTU) was used that contained 1500 mg/L dissolved solids and 10 mg/L humid acid. At 340-L and 378-L challenges, worst-case water quality was adjusted to pH 5.0. Units were tested after stagnation for 48 hours following passage of 190, 340, and 378 L of water. RESULTS: The geometric average removal exceeded 99.9999% for bacteria, 99.99% for viruses, and 99.9% for Cryptosporidium parvum oocysts. CONCLUSION: These units comply with the criteria guidelines for microbial removal under the United States Environmental Protection Agency's "Guide Standard and Protocol for Testing Microbiological Water Purifiers."

Animals↗
PubMed1993

Methylene chloride toxicity.

The effects of acute exposure to methylene chloride (dichloromethane) are due to its central nervous system depressant properties, which have resulted in fatalities. Manifestations of acute exposure include mental confusion, fatigue, lethargy, headache and chest pain. Metabolic conversion of methylene chloride to carbon monoxide may place persons with preexisting coronary artery disease at increased risk. Sequelae following chronic exposure are unknown, but data suggest serious long-term effects. The Environmental Protection Agency considers methylene chloride to be a probable human carcinogen.

Aged↗
PubMed2005

Cotton liners to mediate glove comfort for greenhouse applicators.

Greenhouse applicators' acceptance of cotton knit gloves worn as liners under nitrile chemical-resistant gloves (CRG) for pesticide application was investigated through a wear study in Iowa and New York. Comfort was assessed by questionnaires and interviews with 10 applicators. Contamination levels of four pesticides on CRG and liners at thumb, forefinger, palm, and cuff locations were determined by chemical analysis using high-performance liquid chromatography or gas chromatography. Applicators reported feeling more comfortable with cotton liners under their CRG than without and that cotton liners were easy to manage. Contamination was significantly greater on nitrile CRG than on cotton liners underneath, but a few liner specimens had measurable contamination. No significant contamination differences were found between right- and left-hand gloves. Contamination varied significantly by hand location, with cuffs least, and by pesticide, with chlorpyrifos most. These results support the Environmental Protection Agency's recommendation that liners should be disposable, but further work on liners and their laundering feasibility seems indicated.

Agriculture↗
PubMed2001

Compilation and evaluation of a Paso del Norte emission inventory.

Emission inventories of ozone precursors are routinely used as input to comprehensive photochemical air quality models. Photochemical model performance and the development of effective control strategies rely on the accuracy and representativeness of an underlying emission inventory. This paper describes the tasks undertaken to compile and evaluate an ozone precursor emission inventory for the El Paso/Ciudad Juárez/Southern Doña Ana region. Point, area and mobile source emission data were obtained from local government agencies and were spatially and temporally allocated to a gridded domain using region-specific demographic and land-cover information. The inventory was then processed using the US Environmental Protection Agency (EPA) recommended Emissions Preprocessor System 2.0 (UAM-EPS 2.0) which generates emissions files compatible with the Urban Airshed Model (UAM). A top down evaluation of the emission inventory was performed to examine how well the inventory represented ambient pollutant compositions. The top-down evaluation methodology employed in this study compares emission inventory ratios of non-methane hydrocarbon (NMHC)/nitrogen oxide (NOx) and carbon monoxide (CO)/NOx ratios to corresponding ambient ratios. Detailed NMHC species comparisons were made in order to investigate the relative composition of individual hydrocarbon species in the emission inventory and in the ambient data. The emission inventory compiled during this effort has since been used to model ozone in the Paso del Norte airshed (Emery et al., CAMx modeling of ozone and carbon monoxide in the Paso del Norte airshed. In: Proc of Ninety-Third Annual Meeting of Air & Waste Management Association, 18-22 June 2000, Air & Waste Management Association, Pittsburgh, PA, 2000).

Databases, Factual↗
PubMed2005

Principles and practices of neurodevelopmental assessment in children: lessons learned from the Centers for Children's Environmental Health and Disease Prevention Research.

Principles and practices of pediatric neurotoxicology are reviewed here with the purpose of guiding the design and execution of the planned National Children's Study. The developing human central nervous system is the target organ most vulnerable to environmental chemicals. An investigation of the effects of environmental exposures on child development is a complex endeavor that requires consideration of numerous critical factors pertinent to a study's concept, design, and execution. These include the timing of neurodevelopmental assessment, matters of biologic plausibility, site, child and population factors, data quality assurance and control, the selection of appropriate domains and measures of neurobehavior, and data safety and monitoring. Here we summarize instruments for the assessment of the neonate, infant, and child that are being employed in the Centers for Children's Environmental Health and Disease Prevention Research, sponsored by the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency, discuss neural and neurobiologic measures of development, and consider the promises of gene-environment studies. The vulnerability of the human central nervous system to environmental chemicals has been well established, but the contribution these exposures may make to problems such as attention deficit disorder, conduct problems, pervasive developmental disorder, or autism spectrum disorder remain uncertain. Large-scale studies such as the National Children's Study may provide some important clues. The human neurodevelopmental phenotype will be most clearly represented in models that include environmental chemical exposures, the social milieu, and complex human genetic characteristics that we are just beginning to understand.

Central Nervous System↗
PubMed1992

Predicting blood lead concentrations from environmental concentrations.

A method is presented by which blood lead concentrations can be estimated from environmental concentrations using a multipathway analysis. For the ingestion and dermal uptake pathways the incremental increase in blood lead concentration is estimated as the product of the concentration in the relevant medium, a medium-specific contact rate, and an empirically determined ratio between intake and blood level. The inhalation pathway omits the contact rate and uses a ratio between the concentration in blood and the concentration in air. Model outputs corresponding to various input parameters are presented, and some of these are compared with outputs from the U.S. Environmental Protection Agency's Lead Biokinetic/Uptake model, Lead 5.

Adult↗
PubMed2003

Lead exposure in day care centres in the Caracas Valley--Venezuela.

Lead has been used as an additive to improve the anti-knock quality of gasoline. However, the combustion of lead gasoline produces particles rich in this element. These kinds of particles impact the alveoli and move into the bloodstream, causing serious health problems. The objective of this study is to determine the granulometric distribution, mineralogy, and lead levels in samples such as settled dust and soil, as well as lead concentration in drinking water, in different day care centers located in the metropolitan area of Caracas, which have been previously studied and classified, according to the Total Suspended Particles (TSP) levels by the national environmental office, as high (80 microg m(-3)) and low (50 microg m(-3)) polluted areas. The chemical analysis was performed by atomic absorption spectroscopy and atomic emission spectroscopy-inductively coupled plasma. The mineralogy was determined using X-ray differentiation. Results show that all samples are enriched by small particles (<44 microm). Lead concentrations in day care centres located in areas of high vehicular density were higher than those in areas of low vehicular traffic. Lead concentration for drinking water samples was below the standard value reported by the Environmental Protection Agency (EPA) (15 microg Pb/l).

Child↗
PubMed2002

Ambient air measurement of acrolein and other carbonyls at the Oakland-San Francisco Bay Bridge toll plaza.

Interest in ambient concentrations of acrolein and other alpha,beta-unsaturated aldehydes and dicarbonyls (e.g., crotonaldehyde, methyl glyoxal, glyoxal, malonaldehyde (malondialdehyde)) is growing because either they exist at high levels in motor vehicle emissions or they arise from photooxidation of other hydrocarbons emitted from mobile sources. In addition, their mutagenic, genotoxic, or carcinogenic properties are well-established, and the results of a dispersion-modeling study regarding the health risks posed by the 188 hazardous air pollutants in California attributes the highest noncancer risk to exposure to acrolein. Such modeling studies, conducted by the U.S. Environmental Protection Agency (U.S. EPA), also predict median ambient air concentrations of acrolein higher than 0.06 microg/m3, the chronic inhalation reference exposure level stipulated by the California Office of Environmental Health Hazard Assessment in counties surrounding the Oakland-San Francisco Bay Bridge. We measured acrolein and other potentially toxic carbonyls in air sampled at the San Francisco Bay Bridge toll plaza during rush hour traffic, which may be considered a "worst case scenario" for outdoor airborne carbonyls. We identified 36 carbonyls in the sample extracts, including 14 saturated aliphatic carbonyls, six unsaturated carbonyls, four aromatic carbonyls, six dicarbonyls, and six hydroxy carbonyls. Structural information to support tentative identification of carbonyls and hydroxycarbonyls was obtained by using a method that involves O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and PFBHA/bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization in concert with gas chromatography/ion trap mass spectrometry. Most notably, we report for the first time the presence of malonaldehyde in the ambient atmospheric environment. A relatively linear relationship between retention time and the molecular weight of the derivatives was established to assist in obtaining structural information about chemicals for which authentic standards are not readily available. Levels of acrolein exceeded the California reference exposure level during morning rush hour traffic. The measured values, however, were significantly lower than estimates of county-wide average acrolein concentrations predicted by a U.S. EPA modeling study based on 1996 data. Successful regulatory efforts such as the introduction of reformulated gasoline, together with the advancement of new catalysts and fleet turnover throughout the 1990s, are likely to account for part of the gap between our determination and the 1996 levels.

Acrolein↗
PubMed1993

Arsenic and cadmium exposure in children living near a smelter complex in San Luis Potosí, Mexico.

The main purpose of this study was to assess environmental contamination by arsenic and cadmium in a smelter community (San Luis Potosí City, México) and its possible contribution to an increased body burden of these elements in children. Arsenic and cadmium were found in the environment (air, soil, and household dust, and tap water) as well as in the urine and hair from children. The study was undertaken in three zones: Morales, an urban area close to the smelter complex; Graciano, an urban area 7 km away from the complex; and Mexquitic, a small rural town 25 km away. The environmental study showed that Morales is the most contaminated of the zones studied. The range of arsenic levels in soil (117-1396 ppm), dust (515-2625 ppm), and air (0.13-1.45 micrograms/m3) in the exposed area (Morales) was higher than those in the control areas. Cadmium concentrations were also higher in Morales. Estimates of the arsenic ingestion rate in Morales (1.0-19.8 micrograms/kg/day) were equal to or higher than the reference dose of 1 microgram/kg/day calculated by the Environmental Protection Agency. The range of arsenic levels in urine (69-594 micrograms/g creatinine) and hair (1.4-57.3 micrograms/g) and that of cadmium in hair (0.25-3.5 micrograms/g) indicated that environmental exposure has resulted in an increased body burden of these elements in children, suggesting that children living in Morales are at high risk of suffering adverse health effects if exposure continues.

Air Pollutants↗
PubMed1998

Human health perspective on environmental exposure to hydrazines: a review.

Hydrazines are colorless liquid compounds that have been found at various Department of Defense hazardous waste sites. They are designated as environmental contaminants causing adverse effects to public health and have been identified at many National Priorities List (NPL) hazardous waste sites and federal facilities sites in the United States. Three chemically similar hydrazines-hydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine--occur in the environment and cause adverse health effects to persons living near hazardous waste sites. Humans are exposed to hydrazines by drinking contaminated, water, by inhaling contaminated air, or by swallowing or touching contaminated dust. Human occupational data and studies in laboratory animals suggest that people exposed to hydrazines may develop adverse systemic health effects or cancer. Hydrazines have caused cancer in animals following acute- or intermediate- duration exposure by the oral and inhalation routes. The U.S. Environmental Protection Agency, the U.S. Department of Health and Human Services, the International Agency for Research on Cancer, and the World Health Organization have classified hydrazines as possible cancer-causing environmental contaminants.

Animals↗
PubMedDate not supplied

Preliminary assessment of worker and ambient air exposures during soil remediation technology demonstration.

Hazardous waste site remediation workers or neighboring residents may be exposed to particulates during the remediation of lead-contaminated soil sites. Industrial hygiene surveys and air monitoring programs for both lead and dust were performed during initial soil sampling activities and during pilot scale technology demonstration activities at two lead-contaminated soil sites to assess whether worker protection or temporary resident relocation would be suggested during any subsequent remediation technology activities. The concentrations of lead and dust in the air during pilot scale technology demonstration studies were within applicable exposure guidelines, including Occupational Health and Safety Administration permissible exposure limits, National Institute for Occupational Safety and Health recommended exposure limits, American Conference of Governmental Industrial Hygiene threshold limit values, and the United States Environmental Protection Agency's National Ambient Air Quality Standards program limits.

Air Pollutants, Occupational↗
PubMed1978

The current status of hazardous solid waste management.

Growth of the population and of industrialization, and substandard disposal of the increased waste products thus generated, have resulted in numerous documented cases of harm to human, plant, and animal health. The Resource Conservation and Recovery Act (1976), its stated goals, and its intended means of implementation, are discussed relative to hazardous waste problems. Subtitle C of this Act, and the authority granted by it to the U.S. Environmental Protection Agency, are explained. Standards and regulations have been imposed upon those responsible for generating and transporting hazardous wastes, to ensure the ultimate safe disposal of such wastes in environmentally suitable, properly licensed facilities.

Environmental Pollution↗
PubMed2003

Joint occupational and environmental pollution prevention strategies: a model for primary prevention.

Occupational and environmental health issues are not always considered simultaneously when attempting to reduce or eliminate hazardous materials from our environment. Methods used to decrease exposure to hazardous chemicals in the workplace often lead to increased exposure in the environment and to the community outside the workplace. Conversely, efforts to control emissions of hazardous chemicals into the environment often lead to increased exposure to the workers inside the plant. There are government regulations in place that ensure a safe work environment or a safe outside environment; however, there is little integration of both approaches when considering the public's health as a whole. This article examines some of the reasons behind this dichotomy, focusing on the regulatory and policy frameworks with respect to workplace and environment that have resulted in the inability of the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) to coordinate their efforts to protect public health. The components of the Pollution Prevention Act and its potential to serve as a model for integrating occupational and environmental health are discussed. Limitations regarding enforcement of pollution prevention, as well as its disconnection from the work environment are equally highlighted. The article finishes by examining the barriers to integrating the occupational and environmental health paradigms and the promotion of primary prevention in public health.

Journal Article↗