Toxicological evaluation for the hazard assessment of tire crumb for use in public playgrounds

Disposal of used tires has been a major problem in solid waste management. New uses will have to be found to consume recycled tire products. One such proposed use is as ground cover in playgrounds. However, concern has been expressed regarding exposure of children to hazardous chemicals and the environmental impact of such chemicals. We designed a comprehensive hazard assessment to evaluate and address potential human health and environmental concerns associated with the use of tire crumb in playgrounds. Human health concerns were addressed using conventional hazard analyses, mutagenicity assays, and aquatic toxicity tests of extracted tire crumb. Hazard to children appears to be minimal. Toxicity to all aquatic organisms (bacteria, invertebrates, fish, and green algae) was observed; however, this activity disappeared with aging of the tire crumb for three months in place in the playground. We conclude that the use of tire crumb in playgrounds results in minimal hazard to children and the receiving environment.     

Market solutions for sustainable cities

Sustainable development has become a globally accepted policy objective. It is, however, increasingly recognised that the implementation of sustainability strategies has to take place at a decentralised level. This has also provoked the idea of urban sustainability. This paper aims to offer a refreshing contribution by making a plea for market solutions for urban sustainability problems. Particular attention is given to the potential contribution of tradeable permits for various polluting activities (air pollution, water pollution, congestion energy consumption, etc.). The idea is that such market strategies may favour efficiency, equity and environmental quality in the city. An overview of various possibilities is given, followed by policy guidelines and conclusions.     

A Cyclone for Size-Selective Sampling of Ambient Air

A cyclone with a 47 mm after-filter has been developed for ambient air size-selective monitoring. It has been extensively evaluated with laboratory-generated aerosol. Variation of the pressure drop and 50% cut point with flow rate show that the cyclone operates in a single flow regime with a vortex in the outlet flow. The particle size cutoff curve is comparable in sharpness to a cascade impactor and is the same for solid or liquid particles. At 21.7 L/min, D ₅₀ is 2.5μm and at 15.4 L/min, D ₅₀ is 3.5 μm. Collection efficiency data for flow rates from 8 to 27 L/min fit a universal curve when plotted vs. the normalized particle diameter, (D-D ₅₀)/D ₅₀ Reentrainment of previously deposited particles is less than 1 % of the loading per day. In field tests the cyclone has proved to be a very satisfactory size-selective sampler.     

Determination of Henry's law constant for elemental mercury

The assessment of the global mercury cycle involves estimations of the evasion of mercury form oceanic waters. In such estimations Henry's law constant is often used. In this study the Henry's law constant for elemental mercury has been re-determined in MQ water and artificial sea water. Moreover, for the first time it has been determined for 1.5M sodium chloride (NaCl) solution which is of relevance for modeling of atmospheric waters at coastal locations. For all solutions, experiments has been conducted at five different temperatures between 278 and 308K, using a novel technique, for mercury, based on direct measurements of the portioning of mercury between the aqueous and gaseous phase. Elemental mercury was extracted from the water column and the logarithm of the mass of extracted mercury was plotted against time. A dimensionless Henry's law constant, defined as: [Formula: see text] was obtained from the slope of the curve. Almost no difference was observed in the values comparing the Milli-Q water and artificial sea water, however for the 1.5M NaCl solution a salting-out effect was seen, i.e. the solubility of mercury in the water phase decreased. The decreased solubility will generate an increase in the value of Henry's law constant.     

Toxicological Evaluation for the Hazard Assessment of Tire Crumb for Use in Public Playgrounds

Abstract

Disposal of used tires has been a major problem in solid waste management. New uses will have to be found to consume recycled tire products. One such proposed use is as ground cover in playgrounds. However, concern has been expressed regarding exposure of children to hazardous chemicals and the environmental impact of such chemicals. We designed a comprehensive hazard assessment to evaluate and address potential human health and environmental concerns associated with the use of tire crumb in playgrounds. Human health concerns were addressed using conventional hazard analyses, mutagenicity assays, and aquatic toxicity tests of extracted tire crumb. Hazard to children appears to be minimal. Toxicity to all aquatic organisms (bacteria, invertebrates, fish, and green algae) was observed; however, this activity disappeared with aging of the tire crumb for three months in place in the playground. We conclude that the use of tire crumb in playgrounds results in minimal hazard to children and the receiving environment.     

A performance-based framework for demonstrating appropriate use of an alternate method for wastewater compliance monitoring.

The choice of wastewater compliance methods used in the United States has been largely prescribed; however, in some cases, this has led to data of unknown or poor quality. This problem is further compounded by the relatively slow regulatory approval process to incorporate discharge-specific method modifications or flexibility to using alternate, potentially better technologies. In this study, a framework is presented, using a performance-based-system approach, which a discharger could use to verify proper use of an alternate or modified method. An example, using two chemical oxygen demand methods (a currently approved method and an alternate method that does not generate hazardous waste) demonstrates that the protocol is simple to use, yet scientifically defensible and effective and that this approach should be readily understandable to both regulators and the regulated community. Our results also suggest that the reference method approach, without associated measurement quality objectives, may yield a false sense of competency with an alternate method.     

Wet Electrostatic Precipitators for Control of Submicron Particles

The application of wet electrostatic precipitators is rapidly gaining popularity. The emission regulations are becoming more and more stringent and they are being enforced. The emphasis on removal of fine particles and organic liquid droplets in the submicron range is increasing. In order to meet the required outlet loadings and opacities, the pressure drop that has to be applied across a conventional scrubber has increased exponentially. The wet electrostatic precipitator is emerging as an economic alternative by virtue of its very low power consumption and its potential for removal of submicron particles with efficiencies in the high nineties. Several applications of the wet electrostatic precipitator will be reviewed in this paper.     

Rationale for assessment of risk from exposure to 2,3,7,8-TCDD

The human health risk assessment is supported by methodology for utilizing toxic effects in animals consisting of carcinogenic and noncarcinogenic responses as a result of chronic, subchronic and acute exposures. One of the initial steps in a risk assessment activity involves the estimation of exposure levels. These estimates are typically based on either direct environmental measurements or predictions obtained from fate and transport models. The decision to develop assessment of risk from chronic exposure based on a nonthreshold model is made if a chemical demonstrates carcinogenic activity in animal bioassays and/or in human epidemiological studies. In the absence of any positive human epidemiologic data, it is assumed that a substance which induces a statistically significant carcinogenic response in animals has the probability to cause cancer in humans. The carcinogenic potential of 2,3,7,8-TCDD has been established based on chronic exposure in rodents. In addition, 2,3,7,8-TCDD has also been shown to be a liver cancer promoter in rodents. In the risk assessment on dioxins based on chronic exposure in experimental animals, 2,3,7,8-TCDD is regarded as a carcinogenic substance. Carcinogenic data from animal bioassays are utilized for the assessment of risk for the purpose of estimating the likelihood of 2,3,7,8-TCDD being carcinogenic for humans and to determine the magnitude of the potential impact on public health.     

Development of a new hydrocarbon index for oil-in-water

A new robust method for determination of hydrocarbons in water without use of Freon^™ or other halogenated solvents has been validated and subjected to an interlaboratory exercise. The method is based on extraction with a light hydrocarbon (boiling point in the 39–69°C range), followed by cleanup for removal of polar components and detection by gas chromatography (GC) with flame ionisation (FID) detection. The performance characteristics of the method are comparable with that of the previous Freon-IR method with recoveries in the 60–80% range and reproducibility (between laboratory variations) of about 30%.

A screening method for hydrocarbons in the range 5 ppm and above based on infrared spectroscopy (IR), and a promising method for detection of low levels based on solid phase extraction (SPE) has been tested and validated.     

Applicability of the sequencing batch reactor for wastewater treatment

The sequencing batch reactor is a viable and flexible tool for the treatment of domestic and industrial wastewater. It removes not only carbonaceous matter, but also nitrogenous species and some biological nutrients. From the economic and operational points of view, it has advantages over the so-called conventional activated sludge system. Besides this, it can be used in various wastewater environments without any major problem. This paper explores the relative advantages of the reactor, its technical background, and its application in various fields. Some case studies in which it has been successfully adopted are described.     

Evaluation of approaches for terrestrial hazard classification

Hazard assessment is an essential element in the evaluation of the potential effects of chemical substances on the environment. To date, most work has focused on hazard assessment schemes for the aquatic environment, but in recent years, a number of proposals have been developed for other environmental compartments. Due to limited datasets, the suitability of the toxicity cut-off values in these schemes has not been fully determined and the practicalities associated with using these approaches have not been fully established. This study, which focused on the soil compartment, was performed to examine cut-off values proposed by two terrestrial hazard assessment schemes and establish the availability of data. Data on earthworms indicated that current proposals for toxicity cut-off values are appropriate. However, analysis of IUCLID (International Uniform ChemicaL Information Database) indicates that even for commonly used high production volume chemicals, insufficient data are available to enable classification. Whilst the necessary data may already be available for selected groups of substances (e.g. pesticides and veterinary medicines), a significant experimental testing programme would therefore be required before a terrestrial classification system could be applied widely. Such data may become available in the future as a result of initiatives such as REACH.     

Novel approaches for remediation of pesticide pollutants

The use of synthetic pesticides has become an indispensable tool in agriculture for the control of pests. Therefore, the search for remedies and techniques for decontamination and detoxification of a pesticide-contaminated environment has become an important part of the research. Currently, bioremediation seems to be one of the most environmentally safe and cost-effective methods. In nature, the existence of abundant material resources can be used to degrade the environmental pesticide pollutants. At present, a number of microorganisms, capable of degrading pesticides, have been isolated and characterised. For insects, insecticide resistance-associated esterases have been purified and characterised from several insect species, and a new family of cytochrome P450 apparently associated with insecticide resistance in the tobacco budworm, was discovered. Generally, two bioremediation approaches have been used one directly based on microorganisms, and the other involved in isolated enzymes. For the former, in addition to using natural microorganism strains, with genetic techniques certain desirable biodegradation pathways from different organisms are brought together in a single host. However, because of their own limits, especially problems associated with releasing genetically altered microorganisms into the environment, the strategy based on enzymes seems more feasible. In the long term, collaborations between microbiologists, biochemists, and engineers will become increasingly important to efficiently dispose of the pesticide pollutants.     

Quality Assurance for the SITE Program Demonstrations

The U.S. Environmental Protection Agency has implemented a rigorous quality assurance (QA) program to ensure that the performance data generated during their Superfund Innovative Technology Evaluation (SITE) Demonstration projects are of known and adequate quality to support decisions to use such technologies for hazardous waste site characterizations or remediations. A general overview of the ways in which this QA program has been conducted and of the results it has produced is presented.     

Evaluation of the efficiency of monopolar and bipolar BDD electrodes for electrochemical oxidation of anthraquinone textile synthetic effluent for reuse

The efficiency of the electrochemical degradation of synthetic wastewater containing an anthraquinone dye has been comparatively studied in two electrolytic cells with a synthetic boron-doped diamond (Si/BDD) as an anode. The first is an individual cell (Cell 1) with monopolar electrode BDD and the second (Cell 2) has two bipolar electrodes BDD self-polarized. The bulk electrolysis was performed at the same initial operating conditions in order to quantify the influence of the initial pH and current density on dye discoloration and global mineralization removal. The current efficiency and the consumption energy were also evaluated. When the same solutions have been comparatively treated with the two cells, a quite good mineralization is found in Cell 2. This result supposed more fraction of the applied current is used for the electrocombustion reaction on Cell 2 if compared to Cell 1 and small amount rest for the side reaction of oxygen evolution. The HPLC analyses confirmed this hypothesis and showed that the concentration trend of intermediates (sulfanilic acid, phthalate acid and salicylic acid) with electrolysis time was different on two cells. Phototoxicity tests show that the electrochemical oxidation with BDD electrodes could be useful as a pretreatment technique for reducing hazardous wastewater toxicity.     

Evaluation of the Effectiveness of The Lead Peroxide Method for Atmospheric Monitoring of Sulfur Dioxide

This paper presents a simplified analysis to determine the variables that affect the empirical correlation factor used in the lead peroxide method. The rate of sulfation has been determined from two different models. In the first model, the mass transfer rate is calculated from the gas phase resistance alone whereas in the second model, the diffusion resistance in the gel phase is assumed to be the rate limiting step. Although the gas phase and the gel phase resistances may be both important in the actual case, it has been found that the correlation factor based on the first model is adequate to describe general experimental observations. Reasonable agreement has been obtained between the measured and the calculated va|ue of the correlation factor.     

Development of a new model for batch sedimentation and application to secondary settling tanks design.

Assuming that settling takes place in two zones (a constant rate zone and a variable rate zone), a model using four parameters accounting for the nature of the water-suspension system has been proposed for describing batch sedimentation processes. The sludge volume index (SVI) has been expressed in terms of these parameters. Some disadvantages of the SVI application as a design parameter have been pointed out, and it has been shown that a relationship between zone settling velocity and sludge concentration is more consistent for describing the settling behavior and for design of settling tanks. The permissible overflow rate has been related to the technological parameters of secondary settling tank by simple working equations. The graphical representations of these equations could be used to optimize the design and operation of secondary settling tanks.     

Epidemiological Bases for Possible Air Quality Criteria for Carbon Monoxide

Exposures to adequate environmental levels of CO will increase COHb concentrations in human subjects. The amount of this increase is reasonably predictable, and must be considered in relation to exposure to CO in inhaled cigarette smoke as well as to occupational and domestic exposures. The increase in body COHb will result in some degree of impairment of tissue oxygenation.

Methods for estimating COHb levels in large populations are relatively simple. The assumption that an exposure to 30 ppm CO for eight hours will produce on the average, an increase in COHb of 5%, has been substantiated by available data.

Exposure for five hours to between 10 and 12 ppm of CO has been shown to increase the COHb levels in nonsmokers by at least 0.5%. Such an increase adds appreciably to the body burden of COHb in those who do not already have such a body burden from cigarette smoking. Longer exposures could have produced a somewhat greater increase.

Apart from increases in COHb, three possible effects have been a source of major consideration in epidemiologic studies. The first is the production of some persistent toxic reaction. This possibility has been examined with respect to occupational exposure, and the evidence for the occurrence of such a condition is insufficient.

The possible contribution of ambient community CO exposure to the mortality of persons hospitalized with myocardial infarction has been investigated. The evidence suggests that daily average CO values in excess of about 10 ppm may be associated with an increase in mortality in hospitalized patients with myocardial infarction. Substantiation of this impression will require a study of the prognosis of myocardial infarction patients in relationship to COHb levels measured at admission to the hospital.

Finally, in two studies, persons driving motor vehicles which were involved in accidents had higher COHb levels than "control" populations. Controls were not ideal, however. Possible mechanisms by which CO might affect the ability to drive a motor vehicle is suggested in the available data on CO effects upon visual sensitivity, psychological test performance and accurate estimation of time intervals. As little as 2 percent COHb can produce these effects in laboratory studies, and the available epidemiologic information confirms that such an increase in COHb levels among drivers might influence the frequency of accidents.

Specific areas where research is indicated to clarify uncertainties relating to health effects of CO are: 1. The increment in COHb which can be produced by exposures to an average of 20 ppm CO for an eight hour period and the increment which can be produced by 15 ppm for such a period and by 10 ppm for up to twenty-four hours.

2. The relationship of ambient CO levels and of COHb levels to the survival of hospitalized patients with myocardial infarction.

3. The prognostic significance with respect to cardiovascular conditions of elevated levels of COHb.

4. The relationship, if any, between ambient CO and COHb levels and the occurrence of motor vehicle accidents when weather and driving conditions, cigarette smoking, alcohol and drug use, and other factors are adjusted and controlled.

     

Comparison of EGR ratios determined by four different methods for electronic re-circulation gate control

In this study, low pressure systems have been applied for exhaust gas recycling (EGR), which is applied in certain operating conditions. Induction air, exhaust gas flow, amount of exhaust gas added to the induction air, amount of carbon dioxide (CO₂) in the exhaust gas, and amount of carbon dioxide in the induction air mixed with the exhaust gas, have been measured and the EGR ratio has been determined using four different calculation methods. The obtained results have been compared, and it has been noted that all the four methods have given similar results, and the deviation among them has been noted to be 1% at most. Deviations among the results have been explained. In the concluding section, a relation has been formed between the variables chosen as basic parameters, electronic re-circulation gate control, and variables utilised in EGR ratio determination methods.     

Fixed bed adsorption for the removal of pollutants from water

The adsorption of phenol, p-chlorophenol and mercuric ions from aqueous solution onto activated carbon has been studied in fixed bed columns. The influence of varying parameters such as bed depth, solution flowrate and pollutant concentration has been studied. The Bed Depth Service Time has been used to analyse the experimental data and identify design correlations. Furthermore, an optimization procedure based on the Empty Bed Residence Time has been applied to the data.