Use of Probabilistic Methods to Understand the Conservatism in California’s Approach to Assessing Health Risks Posed by Air Contaminants

Many state and federal agencies have prepared risk assessment guidelines, which describe methods for quantifying health risks associated with exposure to vapors and particulates emitted from point and area sources (e.g., California Air Pollution Control Officers Association [CAPCOA] under the Air Toxics “Hot Spots” Act [Assembly Bill 2588] and the U.S. Environmental Protection Agency [EPA] under the Clean Air Act). In general, these guidelines recommend or require the use of upper bound “point” estimates for numerous exposure parameters. This methodology yields a single risk estimate, which is intended not to underestimate the true risk and may significantly overstate it. This paper describes a risk assessment of a facility’s airborne emissions using a probabilistic approach, which presents a range and distribution of risk estimates rather than a single point estimate. The health risks to residents living near a food processing facility, as estimated using techniques recommended by California AB2588, are compared to the results of a probabilistic analysis. Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were identified as the emitted chemicals of concern. The point estimate method recommended by CAPCOA resulted in estimates that were greater than the 99.99th percentile risk predicted by the probabilistic analysis. As shown in other assessments of persistent airborne chemicals, secondary or indirect exposure pathways (i.e., ingestion of beef, ingestion of cow’s milk, and ingestion of mother’s milk) rather than inhalation, were the greatest contributors to risk. In this analysis, the probability distributions for the cancer potency factor and ingestion of cow’s milk had the largest impact on the results of the 33 exposure factors considered.     

Physical and Thermal Analysis of the Degradation of Poly(3-Hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-4-Hydroxybutyrate) Coated Paper in a Constructed Soil Medium

The degradation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) coated brown Kraft paper and its components in a constructed soil environment was investigated. Soil burial tests were carried out over 8 weeks. Weight loss measurements, photographic analysis, environmental scanning electron microscopy (ESEM), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) were conducted to assess the physical, structural, mechanical and thermal behavior before and after the soil burial test. Paper showed the highest physical degradation and weight loss. With respect to the control samples, the stiffness of the partially degraded samples decreased. The overall crystallinity of the biopolymer and the coated paper was affected significantly by burial. The pure biopolymer’s weight loss was substantially enhanced when coated on paper. This result reveals a possible increased microbial population in the coated paper relative to the pure biopolymer.     

Nutritional exchange in a tropical tripartite symbiosis: direct evidence for the transfer of nutrients from anemonefish to host anemone and zooxanthellae

The relationship between anemones and anemonefishes is an oft-cited and endearing example of a mutualistic symbiosis. Current research on mutualistic symbioses suggests these relationships are more commonplace and have greater importance at the ecosystem level on nutrient dynamics and evolutionary processes than previously thought. Using stable isotopes ¹⁵N and ¹³C, both field and laboratory experiments were designed to investigate whether nutrient transfer from two species of resident anemonefishes (Amphiprion perideraion and A. clarkii) to host anemones (Heteractis crispa) occurs. Mass spectroscopy indicated that both ¹⁵N and ¹³C were significantly elevated in the tissues of anemonefishes and in both host anemone and zooxanthellae fractions. These experiments provide the first direct empirical evidence of nitrogen and carbon transfer from resident anemonefishes to host anemones and endosymbiotic zooxanthellae. Such transfer of elements within this intriguing tripartite association underscores the central role that nutrient dynamics contributes to the evolutionary processes of these marine symbioses.     

A Template for Integrated Community Sustainability Planning

This article describes a template for implementing an integrated community sustainability plan. The template emphasizes community engagement and outlines the components of a basic framework for integrating ecological, social and economic dynamics into a community plan. The framework is a series of steps that support a sustainable community development process. While it reflects the Canadian experience, the tools and techniques have applied value for a range of environmental planning contexts around the world. The research is case study based and draws from a diverse range of communities representing many types of infrastructure, demographics and ecological and geographical contexts. A critical path for moving local governments to sustainable community development is the creation and implementation of integrated planning approaches. To be effective and to be implemented, a requisite shift to sustainability requires active community engagement processes, political will, and a commitment to political and administrative accountability, and measurement.     

A macroinvertebrate assessment of Ozark streams located in lead–zinc mining areas of the Viburnum Trend in southeastern Missouri, USA

The Viburnum Trend lead–zinc mining subdistrict is located in the southeast Missouri portion of the Ozark Plateau. In 2003 and 2004, we assessed the ecological effects of mining in several watersheds in the region. We included macroinvertebrate surveys, habitat assessments, and analysis of metals in sediment, pore water, and aquatic biota. Macroinvertebrates were sampled at 21 sites to determine aquatic life impairment status (full, partial, or nonsupport) and relative biotic condition scores. Macroinvertebrate biotic condition scores were significantly correlated with cadmium, nickel, lead, zinc, and specific conductance in 2003 (r?=??0.61 to ?0.68) and with cadmium, lead, and pore water toxic units in 2004 (r?=??0.55 to ?0.57). Reference sites were fully supporting of aquatic life and had the lowest metals concentrations and among the highest biotic condition scores in both years. Sites directly downstream from mining and related activities were partially supporting, with biotic condition scores 10% to 58% lower than reference sites. Sites located greater distances downstream from mining activities had intermediate scores and concentrations of metals. Results indicate that elevated concentrations of metals originating from mining activities were the underlying cause of aquatic life impairment in several of the streams studied. There was general concurrence among the adversely affected sites in how the various indicators responded to mining activities during the overall study.     

Degradation of ciprofloxacin by cryptomelane-type manganese(III/IV) oxides

The objective of this study is to investigate and understand the oxidizing properties of a manganese oxide, specifically synthetic cryptomelane (KMn₈O₁₆) and its derivatives, in aqueous solution. Ciprofloxacin (CIP), a commonly used fluoroquinolone antibiotic, was used as the probe. Synthetic cryptomelane, known as octahedral molecular sieves (OMS-2), was synthesized, and its derivatives were prepared by adding transition metal oxides, V₂O₅ or MoO₃, as dopants during synthesis. The solids were characterized by x-ray powder diffraction (XRD), SEM–energy-dispersive spectrometry (SEM-EDX), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), Raman spectra, and N₂-Brunauer-Emmett-Teller method. Degradation of CIP by different doped OMS-2 was carried out. Process conditions were optimized using response surface methodology (RSM). XRD patterns indicated the crystal phase of regular and doped OMS-2 as the cryptomelane type. Presence of the dopants in doped cryptomelane was confirmed by SEM-EDX and XPS. FTIR and Raman results suggested that the dopants were substituted into the framework in place of manganese. SEM images, XRD analysis, and surface area analysis of doped OMS-2 indicated decreased particle size, decreased crystallinity, and increased surface area compared to regular OMS-2. Higher oxidizing reactivity of doped OMS-2 was also observed with increased CIP removal rates from aqueous solution. The enhancement of reactivity may be due to the increase of surface areas. Nine percent Mo/OMS-2, the most effective oxidant of all synthesized derivatives, was selected for optimization study. Favorable treatment conditions were obtained using RSM at pH 3 with molar ratio [9 % Mo/OMS-2]/[CIP]?≥?50. Under such conditions, more than 90 % CIP can be removed in 30 min. The degradation kinetics was modeled by a modified first order rate with introduction of a retardation factor-α (R ²?>?0.98). Analysis of degradation products indicated that oxidation takes place mainly on the piperazine ring of CIP.     

Biological Integrity in Mid-Atlantic Coastal Plains Headwater Streams

The objective of this study was to assess the applicability of using landscape variables in conjunction with water quality and benthic data to efficiently estimate stream condition of select headwater streams in the Mid-Atlantic Coastal Plains. Eighty-two streams with riffle sites were selected from eight-two independent watersheds across the region for sampling and analyses. Clustering of the watersheds by landscape resulted in three distinct groups (forest, crop, and urban) which coincided with watersheds dominant land cover or use. We used non-parametric analyses to test differences in benthos and water chemistry between groups, and used regression analyses to evaluate responses of benthic communities to water chemistry within each of the landscape groups. We found that typical water chemistry measures associated with urban runoff such as specific conductance and dissolved chloride were significantly higher in the urban group. In the crop group, we found variables commonly associated with farming such as nutrients and pesticides significantly greater than in the other two groups. Regression analyses demonstrated that the numbers of tolerant and facultative macroinvertebrates increased significantly in forested watersheds with small shifts in pollutants, while in human use dominated watersheds the intolerant macroinvertebrates were more sensitive to shifts in chemicals present at lower concentrations. The results from this study suggest that landscape based clustering can be used to link upstream landscape characteristics, water chemistry and biotic integrity in order to assess stream condition and likely cause of degradation without the use of reference sites. Notice: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.     

Biofiltration of airstreams contaminated with MTBE

The treatment of groundwater contaminated with low concentrations of methyl tertiary butyl ether (MTBE) is of nationwide concern. Many treatment techniques include removing MTBE vapors from groundwater, resulting in airstreams that require treatment. One method used for air‐phase MTBE treatment is biofiltration. In a biofilter, the vapors pass through a reactor that contains MTBE‐biodegrading organisms attached to a porous media. This article reports the results of a biofiltration study to treat air contaminated with MTBE at concentrations of 0.2 to 0.33 mg/l, concentrations frequently encountered in the field. The results indicate that MTBE removal at these low concentrations is not as efficient as removals seen at higher concentrations. Activated carbon was shown to be a superior biofiltration medium, compared with media that do not adsorb MTBE vapors. Activated carbon was especially helpful in treatment shock loads of MTBE. © 2002 Wiley Periodicals, Inc.     

Drivers and barriers to water transfer in a New Zealand irrigation scheme

Policy makers, economists and water researchers have advocated water transfer and trade as a key potential response to worldwide water scarcity and/or efficiency problems. This paper examines aspects of an operational irrigation scheme in New Zealand that enables transfer of water between shareholders, arguing that the set-up and processes involved with the scheme can provide a wider context for analysis and consideration of social and cultural issues involved with resource allocation. Analysis of the key drivers and barriers for water reveal that while there is potential for real benefits from transferring water for farmers and the community, an examination of some of the processes used, and barriers to transfer reveals important lessons for planning and regulatory perspectives, including the importance of looking at the issues from a procedural and distributive justice viewpoint.