Industrial Pollution Prevention

The 1992 A&WMA Critical Review was authored by Harry Freeman and members of his staff at the Pollution Prevention Research Branch, Risk Reduction Engineering Laboratory, U.S. Environmental Protection Agency in Cincinnati, Ohio. Mr. Freeman presented the paper "Industrial Pollution Prevention," at the Critical Review session held during the 85th Air & Waste Management Association Annual Meeting in Kansas City, Missouri. Prepared discussions and invited comments presented during the session are published here, as well as closing remarks by Mr. Freeman.     

PCB remediation in schools: a review

Growing awareness of polychlorinated biphenyls (PCBs) in legacy caulk and other construction materials of schools has created a need for information on best practices to control human exposures and comply with applicable regulations. A concise review of approaches and techniques for management of building-related PCBs is the focus of this paper. Engineering and administrative controls that block pathways of PCB transport, dilute concentrations of PCBs in indoor air or other exposure media, or establish uses of building space that mitigate exposure can be effective initial responses to identification of PCBs in a building. Mitigation measures also provide time for school officials to plan a longer-term remediation strategy and to secure the necessary resources. These longer-term strategies typically involve removal of caulk or other primary sources of PCBs as well as nearby masonry or other materials contaminated with PCBs by the primary sources. The costs of managing PCB-containing building materials from assessment through ultimate disposal can be substantial. Optimizing the efficacy and cost-effectiveness of remediation programs requires aligning a thorough understanding of sources and exposure pathways with the most appropriate mitigation and abatement methods.     

Dissipation, half-lives, and mass spectrometric identification of endosulfan isomers and the sulfate metabolite on three field-grown vegetables

Endosulfan 3 EC, a mixture of α- and β-stereo isomers, was sprayed on field-grown pepper, melon, and sweet potato plants at the recommended rate of 0.44 kg A.I. acre(-1). Plant tissue samples (leaves, fruits, or edible roots) were collected 1 h to 30 days following spraying and analyzed for endosulfan isomers (α- and β-isomers). Analysis of samples was accomplished using a gas chromatograph (GC) equipped with a mass detector in total ion mode. The results indicated the formation of endosulfan sulfate as the major metabolite of endosulfan sulfite and the relatively higher persistence of the β-isomers as compared to the α-isomer. The initial total residues (α- and β-isomers plus endosulfan sulfate) were higher on leaves than on fruits. On pepper and melon fruits, the α-isomer, which is the more toxic to mammals, dissipated faster (T(1/2) = 1.22 and 0.95 d, respectively) than the less toxic β-isomer (T(1/2) = 3.0 and 2.5 d, respectively). These results confirm the greater loss of the α-isomer compared to the β-isomer, which can ultimately impact endosulfan dissipation in the environment. Additionally, the higher initial residues of endosulfan on pepper and sweet potato leaves should be considered of great importance for timing field operations and the safe entry of harvesters due to the high mammalian toxicity of endosulfan.     

Delineating landfill leachate discharge to an arsenic contaminated waterway

Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.     

Grain size partitioning of platinum-group elements in road-deposited sediments: implications for anthropogenic flux estimates from autocatalysts

Twelve road-deposited sediment samples were analyzed for platinum-group elements (PGEs) and Pb in the <63 microm fraction of an urban watershed in Hawaii. Three samples were further fractionated into five size classes, from 63-125 microm to 1000-2000 microm, and these were analyzed for PGEs and Pb. Concentrations in the <63 microm fraction reached 174 microg/kg (Pt), 101 microg/kg (Pd), 16 microg/kg (Rh), and 1.3 microg/kg (Ir). Enrichment ratios followed the sequence Rh>Pt=Pd>Ir. Iridium was geogenic in origin, while the remaining PGEs indicated significant anthropogenic contamination. Palladium, Pt and Rh concentrations and enrichment signals were consistent with PGE bivariate ratios and PGE partitioning in three-way catalysts. Size partitioning indicated that the <63 microm fraction had the lowest PGE concentrations and mass loading percentages. These data suggest that autocatalyst PGE flux estimates into the environment will be significantly underestimated if only a fine grain size fraction is analyzed.     

Measurement of transferable chemical residue from nylon carpet using the California roller and a new mega-California roller

Human chemical exposures resulting from transfer of surface deposition on indoor nylon carpets may be estimated by measuring transferable residues (mu g chemical/cm2 carpet). A weighted roller developed at California Department of Food and Agriculture (CDFA) has been extensively used to sample transferable residue for estimates of human exposure in risk characterization. A modified roller has been developed to evaluate the influence of pressure on transferable chemical residue since weight and force (or pressure, kg/m2) may vary person-to-person and activity-to-activity. A 30.5 cm diameter roller was used to apply 60 to 2100 kg/m2 to bracket pressures exerted by humans on a flat nylon-carpeted surface. Measurements of transferable cyfluthrin residues were made after 1, 7, and 21 days. Total Soxhlet extractable cyfluthrin residues were relatively constant during the test period. Residue transferability decreased during the study period. Modest increases in the transferability of surface residues were observed over the broad range of pressures applied by the modified roller.