Residential Scenario Research Articles

Human skin penetration of selected model mycotoxins

Dermal exposure data for mycotoxins are very scarce and fragmentary, despite their widespread skin contact and hazard toxicity. In this study, the transdermal kinetics of aflatoxin B1 (AFB1), ochratoxin A (OTA), fumonisin B1 (FB1), citrinin (CIT), zearalenone (ZEA) and T-2 toxin (T-2) were quantitatively evaluated, using human skin in an in vitro Franz diffusion cell set-up. All mycotoxins penetrated through the skin, except for FB1, which showed concentrations in the receptor fluid below the LoD, resulting in a Kp<3.24×10−6cm/h. OTA showed the highest permeation (Kp=8.20×10−4cm/h), followed by CIT (Kp=4.67×10−4cm/h). AFB1 and ZEA showed lower permeability rates (Kp=2.11 and 2.33×10−4cm/h, respectively). T-2 was found to have the lowest permeability (Kp=6.07×10−5cm/h). From literature-based mycotoxin-concentrations, dermal contact surface, exposure time and apparent Kp's obtained in this study, the daily dermal exposure (DDE) in two industrial and one residential scenario was estimated. Dermal exposure to the DNA-reactive genotoxic carcinogenic AFB1 can lead to a health risk for agricultural workers which are exposed to a mycotoxin contaminated solution in a worst case situation. For all the other investigated mycotoxins, no significant health risk is calculated after dermal contact in neither agricultural nor residential environments.

Polish Soil Quality Standards Versus Risk-Based Soil Screening Levels for Metals and Arsenic

ABSTRACT The main objective of the study was derivation of risk-based soil screening levels (RBSSLs) under two basic exposure scenarios—industrial and residential, and their comparison with the relevant soil quality standards (SQSs), applied in Poland as remedial targets. The RBSSLs were derived from standardized sets of equations that are based on the recently updated U.S. Environmental Protection Agency's human health risk assessment methods. The article presents the results concerning 12 contaminants listed in the SQS ordinance: arsenic, barium, cadmium, cobalt, chromium, copper, mercury, molybdenum, nickel, lead, tin, and zinc. Taking only the human health protection criterion into account, most of SQSs for non-carcinogenic metals under both industrial and residential scenarios seem to be too stringent if used as the remedial levels, which may lead to unnecessary remediation. On the other hand, the SQSs for carcinogenic contaminants (As, CrVI) correspond to cancer risk levels significantly higher than the acceptable level of 1E-06. The findings of the study may constitute the first step to justify the amendment of the Polish SQS ordinance aimed at establishing the new soil quality values based on clearly defined criteria.

Environmental Risks Caused by Pesticides at Forest Nurseries in Finland

ABSTRACT Previously, various persistent pesticides were used extensively in the production of seedlings at Finnish forest nurseries. The extent and magnitude of the risks arising from the consequent environmental contamination are largely unknown. Therefore, we selected two representative nurseries for which we conducted tiered health risk assessments (HRA) using risk-based benchmarks and two calculation tools (SSL and Risc-Human software). Ecological risk assessments (ERA) involved comparisons of environmental concentrations with ecotoxicological benchmarks. Site investigations revealed that the concentration of several pesticides exceeded the Finnish soil quality guidelines in some places. The compost pile for organic residues and the pond receiving runoffs contained traces of pesticides and the maximum concentration of atrazine and terbuthylazine in groundwater exceeded the corresponding guideline for household water. Hexachlorobenzene proved to pose the highest health risks, the maximum hazard quotient being around 10 (carcinogenity-based) in the residential land use scenario. Owing to the conservative assumptions, health risks are expected to remain insignificant, however. Risks to the local terrestrial ecosystem would also remain low, while only further studies will reveal the actual risks to the adjoining aquatic ecosystem. Both calculation tools showed shortcomings that generate uncertainty in the HRA, whereas the ERA was hampered particularly by the lack of benchmarks.

Comparison of the Link Budget with Experimental Performance of a WiMAX System

The performance of different modulation schemes of a broadband fixed wireless 802.16 (WiMAX) system in a sector is experimentally determined and compared to link budget calculations using different path loss models. A link budget based on path loss measurements of the actual WiMAX signal at 3.5GHz for a typical residential scenario in a suburban environment is determined. The link budget calculations show a reasonable agreement with actual performance measurements with certified WiMAX modems. Carefulness is advised when these models are used for the actual deployment of a WiMAX network in a specific area.

Auralization as a tool for acoustical design of single family residences.

Acoustical requirements play an increasing role in residential building design. In an effort to understand these changes USG Corp., a manufacturer of building materials and developer of acoustical solutions for residential and commercial markets, engaged Acentech Inc. to develop aural demonstrations, or auralizations, of common acoustical issues in single family residences. Using computer modeling and audio processing techniques, a number of convincingly realistic simulations of familiar residential scenarios were developed. These auralizations allowed USG to better understand acoustical issues and recommend appropriate products and systems. This paper shares the experience of this project.

Suitable Housing Placement: A GIS-Based Approach

The intent of this paper is to operationalize some aspects of local sustainability in a suitable development scenario and to compare its energy-use and environmental impacts to trend development. After a discussion of suburban sprawl, local sustainability, and the current state of the Pennypack Creek Watershed in the Philadelphia metro region, these residential location scenarios are presented. The latter were created using geographic information systems software and are based on projections from the Delaware Valley Regional Planning Commission. The impacts of the scenarios on energy use, air emissions, greenhouse gas emissions, water quality, and biological integrity were estimated with very few data, and the effect on the value of generic ecosystem services was assessed. The suitable development scenario was 29% better in terms of energy use and air and greenhouse gas emissions, 2.4% worse on water quality, and 2.6% better with respect to biological integrity. Given its net beneficial results, recommendations for policies to engender suitable development are made, and an outline of an implementation plan is proposed. Thoughts regarding refinements of the present work and the applicability of the methods used here to other watersheds conclude the work.

Dose Assessment for Reentry or Reoccupancy and Recovery of Urban Areas Contaminated by a Radiological Dispersal Device: The Need for a Consensus Approach

Should an attack occur in an urban area with a Radiological Dispersal Device (RDD), guidance is available on the acceptable total dose equivalent for reentering the contaminated zone, and there is an accepted methodology for plume projection in the model used by the Federal Radiological Monitoring and Assessment Center (FRMAC). After initial characterization of the impact of the plume caused by an RDD, there will be considerable pressure from the public to allow them to return and quickly collect their belongings, and, eventually, to reoccupy residences and to reopen businesses. The FRMAC procedures principally deal with early and intermediate phase dose assessment, but do include late phase assessment procedures. However, the late phase assessments do not include complex geometries, such as the internal structure of buildings. This paper identifies areas where more specificity is needed to rapidly provide assessments to health officials and senior decision-makers. In this regard, there is no national consensus method to calculate projected dose inside buildings after an RDD event that addresses selecting the exposure pathways, scenarios, key parameters, etc. Therefore, to demonstrate an approach that exemplifies some of the technical and policy issues, which are unresolved, four exposure scenarios (residential, industrial, public park, park worker) were evaluated to determine the level of contamination that would deliver a dose equivalent of 10 mSv in the first year, excluding exposure during the first 4 d (emergency phase). In addition, the retrieval of personal belongings was simulated by assessing a 1-h exposure for the residential and industrial scenarios. RESRAD-BUILD was used to calculate the surface concentration of 60Co, 90Sr, 137Cs, 192Ir, 226Ra, 238Pu, 241Am, and 252Cf that would lead to a 10 mSv reference dose for these exposure periods. These example studies are intended to provide insights and guidance on how a municipal health agency can begin to develop a response plan, and to understand how the assessment process will determine the dose impacts resulting from an RDD event. The model's predictions heavily depend on the choice of the model's parameters; for several key ones, there are large uncertainties about their appropriate values. To avoid having to make hasty decisions during an emergency after an RDD attack, this analysis demonstrates that a detailed protocol for calculating dose should be developed prospectively so that decision-makers already are fully familiar with the process and its ensuing products.

Impact of telecommuting and intelligent transportation systems on residential location choice

The impacts of telecommuting and intelligent transportation systems (ITS) on urban development patterns were investigated in terms of households' residential location choice decisions. A discrete choice modelling approach framework was used. A stated preference (SP) logit analysis was carried out to estimate the parameters of the utility function. An attitude survey of employees of selected public and private sector organizations in the Ottawa-Carleton Region (Canada) yielded the required data for model estimation. In addition to obtaining background information, the survey elicited SP responses by presenting a number of hypothetical residential choice scenarios defined according to the principles of SP experimental design. Results show that telecommuting and ITS measures are highly significant factors in the residential choice model. This leads to the conclusion that these reinforce dispersed residential patterns and encourage moves towards outlying sites. Implications of this conclusion for urban land development planning are noted.

Dose Assessment for Process Water Tunnels at Hanford Site

The RESRAD-BUILD and RESRAD computer codes were used for dose assessment of the 105-C Process Water Tunnels at the Hanford Site. The evaluation assessed three different exposure scenarios: recreational use, tunnel maintenance worker, and residential use. The recreationist and maintenance worker scenarios were evaluated by using RESRAD-BUILD, a computer model for analyzing the radiological doses resulting from remediation and occupancy of structures contaminated with radioactive material. The recreationist was assumed to use the tunnels as an overnight shelter for eight hours per day for one week. The maintenance worker was assumed to spend 20 hours per year working in the the tunnel. Six exposure pathways were considered for both scenarios in dose assessment. The gradual removal of surface contamination over time and ingrowth of decay products were considered in calculating the dose at different times. The maximum dose would occur immediately after the release and was estimated to be 1.9 mrem/yr for the recreationist and 0.9 mrem/yr for the maintenance worker. The residential scenario was evaluated by using the probabilistic RESRAD code. It was assumed that total activity from the tunnels would be brought into the near-surface layer by future human activities. Eight exposure pathways were considered. The maximum yearly dose for this very unlikely scenario would occur immediately after the release and was less than 4 mrem/yr for the maximally exposed individual. The assessment demonstrates that both codes are suitable for nuclear facility decontamination and decommissioning sites, where buildings and structures with residual radioactivity must be evaluated to facilitate property transfer or release.

Geostatistical Approach for Managing Uncertainty in Environmental Remediation of Contaminated Soils: Case Study

Variability in the spatial distribution of soil contaminants and limited (non-exhaustive) sampling create uncertainty in planned remediation activities at a site. Geostatistical simulation techniques can be applied to existing data to map the probability of exceeding a regulatory threshold (action level) across the site. This probability map can be used to devise a remediation plan based on an allowable probability of exceeding the regulatory action level that is acceptable to regulators and stakeholders. Compared with the traditional, deterministic approach to defining areas to be remediated, this probabilistic approach requires an acknowledgment of a nonzero probability of failure (failing to remove material actually exceeding the action level) that must be agreed upon by the regulators and stakeholders. Evaluation of costs for remediation alternatives and for potential regulatory failure can be combined with probability maps to provide site operators, regulators and stakeholders with cost-risk information from which key decisions can be effectively understood and negotiated. Approximately 300 samples were collected from a site in central New Mexico. These samples show concentrations of lead ranging from the 0.1 to 3,000 ppm. Initial negotiations with stakeholders and regulators resulted in two action levels being considered where each action level defined an acceptable human health risk for a residential or a industrial future land-use scenario. Probability-of-exceedence maps were created through geostatistical simulation at both action levels. Maps of areas to be remediated for several acceptable probabilities of exceedence, and the corresponding remediation costs as a function of proposed action level allowed the regulators and stakeholders to see clearly the economic consequences of their decisions. In the final decision, the regulators and stakeholders accepted a higher action level and a remediation map constructed with a five percent probability of exceedence. The cost difference between the selected action level, corresponding to an industrial future land-use scenario, and the alternative action level, corresponding to a residential future land-use scenario resulted in a projected savings in remediation costs of approximately $6.6 million.

Radionuclides in soils collected from within and around Los Alamos national laboratory: 1974–1996

A soil sampling program is the most direct means of determining the types, concentration/activity, and distribution of radionuclides within and around nuclear facilities. Los Alamos National Laboratory (LANL), for example, has had a soil surveillance program since the early 1970s and the purpose of this paper was to 1) evaluate this 20+ year data set to determine if there are any statistical differences in radionuclides (3H, 137Cs, 238Pu, 239,240Pu, 241Am, 90Sr, totU) and radioactivity (gross a, ß, and γ), as a function of air emissions and fugitive dust, in surface soils (0–5 cm depth) collected from LANL, perimeter (PM) and background (BG) sites, and 2) determine if radionuclide concentrations are increasing or decreasing over time. Also, the total effective dose equivalent (TEDE) and the corresponding risk of excess cancer fatalities (RECF) to a PM community were estimated. Based on the long‐term average, nine out of the ten radionuclide parameters measured in LANL soils (n=12) were significantly (p<0.05) higher in concentration than BG (n=6). Perimeter soils (n=10), on the other hand, showed less differences with only four out of the ten parameters being statistically higher in concentration than BG. Most radionuclides in LANL and PM areas, with the exception of 238Pu in soils from PM, significantly decrease in concentration over time, so that by 1996 most radionuclides were approaching values similar to BG. The maximum net positive TEDE (i.e., the TEDE + two sigma for each radioisotope minus background and then only the positive doses summed) for a resident living around the PM of LANL, as modeled by the residual radioactive (RESRAD) code using a residential scenario for soils collected from 1974–1996, 1993–1996, and in 1996 was 2.9 mrem y‐1 (29 μSv y‐1), 2.3 mrem y‐1 (23 μSv y‐1), and 0.8 mrem y‐1 (8 μSv y‐1), respectively. All upper bound TEDEs were far below the International Commission of Radiological Protection permissible dose limit of 100 mrem y‐1 (1000 μSv y‐1) for all pathways, and the highest TEDE corresponds to a RECF of 1.5 × 10‐6—an estimate far below the Environmental Protection Agency guideline of 10‐4.

On the Impact of Future Land Use Assumptions on Risk Analysis for Superfund Sites

ABSTRACT In this paper, assumptions regarding future land use as a key uncertainty is considered and its impact on risk analysis for contaminated sites is assessed. Risks are assessed for two land use scenarios (current-use industrial and future-use residential) using probabilistic models that incorporate uncertainty and variability in the exposure parameters. Residual risks are calculated for both industrial and residential cleanup standards. A Superfund site in northern California is considered. In general, for the unremediated case, the future-use residential scenarios produce larger risks (1 to 3 orders of magnitude) than current- (continued) use industrial scenarios. For the Superfund site studied, the residual risks calculated for the remedy selected was not sufficiently protective of future-use residents in that it did not meet .S. Environmental Protection Agency (EPA) risk goals, but was protective of current-use workers, even though the cleanup criteria were based on residential use. Alternative risk management practices, such as deed restrictions, can be used in such cases.

Predicted Infant Exposure to Tetrachloroethene in Human Breastmilk

Based on a variety of maternal occupational and residential inhalation exposure scenarios, estimates of infant exposure to the dry-cleaning solvent tetrachlorothylene (perchloroethylene, PCE) in breastmilk were made. Physiologically based pharmacokinetic (PBPK) modeling indicates that infants may be exposed to elevated levels of PCE in breastmilk due to their mothers' inhalation of PCE. The PBPK-predicted breastmilk PCE concentrations agree very well with measured concentrations, where available. Based on this analysis, infants may be exposed to this workplace chemical via breastmilk at doses corresponding to rather high levels of risk. Predicted breastmilk doses provide the infant with little margin of exposure to doses associated with adverse health effects. In addition, the estimated increased cancer risks associated with these infant exposures are large under certain exposure scenarios. The actual concentrations of PCE in breastmilk of exposed mothers can only be known with certainty if monitoring is conducted. Due to the widespread exposure potential, monitoring studies should be undertaken so that the appropriate risk management alternatives can be better evaluated.

Future risk from a hypothesized RCRA site disposing of carcinogenic metals should a loss of societal memory occur

The future risk of a hypothesized Resource Conservation and Recovery Act (RCRA) site disposing of carcinogenic metals, arsenic, chromium, nickel, cadmium, and beryllium in the U.S. is assessed. Societal memory is assumed to be lost regarding the site. A human intrusion scenario on the site and a residential scenario one kilometer down-gradient of the groundwater flow direction from the site are assumed, starting at 1000 years after the site's closure. For the human intrusion scenario, the exposure pathways considered are fruit and vegetable intake, soil ingestion, and dermal contact with soil. The quantitative results obtained for the three pathways are as follows: lifetime excess cancer risk due to fruit and vegetable intake is 0.18; isk due to dermal contact with the soil is 0.12; and risk due to soil ingestion is 2.6 x 10 ṫ. For the residential scenario, only qualitative discussion of exposure via groundwater is presented due to the large uncertainties. The U.S. EPA (Environmental Protection Agency) attention to and requirements concerning long-term risk from RCRA sites containing metal carcinogens, which never change due to radioactive decay, stand in sharp contrast to the stringent requirements over 10,000 years posed by EPA for geologic disposal of high level radioactive wastes, and the long-term requirements posed by the U.S. Nuclear Regulatory Commission for low level radioactive waste disposal sites.

Human health‐based soil cleanup guidelines for diesel fuel no. 2

Abstract Soil cleanup guidelines were developed for diesel fuel No. 2 that are protective of human health. Guidelines were conservatively based on a residential land use scenario. This scenario estimates human health risks associated with long‐term exposure to site soil via the inhalation, dermal, and ingestion routes of exposure. Lifetime dermal cancer studies were selected as the basis for deriving a safe level of diesel fuel in soil. Soil cleanup guidelines for diesel fuel No. 2 ranged from 1166 to 11,287 mg/kg for adult or child residents and represent contaminant levels that pose acceptable health risks for both present and proposed future uses of a site.