A systematic review of risk assessment tools for contaminated sites - Current perspectives and future prospects.

Health and safety hazards associated with the redevelopment of contaminated sites can be complex and pose considerable risks. A systematic literature review was conducted on risk assessment tools for contaminated sites. These tools have been identified from searching through leading academic databases and other professional sources. For each of the identified tools the relevant risk assessment stages, harm type, hazard category, receptor type and pathways are reported. Findings reveal that despite growing interest in the development of risk assessment tools, there are persistent knowledge gaps identified in this study, which serve as a basis for future research direction to where more advanced practical tools could be invented. For instance, it is evidenced there is a shortfall in practical tools available to contaminated site assessors conducting investigations at the preliminary risk assessment stage. Addressing this opening can benefit the planning process, coordinated between relevant stakeholders and, moreover, reduce uncertainty in the decision-making of contaminated site developers.

Phosphate rock solubilization and the potential for lead immobilization by a phosphate-solubilizing bacterium (Pseudomonas sp.).

Lead (Pb) pollution is getting more and more serious in phosphate mining wastelands recently. However, seldom studies focused on the bioremediation of Pb pollution in phosphate mining wastelands by phosphate-solubilizing bacterium (PSB). In this study, a PSB named LA with high Pb tolerance was isolated from a phosphate mining wasteland. Based on its cell morphology, physiology, and phylogenetic analysis, it was identified as Pseudomonas sp. Its capabilities to solubilize mid-low-grade phosphate rock (PR) and immobilize Pb were assessed in this study. It was found that LA could effectively solubilize PR on PKO culture medium and release soluble phosphate in the culture medium. PR solubilization and Pb immobilization were investigated at different initial Pb concentrations and pH levels. The results showed that soluble phosphate was highly effective in immobilizing Pb and that when the initial concentration of Pb2+ was 100 mg/L, the immobilization rate of Pb was enhanced. Further, the mechanisms underlying solubilization of PR and biomineralization of Pb ions in LA were evaluated by Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that some functional groups on the PR surface and LA were altered, and LA could form hydroxyapatite and pyrophosphate with Pb ions.

Environmental Problems of Mining Waste Disposal Sites in Russia.

The exploitation of mineral deposits is followed by the formation of huge amounts of wastes, which have strong negative impacts on the surrounding environment. This paper presents the results of the compilation of data on general environmental problems in sites of waste disposal from mining and ore processing in Russia, based on the analysis of published data and own research. The own research of the authors relates to the estimation of the environmental hazards of mining waste using geochemical investigations and biotesting, as well as the development of the classification of technogenic mineral resources counting the reasons of the accumulation of precious components in them and findings on their environmental impact. The influence of waste disposal was determined as significant and diverse, leading to the transformation of all natural compartments surrounding waste disposal sites. The situation is especially aggravated when there are some mining and processing facilities within one relatively small territory. As a result, strong influence zones are formed. These zones have pronounced geochemical features reflecting the specificity of extracted rocks and produced raw materials. The analyzed information can serve as a basis for the development of nature protection measures for the mining waste disposal sites in Russia. Such measures using modern technical means for monitoring can minimize environmental damage from technogenic mineral formations.

Evaluation of ecological resources at operating facilities at contaminated sites: The Department of Energy's Hanford Site as a case study.

The U.S. and other developed nations are faced with many contaminated sites remaining from World War II, the Cold War, and abandoned industries, that require remediation and restoration to allow future land uses with minimum acceptable risk to humans and ecological resources. For large Department of Energy (DOE) sites with massive remediation tasks remaining, it is important for managers to be able to assure regulators, Tribal Nations, and the public that human and ecological health are protected. Hanford Site has the largest and most expensive cleanup task within the DOE complex; cleanup will continue beyond 2090. Cleanup involves the use of operating facilities, which also may present a risk to humans or ecological resources. We present a brief description of a methodology to evaluate risks to ecological receptors at the Hanford Site from remaining remediation tasks, and evaluate the risk to ecological resources that operating facilities present currently, during active cleanup of these facilities, and during the post cleanup period. Operating facilities include current, active operations that are located on the site and aid in site cleanup, including both storage and treatment operations. At the Hanford Site, they include waste treatment plants, sludge basins, waste trenches, Central Waste Complex, storage facilities, and disposal facilities, among others. Risk ratings for ecological resources are highest during the remediation phase. Risk ratings for the operating facilities at the Hanford Site range from not discernible to medium currently, from not discernible (ND) to high during active cleanup, and from not discernible to medium following cleanup. The highest ratings are for the Waste Treatment and Immobilization Plant that is being constructed to stabilize radioactive and chemical wastes, and the Liquid Effluent Retention and Treatment Facility that removes and deactivates hazardous contaminants from waste water. Higher ratings in the post-cleanup period are largely due to restoration of ecological resources during cleanup, which increases the potential for injury (if these resources are harmed) because a site will then have higher quality resources after cleanup than it did before. Assessing the value of ecological resources, and determining potential consequences during active remediation and after remediation is essential for compliance with state and federal laws. Understanding the risks to ecological resources from now until clean-up is completed at these facilities is important because of the potential for ecological resources of high value to be degraded, and because cleanup completion is not expected until 2090 or later. The methodology can be applied to any contaminated site requiring a rapid method of assessing potential damages to ecological resources from proposed management actions.

Investigation of a hazardous uncontrolled dumpsite in an oxbow lake of the Nitra River for pollution potential: a case study.

This paper deals with the engineering-geological investigation of uncontrolled dumpsites that are abundant in post-communist countries. The sites may be redeveloped in an optimal manner by using the applied methodology of engineering-geological investigations. The research tool is a case study dealing with hazardous uncontrolled dumpsites chemically contaminated by various substances, particularly carcinogenic chromium. The dumpsite is located in the alluvial sediments of an oxbow lake of the Nitra River in the Slovak Republic. The hazard is seen in the fact that the alluvial sediments are permeable and thus the contamination may spread easily. At the same time, it is located near a river, which makes the hazard greater. Apart from the risk of contamination, another risk is related to the methane generated by the dumpsite and thus the risk of self-ignition. In order to identify the uncontrolled dumpsite body, the research was grounded in the different physical properties of the diverse geological environments. Quasi-homogenous blocks of the dumpsite body and its alluvial surroundings were well identified by using the combined three geophysical methods, namely dipole electromagnetic profiling (DEMP), electrical resistance tomography (ERT) and spontaneous polarization (SP). In order to eliminate the risk of contamination spread, redevelopment measures for the uncontrolled dumpsite in the form of sealing walls and surface sealing foil were proposed. A system of methane drainage boreholes was proposed to eliminate the risk of self-ignition. The methodology in this case study is well applicable for other uncontrolled dumpsites, which is an important outcome of the study.

Compilation of a model for hazardous waste disposal site selection using GIS-based multi-purpose decision-making models.

Nowadays, given the high production volume of industrial and dangerous materials and their impacts on the human society and environment, disposal of waste materials in the environment and finding the best disposal site for industrial and hazardous wastes, as the most significant managerial measure, have become one of the most important and complex decisions in urban management. In order to find a disposal site, analysis of spatial data, laws, and large socioeconomic and environmental criteria is required. Multi-criteria analysis techniques coupled with GIS capabilities can be a good solution for this. Due to numerous industrial units, especially refineries in Bushehr province, it is essential to find a management solution for hazardous wastes of this province. The main objective of this study is to find an optimal location which has the lowest environmental risk and economically favorable. For this purpose, ecological and socioeconomic criteria were identified and normalized by fuzzy method. The weight of the parameters was determined by analytical network process method combined with the weighted linear combination method. In the capability of the area to locate the hazardous waste disposal, the results showed that the highest weight belonged to ecological criteria (61.34%) and land use (0.27), respectively. Also, 6.13% of the province areas are identified with high potentials for disposal of hazardous wastes. The results of this study showed the importance and significant weight of environmental criteria in prioritizing the proposed areas for disposal of this type of waste. Efficiency of the employed models, integrated with GIS and MCDM, was also proven.

Remediation of soil contaminated with persistent organic pollutants in Sumgait, Azerbaijan.

The Sumgait remediation project was implemented in 2015 as a partnership between Blacksmith Institute and the site owner Azerikimya Joint Stock Company (Azerikimya) in Sumgait City, Azerbaijan Republic, about 30 km northwest of Baku. The project was financed by the European Commission and supported by the Ministry of Ecology and Natural Resources (MENR) and Sumgait Municipality. The site is a place on the Caspian Sea coast that was formerly an industrial area highly contaminated with various pollutants and particularly benzo(a)pyrene, benzene, and polychlorinated biphenyls (PCBs). As part of initial environmental assessment, the project team took soil samples at 19 locations at the surface and at the depth of 0.5 m. The maximum topsoil benzo(a)pyrene concentration was 76.21 mg/kg, benzene, 121.5 mg/kg, and PCBs, 121.02 mg/kg. The remediation project involved the removal of 804 m3 of contaminated soil and disposal of the contaminated soil at the MENR Hazardous Waste Polyqon (landfill). A comparison of pre- and post-excavation sampling shows that average contaminant levels in soils in the upper 0.5 m were reduced by an average of 97%. These actions were followed by bioremediation activities. More than 13,000 m3 of clean soil and organic fertilizer were placed and leveled over an area of two hectares. Approximately 1200 locally grown native tree species were planted, and a drip irrigation system was installed. The area is now a park close to the beach.

Evaluating toxicity risk in sediments after remediation at a Superfund megasite using a Triad approach.

The Pine River downstream of the Velsicol Superfund site has been contaminated with various hydrophobic organic pollutants for more than 50 years. Remediation and sediment dredging near the site began in spring of 1999, and was completed in 2006. In 2011, the Michigan Department of Environmental Quality completed a baseline assessment report long-term monitoring plan for the Pine River. However, there has been limited assessment of the benthic community since this evaluation. The objective of this research was to evaluate the risk of Pine River sediment to aquatic macroinvertebrates downstream from the Superfund site after decades of degradation and dredging using the Triad approach. Three sites were selected downstream from the Superfund site, and an upstream reference site was used. At each site, macroinvertebrates surveys were conducted and sediments were collected for chemical analysis of DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane) and its degradation products and for laboratory toxicity testing for mortality and sublethal effects using Hyalella azteca and Chironomus dilutus. Sediment concentrations of DDT, DDD, and DDE were below levels expected to cause toxicity, and there was no observed toxicity in laboratory tests. Additionally, there were no statistically significant differences in richness, richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) species, total EPT abundance, percent EPT, or percent dominant taxa between the reference site and the downstream sites. There was an observed decrease in abundance of macroinvertebrate taxa at all downstream sites and a shift in macroinvertebrate structure when comparing the reference with most impaired sites. Although the sites downstream of the Superfund site remain different than the upstream control, there are improvements in species composition and abundance. However, more research is needed to evaluate the potential effects on ecosystem function.

Occupational diseases in Italian national priority contaminated sites.

BACKGROUND: The aim of this study was to evaluate the occupational health risks in the Italian National Priority Contaminated Sites (NPCSs). METHODS: Established cases of occupational diseases in 2010-2014 were extracted from the Italian National Institute for Insurance against Accidents at Work (INAIL) archives. Standardized incidence ratios with 95% confidence intervals were estimated by site and by disease group separately for genders. RESULTS: In the 44 NPCSs evaluated, 11 015 cases of occupational diseases (8877 in men and 2138 in women) were ascertained. Overall, an excess of occupational diseases with respect to expected cases of 24.2% was found in men residing in NPCSs. An increased occurrence was detected in 21 NPCSs for men and in eight for women. CONCLUSIONS: The findings suggest a role of occupational diseases in the health profile of NPCSs, reinforcing the need for a permanent surveillance system.

Performance assessment of a single-layer moisture store-and-release cover system at a mine waste rock pile in a seasonally humid region (Nova Scotia, Canada).

Cover systems are commonly applied to mine waste rock piles (WRPs) to control acid mine drainage (AMD). Single-layer covers utilize the moisture "store-and-release" concept to first store and then release moisture back to the atmosphere via evapotranspiration. Although more commonly used in semi-arid and arid climates, store-and-release covers remain an attractive option in humid climates due to the low cost and relative simplicity of installation. However, knowledge of their performance in these climates is limited. The objective of this study was to assess the performance of moisture store-and-release covers at full-scale WRPs located in humid climates. This cover type was installed at a WRP in Nova Scotia, Canada, alongside state-of-the-art monitoring instrumentation. Field monitoring was conducted over 5 years to assess key components such as meteorological conditions, cover material water dynamics, net percolation, surface runoff, pore-gas, environmental receptor water quality, landform stability and vegetation. Water balances indicate small reductions in water influx to the waste rock (i.e., 34 to 28% of precipitation) with the diminished AMD release also apparent by small improvements in groundwater quality (increase in pH, decrease in sulfate/metals). Surface water quality analysis and field observations of vegetative/aquatic life demonstrate significant improvements in the surface water receptor. The WRP landform is stable and the vegetative cover is thriving. This study has shown that while a simple store-and-release cover may not be a highly effective barrier to water infiltration in humid climates, it can be used to (i) eliminate contaminated surface water runoff, (ii) minimize AMD impacts to surface water receptor(s), (iii) maintain a stable landform, and (iv) provide a sustainable vegetative canopy.

Delineation of contaminant plume for an inorganic contaminated site using electrical resistivity tomography: comparison with direct-push technique.

Precise delineation of contaminant plume distribution is essential for effective remediation of contaminated sites. Traditional in situ investigation methods like direct-push (DP) sampling are accurate, but are usually intrusive and costly. Electrical resistivity tomography (ERT) method, as a non-invasive geophysical technique to map spatiotemporal changes in resistivity of the subsurface, is becoming increasingly popular in environmental science. However, the resolution of ERT for delineation of contaminant plumes still remains controversial. In this study, ERT and DP technique were both conducted at a real inorganic contaminated site. The reliability of the ERT method was validated by the direct comparisons of their investigation results that the resistivity acquired by ERT method is in accordance with the total dissolved solid concentration in groundwater and the overall variation of the total iron content in soil obtained by DP technique. After testifying the applicability of ERT method for contaminant identification, the extension of contaminant plume at the study site was revealed by supplementary ERT surveys conducted subsequently in the surrounding area of the contaminant source zone.

Impact of Heavy Metal Pollution on Ammonia Oxidizers in Soils in the Vicinity of a Tailings Dam, Baotou, China.

Soil heavy metal pollution has received increasing attention due to their toxicity to soil microorganisms. We have analyzed the effects of heavy metal pollution on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soils in the vicinity of a tailings dam of Baotou region, China. Results showed that AOB were dominated with Nitrosomonas-like clusters, while AOA was dominated by group1.1b (Nitrososphaera cluster). Single Cd and Cr contents, as well as compound heavy metal pollution levels, had a significant negative impact on soil potential nitrification rate and both diversities of AOA and AOB. No clear relationship was found between any single heavy metal and abundance of AOA or AOB. But compound pollution could significantly decrease AOA abundance. The results indicated that heavy metal pollution had an obviously deleterious effect on the abundance, diversity, activity and composition of ammonia oxidizers in natural soils.

Hazardous waste and health impact: a systematic review of the scientific literature.

Waste is part of the agenda of the European Environment and Health Process and included among the topics of the Sixth Ministerial Conference on Environment and Health. Disposal and management of hazardous waste are worldwide challenges. We performed a systematic review to evaluate the evidence of the health impact of hazardous waste exposure, applying transparent and a priori defined methods. The following five steps, based on pre-defined systematic criteria, were applied. 1. Specify the research question, in terms of "Population-Exposure-Comparators-Outcomes" (PECO). POPULATION: people living near hazardous waste sites; Exposure: exposure to hazardous waste; Comparators: all comparators; Outcomes: all diseases/health disorders. 2. Carry out the literature search, in Medline and EMBASE. 3. Select studies for inclusion: original epidemiological studies, published between 1999 and 2015, on populations residentially exposed to hazardous waste. 4. Assess the quality of selected studies, taking into account study design, exposure and outcome assessment, confounding control. 5. Rate the confidence in the body of evidence for each outcome taking into account the reliability of each study, the strength of the association and concordance of results.Fifty-seven papers of epidemiological investigations on the health status of populations living near hazardous waste sites were selected for the evidence evaluation. The association between 95 health outcomes (diseases and disorders) and residential exposure to hazardous waste sites was evaluated. Health effects of residential hazardous waste exposure, previously partially unrecognized, were highlighted. Sufficient evidence was found of association between exposure to oil industry waste that releases high concentrations of hydrogen sulphide and acute symptoms. The evidence of causal relationship with hazardous waste was defined as limited for: liver, bladder, breast and testis cancers, non-Hodgkin lymphoma, asthma, congenital anomalies overall and anomalies of the neural tube, urogenital, connective and musculoskeletal systems, low birth weight and pre-term birth; evidence was defined as inadequate for the other health outcomes. The results, although not conclusive, provide indications that more effective public health policies on hazardous waste management are urgently needed. International, national and local authorities should oppose and eliminate poor, outdated and illegal practices of waste disposal, including illegal transboundary trade, and increase support regulation and its enforcement.

Systematic literature review of reproductive outcome associated with residential proximity to polluted sites.

This study aims to assess the evidence on adverse pregnancy outcome associated with living close to polluted industrial sites, and identify the strengths and weaknesses of published epidemiological studies. A systematic literature search has been performed on all epidemiological studies published in developed countries since 1990, on the association between residential proximity to industrial sites (hazardous waste sites, industrial facilities and landfill sites) and adverse pregnancy outcome (low birth weight, preterm birth, small for gestational age, intrauterine growth retardation, infant mortality, congenital malformation). Based on 41 papers, our review reveals an excess risk of reproductive morbidity. However, no studies show significant excess risk of mortality including fetal death, neonatal or infant mortality and stillbirth. All published studies tend to show an increased risk of congenital abnormalities, yet not all are statistically significant. All but two of these studies revealed an excess risk of low birth weight. Results for preterm birth, small for gestational age and intrauterine growth retardation show the same pattern. There is suggestive evidence from the post-1990 literature that residential proximity to polluted sites (including landfills, hazardous waste sites and industrial facilities) might contribute to adverse reproductive outcomes, especially congenital malformations and low birth weight-though not mortality. This body of evidence has limitations that impede the formulation of firm conclusions, and new, well-focused studies are called for. The review findings suggest that continued strengthening of rules governing industrial emissions as well as industrial waste management and improved land use planning are needed.

Microbial fouling and corrosion of carbon steel in deep anoxic alkaline groundwater.

Understanding the corrosion of carbon steel materials of low and intermediate level radioactive waste under repository conditions is crucial to ensure the safe storage of radioactive contaminated materials. The waste will be in contact with the concrete of repository silos and storage containers, and eventually with groundwater. In this study, the corrosion of carbon steel under repository conditions as well as the microbial community forming biofilm on the carbon steel samples, consisting of bacteria, archaea, and fungi, was studied over a period of three years in a groundwater environment with and without inserted concrete. The number of biofilm forming bacteria and archaea was 1,000-fold lower, with corrosion rates 620-times lower in the presence of concrete compared to the natural groundwater environment. However, localized corrosion was detected in the concrete-groundwater environment indicating the presence of local microenvironments where the conditions for pitting corrosion were favorable.

[Environmental justice in the epidemiological surveillance system of residents in Italian National Priority Contaminated Sites (SENTIERI Project)]. / Environmental justice nel sistema di sorveglianza epidemiologica SENTIER.

OBJECTIVES: descriptive evaluation of distributional justice in the epidemiological surveillance system of populations residing in Italian National priority Contaminated Sites (NPCSs) of SENTIERI project. Analysis of the feasibility of monitoring different Environmental Justice dimensions in SENTIERI. DESIGN: descriptive study and ecological meta-analysis. SETTING AN PARTICIPANTS: residents in 298 municipalities included in 44 NPCSs in SENTIERI. Description of their level of deprivation and mortality analysis by deprivation level in the first period evaluated in SENTIERI, years 1995-2002. MAIN OUTCOME MEASURES: an index of multiple deprivation at municipality level DI-SENTIERI, built using 4 indicators based on variables from the Italian 2001 Census, was used to describe deprivation in communities living in NPCSs. The risk of mortality for all causes and all tumors in the pool of NPCSs municipalities by deprivation level was assessed using meta-Standardized Mortality Ratios (meta-SMRs). RESULTS: sixty percent of municipalities (No. 179) in NPCSs belong to the two more deprived quintiles. The socioeconomic disadvantage of communities resident in NPCS has a North-South gradient: the proportion of municipalities belonging to the two more deprived quintiles is 29% in the North, 68% in the Centre, 92% in the South. Meta-SMRs for all causes in less deprived municipalities were 98 (90%CI 95-100) in men e 101 (90%CI 97-104) in women, the values for all cancers were 99 (90%CI 94-103) in men and 100 (90%CI 95-105) in women. The corresponding estimates in more deprived municipalities were, respectively in men and women, 103 (90%CI 101- 104) and 102 (90%CI 100-104) for all causes, 104 (90%CI 102-106) and 102 (90%CI 100-104) for all cancers. CONCLUSIONS: residents in NPCSs are exposed to environmental stressors and are generally more deprived. The socioeconomic disadvantage is mostly affecting Central and Southern Italy populations. Furthermore, in these deprived communities the risk of mortality for all diseases and all cancers is higher. Populations living in NPCSs are affected by distributional injustice. To monitor the different dimensions of Environmental Justice, the DI-SENTIERI should be developed and other socioeconomic indicators implemented.

Residential cancer cluster investigation nearby a Superfund Study Area with trichloroethylene contamination.

PURPOSE: Trichloroethylene (TCE) is an industrial solvent associated with liver cancer, kidney cancer, and non-Hodgkin's lymphoma (NHL). It is unclear whether an excess of TCE-associated cancers have occurred surrounding the Middlefield-Ellis-Whisman Superfund site in Mountain View, California. We conducted a population-based cancer cluster investigation comparing the incidence of NHL, liver, and kidney cancers in the neighborhood of interest to the incidence among residents in the surrounding four-county region. METHODS: Case counts and address information were obtained using routinely collected data from the Greater Bay Area Cancer Registry, part of the Surveillance, Epidemiology, and End Results program. Population denominators were obtained from the 1990, 2000, and 2010 US censuses. Standardized incidence ratios (SIRs) with two-sided 99 % confidence intervals (CIs) were calculated for time intervals surrounding the US Censuses. RESULTS: There were no statistically significant differences between the neighborhood of interest and the larger region for cancers of the liver or kidney. A statistically significant elevation was observed for NHL during one of the three time periods evaluated (1996-2005: SIR = 1.8, 99 % CI 1.1-2.8). No statistically significant NHL elevation existed in the earlier 1988-1995 (SIR = 1.3, 99 % CI 0.5-2.6) or later 2006-2011 (SIR = 1.3, 99 % CI 0.6-2.4) periods. CONCLUSION: There is no evidence of an increased incidence of liver or kidney cancer, and there is a lack of evidence of a consistent, sustained, or more recent elevation in NHL occurrence in this neighborhood. This evaluation included existing cancer registry data, which cannot speak to specific exposures incurred by past or current residents of this neighborhood.

Burden of disease resulting from lead exposure at toxic waste sites in Argentina, Mexico and Uruguay.

BACKGROUND: Though lead contaminated waste sites have been widely researched in many high-income countries, their prevalence and associated health outcomes have not been well documented in low- and middle-income countries. METHODS: Using the well-established health metric disability-adjusted life year (DALY) and an exposure assessment method developed by Chatham-Stephens et al., we estimated the burden of disease resulting from exposure to lead at toxic waste sites in three Latin American countries in 2012: Argentina, Mexico and Uruguay. Toxic waste sites identified through Pure Earth's Toxic Sites Identification Program (TSIP) were screened for lead in both biological and environmental sample media. Estimates of cardiovascular disease incidence and other outcomes resulting from exposure to lead were utilized to estimate DALYs for each population at risk. RESULTS: Approximately 316,703 persons in three countries were at risk of exposure to pollutants at 129 unique sites identified through the TSIP database. Exposure to lead was estimated to result in between 51,432 and 115,042 DALYs, depending on the weighting factor used. The estimated burden of disease caused by exposure to lead in this analysis is comparable to that estimated for Parkinson's disease and bladder cancer in these countries. CONCLUSIONS: Lead continues to pose a significant public health risk in Argentina, Mexico, and Uruguay. The burden of disease in these three countries is comparable with other widely recognized public health challenges. Knowledge of the relatively high number of DALYs associated with lead exposure may be used to generate support and funding for the remediation of toxic waste sites in these countries and others.

Managing risks of noncancer health effects at hazardous waste sites: A case study using the Reference Concentration (RfC) of trichloroethylene (TCE).

A method for determining a safety range for non-cancer risks is proposed, similar in concept to the range used for cancer in the management of waste sites. This safety range brings transparency to the chemical specific Reference Dose or Concentration by replacing their "order of magnitude" definitions with a scientifically-based range. EPA's multiple RfCs for trichloroethylene (TCE) were evaluated as a case study. For TCE, a multi-endpoint safety range was judged to be 3 µg/m(3) to 30 µg/m,(3) based on a review of kidney effects found in NTP (1988), thymus effects found in Keil et al. (2009) and cardiac effects found in the Johnson et al. (2003) study. This multi-endpoint safety range is derived from studies for which the appropriate averaging time corresponds to different exposure durations, and, therefore, can be applied to both long- and short-term exposures with appropriate consideration of exposure averaging times. For shorter-term exposures, averaging time should be based on the time of cardiac development in humans during fetal growth, an average of approximately 20-25 days.