Risk-based Screening Levels Research Articles

Chemical mixtures of mercury, PCBs, PFAS/PFOS, and pesticides in freshwater fish in the US and the risks they pose for fish consumption

Freshwater fish are important food sources that also pose risks to human and wildlife health because of the bioaccumulation of environmental chemicals in their tissues. Although most studies, fish consumption advisories, and regulations focus on individual contaminants, fish consumers are exposed to mixtures of chemicals, including legacy contaminants and contaminants of emerging concern, that can have combined effects. Chemicals of emerging concern represent one source of hazard, but legacy contaminants can still pose threats to fish consumers due to their persistence in the environment. We investigate the following questions: 1) Do different chemicals correlate with one another in fish tissue, and if so, how? 2) How do levels of different chemicals in fish tissue vary by time and location? and 3) How do observed chemical levels compare with risk-based screening levels? Using several national data sources established and maintained by the US Environmental Protection Agency (NRSA, NCCA-GL, GLENDA, and NLFTS), this study examines the co-occurrence of chemicals in freshwater fish in lakes, ponds, streams, and rivers in the US. We determine that organic contaminants correlate with one another, but generally not with mercury; organic chemicals have declined over time, but mercury has not; and fish concentrations of legacy contaminants-even those banned for decades-continue to exceed risk-based screening levels. Despite some successes in curtailing release of pollutants, some contaminants in fish tissue have not declined and legacy and emerging pollutants continue to pose risks to fish consumers in the US. Correlations between chemicals in fish tissue suggest that exposures to mixtures is prevalent in the US but that organic contaminants do not generally correlate with mercury-noteworthy particularly since fish consumption advisories in the US are frequently driven by the level of mercury, and do not account for exposure to multiple contaminants. While programs such as the National Aquatic Resource Surveys (NARS) Program seek to systematically monitor contaminants in fish tissue and other environmental indicators, continuous support from the US federal government is required to sustain this monitoring. Moreover, greater legislative and regulatory efforts are required at both the state and federal levels to reduce continuing sources and ongoing contamination.

Water Quality and the First-Flush Effect in Roof-Based Rainwater Harvesting, Part I: Water Quality and Soil Accumulation

Rainfall runoff may be captured and stored for later use, but the quality of this water can be detrimental in some uses without the use of appropriately designed first-flush diverters. The rainfall runoff water quality was measured on nineteen new small-scale and two aged commercial roofs located near high traffic highways. Roof coverings included asphalt shingles, sheet metal, clay tiles, and tar and gravel. Runoff samples were evaluated for polycyclic aromatic hydrocarbons (PAHs), phosphorus flame retardants (PFRs), and pyrethroid insecticides. Eighteen small-scale roofs were subjected to a range of simulated rainfall events, while natural runoff was sampled on the commercial roofs and one small-scale roof. Runoff was analyzed for pH, conductivity, turbidity, total suspended solids, boron, iron, copper, zinc, manganese, sodium adsorption ratio, nitrate-nitrogen, seventeen PAHs, tris(2-chloroethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate, bifenthrin, cypermethrin, and lambda-cyhalothrin. Samples from four natural storm events were also analyzed for total coliforms and Escherichia coli. In addition, soils below seventeen existing gutter downspouts were sampled to determine long-term pollutant accumulation. Atmospheric deposition was the main contributor of pollutants in the roof runoff. A majority of samples fell within the U.S. EPA guidelines for non-potable urban and agricultural water reuse. Trace levels of PAHs, PFRs, and insecticides were detected, but all detections were three orders of magnitude below the USGS health-based screening level benchmark concentrations. Results indicate that diverting the first flush, based on turbidity, total suspended solids, or conductivity, can improve the overall water quality and reduce the concentrations of PAHs in harvested rainwater. Downspout soil sampling showed potential for the long-term accumulation of PAHs at concentrations exceeding the minimum human-health risk-based screening levels at these high runoff-loading locations.

Environmental impacts and risk assessment in the re-use of Cr-bearing pyrolyzed tannery wastes: A case study in a residential area

Increasing concern has been raised on the environmental impacts of chromium-tanning wastes recycling. In particular, the pyrolytic conversion of leather industry sludges into Cr(VI)-free carbonized residues is believed to represent a viable route for a sustainable re-use of this type of wastes. The aim of this study was to determine the impact of recycled Cr-bearing pyrolyzed char (named KEU) as backfilling material for road construction in an urban area in Tuscany (Italy). Geochemical and chromium-isotope data, together with microstructural analyses (HR-TEM and XAS), indicate that the presence of KEU results in a significant enhancement of the natural Cr background. The results support the hypothesis that, in environmental conditions, the Cr (III) hosted in KEU is converted into Cr(VI), which is leached out by rainwater. Indeed, Cr(VI) is dispersed in surface water, reaching concentrations up to 18 mg/L and it also occurs in coatings on the surface gravel of unpaved roads. The 53Cr/52Cr ratio measured in KEU, reported in δ53Cr notation, was in the restricted range δ53Cr = −0.031 ± 0.057 ‰; on the contrary, the δ53Cr in water varied between +1.581 ± 0.038 ‰ and +3.261 ± 0.191 ‰, indicating the reduction of Cr(VI) after the pristine oxidative mobilization. The risk-based soil screening levels (SSLs) for total Cr are well above the concentration measured in soil for all the exposure pathways. On the contrary, the SSL for Cr(VI)indicates that soil contamination poses health hazards for residents.

Development of updated RfD and RfC values for medium carbon range aromatic and aliphatic total petroleum hydrocarbon fractions

ABSTRACT Using total petroleum hydrocarbon (TPH) measurements as a tool for assessing potential human health risks associated with exposures to petroleum products in the environment poses unique challenges, as TPH represents highly variable and complex mixtures containing hundreds of individual chemicals with wide-ranging chemical and physical properties. Current risk assessment practice generally involves analysis of environmental samples for various TPH fractions and summation of risk across those fractions. The United States Environmental Protection Agency (USEPA) derived provisional toxicity criteria for low, medium, and high carbon range aromatic and aliphatic hydrocarbon fractions over a decade ago. These criteria have been used, in whole or in part, to derive risk-based cleanup levels for TPH contamination in soil and groundwater. Herein, we evaluate and update oral and inhalation toxicity criteria for two of these fractions – medium carbon range aromatics and aliphatics – using, where applicable, newer data, updated modeling techniques, and new/alternative analyses of certain endpoints, human relevance, and uncertainty. The results of the analyses support an ~10-fold increase in the USEPA provisional reference concentration (p-RfC) values from 0.1 mg/m3 to 1 mg/m3 for both medium carbon range aromatics (different uncertainty factor) and aliphatics (new study and different judgment of toxicity data from existing study). Compared to the USEPA provisional oral reference dose (p-RfD) values for the medium carbon range aromatics and aliphatics of 0.03 mg/kg-day and 0.01 mg/kg-day, respectively, the present analyses suggest the RfD for medium carbon range aromatics could be increased >6.6-fold to 0.2 mg/kg-day (updated modeling and different uncertainty factors), and the RfD for medium carbon range aliphatics could be increased ~20-fold to 0.2 mg/kg-day (new study). These updated toxicity criteria could be used by regulatory agencies to reevaluate risk-based screening levels or by risk managers to support cleanup levels for medium carbon range aromatics and aliphatics, while still ensuring adequate health protection. Implications: Petroleum products represent complex mixtures of hydrocarbons broadly comprised of aliphatic compounds (straight-chain, branched-chain, and cyclic alkanes and alkenes) and aromatic compounds such as benzene, alkylbenzenes, and polycyclic aromatic hydrocarbons. The complex nature of petroleum products presents challenges for assessing potential health risks associated with exposure to petroleum hydrocarbon contamination in the environment. It has been over ten years since the U.S. Environmental Protection Agency derived provisional toxicity criteria for low, medium, and high carbon range aromatic and aliphatic hydrocarbon fractions. In that time, risk assessment guidance and tools have evolved, and new studies have been published. Our analyses indicate that current provisional toxicity criteria for medium carbon range aromatics and aliphatics fractions are overly conservative by approximately an order of magnitude.

Development of Per and Polyfluoroalkyl Substances Ecological Risk-Based Screening Levels.

Evaluation of chemical risks to threatened and endangered species is a requirement for Superfund ecological risk assessments; however, screening levels to evaluate the potential for toxicity associated with ecological receptor exposure to per- and polyfluoroalkyl substances (PFAS) are lacking. Therefore, PFAS risk-based screening levels (RBSLs) were developed. Wildlife RBSLs were developed using surrogate receptors selected to be representative of threatened and endangered species with different habitat types, feeding guilds, and trophic levels. Published uptake and toxicity data were combined with receptor exposure factors to derive RBSLs for terrestrial and aquatic wildlife for several PFAS, including perfluorononanoic acid, perfluorooctanesulfonic acid, perfluorooctanoic acid, perfluorohexanoic acid, perfluorobutanesulfonic acid, and pentafluorobenzoic acid. Uptake information for surrogate PFAS were considered to calculate RBSLs for PFAS with toxicity data and insufficient bioaccumulation data to develop an RBSL. Both no-observed-adverse effect level (NOAEL)- and lowest-observed-adverse effect level-based wildlife RBSLs were calculated to allow for a range of risk estimates appropriate to individual threatened and endangered species and populations of nonlisted wildlife receptors, respectively. Recommended water quality RBSLs protective of aquatic life were developed for 23 PFAS based on published literature reviews and peer-reviewed aquatic toxicity studies and Great Lakes Initiative methodology. For wildlife receptors, NOAEL RBSLs ranged from to 0.013 to 340 mg/kg for soil, 0.0014 to 370 mg/kg for sediment, and 0.000075 to 1600 mg/L for surface water. For aquatic life, chronic RBSLs ranged from 0.00022 to 3.4 mg/L. For terrestrial plants and soil invertebrates, the no-observed-effect concentration screening levels range from 0.084 to 642 mg/kg and from 1 to 50 mg/kg, respectively. Environ Toxicol Chem 2021;40:921-936. © 2020 SETAC.

Rationale for Soil‐Gas Sampling to Improve Vapor Intrusion Risk Assessment in China

Rationale for Soil‐Gas Sampling to Improve Vapor Intrusion Risk Assessment in China

Risk and performance assessment of cement made using municipal solid waste incinerator bottom ash as a cement kiln feed

To assess the feasibility of incorporating municipal solid waste incineration (MSWI) bottom ash (BA) as a replacement for traditional raw materials in cement kiln feed, an industrial-scale kiln trial was performed. Leach testing and chemical and physical characterization data from a cement product made at a replacement percentage of 2.8% by mass of kiln feed were comparable to results from ordinary portland cement. The concentrations of constituents of concern in leach tests were generally below risk-based screening levels or of similar or lower magnitude than leachate from control products. Ash-amended cement exhibited greater early age reactivity, and this was reflected in initial mortar compressive strength results; ultimate compressive strength results were higher in the control mortar. The ash-amended and control cements were similar in characteristic, but quantitative x-ray diffraction results reveal differences in alite and aluminate formation during the clinker formation process.

Pentachlorophenol, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans in surface soil surrounding pentachlorophenol-treated utility poles on the Kenai National Wildlife Refuge, Alaska USA

Composite surface soil samples were collected at 0, 25, and 50 cm from the base of 12 utility poles on the Kenai National Wildlife Refuge in Alaska, to assess the extent to which pentachlorophenol, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans may have leached from pentachlorophenol-treated poles. Six pairs of utility poles were included, consisting of an “old” pole manufactured in 1959 or 1963, a “new” pole manufactured within the past 20 years, and a suitable background soil sample from the same vicinity. Old poles had greater concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQs) near the pole base and at 25 cm than “new” poles did. For all 12 poles combined, the mean pentachlorophenol levels in soil were 1810, 157, and 17.8 ppm dry weight (d.w.) near the pole bases, at 25 and 50 cm from the poles, respectively, while the mean total TEQ levels in soil were 15,200, 5170, and 1510 parts per trillion d.w. at those distances. Surface soil levels of pentachlorophenol and TCDD-TEQs exceeded both human health and ecological risk-based screening levels. The design and results of this study were similar to another project in Montreal, Quebec in Canada. Together the results are cause for concern, indicating that millions of similarly treated utility poles in North America may be point sources of pentachlorophenol and dioxins/furans to soil.

Vertical screening distances for total petroleum hydrocarbon for vapour intrusion risk assessment at petroleum underground storage tank sites

The US Environmental Protection Agency Office of Underground Storage Tanks (US EPA OUST) and Interstate Technology and Regulatory Council (ITRC) have recently published guidance indicating that buildings separated from light non-aqueous phase liquid (LNAPL) sources by more than 15 ft (4.6 m) are not a concern for vapour intrusion at petroleum underground storage tank (UST) sites. At this distance, there is a greater than 95% probability that soil gas concentrations for all key constituents of potential concern are below risk-based screening levels (RBSLs) between the LNAPL source and building foundation. Vertical screening distances for bulk Total Petroleum Hydrocarbon (TPH), common TPH fractions (C 5 –C 8 aliphatics, C 9 –C 12 aliphatics, and C 9 –C 10 aromatics), and indicator compounds ( n -hexane and naphthalene) are less certain, however, because of a general lack of empirical data and highly variable soil-gas RBSLs. This study addresses these gaps through a statistical analysis of hundreds of soil-gas samples collected above LNAPL sources at more than 30 petroleum UST release sites. Resulting vertical screening distances for the various TPH fractions range between 0 and 7 ft (2.1 m) depending primarily on soil-gas RBSLs, which vary by over 5 orders of magnitude. Vertical screening distances for naphthalene are generally <3 ft (0.91 m). Vertical screening distances for n -hexane range from 12 (3.7) to 16 ft (4.9 m) and vary geographically. Vertical screening distances for total (bulk) TPH generally exceed 15 ft (4.6 m). Petroleum vapour intrusion risk assessments involving total (bulk) TPH are not recommended, however, because of uncertainties in quantifying soil-gas and indoor-air concentrations and defining RBSLs for fuel mixtures with variable source composition, toxicity, and fate and transport properties. Overall, the findings of this study validate the 15-ft screening distance recommended by ITRC and US EPA for application at petroleum UST sites with LNAPL sources.

Chemical exposures in recently renovated low-income housing: Influence of building materials and occupant activities

Health disparities in low-income communities may be linked to residential exposures to chemicals infiltrating from the outdoors and characteristics of and sources in the home. Indoor sources comprise those introduced by the occupant as well as releases from building materials. To examine the impact of renovation on indoor pollutants levels and to classify chemicals by predominant indoor sources, we collected indoor air and surface wipes from newly renovated “green” low-income housing units in Boston before and after occupancy. We targeted nearly 100 semivolatile organic compounds (SVOCs) and volatile organic compounds (VOCs), including phthalates, flame retardants, fragrance chemicals, pesticides, antimicrobials, petroleum chemicals, chlorinated solvents, and formaldehyde, as well as particulate matter. All homes had indoor air concentrations that exceeded available risk-based screening levels for at least one chemical. We categorized chemicals as primarily influenced by the occupant or as having building-related sources. While building-related chemicals observed in this study may be specific to the particular housing development, occupant-related findings might be generalizable to similar communities. Among 58 detected chemicals, we distinguished 25 as primarily occupant-related, including fragrance chemicals 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran (HHCB). The pre- to post-occupancy patterns of the remaining chemicals suggested important contributions from building materials for some, including dibutyl phthalate and xylene, whereas others, such as diethyl phthalate and formaldehyde, appeared to have both building and occupant sources. Chemical classification by source informs multi-level exposure reduction strategies in low-income housing.

A Critical Review of Discrete Soil Sample Data Reliability: Part 2—Implications

ABSTRACTPart 2 of this study investigates the implications of random, small-scale contaminant concentration variability in soil for reliance on discrete soil sample data to guide environmental investigations. Random variability around an individual point limits direct comparison of discrete sample data to risk-based screening levels. “False negatives” can lead to premature termination of an investigation or remedial action. Small-scale distributional heterogeneity of contaminants in soil is expressed as artificial, seemingly isolated “hot spots” and “cold spots” in isoconcentration maps. Surgical removal of hot spots can lead to erroneous conclusions regarding the magnitude of remaining contamination. The field precision of an individual discrete sample data set for estimation of means for a contaminant in a risk assessment is not directly testable. Omission of “outlier” data in order to force data to fit a geostatistical model distorts estimates of mean concentrations and introduces error into a risk assessment. The potential for such errors was pointed out in early USEPA guidance but largely ignored or misunderstood. Decision Unit and Multi Increment sample investigation methods, long known to the agricultural and mining industries, were specifically developed to overcome these inherent shortcomings of discrete sampling methods and provide more reliable and defensible data for environmental investigations.

Application of Citizen Science Risk Communication Tools in a Vulnerable Urban Community.

A public participatory geographical information systems (PPGIS) demographic, environmental, socioeconomic, health status portal was developed for the Stambaugh-Elwood (SE) community in Columbus, OH. We hypothesized that soil at SE residences would have metal concentrations above natural background levels. Three aims were developed that allowed testing of this hypothesis. Aim 1 focused on establishing partnerships between academia, state agencies and communities to assist in the development of a community voice. Aim 2 was to design and conduct soil sampling for residents of the SE community. Aim 3 was to utilize our interactive, customized portal as a risk communication tool by allowing residents to educate themselves as to the potential risks from industrial sources in close proximity to their community. Multiple comparisons of means were used to determine differences in soil element concentration by sampling location at p < 0.05. The results demonstrated that eight metals (As, Cd, Cu, Pb, Mo, Se, Tl, Zn) occurred at statistically-significantly greater levels than natural background levels, but most were below risk-based residential soil screening levels. Results were conveyed to residents via an educational, risk-communication informational card. This study demonstrates that community-led coalitions in collaboration with academic teams and state agencies can effectively address environmental concerns.

Evaluation of site-specific lateral inclusion zone for vapor intrusion based on an analytical approach

In 2002, U.S. EPA proposed a general buffer zone of approximately 100 feet (30m) laterally to determine which buildings to include in vapor intrusion (VI) investigations. However, this screening distance can be threatened by factors such as extensive surface pavements. Under such circumstances, EPA recommended investigating soil vapor migration distance on a site-specific basis. To serve this purpose, we present an analytical model (AAMLPH) as an alternative to estimate lateral VI screening distances at chlorinated compound-contaminated sites. Based on a previously introduced model (AAML), AAMLPH is developed by considering the effects of impervious surface cover and soil geology heterogeneities, providing predictions consistent with the three-dimensional (3-D) numerical simulated results. By employing risk-based and contribution-based screening levels of subslab concentrations (50 and 500μg/m3, respectively) and source-to-subslab attenuation factor (0.001 and 0.01, respectively), AAMLPH suggests that buildings greater than 30m from a plume boundary can still be affected by VI in the presence of any two of the three factors, which are high source vapor concentration, shallow source and significant surface cover. This finding justifies the concern that EPA has expressed about the application of the 30 m lateral separation distance in the presence of physical barriers (e.g., asphalt covers or ice) at the ground surface.

Risk-Based Evaluation of Total Petroleum Hydrocarbons in Vapor Intrusion Studies

This paper presents a quantitative method for the risk-based evaluation of Total Petroleum Hydrocarbons (TPH) in vapor intrusion investigations. Vapors from petroleum fuels are characterized by a complex mixture of aliphatic and, to a lesser extent, aromatic compounds. These compounds can be measured and described in terms of TPH carbon ranges. Toxicity factors published by USEPA and other parties allow development of risk-based, air and soil vapor screening levels for each carbon range in the same manner as done for individual compounds such as benzene. The relative, carbon range makeup of petroleum vapors can be used to develop weighted, site-specific or generic screening levels for TPH. At some critical ratio of TPH to a targeted, individual compound, the overwhelming proportion of TPH will drive vapor intrusion risk over the individual compound. This is particularly true for vapors associated with diesel and other middle distillate fuels, but can also be the case for low-benzene gasolines or even for high-benzene gasolines if an adequately conservative, target risk is not applied to individually targeted chemicals. This necessitates a re-evaluation of the reliance on benzene and other individual compounds as a stand-alone tool to evaluate vapor intrusion risk associated with petroleum.

Spatiotemporal variability of tetrachloroethylene in residential indoor air due to vapor intrusion: a longitudinal, community-based study

The migration of volatile contaminants from groundwater and soil into indoor air is a potential health threat at thousands of contaminated sites across the country. This phenomenon, known as vapor intrusion, is characterized by spatial and temporal heterogeneity. This study examined short-term fluctuations in concentrations of tetrachloroethylene (PCE) in the indoor air of residential homes due to vapor intrusion in a community in San Antonio, Texas, that sits atop an extensive, shallow plume of contaminated groundwater. Using a community-based design, we removed potential indoor sources of PCE and then collected twelve 3-day passive indoor air samples in each of the 20 homes. Results demonstrated a one-order-of-magnitude variability in concentration across both space and time among the study homes, although all measured concentrations were below risk-based screening levels. We found that within any given home, indoor concentrations increase with the magnitude of the barometric pressure drop (P=0.048) and humidity (P<0.001), while concentrations decrease as wind speed increases (P<0.001) and also during winter (P=0.001). In a second analysis to examine sources of spatial variability, we found that indoor air PCE concentrations between homes increase with groundwater concentration (P=0.030) and a slab-on-grade (as compared with a crawl space) foundation (P=0.028), whereas concentrations decrease in homes without air conditioners (P=0.015). This study offers insights into the drivers of temporal and spatial variability in vapor intrusion that can inform decisions regarding monitoring and exposure assessment at affected sites.

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.

다양한 위해성평가 방법에 따라 도출한 오염토양 선별기준의 차이에 관한 연구 (I): 매체 간 이동현상 해석에 따른 차이

Risk-based screening levels (RBSLs) of some pollutants for residential adults were derived with risk assessment tools developed by United States Environmental Protection Agency (USEPA), American Society for Testing and Materials (ASTM), and Korea Ministry of Environment (KMOE) and compared each other. To make the comparison simple, ingestion of soil, dermal contact with soil, outdoor inhalation of vapors, indoor inhalation of vapors, and inhalation of soil particulates were chosen as exposure pathways. The results showed that the derived RBSLs varied for every exposure pathway. For direct exposure pathways (i.e., ingestion of soil and dermal contact with soil), the derived RBSLs varied mainly due to the different default values for exposure factors and toxicity data. When identical default values for the parameters were used, the same RBSLs could be derived regardless of the assessment tools used. For inhalation of vapors and inhalation of soil particulates, however, different analysis methods for cross-media transfer rates were used and different assumptions were established for each tool, identical RBSLs could not be obtained even if the same default values for exposure factors were used. Especially for inhalation of soil particulates pathway, screening level derived using KMOE approach (most conservative) was approximately 5000~10000 times lower than the screening level derived using ASTM approach (least conservative). Our results suggest that, when deriving RBSL using a specific tool, it is a prerequisite to technically review the analysis methods for cross-media transfer rates as well as to understand how the assessment tool derives the default values for exposure factors.

Toxicological Relevance of Pharmaceuticals in Drinking Water

Interest in the public health significance of trace levels of pharmaceuticals in potable water is increasing, particularly with regard to the effects of long-term, low-dose exposures. To assess health risks and establish target concentrations for water treatment, human health risk-based screening levels for 15 pharmaceutically active ingredients and four metabolites were compared to concentrations detected at 19 drinking water treatment plants across the United States. Compounds were selected based on rate of use, likelihood of occurrence, and potential for toxicity. Screening levels were established based on animal toxicity data and adverse effects at therapeutic doses, focusing largely on reproductive and developmental toxicity and carcinogenicity. Calculated drinking water equivalent levels (DWELs) ranged from 0.49 microg/L (risperidone) to 20,000 microg/L (naproxen). None of the 10 detected compounds exceeded their DWEL. Ratios of DWELs to maximum detected concentrations ranged from 110 (phenytoin) to 6,000,000 (sulfamethoxazole). Based on this evaluation, adverse health effects from targeted pharmaceuticals occurring in U.S. drinking water are not expected.

Definição de níveis aceitáveis baseados no risco para hidrocarbonetos no Município de Porto Alegre segundo a metodologia RBCA

O presente estudo definiu valores de NABR (Níveis Aceitáveis Baseados no Risco) para hidrocarbonetos no Município de Porto Alegre, de acordo a metodologia RBCA, adotando-se dados hidrogeológicos dos compartimentos Embasamento Cristalino alterado e Depósitos Sedimentares Quaternários. Os parâmetros de exposição adequados à população do município, bem como dados de toxicidade dos compostos selecionados, foram definidos a partir de fontes bibliográficas e bancos toxicológicos disponíveis. As tabelas de referência geradas são, em geral, mais restritivas para o Embasamento Cristalino em relação aos Depósitos Sedimentares. Comparados às tabelas de referência da Cetesb, os valores correspondentes a Porto Alegre são inferiores, resultando na necessidade de investigações ambientais mais detalhadas em áreas impactadas por hidrocarbonetos.

Dioxin-Like Toxicity in the Saginaw River Watershed: Polychlorinated Dibenzo-p-Dioxins, Dibenzofurans, and Biphenyls in Sediments and Floodplain Soils from the Saginaw and Shiawassee Rivers and Saginaw Bay, Michigan, USA

Sediment and floodplain soils in the Saginaw River Watershed, Michigan, USA, have been demonstrated to be contaminated with a variety of organic compounds, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). Existing data indicate that, at some locations, the contamination exceeds human health risk-based regulatory levels and ecological risk-based screening levels. In this study, concentrations of PCBs including non-ortho coplanar congeners, PCDDs, and PCDFs were measured in more than 120 sediment and floodplain soil samples collected from the Shiawassee River (a tributary of the Saginaw River), the Saginaw River, and Saginaw Bay, to determine the sources and magnitude of contamination, and to elucidate the contributions from individual contaminant groups to the overall 2,3,7,8-tetrachlorodibezo-p-dioxin equivalents (TEQs). Sediment and soil extracts were also analyzed for total dioxin-like activity by means of the H4IIE-luc cell bioassay. Elevated concentrations of PCBs (>1000 ng/g, dry weight) were found in surface sediment and floodplain soil samples collected from the Shiawassee River near Chase Lake, from Middleground Island in the Saginaw River, and from subsurface sediments in Saginaw Bay. Concentrations of PCDDs and PCDFs in sediment and floodplain soils from the Saginaw River and Saginaw Bay were 2 to 3 orders of magnitude higher than concentrations in the samples from the Shiawassee River. The highest PCDD/F concentration (55,200 pg/g, dry weight in a subsurface layer) was found in sediment collected at the mouth of the Saginaw River. Concentrations of PCDFs were greater than the concentrations of PCDDs in sediment from the Saginaw River. 2,3,7,8-TCDF, 1,2,3,7,8-PeCDF, and 2,3,4,7,8-PeCDF were the major PCDF congeners found in sediments from the Saginaw River. The elevated concentrations of PCDFs, and the predominance of the less highly chlorinated PCDF congeners, in sediments from the Saginaw River were similar to previously determined characteristics of the PCDF contamination of the Tittabawassee River, another tributary of the Saginaw River. These results suggest the existence of a major source of PCDFs within the watershed. A few localized areas of high PCDD/F and PCB concentrations, with unique congener compositions, in the Saginaw River indicated the presence of other minor sources, such as wastewater treatment plants. PCDFs were the major contributors to TEQs in sediment and soils from the Saginaw River and Saginaw Bay. Approximately 30% of the samples analyzed in this study had values exceeding the screening level of 50 pg TEQ/g, dry wt, suggested for soils by the Agency for Toxic Substances and Disease Registry.