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PubMed2005

Clearing the air: a model for investigating indoor air quality in Texas schools.

This pilot project focused on the assessment of indoor air quality at a local high school in Galveston, Texas, using methods based on guidelines for the U.S. Environmental Protection Agency's Indoor Air Quality Tools for Schools program. Tools for Schools, developed for evaluating and ensuring acceptable air quality for schools, takes a low-cost, minimal-involvement, primarily educational approach. The authors also compared the findings from this approach with the results of an air-sampling program. The overall goal was to determine if use of Tools for Schools was sufficient to identify conditions with the potential to cause adverse health effects. The primary objectives were to 1) establish an indoor air quality committee for the school to implement Tools for Schools assessments and management strategies, 2) collect air quality data in high-risk areas identified within the school by the indoor air quality committee, 3) collect outdoor air quality data at or in close proximity to the school, and 4) develop methods and instruments for assessing environmental risks associated with daily school attendance. Data were gathered on levels of formaldehyde and other volatile organic compounds (VOCs), ozone, particulate matter (PM10), mold, relative humidity, and temperature. Data values for each sampled pollutant were compared with federal standards, recommended values established by the American Conference of Governmental Industrial Hygienists for non-industrial populations, and effects screening levels developed by the Texas Commission on Environmental Quality. Levels of all VOCs except formaldehyde were found to be well within guidelines, as were ozone and particulate-matter levels. Mold, however, was widespread, including both common species and species associated with allergy and asthma, such as Aspergillus and Alternaria. In general, Tools for Schools provides an excellent foundation for a school indoor air quality program, although the authors did find it necessary to streamline data collection and did find that mold with the potential for adverse health effects was present, albeit not visible in some areas.

Air Pollutants↗
PubMed1997

Pesticide residues in food: investigation of disparities in cancer risk estimates.

Much of the public perceives that exposure to synthetic pesticide residues in the diet is a major cause of cancer. The National Research Council (NRC), in a 1987 report, Regulating Pesticides in Food: The Delaney Paradox, evaluated cancer risks for 29 pesticides that are rodent carcinogens and estimated that the risks for 23 were greater than one-in-a-million. In contrast, our group has ranked possible carcinogenic hazards from a variety of human exposures to rodent carcinogens using the HERP (Human Exposure/Rodent Potency) index, and found that dietary residues of synthetic pesticides ranked low. This paper evaluates the disparities in these analyses by examining the two components of risk assessment: carcinogenic potency in rodents and human exposure. Potency estimates based on rodent bioassay data are shown to be similar whether calculated, as in the NRC report, as the regulatory q1* or as TD50. In contrast, estimates of dietary exposure to residues of synthetic pesticides vary enormously, depending on whether they are based on the Theoretical Maximum Residue Contribution (TMRC) calculated by the Environmental Protection Agency vs. the average dietary residues measured by the Food and Drug Administration in the Total Diet Study (TDS). The TMRC is the theoretical maximum human exposure anticipated under the most severe field application conditions, which are far greater than dietary residues measured in the TDS. Several independent exposure studies suggest that the FDA dietary residues are reasonable estimates of average human exposures, whereas TMRC values are large overestimates. Using standard methodology and measured dietary residues in the TDS, the estimate of excess cancer risk from average lifetime exposure to synthetic pesticide residues in the diet appears to be less than one-in-a-million for each of the ten pesticides for which adequate data were available.

Animals↗
PubMed1995

Evaluation of the use of uncertainty factors in deriving RfDs for some chlorinated compounds.

Risk assessment of exposure to chemicals having a toxic endpoint routinely uses the reference dose (RfD) approach based on uncertainty factors of 10. The purpose of this investigation was to evaluate whether the magnitude of the U.S. Environmental Protection Agency (EPA) 10x uncertainty factors has scientific merit when compared with data from recent human and animal experimental studies. A compilation and comparison of ratios between LOAEL/NOAEL (lowest observed adverse effect level/no observed adverse effect level) and subchronic/chronic values was made for six chlorinated compounds, namely, carbon tetrachloride, methylene chloride, pentachlorophenol, monochlorobenzene, chlorpyrifos, and 1,1-dichloroethane. Data sets demonstrated that 91.3% of the LOAEL/NOAEL ratios were < or = 6 while 87% of the ratios for the same parameter were < or = 5. Furthermore, subchronic/chronic ratios were < or = 3.5. From our investigation we concluded that automatic safety factors of 10x are not scientifically supportable and are overly conservative for the chlorinated compounds studied here.

Animals↗
PubMedDate not supplied

A review of the USEPA's single breath canister (SBC) method for exhaled volatile organic biomarkers.

Exhaled alveolar breath can provide a great deal of information about an individual's health and previous exposure to potentially harmful xenobiotic materials. Because breath can be obtained non-invasively and its constituents directly reflect concentrations in the blood, its use has many potential applications in the field of biomarker research. This paper reviews the utility and application of the single breath canister (SBC) method of alveolar breath collection and analysis first developed by the US Environmental Protection Agency (USEPA) in the 1990s. This review covers the development of the SBC technique in the laboratory and its application in a range of field studies. Together these studies specifically show how the SBC method (and exhaled breath analysis in general) can be used to clearly demonstrate recent exposure to volatile organic compounds, to link particular activities to specific exposures, to determine compound-specific uptake and elimination kinetics, and to assess the relative importance of various routes of exposure (i.e. dermal, ingestion, inhalation) in multi-pathway scenarios. Specific investigations covered in this overview include an assessment of exposures related to the residential use of contaminated groundwater, exposures to gasoline and fuel additives at self-service gas stations, swimmers' exposures to trihalomethanes, and occupational exposures to jet fuel.

Biomarkers↗
PubMed1993

Human health and environmental toxicity issues for evaluation of halon replacements.

The Clean Air Act Amendments of 1990 require the US Environmental Protection Agency (EPA) to phase out production and use of ozone-depleting chemicals--among them, the fire suppressants, halons. As part of its rulemaking efforts EPA must evaluate the potential hazards to human health and the environment that could result from exposure to compounds that may substitute for halons. The EPA bases health hazard assessment on data obtained in studies involving short-term and long-term exposures. The former are used to evaluate potential risks of acute or delayed effects potentially resulting from short exposures at high concentrations, such as might be experienced in episodic emissions in the workplace. Studies with long-term exposure are used to assess potential adverse effects from continued exposure to low ambient concentrations. In addition, reproductive and developmental hazards are evaluated in several animal species. About ten chlorinated-, brominated-, and/or fluorinated-hydrogen-containing hydrocarbons, to be used alone or in combination, have been proposed as halon substitutes. In addition to health and safety, environmental, efficacy, and marketability considerations (Table I) need to be addressed for the selection of proposed halon substitutes. This presentation will discuss current EPA/Office of Air and Radiation thinking on a decision-tree approach for testing the toxicity of halon substitutes under the Significant New Alternatives Policy program.

Air Pollution↗
PubMedDate not supplied

Pesticide residues in composited milk collected through the U.S. Pasteurized Milk Network.

The U.S. Food and Drug Administration (FDA) has implemented a comprehensive monitoring program to determine the incidence and levels of organohalogen pesticide residues in milk representing most of the U.S. supply consumed in metropolitan areas. Residue findings for 806 composite milks collected through the Pasteurized Milk Program by the U.S. Environmental Protection Agency (EPA) in 1990-1991 are reported. Milk was collected on a monthly basis from 63 stations selected by EPA for radionuclide monitoring. These stations provide an estimated 80% of the milk delivered to U.S. population centers. At each station, milk from selected sources had been composited to represent the milk routinely consumed in its metropolitan area. Portions of these composites were forwarded to an FDA contract laboratory for pesticide residue analysis. Pesticide residues were found in 398 (49.4%) of 806 test samples, on the basis of a 0.0005 ppm limit of detection for each residue on a whole-product basis. A total of 455 occurrences of pesticide residues were found; p,p'-DDE and dieldrin accounted for 384 (84.4%) of these occurrences. The highest level was 0.019 ppm p,p'-DDE.

Animals↗
PubMed1997

Comparison of noncancer risk assessment approaches for use in deriving drinking water criteria.

The development and promulgation of drinking water regulations to protect exposed human populations from contaminants that may occur in public drinking water supplies has been a major regulatory concern and effort of the United States Environmental Protection Agency for decades. Risk assessment, as applied in the development of drinking water regulations, involves the quantification of the level below which adverse health effects are not expected to occur. Traditionally, the oral reference dose (RfD) has been the preferred approach for characterizing these noncancer health risks. The benchmark dose approach to derive RfDs has increasingly gained scientific and regulatory acceptance as a risk assessment methodology since its introduction in 1984. Similarly, the use of categorical regression techniques were introduced at about the same time. The objective of this paper is to present an evaluation of the strengths and weaknesses of each risk assessment method as related to the development of drinking water criteria for noncarcinogenic chemicals. The data base requirements, performance record, mathematical or statistical basis, and other parameters are described and compared.

Humans↗
PubMed2004

Factors considered in using birds for evaluating endocrine-disrupting chemicals.

Documented effects on fish and wildlife populations, coupled with evidence from human poisonings, epidemiology, and experimental toxicology, led to the formation of the Endocrine Disruptor Screening Program within the US Environmental Protection Agency. The main objectives of the program are to validate and implement the screens and tests that have been proposed for evaluating possible endocrine-disrupting activity of chemicals. An avian two-generation test is one of the recommended higher tier tests currently undergoing prevalidation. The advantages and disadvantages of the two species of quail considered as candidates, the northern bobwhite (Colinus virginianus) and the Japanese quail (Coturnix japonica), are described as well as the basis for final selection of the Japanese quail. Among the numerous considerations necessary for ultimately optimizing a two-generation test method using birds, the following key factors are discussed: the number of birds used in the test, when to begin exposure of the P generation, selection and exposure of the F1 generation, and endpoints.

Animals↗
PubMed1990

Sources of mutagenic activity in urban fine particles.

Samples were collected during the winter of 1984-1985 in the cities of Albuquerque, NM and Raleigh NC as part of a US Environmental Protection Agency study to evaluate methods to determine the emission sources contributing to the mutagenic properties of extractable organic matter (EOM) present in fine particles. Data derived from the analysis of the composition of these fine particles served as input to a multi-linear regression (MLR) model used to calculate the relative contribution of wood burning and motor vehicle sources to mutagenic activity observed in the extractable organic matter. At both sites the mutagenic potency of EOM was found to be greater (3-5 times) for mobile sources when compared to wood smoke extractable organics. Carbon-14 measurements which give a direct determination of the amount of EOM that originated from wood burning were in close agreement with the source apportionment results derived from the MLR model.

Air Pollutants↗
PubMed1996

Comparison of gas chromatography/mass spectrometry and immunoassay techniques on concentrations of atrazine in storm runoff.

Gas chromatography/mass spectrometry (GC/MS) and enzyme-linked immunosorbent assay (ELISA) techniques were used to measure concentrations of dissolved atrazine in 149 surface-water samples. Samples were collected during May 1992-September 1993 near the mouth of the White River (Indiana) and in two small tributaries of the river. GC/MS was performed on a Hewlett-Packard 5971A with electron impact ionization and selected ion monitoring of filtered water samples extracted by C-18 solid phase extraction; ELISA was performed with a magnetic-particle-based assay with photometric analysis. ELISA results compared reasonably well to GC/MS measurements at concentrations below the Maximum Contaminant Level for drinking water set by the U.S. Environmental Protection Agency (3.0 microg/L), but a systematic negative bias was observed at higher concentrations. When higher concentration samples were diluted into the linear range of calibration, the relation improved. A slight positive bias was seen in all of the ELISA data compared to the GC/MS results, and the bias could be partially explained by correcting the ELISA data for cross reactivity with other triazine herbicides. The highest concentrations of atrazine were found during the first major runoff event after the atrazine was applied. Concentrations decreased throughout the rest of the sampling period even though large runoff events occurred during this time, indicating that most atrazine loading to surface waters in the study area occurs within a few weeks after application.

Atrazine↗
PubMed1995

Development of structure-activity relationship rules for predicting carcinogenic potential of chemicals.

Since the inception of Section 5 (Premanufacturing/Premarketing Notification, PMN) of the Toxic Substances Control Act (TSCA), structure-activity relationship (SAR) analysis has been effectively used by U.S. Environmental Protection Agency's (EPA) Structure Activity Team (SAT) in the assessment of potential carcinogenic hazard of new chemicals for which test data are not available. To capture, systematize and codify the Agency's predictive expertise in order to make it more widely available to assessors outside the TSCA program, a cooperative project was initiated to develop a knowledge rule-based expert system to mimic the thinking and reasoning of the SAT. In this communication, we describe the overall structure of this expert system, discuss the scientific bases and principles of SAR analysis of chemical carcinogens used in the development of SAR knowledge rules, and delineate the major factors/rules useful for assessing the carcinogenic potential of fibers, polymers, metals/metalloids and several major classes of organic chemicals. An integrative approach using available short-term predictive tests and non-cancer toxicological data to supplement SAR analysis has also been described.

Animals↗
PubMed1999

Evaluation of the EPA exposure assessment for phosphoric acid.

The philosophy of this paper is that the Environmental Protection Agency's (EPA) 1990 exposure assessment for phosphoric acid is not based on sound science and therefore does not accurately characterize the eutrophication potential of phosphoric acid releases from Toxic Release Inventory (TRI) reporting facilities. This error propagates the myth that eutrophication is triggered by the release of phosphoric acid from facilities reporting releases in the TRI. A detailed evaluation of EPA's 1990 exposure assessment for phosphoric acid reveals critical flaws in their applied methodology. Significant methodological improvements detailed in this paper fundamentally alter EPA's 1990 exposure assessment and demonstrate that, contrary to EPA's conclusion, these sources of phosphoric acid do not have the potential to trigger eutrophication in surface waters. Therefore, when sound scientific principles are applied in this comparative exposure assessment, EPA's policy maintaining phosphoric acid on the TRI list is inappropriate.

Agrochemicals↗
PubMed2004

Predicting premature mortality from new power plant development in Virginia.

The authors estimated the number of premature deaths from particulate matter less than 2.5 microm (PM2.5) that would result from making 29 proposed fossil fuel power plants in Virginia operational. We used a U.S. Environmental Protection Agency air quality model (Climatological Regional Dispersion model) to calculate changes in ambient concentrations of PM2.5 and Cox proportional hazard modeling to calculate the resulting premature mortality. The model predicted that if all 29 plants were operational, PM2.5 concentrations would rise in 271 counties across 19 states 5 and increased average annual PM2.5 concentrations would result in a rate of 17 deaths per 37,900,026 people aged 30 yr and older (0.45 deaths per million, 95% confidence interval = 0.31, 0.59) per year by the end of 2004, increasing thereafter. Over a 6 yr period, 104 cumulative excess deaths would occur due to operations of these proposed plants. The authors recommend that precautionary principles be considered when policy decisions related to energy production from fossil fuels are made.

Air Pollutants↗
PubMedDate not supplied

U.S. Food and Drug Administration monitoring of pesticide residues in infant foods and adult foods eaten by infants/children.

The U.S. Food and Drug Administration uses 3 approaches to monitor pesticide residues in foods: regulatory monitoring, incidence/level monitoring, and the Total Diet Study. The results of monitoring infant foods and adult foods that may be eaten by infants/children under these 3 approaches are presented. Under regulatory monitoring, which is performed to enforce tolerances set by the U.S. Environmental Protection Agency (EPA), during fiscal years 1985-1991, over 10,000 such domestic and imported food samples were collected and analyzed, and under the Total Diet Study, in which pesticide residue intakes are estimated in foods prepared for consumption, the food items in 27 market baskets were analyzed. Under incidence/level monitoring, which is complementary to regulatory monitoring, over 4000 analyses were performed on infant foods and adult foods eaten by children. Fewer than 50 of the 10,000 regulatory samples had violative residues; nearly all of those were residues for which there was no tolerance for the particular commodity/pesticide combination. Under incidence/level monitoring and the Total Diet Study, the levels of pesticide residues found in infant foods and adult foods eaten by children were well below tolerances set by EPA.

Child↗
PubMed2001

Perchlorate levels in samples of sodium nitrate fertilizer derived from Chilean caliche.

Paleogeochemical deposits in northern Chile are a rich source of naturally occurring sodium nitrate (Chile saltpeter). These ores are mined to isolate NaNO3 (16-0-0) for use as fertilizer. Coincidentally, these very same deposits are a natural source of perchlorate anion (ClO4-). At sufficiently high concentrations, perchlorate interferes with iodide uptake in the thyroid gland and has been used medicinally for this purpose. In 1997, perchlorate contamination was discovered in a number of US water supplies, including Lake Mead and the Colorado River. Subsequently, the Environmental Protection Agency added this species to the Contaminant Candidate List for drinking water and will begin assessing occurrence via the Unregulated Contaminants Monitoring Rule in 2001. Effective risk assessment requires characterizing possible sources, including fertilizer. Samples were analyzed by ion chromatography and confirmed by complexation electrospray ionization mass spectrometry. Within a lot, distribution of perchlorate is nearly homogeneous, presumably due to the manufacturing process. Two different lots we analyzed differed by 15%, containing an average of either 1.5 or 1.8 mg g-1. Inadequate sample size can lead to incorrect estimations; 100-g samples gave sufficiently consistent and reproducible results. At present, information on natural attenuation, plant uptake, use/application, and dilution is too limited to evaluate the significance of these findings, and further research is needed in these areas.

Chile↗
PubMed2000

Continuous emissions monitoring using spark-induced breakdown spectroscopy.

A new technology for monitoring airborne heavy metals on aerosols and particulates based on spark-induced breakdown spectroscopy (SIBS) was evaluated at a joint U.S. Environmental Protection Agency (EPA)/U.S. Department of Energy test at the rotary kiln incinerator simulator (RKIS) facility at EPA/Research Triangle Park, NC, in September 1997. The instrument was configured to measure lead and chromium in a simulated combustion flue gas in real time and in situ at target levels of 15 and 75 micrograms/dry standard cubic meters. Actual metal concentrations were measured during the tests using EPA Reference Method (RM) 29. The SIBS technology detected both lead and chromium at the low- and high-level concentrations. Additionally, the hardware performed without failure for more than 100 hr of operation and acquired data for 100% of the RM tests. The chromium data were well correlated with concentration increases resulting from duct operations and pressure fluctuations that are known to entrain dust.

Aerosols↗
PubMed2004

Use of reversed-phase high-performance liquid chromatography-diode array detection for complete separation of 2,4,6-trinitrotoluene metabolites and EPA Method 8330 explosives: influence of temperature and an ion-pair reagent.

Explosives such as 2,4,6-trinitrotoluene (TNT), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are widely distributed environmental contaminants. Complete chromatographic separation is necessary in order to accurately determine and quantify explosives and their degradation products in environmental samples and in (bio)transformation studies. The present study describes a RP-HPLC method with diode array detection using a LC-8 guard column, a Supelcosil LC-8 chromatographic column, and a gradient elution system. This gradient method is capable of baseline separating the most commonly observed explosives and TNT transformation metabolites including 2,4,6-triaminotoluene (TAT) in a single run. The TNT metabolites separated were 2-hydroxylamino-4,6-dinitrotoluene, 4-hydroxylamino-2,6-dinitrotoluene, 2,4-dihydroxylamino-6-nitrotoluene, 4,4',6,6'-tetranitro-2,2'-azoxytoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, 4,4',6,6'-tetranitro-2,2'-azotoluene, 2,2',6,6'-tetranitro-4,4'-azotoluene, 2-amino-4,6-dinitrotoluene, 4-amino-2, 6-dinitrotoluene, 2,6-diamino-4-nitrotoluene, 2,4-diamino-6-nitrotoluene, and TAT. The same gradient method at a different column temperature can also be used to baseline separate the explosives targeted in the Environmental Protection Agency (EPA) Method 8330 with approximately 22% reduction in total run time and 48% decrease in solvent consumption compared to previously published methods. Good separation was also obtained when all TNT metabolites and EPA Method 8330 compounds (a total of 23 compounds) were analyzed together; only 2,6-DANT and HMX co-eluted in this case. The influence of temperature (35-55 degrees C) and the use of an ion-pair reagent on the chromatographic resolution and retention were investigated. Temperature was identified as the key parameter for optimal baseline separation. Increased temperature resulted in shorter retention times and better peak resolution especially for the aminoaromatics investigated. The use of an ion-pair reagent (octanesulfonic acid) generally resulted in longer retention times for compounds containing amine functional groups, more baseline noise, and decreased peak resolution.

Chromatography, High Pressure Liquid↗
PubMed2000

Public health concerns about caliciviruses as waterborne contaminants.

Caliciviruses are disseminated by the fecal-oral route and are found in contaminated surface and ground waters. The US Environmental Protection Agency (EPA) is interested in preventing calicivirus contamination in treated waters used for consumption, and these viruses are on the EPA's "contaminant candidate list" for regulatory consideration in drinking waters. These viruses also present a health threat for recreation and shellfish-growing waters. However, before EPA can make regulatory decisions regarding caliciviruses, significant information and technology needs must be established, including analytical methods for sampling, identifying, and quantifying the viruses; applicability of surrogates to determine their presence; efficacy of water and wastewater treatment or disinfection; waterborne occurrence levels and distribution; dose response; and the viruses' effect(s) on health. Future drinking-water regulations may need to ensure that treatments are adequate to remove caliciviruses from source waters. For recreation and shellfish-growing waters, surrogate indicators and health criteria may need to be based upon establishing risks of exposure to caliciviruses.

Caliciviridae↗