Regulatory Action Level Research Articles

Effect of Community Water Service on Lead in Drinking Water in an Environmental Justice Community.

Multiple recent studies have found elevated lead (Pb) concentrations in tap water in U.S. homes relying on unregulated private wells. The main Pb source is dissolution from household plumbing, fixtures, and well components. Here, we leverage a natural experiment and citizen science approach to evaluate how extending community water service to an environmental justice community relying on private wells affects Pb in household water. We analyzed Pb in 260 first-draw kitchen tap water samples collected by individual homeowners over a 5-month period in residences that did and did not connect to the community system. Before the community water system was extended, 25% of homes had Pb > 15 μg/L (the U.S. regulatory action level for community water systems) in first-draw water samples. Pb was significantly correlated with nickel (ρ = 0.61), zinc (ρ = 0.50), and copper (ρ = 0.40), suggesting that corrosion of brass fittings and fixtures is the main Pb source. Among homes that connected to the community system, Pb decreased rapidly and was sustained at levels well below 15 μg/L over the study period. Overall, connecting to the municipal water supply was associated with a 92.5% decrease in first-draw tap water Pb.

Comparison of State-Level Regulations for Cannabis Contaminants and Implications for Public Health.

Background:The presence of contaminants in cannabis presents a potential health hazard to recreational users and susceptible patients with medical conditions. Because of the federally illegal status of cannabis, there are no unified regulatory guidelines mitigating the public health risk of cannabis contaminants.Objective:To inform further research and provide solutions to the public health risk of cannabis contaminants at a national level, we examined the current landscape of state-level contaminant regulations, and cannabis contaminants of concern, as well as patient populations susceptible to contaminants.Methods:We examined the regulatory documents for medical and recreational cannabis in all legalized U.S. jurisdictions and compiled a complete list of regulated contaminants, namely, pesticides, inorganics, solvents, microbes, and mycotoxins. We data mined the compliance testing records of 5,654 cured flower and 3,760 extract samples that accounted for of California’s legal cannabis production in 2020–2021. We also reviewed the publicly available medical cannabis use reports to tabulate the susceptible patient populations.Results:As of 18 May 2022, 36 states and the District of Columbia listed a total of 679 cannabis contaminants as regulated in medical or recreational cannabis, including 551 pesticides, 74 solvents, 12 inorganics, 21 microbes, 5 mycotoxins, and 16 other contaminants. Different jurisdictions showed significant variations in regulated contaminants and action levels ranging up to four orders of magnitude. A failure rate of 2.3% was identified for flowers and 9.2% for extracts in the California samples. Insecticides and fungicides were the most prevalent categories of detected contaminants, with boscalid and chlorpyrifos being the most common. The contaminant concentrations fell below the regulatory action levels in many legalized jurisdictions, indicating a higher risk of contaminant exposure. Cannabis use reports indicated usage in several patient populations susceptible to contamination toxicity, including cancer (44,318) and seizure (21,195) patients.Discussion:Although individual jurisdictions can implement their policies and regulations for legalized cannabis, this study demonstrates the urgent need to mitigate the public health risk of cannabis contamination by introducing national-level guidelines based on conventional risk assessment methodologies and knowledge of patients’ susceptibility in medical use. https://doi.org/10.1289/EHP11206

What Can Utilities Expect from New Lead Fifth-Liter Sampling Based on Historic First-Draw Data?

The United States Environmental Protection Agency recently released their most sweeping overhaul to the Lead and Copper Rule in three decades. One of the most significant changes is requiring a fifth-liter (L5) sample at homes with lead service lines (LSLs) rather than the original first-liter (L1) sample for a demonstration of compliance with water lead level (WLL) limits. We analyzed sequential sampling data from three large water systems and compliance data from Michigan utilities-which base compliance on the 90th percentile of the greater of L1 and L5 samples-to evaluate whether L5 WLLs better represent water in contact with LSLs and to explore regulatory impacts of including L5 samples in compliance monitoring. The sequential sampling data demonstrated that it is impossible to use a single sample volume within a sequential profile to universally capture the volume of water in an LSL. While L5 is not always a reliable indicator of water in contact with an LSL, Michigan compliance data showed that the L5 sample is more likely to be from an LSL and can identify utilities that benefit from an improved corrosion control treatment. Michigan compliance data indicate that it is likely that L5 sampling will result in more systems having a higher 90th percentile WLL and that a high proportion of the systems likely to exceed regulatory action levels based on L5 samples can be identified through a retrospective analysis of historic L1 data. The impact of the switch to L5 sampling on the effectiveness of corrosion control treatment over time has yet to be determined.

Background concentration, risk assessment and regulatory threshold development: Polycyclic aromatic hydrocarbons (PAH) in Milwaukee, Wisconsin surface soils.

Inputs of polycyclic aromatic hydrocarbons (PAHs) of regulatory interest from diffuse atmospheric sources within urban areas frequently elevate local soil concentrations to levels requiring remediation despite the lack of in-situ contamination. This research sought to determine the distribution and potential health effects of aerially deposited PAHs in soil within the urban core of metropolitan Milwaukee, Wisconsin, U.S.A. as part of a soil regulatory standards reevaluation. Park areas (n=27) identified as undisturbed for 80+ years, containing no fill material, and receiving only atmospheric deposition were selected for composite surface and 92cm core soil sample collection (n=295). Samples were analyzed for the 16 USEPA priority PAHs, 1- and 2- methylnapthalene and ancillary soil properties. Soil core and ancillary data confirm lack of site disturbance. PAH diagnostic ratios and homologue summations indicate that diffuse multiple point source emissions contribute equally to PAH deposition throughout the area. Benzo(a)pyrene (BaP) and dibenz(a,h)anthracene mean concentrations exceed health-based clean up levels. Risk assessment shows only a worst-case exposure scenario (BaP at the 95% upper confidence limit) increasing cancer risk (1.67×10-6) over current regulatory thresholds (1.0×10-6). Health quotients show potential health risks from fluoranthene and pyrene for daily park users and from BaP for all others. Mean soil PAH values are similar to New Orleans, but lower than Chicago, Boston, and London reflecting industrial history and site selection protocols. The soil PAH results presented here for sites selected for non-manipulated soils combined with an almost 100-year uninterrupted atmospheric exposure effectively show the maximum potential PAH values that can be found at any given undisturbed location within the Milwaukee urban core due solely to atmospheric deposition.

Fruit infected with Paecilomyces niveus: A source of spoilage inoculum and patulin in apple juice concentrate?

Paecilomyces niveus has long been recognized as an important heat-resistant mold (HRM) causing spoilage in thermally processed apple products. With the recent discovery that P. niveus causes an apple disease called Paecilomyces rot, there is a need to evaluate the possibility that the spores can be introduced via infected fruit and survive thermal processing to contaminate apple products. Previously, research characterizing P. niveus survival and spoilage has been based on simple inoculation of cultured ascospores directly into juice. To determine whether ascospores formed in infected fruit survive through thermal processing with rotating vacuum evaporation (2.5 h, 70 °C), apples infected with P. niveus were used to make apple juice concentrate. Viable P. niveus was quantified in samples taken throughout the apple juice concentrate process: in cider, centrifuged juice, apple solids, and in juice made from concentrate. Additionally, the concentration of the mycotoxin patulin was determined in a subset of samples. Results show that P. niveus survived juice concentration. The thermal process used significantly reduced P. niveus (P = 0.0017); from an average of 5.5 log CFU L−1 in the initial cider made from diseased fruit to an average of 1.5 log CFU L−1 in single strength apple juice diluted from concentrate. Ascospores were observed at a greater abundance than intact asci throughout the concentration process. Patulin concentrations at all stages of apple juice concentration exceeded the United States’ regulatory defect action level of 50 ppb. This is the first report that apples infected with P. niveus can survive and remain viable in finished apple products and that patulin is produced in these apples. It raises important questions about the use of damaged and infected fruit as a source of HRM which contribute to spoilage and mycotoxins in apple juice concentrate.

Assessing the risk of lead exposure to children from drinking water in Metro Vancouver child care facilities


 Background: Environmental lead exposure has been a concern since the early 1970’s. With the reduction of airborne lead for inhalation, ingestion from food and water has become the major route of exposure leading to elevated blood lead levels. Previous research and the recent lead contamination of drinking water in Flint, Michigan demonstrate the vulnerability of young children and potential for exposure through drinking water. The purpose of this study was to assess and characterize the risk of lead contamination of drinking water for Metro Vancouver-area early childhood care facilities, and the effect of flushing fixtures as a control measure. Method: 91 drinking water samples were collected from various fixtures at 16 child care facilities at progressive time points to observe the effects of flushing and re-stagnation on total dissolved lead content. Analysis was performed using Varian AAS-240 coupled with GTA-120 graphite furnace atomic absorption spectroscopy. Results were analysed statistically using Excel 2010 and SAS/STAT® 14.2 software with SAS Studio 3.6 interface. Results: The mean (SD, min-max) lead concentrations of the water samples were 0.69 (2.32, 0.1-11.27) μg/L at zero minutes of flushing, 0.21 (0.44, 0.1-2.19) μg/L after one minute of flushing, 0.15 (0.17, 0.1- 0.87) μg/L after five minutes of flushing, 0.18 (0.17, 0.1 -0.64) μg/L after re-stagnation, and 0.31 (1.20, 0.1-11.27) μg/L overall. One outlier sample had a lead concentration of 11.27 μg/L, which exceeded Health Canada’s maximum allowable concentration of 10 μg/L. The decrease in mean lead concentration between zero minutes and one minute of flushing was statistically significant (p=0.0020). Conclusions: The results indicate that lead contamination of drinking water in child care facilities is present but below regulatory action levels under normal circumstances. The flushing of fixtures for at least one minute was shown to be effective in lowering lead concentrations further. Efforts should be taken to identify facilities at higher risk of lead contamination and to educate operators of flushing as an effective control measure.

Preliminary study to assess mycotoxin concentrations in whole corn in the California feed supply

Mycotoxins are naturally occurring environmental contaminants recognized worldwide in a variety of food and feed products. Produced as secondary metabolites by filamentous fungi, mycotoxins can have acute and chronic effects. Differing seasonal weather patterns and harvesting and storage conditions put corn grain at high risk for mycotoxin contamination. The objective of this study was to assess the risk of mycotoxin exposure posed to California livestock from whole corn. Random samples (n=50) of whole corn were collected and analyzed for 6 different mycotoxins, including aflatoxins, fumonisins, ochratoxins, trichothecenes (deoxynivalenol and T-2 toxin), and zearalenone. The samples represented a cross section of the corn entering California from various corn-growing states (n=43) as well as additional samples from California-grown corn (n=7). The experiment was a randomized sampling design. Over the course of a 6-mo period, 16 trains in California (100–110 railcars) and 5 California grain elevators were randomly sampled. Aflatoxins were detected in 14 samples, with 1 sample containing a concentration of 41.3μg/kg (as-is basis), which was above the action level of 20μg/kg for corn fed to dairy cattle. The average concentration of aflatoxins for the 13 samples below the regulatory action level was 8.69μg/kg (range 4.67 to 13.82μg/kg). Deoxynivalenol was found in 15 samples and averaged 553μg/kg (range 340 to 1,072μg/kg), which was below the federal advisory level of 5,000μg/kg for grain fed to dairy cattle. Fumonisins were found in 38 samples and averaged 1,687μg/kg (range 435 to 4,843μg/kg), which was below the federal guidance level of 30,000μg/kg in corn for dairy cattle. Ochratoxins, T-2 toxins, and zearalenone were not detected in any samples of whole corn. Fumonisins were the most prevalent mycotoxins found.

Onboard screening dockside testing as a new means of managing paralytic shellfish poisoning risks in federally closed waters

Paralytic shellfish poisoning (PSP) is the foodborne intoxication associated with the consumption of seafood contaminated with naturally occurring neurotoxins known as paralytic shellfish toxins. To protect public health from this potentially fatal syndrome, harvesting closures are implemented when toxins exceed the regulatory action level. Traditional monitoring programs established by state shellfish authorities allow for timely closures in state waters with minimal negative impacts on industry. However, such monitoring programs are not feasible in federal offshore waters given their distance from shore and the range of their spatial coverage. Thus innovative management strategies were investigated for these offshore resources. Georges Bank, an offshore resource with an estimated market value of more than $3 billion in Atlantic surfclams and ocean quahogs, has been closed to harvesting following a temporary ban in 1989 and a subsequent indefinite closure in 1990 due to the risk of PSP. As a means of managing this risk and allowing harvest of safe shellfish from this important resource, the Onboard Screening Dockside Testing Protocol (referred to as the Protocol) was developed by the US Food and Drug Administration (FDA), National Marine Fisheries Service (NMFS), state shellfish control authorities, and industry. The Protocol, which sets forth control measures to ensure product safety and public health protection, was endorsed by the Interstate Shellfish Sanitation Conference (ISSC) for pilot testing. Briefly, the pilot study Protocol required that (1) the fishing vessel receive a permit from NMFS to harvest in closed waters, (2) a minimum of five shellfish samples per intended harvest lot be tested for PSP toxins onboard, and (3) harvesting only occur when the samples tested from the intended fishing area are negative using the Jellett Rapid Tests or Abraxis Shipboard ELISA kits. Finally, product landed under the Protocol was confirmed to be safe for consumption using the mouse bioassay (MBA) prior to its introduction into commerce. This paper presents data from the pilot study, with primary focus on the advantages and challenges of the field kits employed onboard compared to the dockside MBA, which has served as the longstanding regulatory method for PSP toxins. In 2010 alone, the successful pilot study resulted in the safe harvest of over $2.7 million worth of surfclams in an area that has otherwise been unavailable for decades. Due to the success of this pilot study, the Protocol was adopted into the National Shellfish Sanitation Program Model Ordinance as an approved marine biotoxin control strategy for use in federal waters at the 2011 ISSC Biennial Meeting. In January 2013 a portion of Georges Bank was reopened for the harvest of Atlantic surfclams and ocean quahogs to fishermen following the Protocol.

Prevalence of Veterinary Drug Residues and Heavy Metals in Catfish Nuggets

Seafood such as catfish can sometimes become contaminated with chemicals and heavy metals at levels which would harm human health. There has been renewed interest by the USDA Food Safety Inspection Service (FSIS) in determining the incidence and prevalence of potentially harmful contaminants in catfish products. Many studies of retail catfish have focused on the fillet portion of the fish. Catfish nuggets are the fatty belly flap of the fish which is removed during processing and are sold as a separate product. Retail catfish nuggets from domestically raised catfish were collected in New Jersey, Pennsylvania, New York and Delaware and then tested for the presence of chemical contaminants including the heavy metals arsenic, lead, mercury, and cadmium. Of the 24 nugget samples tested none tested positive for the presence of arsenic or lead. Cadmium was detected in nine samples, but the levels were well below the regulatory action levels indicated for seafood. Mercury was detected in one catfish sample, but again the concentration was well below the U.S. FDA action limit for methyl mercury in fish. In addition, the presence of veterinary drug residues including malachite green, gentian violet and chloramphenicol in domestic catfish nuggets was also determined. One sample tested positive for the presence of gentian violet, however, given the low level detected (1.1 ppb) it is theorized to have occurred due to post-process contamination.

First report of the use of a saxitoxin–protein conjugate to develop a DNA aptamer to a small molecule toxin

Saxitoxin (STX) is a low molecular weight neurotoxin mainly produced by certain marine dinoflagellates that, along with its family of similarly related paralytic shellfish toxins, may cause the potentially fatal intoxication known as paralytic shellfish poisoning. Illness and fatality rates are low due to the effective monitoring programs that determine when toxins exceed the established regulatory action level and effectuate shellfish harvesting closures accordingly. Such monitoring programs rely on the ability to rapidly screen large volumes of samples. Many of the screening assays currently available employ antibodies or live animals. This research focused on developing an analytical recognition element that would eliminate the challenges associated with the limited availability of antibodies and the use of animals. Here we report the discovery of a DNA aptamer that targets STX. Concentration-dependent and selective binding of the aptamer to STX was determined using a surface plasmon resonance sensor. Not only does this work represent the first reported aptamer to STX, but also the first aptamer to any marine biotoxin. A novel strategy of using a toxin–protein conjugate for DNA aptamer selection was successfully implemented to overcome the challenges associated with aptamer selection to small molecules. Taking advantage of such an approach could lead to increased diversity and accessibility of aptamers to low molecular weight toxins, which could then be incorporated as analytical recognition elements in diagnostic assays for foodborne toxin detection. The selected STX aptamer sequence is provided here, making it available to any investigator for use in assay development for the detection of STX.

MR safety: simultaneous B 0, dΦ/dt, and dB/dt measurements on MR-workers up to 7 T

The EU directive on safety requirements (2004/40/EC) limits the exposure to time varying magnetic fields to dB /dt=200 mT/s. This action value is not clearly defined as it considers only the temporal change of the magnitude of B. Thus, only the translational motion in the magnet's fringe field is considered and rotations are neglected. A magnetic field probe was constructed to simultaneously record the magnetic flux density B(x, y, z) with a 3-axis Hall sensor and the induced voltage due to movements with a set of three orthogonal coils. Voltages were converted into time-varying magnetic flux d Φ(x, y, z)/dt serving as an exposition parameter for both translations and rotations. To separate the two types of motion, d B/dt was additionally calculated on the basis of the Hall sensor's data. The calibrated probe was attached to the forehead of 8 healthcare workers and 17 MR physicists, and B and dΦ/dt were recorded during standard operating procedures at three different MR systems up to 7 T. The maximum percentage of the translational motion referring the data including both translations and rotations amounts to 32%. During volunteer measurements, maximum exposure values of dΦ/dt=21 mWb/s, dB/dt=1.40 T/s and |B|=2.75 T were found. The findings in this work indicate that both translations and rotations in the vicinity of an MR system should be taken into account, and that a single regulatory action level might not be sufficient.

An improved immunoassay for detection of saxitoxin by surface plasmon resonance biosensors

Saxitoxin and its analogs, the causative agents of paralytic shellfish poisoning (PSP), are a worldwide threat to seafood safety. Effective monitoring of potentially contaminated fishing areas as well as screening of seafood samples is necessary to adequately protect the public. While many analytical methods exist for detecting paralytic shellfish toxins (PSTs), each technique has challenges associated with routine use. One recently developed method [1] that overcomes ethical or performance-related issues of other techniques is the surface plasmon resonance (SPR) bioassay. Notwithstanding the advantages of this method, much research remains in optimizing the sensor substrate and assay conditions to create a robust technique for rapid and sensitive measurement of PSTs. This manuscript describes a more rigorous and stable SPR inhibition immunoassay through optimization of the surface chemistry as well as determination of optimum mixture ratios and mixing times. The final system provides rapid substrate formation (18 h saxitoxin conjugation with low reagent consumption), contains a reference channel for each assay, and is capable of triplicate measurements in a single run with detection limits well below the regulatory action level.

Effect of temperature, rainfall and planting date on aflatoxin and fumonisin contamination in commercial Bt and non-Bt corn hybrids in Arkansas

Corn (maize, Zea mays) is susceptible to contamination with aflatoxins, fumonisins and other mycotoxins, particularly in the southeastern USA. In principle, mycotoxin contamination could be reduced in commercial corn hybrids with shorter growing seasons by planting at dates which minimize plant stress during the critical kernel-filling period. To evaluate this strategy, commercial Bt and non-Bt hybrids were planted in Arkansas in mid-April and early May of 2002, 2004 and 2005. The mid-April planting date resulted in lower aflatoxin contamination in harvested corn each yr and in significantly less frequent contamination above a regulatory action level in 2005 and overall than did the early-May planting date in both Bt and non-Bt corn. The mid-April planting date resulted in significantly lower total fumonisin contamination in harvested corn and in less frequent contamination above a regulatory advisory level than the early May planting date in 2 of 3 yr and overall in both Bt and non-Bt corn. All fumonisin subtypes studied were reduced. Frequent co-occurrence of aflatoxin and fumonisin was observed. Fumonisin levels averaged lower in Bt hybrids than in non-Bt hybrids at all plantings. Reduced aflatoxin and fumonisin contamination with mid-April planting could not be explained by any measure of heat stress during the kernel-filling period.

Tracing Contributions of Benzene from Outdoor to Indoor Air

Regulatory action levels for benzene in indoor air are typically unrealistic because they are commonly less than ambient outdoor concentrations. To trace potential benzene contributions to indoor air from outdoor sources, we evaluated data from 66 air samples collected at three sites with known subsurface impacts. Comparison of benzene:tracer ratios from indoor air, outdoor air, and soil gas samples demonstrated that indoor air benzene was primarily contributed by outdoor air and not by soil-vapor intrusion. Principal components analysis also demonstrated that soil gas had a distinctly different volatiles signature than both indoor and outdoor air. Ignoring ambient outdoor benzene contributions may lead to the erroneous conclusion that soil gas is the source of indoor air benzene.

Aflatoxin sequestration in animal feeds by quality-labeled smectite clays: An introductory plan

Over the past two decades the use of smectite to suppress aflatoxin has been demonstrated for many farm animals; yet commercial marketing of smectite as an aflatoxin binder has been stymied and blending of grains containing aflatoxin persists. The suppression of aflatoxin depends of the adsorption capacity of the smectite clay binders but effectiveness is influenced by several factors. Our research indicates that smectite clays can be evaluated by the following methods: X-ray diffraction for smectite identification, Langmuir isotherm for aflatoxin binding effectiveness, structural composition by Fourier transform infrared, and cation exchange capacity for smectite quantification. Particle size determined by laser diffraction is a useful and convenient measure of smectite potential that accounts for 65% of the variability in aflatoxin adsorption by most of the clays investigated. Also, pH and Al influence are poorly understood and subjects that need further research. The organic matter content influences smectite quantitative estimates and may reduce aflatoxin adsorption. This introductory plan is intended to expedite the use of aflatoxin binders for grain while improving the performance of animals by sequestering aflatoxin permitted by regulatory action levels for aflatoxin in animal feeds.

Estimation of Respirable Dust Exposure Among Coal Miners in South Africa

The use of retrospective occupational hygiene data for epidemiologic studies is useful in determining exposure-outcome relationships, but the potential for exposure misclassification is high. Although dust sampling in the South African coal industry has been a legal requirement for several decades, these historical data are not readily adequate for estimating past exposures. This study describes the respirable coal mine dust levels in three South African coal mines over time. Each of the participating mining operations had well-documented dust sampling information that was used to describe historical trends in dust exposure. Investigator-collected personal dust samples were taken using standardized techniques from the face, backbye (underground jobs not at the coal face), and surface from 50 miners at each mine, repeated over three sampling cycles. Job histories and exposure information was obtained from a sample of 684 current miners and 188 ex-miners. Linear models were developed to estimate the exposure levels associated with work in each mine, exposure zone, and over time using a combination of operator-collected historical data and investigator-collected samples. The estimated levels were then combined with work history information to calculate cumulative exposure metrics for the miner cohort. The mean historical and investigator-collected respirable dust levels were within international norms and South African standards. Silica content of the dust samples was also below the 5% regulatory action level. Mean respirable dust concentrations at the face, based on investigator-collected samples, were 0.9 mg/m3, 1.3 mg/m3, and 1.9 mg/m3 at Mines 1, 2, and 3, respectively. The operator-collected samples showed considerable variability across exposure zones, mines, and time, with the annual means at the face ranging from 0.4 mg/m3 to 2.9 mg/m3. Statistically significant findings were found between operator- and investigator-collected dust samples. Model-based arithmetic mean dust estimates at the face were 1.2 mg/m3, 2.0 mg/m3, and 0.9 mg/m3 for Mines 1, 2, and 3, respectively. Using these levels, the mean cumulative exposure for the cohort was 56.8 mg-years/m3. Current miners had a mean cumulative exposure of 66.5 mg-years/m3, compared with ex-miners of 26.8 mg-years/m3. Improvements in dust management or the use of different sampling equipment could account for the significant differences seen between operator- and investigator-collected data. Regression modeling for estimating mean dust levels over time using combined historical and investigator-collected data seems a reasonable method and useful in constructing models to describe cumulative exposures in a cohort of current and ex-miners.

Occurrence and Removal of Chloro-s-Triazines in Water Treatment Plants

Atrazine, simazine, and propazine and their major chlorinated degradates (deethylatrazine, deisopropylatrazine, and didealkylatrazine) are considered as a group to be endocrine-disrupting chemicals by the U.S. Environmental Protection Agency. On this basis, regulatory action levels are currently under consideration for the total chloro-s-triazine (TCT) levels in drinking waters. To assess the concentrations of each of these species in drinking water and their treatability in conventional water treatment, a comprehensive, full-scale studywas conducted that included frequent monitoring at 33 and 47 water utilities during 2003 and 2004, respectively. Approximately 900 paired raw and treated water samples were analyzed using a gas chromatography/mass spectrometry method with preconcentration using a mixed-mode, solid-phase extraction that allowed quantitation of each species including didealkylatrazine. The results showed that atrazine concentrations were generally well within the 3 microg/L maximum contaminant level (MCL) and that simazine and propazine concentrations were generally negligible. Ninety-fifth-percentile values for the ratio of TCT/atrazine were 4.8 and 4.7, respectively. Effectiveness of conventional treatment technologies, including carbon, was observed to vary significantly. Concerns that didealkyatrazine concentrations may be high and significantly elevate the TCT appear to be unfounded. In general, the results suggest that potential treatment requirements for TCT are not likely to be any more difficult for utilities to meet than the current requirements for atrazine.

Comparison of SPME headspace analysis to U.S. EPA method 5030/8260B for MTBE monitoring

AbstractMethyl tert‐butyl ether (MTBE) is one of the most common ground water contaminants in the United States. Ground water contaminated with MTBE is also likely to be contaminated with tert‐butyl alcohol (TBA) because TBA is a component of commercial‐grade MTBE, can also be used as a fuel oxygenate, and is a biodegradation product of MTBE. In California, MTBE is subject to reporting at concentrations >3 μg/L, and TBA has a drinking water action level of 12 μg/L. We describe a simple, automated solid‐phase microextraction (SPME) method for the analysis of MTBE and TBA in water. The headspace (HS) of a water sample is extracted with a carboxen/polydimethylsiloxane SPME fiber and the MTBE and TBA are desorbed into a gas chromatograph (GC) and detected using a mass spectrometer (MS). The method is optimized for the routine analysis of MTBE and TBA, with a level of quantitation of 0.3 and 4 μg/L, respectively, in water. The lower level of detection for MTBE is 0.03 μg/L using this method. This HS extraction SPME is applicable to the measurement of both MTBE and TBA at concentrations below regulatory action levels. This method was compared with the certified U.S. EPA Method 5030/8260B (purge and trap/GC/MS) using split samples. Results from the SPME‐HS/GC/MS method were directly comparable to those from the U.S. EPA Method 5030/8260B. This method provides a simple, inexpensive, accurate, and sensitive alternative to the U.S. EPA Method 5030/8260B for the analysis of MTBE and TBA in water samples.

The Technical Case for Eliminating the Use of the TPH Analysis in Assessing and Regulating Dissolved Petroleum Hydrocarbons in Ground Water

AbstractIn many states, the total petroleum hydrocarbons (TPH) analysis based on gas chromatography‐flame ionization detection (GC‐FID) is still being used to assess and regulate ground water quality at petroleum release sites. The soluble fraction of fresh crude oil or fresh products that could potentially be dissolved into the ground water is limited to relatively few petroleum hydrocarbon constituents (primarily the C6 to C14 aromatics). Research by numerous investigators has shown that the reported TPH concentrations of ground water samples frequently do not represent dissolved petroleum hydrocarbons but rather represent nondissolved petroleum or polar nonhydrocarbon compounds. Nondissolved petroleum is frequently entrained within a sample when sampling ground water within affected soil, and polar nonhydrocarbons are present in ground water as a result of petroleum biodegradation or other factors. These constituents are being measured because the TPH analysis does not include steps to remove nondissolved petroleum or a silica gel cleanup to remove polars.Many states have regulatory action levels for TPH in ground water that are in the 0.1 to 2 mg/L range. The technical basis for these action levels appears to be toxicity and/or organoleptic (taste and odor) properties of the dissolved petroleum hydrocarbons associated with fresh oil or fresh products. The presence of compounds measured as TPH that are not dissolved petroleum hydrocarbons has proven problematic for regulatory decision‐making because the comparison of concentration data to the regulatory criteria may not be correct. Because the TPH analysis does not reliably distinguish between dissolved petroleum hydrocarbons and other compounds, it should not be used to assess or regulate dissolved petroleum hydrocarbons, in ground water. We recommend that constituent‐specific analyses be used to assess and regulate ground water quality at petroleum hydrocarbon release sites. If TPH must be used due to regulatory requirements, samples should be cleaned up with silica gel to remove polars (and turbidity should be removed, if present) prior to analysis so that comparison to regulatory action levels that are based on properties of dissolved petroleum hydrocarbon constituents is technically appropriate.

Population-based dietary intakes and tap water concentrations for selected elements in the EPA region V National Human Exposure Assessment Survey (NHEXAS).

A National Human Exposure Assessment Survey (NHEXAS) field study was performed in U.S. Environmental Protection Agency (EPA) Region V, providing population-based exposure distribution data for selected elements in several personal, environmental, and biological media. Population distributions are reported for the 11 elements that were measured in water and dietary samples. Dietary intakes and home tap water concentrations of lead, arsenic, and cadmium were further examined for intermedia associations, for differences between dietary exposure for adults and children, and to estimate the proportion of the population above health-based reference values (dietary) or regulatory action levels or maximum contaminant levels (water). Water lead and arsenic concentrations were significantly associated with dietary intake. Intake of all elements was higher from solid foods than from liquid foods (including drinking water). Dietary intakes of Pb, As, and Cd were greater than those calculated for intake from home tap water or inhalation on a microg/day basis. Median dietary intakes for the Region V population for Pb, As, and Cd were 0.10, 0.13, and 0.19 microg/kg bw/day, respectively. While Pb, As, and Cd concentrations in the foods consumed by 0 to 6-year-old children were similar to or lower than those for adults, dietary intakes calculated on a body weight basis were 1.5 to 2.5 times higher for young children. Intrapersonal intake differences accounted for most of the variance in short-term (daily) dietary intakes for Pb and As, while interpersonal differences accounted for more of the intake variance for Cd. Only small percentages of the population exceeded health-based intake reference values or concentrations equal to regulatory levels in water for Pb, As, and Cd.