Influences on transfer of selected synthetic pyrethroids from treated Formica to foods.

Children's unstructured eating habits and activities may lead to excess dietary exposures not traditionally measured by the US Environmental Protection Agency. Influence of these activities on transfer of pesticides from treated Formica to foods was studied. The objective was to perform simulation experiments using four foods (bread, apple slices, bologna, and sugar cookies) exposed to treated Formica after varied time intervals between surface contamination and contact (1, 6, and 24 h) and frequency of contact with and without recontamination. Pesticides investigated included permethrin, bifenthrin, cyfluthrin, cypermethrin, and deltamethrin. Data will be used as input parameters for transfer efficiencies (TEs) within the Children's Dietary Intake Model (CDIM), which predicts total dietary exposure of a child. Pesticide transfer from surfaces to bologna and apples was more efficient than to bread and cookies. For the bread and cookies, all pyrethroids had a TE that ranged from below detectible levels to ≤ 4%. A combined average of 32-64% and 19-43% was transferred to bologna and apples, respectively, for the three contact times for all pyrethroids. The TEs of the varied time intervals indicated that increased time between contamination and contact showed little difference for bologna, bread, and cookies, but a significant difference for apples. As long as pesticide levels are measureable on surfaces in children's eating environment, it can be concluded that transfer of pesticides to foods will take place. Foods' characteristics had an important function in the transfer of pesticides when multiple contacts occurred. Regardless of recontamination, pesticides were efficiently transferred from the treated surface to bologna. The bologna did not reach a saturation point during the contacts. Pesticides were also efficiently transferred to apples, but reached a maximum TE during the second contact. The distribution of activity factors within CDIM needs to reflect the differences in the characteristics of the foods.

An overview of measurement method tools available to communities for conducting exposure and cumulative risk assessments.

Community-based programs for assessing and mitigating environmental risks represent a challenge to participants because each brings a different level of understanding of the issues affecting the community. These programs often require the collaboration of several community sectors, such as community leaders, local governments and researchers. Once the primary concerns, community vulnerabilities and assets are identified, participants plan on how to address immediate actions, rank known risks, collect information to support decision making, set priorities and determine an evaluation process to assess the success of the actions taken. The evaluation process allows the community to develop new action plans based on the results obtained from earlier actions. Tracking the success of the community actions may be as simple as a visual/tangible result (e.g., cleaning a park) or as complex as the collection of specific measurements to track the reduction of toxic pollutants or to determine the presence of a specific contaminant. Recognizing that communities may need to perform measurements to meet their goals, this paper provides an overview of the available measurement methods for several chemicals and biologicals in relevant environmental samples to a community setting. The measurement methods are organized into several categories according to their level of complexity, estimated cost and sources. Community project technical advisors are encouraged to examine the objective(s) of the community to be addressed by a measurement collection effort and the level of confidence that needed for the data to make appropriate decisions. The tables provide a starting point for determining which measurement method may be appropriate for specific community needs.

Analysis of permethrin isomers in composite diet samples by molecularly imprinted solid-phase extraction and isotope dilution gas chromatography-ion trap mass spectrometry.

Determination of an individual's aggregate dietary ingestion of pesticides entails analysis of a difficult sample matrix. Permethrin-specific molecularly imprinted polymer (MIP) solid-phase extraction cartridges were developed for use as a sample preparation technique for a composite food matrix. Vortexing with acetonitrile and centrifugation were found to provide optimal extraction of the permethrin isomers from the composite foods. The acetonitrile (with 1% acetic acid) was mostly evaporated and the analytes reconstituted in 90:10 water/acetonitrile in preparation for molecularly imprinted solid-phase extraction. Permethrin elution was accomplished with acetonitrile and sample extracts were analyzed by isotope dilution gas chromatography-ion trap mass spectrometry. Quantitation of product ions provided definitive identification of the pesticide isomers. The final method parameters were tested with fortified composite food samples of varying fat content (1%, 5%, and 10%) and recoveries ranged from 99.3% to 126%. Vegetable samples with incurred pesticide levels were also analyzed with the given method and recoveries were acceptable (81.0-95.7%). Method detection limits were demonstrated in the low ppb range. Finally, the applicability of the MIP stationary phase to extract other pyrethroids, specifically cyfluthrin and cypermethrin, was also investigated.

Development of an analytical scheme for the determination of pyrethroid pesticides in composite diet samples.

Analysis of an individual's total daily food intake may be used to determine aggregate dietary ingestion of given compounds. However, the resulting composite sample represents a complex mixture, and measurement of such can often prove to be difficult. In this work, an analytical scheme was developed for the determination of 12 select pyrethroid pesticides in dietary samples. In the first phase of the study, several cleanup steps were investigated for their effectiveness in removing interferences in samples with a range of fat content (1-10%). Food samples were homogenized in the laboratory, and preparatory techniques were evaluated through recoveries from fortified samples. The selected final procedure consisted of a lyophilization step prior to sample extraction. A sequential 2-fold cleanup procedure of the extract included diatomaceous earth for removal of lipid components followed with a combination of deactivated alumina and C(18) for the simultaneous removal of polar and nonpolar interferences. Recoveries from fortified composite diet samples (10 microg kg(-1)) ranged from 50.2 to 147%. In the second phase of this work, three instrumental techniques [gas chromatography-microelectron capture detection (GC-microECD), GC-quadrupole mass spectrometry (GC-quadrupole-MS), and GC-ion trap-MS/MS] were compared for greatest sensitivity. GC-quadrupole-MS operated in selective ion monitoring (SIM) mode proved to be most sensitive, yielding method detection limits of approximately 1 microg kg(-1). The developed extraction/instrumental scheme was applied to samples collected in an exposure measurement field study. The samples were fortified and analyte recoveries were acceptable (75.9-125%); however, compounds coextracted from the food matrix prevented quantitation of four of the pyrethroid analytes in two of the samples considered.

Surface-to-food pesticide transfer as a function of moisture and fat content.

Transfer of pesticides from household surfaces to foods may result in excess dietary exposure in children (i.e., beyond that inherent in foods due to agricultural application). In this study, transfer was evaluated as a function of the moisture and fat content of various foods. Surfaces chosen for investigation were those commonly found in homes and included Formica, ceramic tile, plastic, carpet, and upholstery fabric. Each surface type was sprayed with an aqueous emulsion of organophosphates, fipronil, and synthetic pyrethroids. In the first phase of the study, multiple foods (apples, watermelon, wheat crackers, graham crackers, white bread, flour tortillas, bologna, fat-free bologna, sugar cookies, ham, Fruit Roll-ups, pancakes, and processed American cheese) were categorized with respect to moisture and fat content. All were evaluated for potential removal of applied pesticides from a Formica surface. In the second phase of the study, representative foods from each classification were investigated for their potential for pesticide transfer with an additional four surfaces: ceramic tile, plastic, upholstery, and carpet. Moisture content, not fat, was found to be a determining factor in most transfers. For nearly all surfaces, more efficient transfer occurred with increased hardness (Formica and ceramic tile). Comparatively, the polymer composition of the plastic delivered overall lower transfer efficiencies, presumably due to an attraction between it and the organic pesticides of interest.

Determination of metals in composite diet samples by inductively coupled plasma-mass spectrometry.

A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4-1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0-11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.

Comparison of five extraction methods for determination of incurred and added pesticides in dietary composites.

The National Exposure Research Laboratory of the U.S. Environmental Protection Agency conducts research to measure exposure of individuals to chemical pollutants through the diet. In support of this research, methods are being evaluated for the determination of pesticides in dietary composite samples. In the present study, Soxhlet, blender, microwave-assisted, pressurized fluid, and supercritical fluid extraction methods were compared for the determination of incurred and added pesticides in 4 dietary composites, which varied in fat and water content. Incurred pesticides were chlorothalonil, chlorpyrifos, DDE, dicloran, dieldrin, endosulfan I, malathion, cis- and trans-permethrin, and trifluralin. Added pesticides were alpha- and gamma-chlordane, hexachlorobenzene, and fonofos. Concentrations of the individual pesticides were between 0.2 and 20 ng/g composite. All 5 methods tested could extract pesticides from dietary composites. Most incurred pesticides were recovered from the dietary composites within the range of 59-140% of expected values. Recoveries of added pesticides were between 60 and 130%. Microwave-assisted extraction led to significantly higher concentrations of 7 pesticides. Blender extraction yielded significantly higher concentrations of chlorothalonil and fonofos. Water content was a significant factor in the recovery of chlorothalonil, and fat content was a significant factor in the recovery of fonofos. In designing an exposure study, the selection of the extraction method would be determined by number of samples to be extracted, analyte stability, and cost.

Thermal Destruction of Escherichia coli and Klebsiella pneumoniae in Human Milk.

A continuous flow high-temperature short-time pasteurization system was used to determine kinetic parameters (D- and z-values) for thermal destruction of the bacterial pathogens, Escherichia coli and Klebsiella pneumoniae , in mature human milk. D-and z-alues of each bacterium were determined from data on survivors enumerated on both selective media, Violet Red Bile agar or MacConkey's, and on a non-selective medium, nutrient agar (NA). For E. coli , D-values were determined at 58, 60, 62 and 64°C. The predicted value of D at 60°C is 31.5 s. The z-value for E. coli is 3.2°C. D-values for K. pneumoniae were determined at 52, 56 and 58°C. Based on these data the predicted value of D at 60°C is 1.3 s. The z-value for K. pneumoniae , is 2.8°C. For both E. coli and K. pneumoniae , counts on NA tend to be higher than on selective media. This is undoubtedly due to the inhibitory nature of the selective media. This also suggests that some degree of thermal injury may occur for each organism.