Sampling household surfaces for pesticide residues: comparison between a press sampler and solvent-moistened wipes.

A modified Press Sampler was evaluated to determine the efficiency of pesticide transfer from household surfaces to collection disks as compared to wiping with a solvent-moistened gauze pad. Organophosphate (OP), pyrazole, and pyrethroid pesticides were applied to three hard flooring materials and carpet at two loading rates. Surfaces were dried and press sampled using C(18), 100% cotton or polyurethane foam (PUF) for either 2 or 10 min or wiped with isopropanol-moistened gauze pads. Transfer efficiencies (TE, %) were calculated as a fraction of surface loadings captured simultaneously on foil deposition coupons. The highest mean TEs (17-55%) for the Press Sampler were observed for OPs from hard surfaces to C(18), considering both contact times. Cotton and PUF transferred 6-27% and 5-30% of OPs, respectively. Corresponding mean TEs for pyrazole and pyrethroid pesticides were only 3% (C(18)), 2-3% (cotton) and 1-2% (PUF). Wipes of hard surfaces removed 84-97% of all pesticides while wipes of carpet removed 31-39%, much higher than transferred to any Press Sampler materials. The mean TEs suggested that the extent of pesticide residue transfer was affected by surface type, pesticide class, and sampling procedure. Wiping was more efficient than press sampling for pesticide surface residue measurements, particularly for loading rates typical of residences.

Measurement of transferable chemical residue from nylon carpet using the California roller and a new mega-California roller.

Human chemical exposures resulting from transfer of surface deposition on indoor nylon carpets may be estimated by measuring transferable residues (mu g chemical/cm2 carpet). A weighted roller developed at California Department of Food and Agriculture (CDFA) has been extensively used to sample transferable residue for estimates of human exposure in risk characterization. A modified roller has been developed to evaluate the influence of pressure on transferable chemical residue since weight and force (or pressure, kg/m2) may vary person-to-person and activity-to-activity. A 30.5 cm diameter roller was used to apply 60 to 2100 kg/m2 to bracket pressures exerted by humans on a flat nylon-carpeted surface. Measurements of transferable cyfluthrin residues were made after 1, 7, and 21 days. Total Soxhlet extractable cyfluthrin residues were relatively constant during the test period. Residue transferability decreased during the study period. Modest increases in the transferability of surface residues were observed over the broad range of pressures applied by the modified roller.

Human exposure to indoor residential cyfluthrin residues during a structured activity program.

Estimations of absorbed daily dosage (ADD) of chemicals following contact with treated surfaces may be required for risk assessment and risk management. Measurements of ADD based upon biomonitoring are a more reliable data than estimates of ADD from environmental measurements since they require fewer default assumptions. Study participants performed a structured activity program (SAP) 24-h after an application of Tempo((R)) 20 WP (cyfluthrin; 3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylic acid cyano(4-fluoro-3-phenoxy-phenyl)-methyl ester) on a medium pile, plush nylon carpet. Measurements of total cyfluthrin residue and transferable cyfluthrin residue (cotton cloth and CDFA roller; personal sock and short dosimetry) were made at 3, 7, 12, 23, 47.5, and 407.5 h. Total cyfluthrin residue extracted from (Soxhlet extraction) carpet was 11.1+/-2.7 microg/cm(2) 1 h prior to the SAP. Transferable cyfluthrin residue obtained through analysis of cotton cloths rolled with a weighted 30-pound cylinder was 0.11 microg/cm(2). Cyfluthrin residues from socks and shorts were 0.74+/-0.23 and 0.15+/-0.03 microg/cm(2), respectively. Urine was collected at 12-h intervals during a 72-h period following the SAP and was analyzed for the cyfluthrin biomarker, 4-fluoro-3-phenoxybenzoic acid (FPBA). The mean cyfluthrin equivalents excreted were 8.4+/-5.7 microg/person (yielding an absorbed dosage of 0.10 microg/kg; n=7). The elimination half-life was 16+/-5 h. All predicted ADDs based upon environmental measurements overestimated the ADDs measured by urinary excretion.

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.