The Importance of Hand Exposures to Absorbed Dosage of Hand Harvesters.

Fruit harvesters' primary pesticide exposure results from direct dermal and clothing contact with foliar residues. The transfer of pesticide residues from foliage to strawberry harvesters' hands and their subsequent dissipation under normal occupational conditions in the field was examined. The effectiveness of latex gloves as sampling dosimeters was evaluated and compared with bare-handed harvester exposures.

Latex Rubber Gloves as a Sampling Dosimeter Using a Novel Surrogate Sampling Device.

Pesticide exposure during harvesting of crops occurs primarily to the workers' hands. When harvesters wear latex rubber gloves for personal safety and hygiene harvesting reasons, gloves accumulate pesticide residues. Hence, characterization of the gloves' properties may be useful for pesticide exposure assessments.

Validity of geographically modeled environmental exposure estimates.

Geographic modeling is increasingly being used to estimate long-term environmental exposures in epidemiologic studies of chronic disease outcomes. However, without validation against measured environmental concentrations, personal exposure levels, or biologic doses, these models cannot be assumed a priori to be accurate. This article discusses three examples of epidemiologic associations involving exposures estimated using geographic modeling, and identifies important issues that affect geographically modeled exposure assessment in these areas.

Fate and distribution of fipronil on companion animals and in their indoor residences following spot-on flea treatments.

Use of fipronil {5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile CAS 120068-37-3} topical pet products on dogs and cats introduces low level residues into residences. Distribution and fate studies of fipronil on pets and in residences were performed to evaluate potential determinants of human exposure. Fipronil, desulfinyl fipronil, fipronil sulfone and fipronil sulfide were measured on hair clippings and brushed hair.

Preformed biomarkers including dialkylphosphates (DAPs) in produce may confound biomonitoring in pesticide exposure and risk assessment.

Low levels of pesticides and their metabolites/degradates occur in produce when pesticides are used in conventional or organic crop protection. Human dietary and nonoccupational urine biomonitoring studies may be confounded by preformed pesticide biomarkers in the diet. The extent of formation of putative urine biomarkers, including malathion specific (MMA, MDA; malathion mono- and diacids), organophosphorus generic (DMP, DMTP, DMDTP; dimethyl-, dimethylthio-, and dimethydithiophosphate), pyrethroid generic (3-PBA; 3-phenoxybenzoic acid), and captan-specific metabolites (THPI; tetrahydrophthalimide), was measured in produce samples containing the parent pesticide.

Occurrence of DDA in DDT-contaminated sediments of the Southern California Bight.

DDT, DDE and some additional lipophilic derivatives are recognized contaminants in sediments of Southern California Bight (SCB). Only about 10% of total DDTs discharged into the SCB are accounted for using available monitoring data (sediment, water, and biota). DDA represented up to 0.

Evaluation of neonicotinoid, organophosphate and avermectin trunk injections for the management of avocado thrips in California avocado groves.

Background: Trunk injections of systemic insecticides were evaluated for the management of avocado thrips. Insecticide residues were quantified in leaves to determine when after treatment, and for how long, toxic concentrations of the insecticides were present. Residues in fruit were quantified to determine whether trunk injection of insecticides might present a greater risk than traditional application methods for contaminating fruit.

Immunochemical analysis of 3-phenoxybenzoic acid, a biomarker of forestry worker exposure to pyrethroid insecticides.

Pyrethroid insecticides widely used in forestry, agricultural, industrial, and residential applications have potential for human exposure. Short sample preparation time and sensitive, economical high-throughput assays are needed for biomonitoring studies that analyze a large number of samples. An enzyme-linked immunosorbent assay (ELISA) was used for determining 3-phenoxybenzoic acid (3-PBA), a general urinary biomarker of exposure to some pyrethroid insecticides.

Deposition and spatial distribution of insecticides following fogger, perimeter sprays, spot sprays, and crack-and-crevice applications for treatment and control of indoor pests.

The indoor surface deposition and distribution of insecticides applied as foggers, baseboard or perimeter sprays, spot sprays and crack-and-crevice sprays represent distinct pathways of potential unintentional and unavoidable residential pesticide exposure of children and adults. Fogger, perimeter spray, crack-and-crevice, and spot sprays using registered commercial products were studied using three 5-part deposition plates positioned in unoccupied residences in Riverside, CA. Pesticide active ingredients included permethrin, chlorpyrifos, cyfluthrin, cypermethrin, and deltamethrin.

Potential exposure of children and adults to cypermethrin following use of indoor insecticide foggers.

The magnitude and distribution of cypermethrin from total release, over-the-counter foggers was studied in a test room and in residences to facilitate evaluation of regulatory exposure algorithms and new human exposure assessments based upon urine biomonitoring. Surface residue (SR) was evenly distributed in a small test room (3.6 mciro g cypermethrin/cm(2)) where thorough mixing of the aerosol occurred.

2,2-bis(4-Chlorophenyl)acetic acid (DDA), a water-soluble urine biomarker of DDT metabolism in humans.

DDT metabolism in humans yields DDA as the principal urinary metabolite and potential exposure biomarker. A method for DDA analysis in human urine was developed using pentafluorobenzyl bromide and diisopropylethyl amine. Dried hexane extracts were reacted for 1 hour at room temperature.

Dialkylphosphates (DAPs) in fruits and vegetables may confound biomonitoring in organophosphorus insecticide exposure and risk assessment.

Trace residues of organophosphorus (OP) pesticides are associated with fruits and vegetables that have been sprayed with those OP pesticides to guard against insect pests. Human dietary exposure to these OP pesticides is commonly estimated by measuring the amount of OP metabolites in urine, assuming a stoichiometric relationship between a metabolite and its parent insecticide. Dialkylphosphates (DAPs) are the OP metabolites that are most often used as markers in such biomonitoring studies.

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.

Determination of methyl isothiocyanate in air downwind of fields treated with metam-sodium by subsurface drip irrigation.

Air concentrations of methyl isothiocyanate (MITC) were determined near two fields treated with metam-sodium (MS) by subsurface drip irrigation. The two study fields showed measurable airborne MITC residues during application of MS and for periods up to 48 h postapplication. Using a Gaussian plume dispersion model, flux values were estimated for all of the sampling periods.

Perchlorate exposure from food crops produced in the lower Colorado River region.

The Colorado River shows low levels of perchlorate derived from aerospace- and defense-related fuel industries once located near the Las Vegas Wash. At sufficiently high dosages perchlorate can disrupt thyroid function by inhibiting uptake of iodide. The Colorado River is the primary source of irrigation water for most food crops grown in Southern California and Southwestern Arizona.

Aldrin epoxidation and dihydroisodrin hydroxylation as probes of in vivo and in vitro oxidative metabolic capability of some caterpillars.

Comparative biochemical studies are productive means to study factors that limit both beneficial and harmful effects of chemicals. Reactions such as aldrin epoxidation and dihydroisodrin hydroxylation are valuable assays of oxidative metabolism in scientific studies of chemical biology in insects, subhuman primates and other living things. The tissue distribution of activity in caterpillars may have functional significance.

Low pilot exposure to pyrethrin during ultra-low-volume (ULV) aerial insecticide application for control of adult mosquitoes.

Pilot exposure to pyrethrin was monitored after 2 aerial applications of a ultra-low-volume (ULV) pyrethrin insecticide for the control of adult mosquitoes. Pyrethrin exposure was estimated by measuring the excretion in urine of a common metabolite, trans-chrysanthemumdicarboxylic acid, of the natural pyrethrin mixture. Pyrethrin exposure estimated by total daily urine volume was well correlated (R2 = 0.

Artificial sweat enhances dermal transfer of chlorpyrifos from treated nylon carpet fibers.

The dermal transfer and absorption of 14C-ring-chlorpyrifos from nylon carpet fibers was measured in skin penetration-evaporation cells with excised pig skin. Prior to application, synthetic sweat was applied to skin in half of the cells. Radioactivity was measured in receptor fluid, dermis, epidermis, tape stripping samples, and vapor trap samples during a 24-h period.

Perspiration increased human pesticide absorption following surface contact during an indoor scripted activity program.

Homeowners and professional applicators frequently use chemicals to control insect pests in urban environments. The identification and evaluation of determinants of human exposure are critical to conduct reliable and responsible human exposure assessments following indoor residential chemical applications. The effect of sweat on absorbed dose in humans was evaluated with human volunteers who participated in a structured activity program (SAP).

Octachlorodipropyl ether (s-2) mosquito coils are inadequately studied for residential use in Asia and illegal in the United States.

Children and their parents in residences are often protected by insecticides from nuisance and disease-bearing mosquitoes. The annual worldwide consumption of the four major types of residential insecticide products--aerosols, mosquito coils, liquid vaporizers, and vaporizing mats--is in the billions of units. Mosquito coils are burned indoors and outdoors in East Asia and to a limited extent in other parts of the world, including the United States.

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.