title: A laboratory comparison of two media for use in the assessment of dermal exposure to pesticides.
abstract: In a laboratory study, gauze pads and Empore filters were compared for their ability to assess the dermal exposure of two insecticides (chlorpyrifos and diazinon) and five herbicides (atrazine, alachlor, metolachlor, cyanazine, and 2,4-D ethylhexyl ester). The analytes, when analyzed by gas chromatography with flame ionization detection, were found to have a linear dynamic range to at least 250 micrograms/mL. While a number of different solvents were examined for the desorption of the analytes, methanol was found to be the best solvent for the recovery of all the analytes from 16-ply gauze pads, while 20 percent ethyl acetate in hexane was the preferred solvent for the styrene divinylbenzene-impregnated Empore filters. Limits of detection (LODs) for the analytes were comparable for both media. For Empore filters, the LODs were 50 micrograms/sample for atrazine, alachlor, chlorpyrifos, diazinon, and 2,4-D ethylhexy ester, with 30 micrograms/sample for metolachlor, and 80 micrograms/sample for cyanazine. For gauze pads, the LODs were 40 micrograms/sample for metolachlor, 50 micrograms/sample for alachlor, diazinon, and 2,4-D ethylhexy ester, 60 micrograms/sample for atrazine and chlorpyrifos, and 80 micrograms/sample for cyanazine. Both gauze pads and Empore filters gave quantitative recovery for all analytes except chlorpyrifos and 2,4-D ethylhexyl ester under ambient conditions (18 degrees C, 70% relative humidity) for up to 30 days; these analytes required refrigeration for that period to reach over 90 percent recovery. To assess the effect of environmental conditions on the recovery of the analytes, samples of each media were spiked at about 125 micrograms per analyte/sample (except cyanazine which was spiked at 190 micrograms) and challenged for 8 hr under high (80%) and low (20%) humidity and high (40 degrees C) and low (5 degrees C) temperature conditions in an environmental chamber. While the Empore samples gave quantitative recovery after being challenged, recovery from the gauze pads was affected by environmental conditions, especially high temperature. Recovery from gauze pads was below 30 percent for some analytes under high temperature/high humidity conditions.
authors.affiliation: Division of Physical Sciences and Engineering, National Institute for Occupational Safety and Health, Cincinnati, Ohio, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Lorberau
authors.forename: J L
authors.initials: JL
authors.lastname: Pride
mesh_terms: D000279:Administration, Cutaneous; D004390:Chlorpyrifos / Q000032:analysis*; D003976:Diazinon / Q000032:analysis*; D005374:Filtration; D006801:Humans; D006813:Humidity; D007306:Insecticides / Q000032:analysis*; D016273:Occupational Exposure / Q000032:analysis*; D012680:Sensitivity and Specificity; D012997:Solvents; D013048:Specimen Handling; D013696:Temperature
chemical_list: D007306:Insecticides; D012997:Solvents; D004390:Chlorpyrifos; D003976:Diazinon