Surface residues, indoor

The many uses of an indoor pesticide require fhaf exposure estimates should be based on fhe mosf likely application dial will lead fo fhe highesf probabilify of dermal and inhalation confacf. For insfance, a broadcasf carpel Ireatmenl is generally presumed fo resull in more pesticide surface residue being accessible to individuals fhan fhe amounf or accessibility of residue when the pesticide is placed inside an insect bait station. 

Ross, J., Thongsinthusak, T., Fong, H.R., Margetich, S., and Krieger, R. (1990) Measuring potential dermal transfer of surface pesticide residue generated from indoor fogger use an interim report, Chemosphere, 20 349-360. 

A United States study examined the aggregate exposures of preschool children to chlorpyrifos and its degradation product, 3,5,6-trichloro-2-pyridinol (TCP) (Morgan et al., 2005). Samples that were collected included duplicate diet, indoor and outdoor air, urine, solid and liquid food, indoor floor dust, play area soil, transferable residues, and surface wipes (hand, food preparation, and hard floor). Generally, levels of chlorpyrifos were higher than levels of TCP in all media, except for solid food samples. For these samples, the median TCP concentrations were 12 and 29 times higher than the chlorpyrifos concentrations at homes and day-care centres,... 

Pesticides may be periodically inttoduced into indoor air by direct application (e.g. insect sprays and bombs, disinfectant sprays and room deodorizers). In addition, there are often sources that continually emit vapors into the living space (e.g. continuous evaporation of residues from crack and crevice treatments and emissions from pest-control strips or other devices). Whether used inside the home or office, or outside on the lawn or garden, pesticides accumulate on indoor surfaces, especially in carpet dust, and also in upholstery and in or on children s toys (Lewis et al 1994b, 1999 Simcox et al., 1995 Nishioka et al 1996, 1999 Gurunathan et al., 1998). 

If wet wipes are used, care must be exercised to avoid damaging the surfaces being monitored. Solvents other than water may remove substances (e.g. furniture and floor waxes) from the surface that can cause analytical interferences. In addition, if the solvent is capable of extracting the pesticide residue from beneath the surface being wiped, the residue recovered may overestimate the amount of dislodgeable residue. Special care should be taken when using flanunable solvents indoors. Toxic solvents should never be used in occupied buildings. While 2-propanol and ethanol are relatively safe for use in occupied indoor... 

Somewhat water-soluble pesticides such as acid herbicides will be washed from foliar surfaces and into subsurface soils by rainfall. For example, dislodge-able turf residues of 2,4-D after a 2.54-cm rainfall have been reported to be only 1-5% of those found at 4-8 h after application (Nishioka et al., 1996 USEPA, 1997c). However, dew or rain on aged turf residues may increase their dislodgeability (Nishioka et al, 1996). OP insecticides are semivolatile and will vaporize from surfaces after applications. Chlorpyrifos vaporizes rapidly from lawns if applied in aqueous formulations. Diazinon, which is used on lawns as well as indoors, dissipates even more rapidly. However, the persistence of OP... 

Indoor surface dislodgeable (or transferable) residue dissipation study... 

Indoor exposure assessments can be more complex than outdoor assessments. The indoor assessments are often complicated by the fact that pesticide application methods and their placement within the indoor environments are very diverse and include, for example, crack and crevice treatment, carpet treatment, room loggers, moth repellents, residual termiticides, disinfectants and pet products. This diversity also means that potential human contact with the residues may range from a low probability (crack and crevice treatment) to a higher probability (indoor broadcast treatment such as an indoor total release logger) because of the nature of the application and the variability in activities that may bring individuals in contact with treated areas. Furthermore, the varied characteristics of the source (e.g. formulation type, application methods, room of application and duration of emission) and the indoor residential environment (e.g. room size, air exchange rates, temperature and types of surfaces, such as carpet, upholstery, vinyl, etc.) significantly influence exposure pofenfial. 

This study provides a means for conservatively estimating potential post-application dermal exposures to treated surfaces following the use of indoor total release foggers by using a high-contact, but reproducible activity. The procedure for estimating potential dermal exposure is based on the use of transfer factors (TFs) derived from the human volunteer dermal dosimetry and treated carpet transferable-residue measurements based on an indoor roller method (Ross et al, 1990, 1991). 

Ross, J.H., T. Thongsinthusak, H.R. Fong, S. Margetich and R. Krieger (1990). Measuring Potential Dermal Transfer of Surface Pesticide Residue Generated from Indoor Fogger Use An Interim Report, Chemosphere, 20, 349-360. 

Pesticides may be tracked into the indoor environment after a certain outdoor apphcation [18, 19] or through transport from the workplace to the home (para-occupational or take-home exposure). Collection of floor dust both prior to and after lawn-apphed 2,4-dichlorophenoxyacetic acid (2,4-D), indicated that turf residues are transported indoors [20]. Carpet dust levels of 2,4-D and dicamba and carpet surface dislodgeable residue levels were highly correlated with turf dislodgeable residue levels [21]. 

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