Exposure pads

Analytical Procedures. The extracts from exposure pads, hand rinses, and apple leaves were evaporated to dryness in the 40-45°C water bath, and the carbaryl residues were determined by the procedure of Maitlen and McDonough (4). In this procedure, the residues were hydrolyzed with methanolic potassium hydroxide to 1-naphthol which was then converted to the mesylate derivative by reaction with methanesulfonyl chloride. The carbaryl mesylate was quantitated with a Hewlett Packard Model 5840A gas chromatograph (GLC) equipped with a flame photometric detector operated in the sulfur mode. The GLC column was a 122 cm x 4.0 mm I.D. glass column packed with Chromosorb G (HP) coated with 5% OV 101. The column was operated at a temperature of 205°C with a nitrogen flow rate of 60 ml/min. 

The total hourly dermal exposures (HDE) were calculated from the residues on exposure pads by the equation of Durham and Wolfe (3) as follows ... 

None detected (ND) limit of detection was 0.07 pg/cm2 on exposure pads and 4.0 pg/hand rinse thus the HDE limit of detection varied with exposure time. 

Table 1.2 Surface areas for regions of the adult body and locations of dermal exposure pads that represent these regions (USEPA, 1987)...

Sell, C.R. and J.C. Maitlen (1983). Procedure for the determination of (2,4-dichlorophenoxy)acetic acid in dermal exposure pads, hand rinses, urine and perspiration from agricultural workers exposed to the herbicide, 7. Agric. Food Chem., 31, 572-575. 

Dermal exposure pads have been constructed of a—cellulose, cloth, polyurethane foam, and combinations of these materials. They are generally designed to collect spray materials and have been used for emulslflable concentrates and wettable powders mixed with water. 

The exposure pad method, combined with measurement of urinary metabolites, has been used to compare worker exposure for different pesticide application methods (33, 34) as well as to monitor formulating plant worker exposure (35) and homeowner exposure (36). 

The exposure pads were removed from the garments and the pads, gloves and urine samples were immediately frozen and shipped with dry ice, by air, to the Pesticide Research Laboratory, Pennsylvania State University. Samples were stored at -20 C until analysis. Samples of the mancozeb formulation used in each test were also sent to the analytical laboratory. 

Applicators and residents of dichlorvos (DDVP) treated structures were monitored for evidence of insecticide exposure using exposure pads, air samplers, serum and red blood cell acetylcholinesterase (AChE) tests, and urine analysis. There was no evidence of DDVP or dichloroacetic acid (DCAA) in the urine of applicators or cooperators. There were slight but significant differences (Pi0.05) in serum AChE activity of residents of treated units, but erythrocyte AChE was unchanged. Applicator AChE test results were inconclusive. It was concluded that there was not a significant risk. In terms of acute toxicity, to either the pesticide applicators or the residents of treated structures. 

Twenty residential structures were treated with dichlorvos insecticide (DDVP) for (Serman cockroach control. Dermal exposure pads, air samplers, blood tests for sensn and erythrocyte acetyl-ciiolinesterase (oizyme) activity and urine analyses were used to monitor both c licators and residents for evidence of 9qx>sure to EDVP. 

Storage tanks, lines, and pumps should be heat traced and insulated to enable product handling. Temperature control is required to prevent product degradation because of color alkan olamines have poor heat transfer properties. Exposure to air will also cause product discoloration. Storage tanks should be nitrogen-padded if low color product is required. 

Free formaldehyde is a mixture of formaldehyde, formaldehyde hydrates, and low molecular oligomers. It imparts a characteristic odor to padding bath or padded fabrics (76,77). CeUulosics fabrics are capable of retaining large quantities of free formaldehyde, which are gradually evolved. Because all finishes degrade to some extent, extractable formaldehyde and releasable formaldehyde must be considered with respect to user exposure. 

Exposure monitoring had not been eondueted at Site A. The deeision not to eonduet monitoring was appropriately doeumented in the site safety plan and was based on the nature of the eontami-nated material. The sediments were always saturated, and the likelihood of airborne eoneentrations of PCBs was extremely low. Area samples had been eolleeted at the waste pad where the material was air-dried prior to shipping. Sample results were below the deteetable limits. 

Radiation exposure can be reduced by placing the radiation source or the potential target behind a shield that captures the radiation. During exposure to X rays for dental imaging, the patient wears a lead-lined pad, because X rays are absorbed more effectively by lead than by any other material. A lead shield a few millimeters thick is sufficient to stop X rays. 

Among the first dermal dosimeters used in exposure research were 4 x 4-in cellulose or gauze patches which were pinned to the outer and inner surfaces of clothing or vests which farm workers would wear during the application or re-entry phase of the smdy. These patches were easy to manufacture and when pinned to the shirt or pants of the worker made for an easily used dosimeter pad. The major advantage to the use of the patch to estimate worker exposure was this method s ability to differentiate the relative contributions of pesticide residues to different parts of the worker s body. This sampling technique in turn could lead to recommendations (i.e., the use of... 

The first pesticide exposure study was reported by Griffiths et al. (1951). Parathion was trapped on respirator filter discs during application to citrus trees. Batchelor and Walker (1954) expanded exposure monitoring to include the estimation of potential dermal exposure using pads attached to workers clothing. Durham and Wolfe (1962), in their classic review of worker exposure methodologies, also provided some experimental validation for the best available methods. 

The most popular and efficient are substantive to the fibre typical examples are N,N -diphenylacetamidine (10.179), which tends to yellow on exposure to oxides of nitrogen, and particularly the diphenylated diamines such as N.N -diphenylethylenediamine (10.180), which does not yellow. Non-substantive inhibitors applied by padding and drying, such as triethanolamine (10.126) and melamine (10.181), have also been used despite the fact that they are removed on washing. The demand for and commercial availability of gas-fume inhibitors have declined. 

Although the single-layer negative resists commonly utilized are simple, they typically do not resolve narrow (0.5 ftm) gaps between wide lines or pads due to proximity effects from backscatter from the substrate during electron beam (E-beam) exposure. Further, there are variations in linewidth which occur when images are written in a single-layer resist which overlies steps in the substrate. 

Infants are able to acquire odor preferences on the first day of life. In one experiment, 12 male and 12 female white, healthy, full-term neonates were exposed to the odors of cherry or ginger on a pad taped to the inside of their crib for 24 hours. After this exposure, they were tested for preferences during active sleep (stage II). The behavior was videotaped and the duration of time oriented to each odor measured. Only the female neonates showed a preference for the familiar odor (Balogh and Porter, 1986). Therefore, even on the first day of life, females outperform males, as often described for children and adults (e.g. Yousem etal, 1999). 

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