Dermal exposure whole body

Both inner and outer whole-body dosimeters are common tools to measure successfully dermal exposure to pesticide workers and are employed in a variety of ways in mixer-loader/applicator or re-entry studies. 

In order to determine the dermal exposure of volunteers to chlorpyrifos, the penetration of chlorpyrifos through the outer whole-body dosimeter (coveralls) to the inner body dosimeter (t-shirt and briefs) was measured. The penetration factor was calculated for each volunteer in the study from the experimental data by dividing the amount of chlorpyrifos on the t-shirt and brief sample by the amount of chlorpyrifos on the torso section of the coveralls. This method of calculation assumes that the surface area of the torso section of the coveralls is nearly the same as the surface area of the t-shirt and briefs worn directly under the torso section of the coveralls. A mean penetration factor for each worker type was calculated by averaging all the worker volunteer... 

Table 4 summarizes the results of using physical techniques to estimate total chlorpyrifos doses of adults following activity on treated grass. Total doses ranged from 3.03 pg/kg to 5.04 pg/kg (mean, 3.88 pg/kg). Approximately 85% of the chlorpyrifos dose came from the whole body dermal route. About 15% came from the inhalation route. Hand exposure was insignificant. 

In order to evaluate "within-worker" variances of dermal exposure and its distribution over the body, whole-body monitoring during three applications and concomitant re-entry was performed for high-volume (HV) applicators (n = 4) and harvesters of carnations (n = 6). 

Dermal exposure assessment Whole-body monitoring... 

Studies in indoor environments of dermal contact transfer required an estimate, and a tight-fitting whole-body dosimeter was adopted and initially considered as a surrogate for skin (Krieger et al., 2000). Contact with treated surfaces was limited to feet, hands, limbs, and torso. Standardized Jazzercize to represent daily human activities and maximum contact was incorporated into protocols for indoor exposure studies (Ross et al., 1990,1991). Comparative studies will be reported elsewhere (Krieger et al., 2000). 

This study was conducted to evaluate and compare ADD determined using whole-body dosimetry with results of two situational exposure studies conducted following use of a flea fogger under natural conditions. Chlorpy-rifos was selected due to its general availability as a fogger for indoor flea control. Chlorpyrifos is poorly absorbed by the dermal route and readily cleared from the body in urine (Nolan et al., 1984). Trichloropyridinol was measured in 24-hr urine specimens of the volunteers and was converted to chlorpyrifos equivalents as a measure of absorbed dose. The study provided an opportunity to determine the relationship between intensive, high-contact dosimetry studies and the amounts of chlorpyrifos absorbed by two sets of adults who re-entered fogger-treated homes. 

Krieger, R.I., Bernard, C.E., Dinoff, T.M., Fell, L., Osimitz, T. G., Ross, J.I., and Thongsinthusak, T. (2000) Biomonitoring and whole body cotton dosimetry to estimate potential human dermal exposure to semivolatile chemicals, /. Exposure Anal. Environ. Epidemiol., 10 50-57. 

In the early 1980s, the whole-body dosimeter (WBD) was introduced as a superior method for passive dermal dosimetry monitoring. A standard protocol was described by the World Health Organization (1982), and Abbott et al. (1987) described some additional options. Chester (1993) reported refinements that permitted exposure estimation by passive dermal dosimetry and biological monitoring simultaneously. 

Finally, comparisons of various techniques for animal exposures indicate that the whole-body exposure technique is the most suitable for safety assessment of gases and vapors and permits simultaneous exposure of a large number of animals to the same concentration of a chug however, this technique is not suitable for aerosol and powder exposures because the exposure condition represents the resultant effects from inhalation, ingestion, and dermal absorption of the drug (Phalen, 1984 Gad and Chengelis, 1998). 

Blood concentrations of 1,1,1-trichloroethane in humans following dermal exposure are dependent on the duration of exposure. A two-hour exposure once a day resulted in higher blood levels than one-hour exposures twice a day (Fukabori et al., 1977). At the end of a whole-body dermal exposure to 600 ppm [3280 mg/m ] 1,1,1-trichloroethane vapour for 3.5 hours, the blood concentration of 1,1,1-trichloroethane reached a maximum of approximately 0.09 mg/L (Riihimaki Pfaffli, 1978). This level quickly dropped after exposure ceased. In comparison, the steady-state blood concentration of 1,1,1-trichloro-ethane during inhalation exposure to 325 ppm [1770 mg/m ] for four hours was approximately 4 mg/L (Astrand et al., 1973) and during exposure to 350 ppm [1910 mg/m ] for six hours was approximately 2 mg/L (Nolan et al., 1984). 

Some studies indicate that ammonia can increase susceptibility to pathogens (Anderson et al. 1964 Broderson et al. 1976 Schoeb et al. 1982 Targowski et al. 1984) and could affect behavior (Tepper et al. 1985). There are no animal toxicity studies specifically on dermal exposure to ammonia gas, but most of the inhalation studies outlined in Table 2-8 involved whole body exposures. Those studies report bums and irritation of the skin, eyes, and mucous membranes of the upper respiratory system. In general, the severity of the damage is related to the concentration and duration of exposure. 

There are no animal toxicity studies specifically on dermal exposure to chlorine gas, but most of the inhalation studies involved whole-body exposures. Those studies reported irritation of the mucous membranes of the respiratory tract and the eyes. 

First, as made evident in the earlier discussion of personal monitoring methods, an accurate assessment of dermal contact exposure is technically challenging. Even whole-body garments worn close to the skin do not provide a complete assessment, as they miss such crucial areas as the neck, face, head and hands. 

For several subsets, measurements of the potential exposure for only specific body parts were also taken into account. For dermal exposure, a further study was made into the observed average distribution of the contamination over the body. This distribution was calculated for each relevant body part per subset and rounded to whole figures (EUROPOEM, 1996). These data may provide an appropriate basis for selection of protective clothing and gloves. 

The acute inhalation LC50 for the rat is greater than 5500mgm (4h whole body exposure). The acute oral LD50 in the rat is greater than 5000 mg kg and the acute dermal LD50 in the rabbit is greater than 3000 mg kg All three of these acute values indicate that the overall toxicity to laboratory animals is relatively low. 

There is extensive dermal and oral exposure in animals exposed whole body (particularly oral exposure in rodents and rabbits which carefully preen themselves after an exposure). For gases and vapors, of course, such considerations have minimal impact. The advantages and disadvantages associated with each of these exposure patterns are summarized in Table 1. 

Absorption, Distribution, Metabolism, and Excretion. There are no quantitative data available on the rates and extent of absorption, distribution, metabolism, or excretion of gasoline in humans or animals following inhalation, oral, or dermal exposure. Although data are available on these parameters for many of the individual components of gasoline (i.e., benzene, toluene, xylene) that may be used to predict the toxicokinetics of gasoline, it is possible that interactions between these components may influence the toxicokinetics of the mixture as a whole. Quantitative data on the toxicokinetics of gasoline following inhalation, oral, and dermal exposure would be useful to predict the behavior of this mixture in the body. 

Information regarding absorption of PCBs in animals following inhalation exposure is limited. Male rats were exposed (whole body) to an aerosol of a PCB mixture, Pydraul A200 (42% chlorine), at a concentration of 30 g/m (0.5-3 pm particle diameter) for 2 hours (Benthe et al. 1972). After a 15-minute exposure, the PCB concentration in the liver was 40 pg/g tissue, and reached a maximum of 70 pg/g after 2 hours of exposure. These results provide qualitative information regarding absorption of this specific PCB mixture, but the data were not sufficient for estimating the amount or rate of absorption. It must be also mentioned that since exposure was not nose-only, the dermal route may have contributed to absorption. 

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