Surface exposure, body, related

In oysters, for example, BCF values varied from 3450 to 6600 after exposure to solutions containing 1.0-3.3 p,g Pb +/L for 140 days, but oysters and their progeny were apparently unaffected at whole body burdens (less sheU) up to 11.4 mg Pb/kg DW. Many species of aquatic biota contain lead in amounts >1000.0 mg/kg FW (>10,000.0 mg/kg DW) including some marine seaweeds, freshwater macroph5 s and algae, annehds, crastaceans, echinoderms, mollusks, and teleosts presumably, the lead was sorbed passively and little, if any, was incorporated biologically. Variations in lead concentrations in aquatic biota probably reflect the ability of individual species to adsorb waterborne lead, and may be a direct function of the ratio of surface to body weight. The residence time of lead in aquatic biota seems to be related to the route of administration Tbl/2 values were 9 days by waterborne routes and 40 days by diet. 

Dermal (skin) contact with sulfur mustard agents causes erythema and lesions (blistering), while contact with vapor may result in first and second degree burns contact with liquid typically produces second and third degree chemical burns. Any burn area covering 25 percent or more of the body surface area may be fatal. Respiratory contact is a dose-related factor in the sense that inflammatory reactions in the upper and lower airway begin to develop several hours after exposure and progress over several days. 

The National Research Council (NRC) published a report, Science and Judgment in Risk Assessment, that critiqued the current approaches to characterizing human cancer risks from exposure to chemicals. One issue raised in the report relates to the use of default options for assessing of cancer risks. These general guidelines can be used for risk assessment when specific information about a chemical is absent. Research on 1,3-butadiene indicates that two default options may no longer be tenable Humans are as sensitive as the most sensitive animal species and the rate of metabolism is a function of body surface area rather than inherent species differences in metabolic capacity. 

The use of fluorescent compounds can be coupled with video-imaging analysis to produce exposure estimates over virtually the entire body (Fenske and Bim-baum, 1997). This approach requires pre- and post-exposure images of skin surfaces under long-wavelength ultraviolet illumination, development of a standard curve relating dermal fluorescence to skin-deposited tracer, and chemical residue sampling to quantify the relationship between the tracer and the chemical substance of interest as they are deposited on the skin. 

In 1990, urine samples from an accidental laboratory exposure to sulfur mustard were obtained (Jakubowski et al., 2000). The erythematous and vesication areas of the individual were estimated to be less than 5% and 1%, respectively, of the total body surface area. The assay measured both free and conjugated TDG using GC-MS (Jakubowski et al., 1990). The maximum TDG urinary excretion rate was 20 (pg/day on day 3. TDG concentrations of 10 ng/mL or greater were observed in some samples for up to a week after the exposure. A first-order elimination was calculated from days 4 through 10 and found to be 1.2 days. A great deal of intraday variability was noted for the TDG urine concentrations. Attempts were made to estimate the total amount of sulfur mustard on the skin of the patient. The estimate was based on two assumptions (1) that the assay for the free and conjugated TDG represents approximately 5% of the total amount of sulfur mustard related products in the blood, and (2) that the bioavailability factor from skin to blood is 10. A total of 0.243 mg of TDG was recovered over a 2 week period. This would represent 4.86 mg in the blood or 48.6 mg on the skin. 

Several case reports described exposure of individuals to ammonia liquid and/or gas that resulted in cutaneous bums (Amshel et al. 2000 da Fonseca et al. 1998 George et al. 2000 Kerstein et al. 2001 Latenser and Lucktong 2000 Leduc et al. 1992 Rosenbaum et al. 1998 Weiser and Mackenroth 1989). All exposures were occupationally related. Total body surface area burned ranged from 14 to 45% and most had at least small areas of fiill-thickness bums that required skin grafting. A summary of 12 case reports of liquid anhydrous ammonia injuries reported a range of percent body surface area burned of... 

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