Field measurement of dermal soil loadings in occupational and recreational activities

Risks associated with dermal exposure to contaminated soil are not well-characterized, but nevertheless must be estimated to define endpoints for remedial strategies. Among the parameters contributing to the uncertainty of these estimates is soil adherence to skin. Pre- and postactivity soil loadings have been obtained from hands, forearms, lower legs, faces, and/or feet of volunteers engaged in various occupational and recreational activities. These data are distinguished from other sources of estimates of soil adherence by the manner of their collection. Soil loads were obtained directly from multiple body parts before and after uncontrived exposure scenarios. Data presented for the first time here supplement prior results and roughly double the available data base. This expanded data base provides a useful perspective on types of behavior likely to lead to soil contact falling within general classes of activity (e.g., background, low, moderate, or high contact). Prior conclusions supported by the additional data include the following: (1) post-activity loadings are typically higher than preactivity levels, demonstrating that exposure is episodic; (2) hand loadings are dependent upon class of activity; (3) hand loadings generally provide conservative estimates of loadings on nonhand body parts within activity classes; and (4) hand loadings do not provide conservative estimates of nonhand loadings across activity classes. Finally quantitative estimates of relative loads on unclothed nonhand body parts are presented.

Field measurement of dermal soil loading attributable to various activities: implications for exposure assessment

Estimates of soil adherence to skin are required for assessment of dermal exposures to contaminants in soils. Previously available estimates depend heavily on indirect measurements and/or artificial activities and reflect sampling of hands only. Results are presented here from direct measurement of soil loading on skin surfaces of volunteers before and after normal occupational and recreational activities that might reasonably be expected to lead to soil contact. Skin surfaces assayed included hands, forearms, lower legs, faces and/or feet. Observed hand loadings vary over five orders of magnitude (roughly from 10(-3) to 10(2) mg/cm2) and are dependent upon type of activity. Hand loadings within the current default range of 0.2 to 1.0 mg/cm2 were produced by activities providing opportunity for relatively vigorous soil contact (rugby, farming). Loadings less than 0.2 mg/cm2 were found on hands following activities presenting less opportunity for direct soil contact (soccer, professional grounds maintenance) and on other body parts under many conditions. The default range does not, however, represent a worst case. Children playing in mud on the shore of a lake generated geometric mean loadings well in excess of 1 mg/cm2 on hands, arms, legs, and feet. Post-activity average loadings on hands were typically higher than average loadings on other body parts resulting from the same activity. Hand data from limited activities cannot, however, be used to conservatively predict loadings that might occur on other body surfaces without regard to activity since non-hand loadings attributable to higher contact activities exceeded hand loadings resulting from lower contact activities. Differences between pre- and post-activity loadings also demonstrate that dermal contact with soil is episodic. Typical background (pre-activity) geometric mean loadings appear to be on the order of 10(-2) mg/cm2 or less. Because exposures are activity dependent, quantification of dermal exposure to soil will remain inadequate until data describing relevant human behavior (type of activity, frequency, duration including interval before bathing, clothing worn, etc.) are generated.

Imaging and treatment of B-cell lymphoma

Ten patients with non-Hodgkin's lymphoma have been evaluated as candidates for experimental radioimmunotherapy and five of those patients have been treated with a single high dose of iodine-131-(131I) labeled anti-pan B-cell antibodies. The evaluation protocol involved collecting biodistribution data by quantitation of gamma camera images and by tumor biopsy from trace labeled doses of antibody, to estimate the relative radiation dose delivered to normal organs and tumor sites. Each patient received up to three escalating mass doses (0.5 mg/kg, 2.5 mg/kg, and 10.0 mg/kg) of radioiodinated antibody for determination of the antibody amount that yielded the most favorable biodistribution for treatment. The millicuries of 131I-labeled to the optimal antibody dose for therapy was selected to deliver 1,000 rads (three patients) or 1,500 rads (two patients) to normal uninvolved organs. Because severe bone marrow toxicity was expected, all patients had their bone marrow cryopreserved prior to entry into the study. This report details the methods and results of quantitative imaging, biodistribution data collection, and absorbed radiation dose estimation in patients with lymphoma receiving high level radioimmunotherapy with 131I-labeled antibodies.

Improving the tumor retention of radioiodinated antibody: aryl carbohydrate adducts

Improved methods for attaching radioiodine to monoclonal antibodies have been developed. Ten aryl carbohydrate adducts were synthesized by the reductive amination of a carbohydrate with an aryl amine, using sodium cyanoborohydride as a reducing agent. After purification by chromatography and characterization by nuclear magnetic resonance they were iodinated using the chloramine-T method. Iodinated adducts were activated with cyanuric chloride and incubated with protein at room temperature. The immunoreactivity and avidity of radioiodinated tyramine cellobiose (TCB) labeled antibody were fully preserved when compared to electrophilically radioiodinated antibody. Radioiodinated TCB-and tyramine glucose-labeled monoclonal antibodies showed much greater intracellular retention of radioiodine when compared to electrophilically radioiodinated monoclonal antibodies. Neither radioiodinated tyramine nor radioiodinated TCB had any specific tissue uptake or retention. In mice the retention of radioiodinated TCB labeled anti-Thy-1.1 antibody (1A14) by Thy-1.1-bearing lymphoma cells was 2 times greater than that of chloramine-T labeled 1A14 antibody, whereas the plasma clearance curve and uptake in normal tissues was not changed. This method of radioiodinating monoclonal antibodies increases the retention time of radioiodine in tumor and thus may obviate the problem of intracellular deiodination, a perceived disadvantage of electrophilically iodinated antibodies, with respect to tumor retention of radioactivity.