Interpretation of Enhanced Fecal and Urinary Plutonium Excretion Data under a 2-y Regular DTPA Treatment Started Months after Intake

Abstract

In a worker who had internalized plutonium, most likely through inhalation of a somewhat soluble compound, an extensive diethylenetriaminepentaacetate (DTPA) treatment regimen was initiated several months after contamination. Numerous radiotoxicological analyses were performed in both fecal and urinary specimens collected, sometimes for three consecutive days after DTPA administration. Activity measurements showed the continued effectiveness of DTPA intravenous infusions in removing plutonium from tissues of retention even if the treatment regimen started very belatedly after contamination. In the present case, the activity excreted through urine within the first 24-h after a DTPA infusion contributed only about half of that activity excreted within the first three days (i.e., the cumulative activity of the first three 24-h urine collections). In addition, the careful study of the data revealed that DTPA-induced excretion of plutonium via fecal pathway significantly contributed to the overall decorporation. The intracellular chelation of plutonium may be responsible for this enhanced excretion of activity in feces as well as for the delayed and sustained increased clearance of activity in urine. The authors would suggest that the occupational physicians offer to individuals who internalized moderately soluble or soluble plutonium compounds undergo a long-term DTPA treatment, especially when it is not initiated promptly after intake. Under this scenario, measurements of plutonium in successive urine and fecal collections after treatment should be required to get a better estimate of the therapeutic benefit. Also, intracellular chelation and fecal route should be taken into account for better interpretation of radiotoxicological data and modeling of plutonium kinetics under delayed DTPA treatment.

Excretion of Pu-238 during Long-term Chelation Therapy by Repeated DTPA Inhalation

“…Delayed DTPA inhalations resulted in similar features as with delayed DTPA infusions previously administered to the patient (Grémy et al 2021). These features are as follows: urinary excretion of 238 Pu was increased and remained more elevated than the baseline rate for at least 3 wk.…”

“…In view of the efficacy of first DTPA administrations in promoting Pu excretion, the treatment was continued. Thus, the worker received 40 intravenous infusions of DTPA spread over 707 d. More details about this first treatment period are available elsewhere (Grémy et al 2021). Afterward, the patient agreed to continue treatment using DTPA administered by inhalation from d 739 after the beginning of the chelation therapy.…”

“…Following the detection of a Pu incorporation in the context of routine annual medical follow-up, the employee started a chelation treatment several months after the presumed date of the intake. The employee received 40 intravenous infusions of DTPA over a 707-d period (data previously published in Grémy et al 2021) followed by 40 inhalations of DTPA over a 610-d period (data reported in the present study).…”

“…The full chelation therapy followed by the individual can be considered effective since it removed approximatively 25% of the estimated initial intake of 238 Pu, by urinary route (Table 4). The overall decorporation was undoubtedly greater since the DTPA-induced fecal excretion of 238 Pu has not been taken into account, although it could be important, at least with DTPA infusions as previously shown (Grémy et al 2021). Unfortunately, this clearance of 238 Pu through biliary route is too difficult to estimate.…”

“…Value from the 4th DTPA inhalation is not listed because there are serious doubts about the time of urine collection. 238 Pu in 24-h urine samples after 1-g DTPA infusion have been already published (Grémy et al 2021).…”