Is Lead Dust Within Nuclear Medicine Departments a Hazard to Pediatric Patients?

MATERIALS AND METHODS

We identified 15 areas within the nuclear medicine department of a children's hospital (Fig. 1) that varied in location and type of surface. These areas were outlined into 1 by 1 ft (1 ft = 0.3048 m) sections with masking tape. HomeSafe Environmental Inc. supplied the materials needed for the lead test kits that were used to obtain the lead dust samples. Guidance on obtaining the samples was also provided and was based on the current industry standard practices and reflected procedures used by certified lead inspectors and risk assessors.

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FIGURE 1. 

Outline of nuclear medicine department of pediatric hospital and areas where wipe samples were obtained.

Once the dust wipes had been opened and the caps of the test tubes removed, disposable gloves were put on. The dust wipe was placed and secured on the palm of the hand with the thumb and little finger. Designated areas to be sampled were wiped from side to side using an S-shaped motion, without touching any region outside the selected area. The dust wipe was then folded in half, placing the dirty sides together. Again, the same area was wiped but this time from top to bottom using the same S-shaped motion. Once again, the dirty sides of the wipe were folded together; the wipe was now roughly a quarter of the original size and was used a third and final time to wipe the area from side to side. The wipe was placed into the properly labeled test tube and the cap was sealed. The disposable gloves were removed and placed into a plastic trash bag. Within the taped sample area, measurements were taken and recorded to the nearest eighth of an inch (to confirm a 1 by 1 ft section). All 15 areas were individually wiped using this method. The procedure was repeated weekly for 3 additional weeks using the same method, number of wipes, and locations within the department. Thus, 60 samples were obtained (4 from each site). To evaluate the removal of lead dust from radiation-shielding surfaces, wipe samples were also obtained from the lead bricks. The lead bricks were not cleaned or manipulated in any way before the wipe samples were collected.

The lead dust wipes were sent to the Environmental Hazard Services Laboratory in Richmond, Virginia, for a complete lead analysis. The results were recorded in μg/ft². Lead contamination for each of the 60 samples was calculated and compared with the Environmental Protection Agency (EPA) lead dust standard (50 μg/ft²). Anything over the EPA standard was considered significant.

RESULTS

The results are shown in Table 1. Lead contamination was present at 6 of the 15 sites sampled, and of the 60 samples taken, 18 exceeded the EPA standard of 50 μg/ft². The samples from location 1 were obtained directly from the lead bricks. These numbers, all of which exceeded the EPA standard, show the amount of lead dust that is readily removed from the surfaces of the lead bricks. Samples obtained from locations 2, 7, and 13 were also much higher than the EPA standard. These areas all contained lead bricks near the sampled area.

DISCUSSION

The U.S. EPA has established maximum allowable levels for lead contamination, which most states adopt as enforceable standards. Among these standards, lead dust is considered a hazard when equal to or exceeding 50 μg/ft² on uncarpeted floors (4). The results of this study confirm that dangerous levels of lead contamination may be present within nuclear medicine departments. Given that lead is an important shielding material for γ- and x-rays, it is generally not feasible to eliminate or substitute it. Therefore, other means must be used to minimize health hazards from dispersible lead (2). Most lead contamination found within the patient areas was around areas that contained lead shielding. This finding suggests that different measures within the department should be taken to minimize the amount of contamination. After injecting a pediatric patient, nuclear medicine technologists use lead shielding as an immobilization device during the imaging. This reduces the amount of patient motion and allows the needle to remain in place so another injection will not be needed later within the study. Although this is a great way to use resources within the department, other methods, such as a sandbag, might be acceptable. Another alternative would be encasing the lead shielding with a material such as vinyl, plastisol, polyurethane, or epoxy, which would decrease the amount of lead contamination. Previous studies have shown that a single coat of polyurethane drastically reduces the amount of lead contamination from the surfaces of radiation shielding (2), yet some manufacturers of radiation shielding available for medical use do not encapsulate their shielding equipment (5). Researchers have also concluded that frequent floor and surface cleanings would help prevent lead levels from exceeding EPA limits (2).

CONCLUSION

At this pediatric clinical site, lead contamination exceeded EPA standards in some areas. By recreating this experiment, nuclear medicine technologists can determine whether the lead contamination within their department is at a level that would be considered hazardous to their pediatric patients.