‘Surface lead contamination on personal lead radiologic protective apparel’ is a recent report published by Kieran Murphy et al (Toronto Western Hospital, Toronto, Canada). The subject of the report is free lead dust on lead aprons: the study involved testing aprons at a Toronto university hospital, which yielded the finding that 60% of aprons and thyroid shields have free surface lead. Murphy et al draw on their results to make recommendations for addressing this professional occupational health issue. The contents of the report will be presented at the Society of Interventional Radiology (SIR) 2022 Annual Scientific Meeting (11–16 June, Boston, USA).
The purpose of the study, the authors outline in their abstract, was to evaluate the extent of surface lead dust contamination on lead radiation protection apparel (RPA) used in Toronto-based university teaching hospital radiology departments. They then compared these results with those from pre-existing reports that point towards lead RPA being a biohazard in and of itself, despite its crucial role in protecting radiologists and other technicians during diagnostic and interventional procedures.
Murphy et al state having surveyed a convenience sample of RPA, which was kept mounted on the wall outside the angiography and emergency departments. As part of the sampling, the team recorded the following information about each specimen: lead equivalency, manufacturer, quality of lead, year of purchase and product type (i.e. lead apron, thyroid collar, or garments combining the two). A combination of visual inspection, fluoroscopy and the use of LeadCheck rapid testing was used to assess both the condition of the RPA and the extent of surface lead contamination.
Of the 69 RPA items surveyed, one failed a radiological quality inspection check, and eight items were in poor condition—the majority of all garments were over five years old and made from a lead/tin-composite material that had a 0.5mm lead equivalency. The authors also break down the RPA items in the report by their type: lead aprons (n=11); lead aprons with thyroid collars (n=25); and separate thyroid collars (n=8). The key finding is as follows: “The overall prevalence of surface lead contamination on RPA surfaces based on LeadCheck sampling was 60.9% (95% confidence interval [CI]: 49.1%, 71.5%). Surface lead contamination was significantly (p=0.0035) higher on thyroid collars (78.8% [95% CI: 62.2%, 89.3%]) than on lead aprons (44.4% [95% CI: 29.5%, 60.4%]).”
Murphy et al then proceed to discuss the significance of their own clinical findings, drawing the conclusion that they support what previous studies conducted in the USA, Europe, Taiwan and Canada have shown: surface lead dust is “[highly prevalent]” in radiology departments. Two studies referenced in the authors’ report went as far as to look at the potential toxicity of lead dust exposure, sampling blood and hair. On the basis of the sum of these investigations (which found the presence of lead in the technologists’ hair, thus indicating ingestion risk), the authors make recommendations for improving conditions for the continued use of lead RPA, in order to reduce risk to personnel wearing the garments.
Firstly, the authors highlight that their recommendations are all the more necessary as there are no current regulations in place to mandate risk assessment for lead exposure from RPA in workplaces with radiation exposure. Moreover, Murphy et al underline that all the RPA they surveyed had passed radiologic quality control tests, but that this does not preclude the presence of surface lead dust. The conclusion from this is that “stringent protocols” must be formulated and followed in terms of cleaning RPA, as well as the shielding structures made of lead. In addition, the authors accentuate the importance of further studies into the toxicity impact of long-term lead exposure among personnel.
Alongside their recommendations, the authors draw attention to the limitations of their investigation, which evaluated “only a small sample of lead aprons and thyroid collars for surface lead dust contamination at a single institution.” They also point to the inexpensive LeadCheck test as yielding less reliable results than may have been achieved with other methods. Murphy et al add to the limitations the fact that the RPA they surveyed was made exclusively of a lead composite material; for this reason, they suggest that their results may not be wholly applicable to solid lead RPA. Lastly, they acknowledge that, when comparing their results with previous studies’, they may not have included all relevant literature, leading to potential omission of key findings which could have produced a different conclusion.
A final note from the authors in their report is that “there is no established safe level of lead” and, therefore, surface lead dust contamination should be continuously monitored where RPA and lead room shields are being used. Likewise, personnel and those responsible for workplace risk assessment should be aware of any defective equipment which may need to be taken out of use to reduce exposure to lead dust.