Aerosol production during autopsies: The risk of sawing in bone

Abstract

When sawing during autopsies on human remains, fine dust is produced, which consists of particles of sizes that may fall within the human respirable range, and can act as vectors for pathogens. The goal of this study was to explore the potential effects of saw blade frequency and saw blade contact load on the number and size of airborne bone particles produced. The methodology involved the use of an oscillating saw with variable saw blade frequencies and different saw blade contact loads on dry human femora. Released airborne particles were counted per diameter by a particle counter inside a closed and controlled environment. Results corroborated with the hypotheses: higher frequencies or lower contact loads resulted in higher numbers of aerosol particles produced. However, it was found that even in the best-case scenario tested on dry bone, the number of aerosol particles produced was still high enough to provide a potential health risk to the forensic practitioners. Protective breathing gear such as respirators and biosafety protocols are recommended to be put into practice to protect forensic practitioners from acquiring pathologies, or from other biological hazards when performing autopsies.

Keywords: Aerosol; Autopsy; Biosafety; Bone dust; Oscillating saw; Pathology.

Fig. 1

Experimental setup used to cut the bone, the setup consisted of: an oscillating saw (a) fastened to a vertical sliding platform (b) guided by 3 stainless steel rods and brass sliding bearings (c). The bone specimen (d) was clamped in a v-groove holder (e), that was connected to an aluminium base plate (f). Interchangeable weights could be attached to the platform (g). The sawing action is further illustrated in Fig. 2.

Fig. 2

Close-up of the saw blade and bone specimen, the setup consisted of: the bone specimen (d) was clamped in place by the v-groove holder (e). The saw blade (h) cut in the bone until the stopper (i) reached the bone for a consistent depth of cut. The Hall-effect sensor (j) acted as a tachometer, and was clamped to the saw with an aluminium block (k).

Fig. 3

Front view of the setup enclosed in the box; an acrylic glass box (l) was used to create an experimental space isolated from the environment. The Fluke 985 particle counter (m) was placed on top of the box with a foam cast, with the nozzle inserted into the box through a hole on top of the box (n). A closable hole with a socketed cap was used for handling the saw during operations inside the box (o).

Fig. 4

Top view of one of the femora that was used in the experiment. The notations of the randomised experimental condition numbers (EC 1 to EC 9) are shown as used during the experiments, divided in 5 blocks. The EC notation was changed to a matrix notation after the experiments for reasons of visibility: EC 1 is changed to 1.1, EC 9 to 3.3, and corresponds to the EC matrix shown in Table 2.

Fig. 5

Stacked bar graphs of the number of aerosol particles produced per experimental condition (marked columns) during the total of n = 10 measurements (coloured layers) for each particle size (0.3 μm top left to 10 μm bottom right). Each layer corresponds with one block of ECs, the bottom layers were from Block A.1, the top layers Block B.5. Note that for reasons of visibility, the vertical axes are scaled differently for each particle size. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 6

Stacked bar graph of the total number of aerosol particles produced per experimental condition (marked columns) during the total of n = 10 measurements (coloured layers). Each layer corresponds with one block of ECs, the bottom layers were from Block A.1, the top layers Block B.5. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 7

Stacked bar graph of the total surface area of the aerosol particles produced per experimental condition (marked columns) during the total of n = 10 measurements (coloured layers). Each layer corresponds with one block of ECs, the bottom layers were from Block A.1, the top layers Block B.5. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 8

Stacked bar graph of the cumulative sawing time over 10 repetitions (coloured layers) per experimental condition (marked columns). Each layer corresponds with one block of ECs, the bottom layers were from Block A.1, the top layers Block B.5. Note that for reasons of visibility, in this plot the ECs are arranged in a different order than in the rest of the figures. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 9

Saw blade frequency during sawing measured by the tachometer displayed over time, averaged over 10 EC repetitions. The error bars show the standard deviations.