Aerosol Generation During Bone-Sawing Procedures in Veterinary Autopsies

At a Glance

Metadata	Details
Publication Date	2017-01-23
Journal	Veterinary Pathology
Authors	L. Wenner, Urs Pauli, Kathrin Summermatter, Hans Gantenbein, Beatriz Vidondo
Institutions	University of Bern, Federal Food Safety and Veterinary Office
Citations	29
Analysis	Full AI Review Included

Expert Analysis: Enhancing Biosafety in High-Risk Cutting Procedures using MPCVD Diamond

This technical documentation, generated by 6CCVD’s engineering team, analyzes the aerosol generation risks associated with bone-sawing procedures in veterinary and human pathology. The study strongly validates the use of diamond-coated cutting instruments as a critical step toward enhancing biosafety and reducing the spread of infectious aerosols. 6CCVD specializes in the material requirements necessary to manufacture superior, next-generation MPCVD diamond components essential for these safer cutting tools.

Executive Summary

Critical Biosafety Risk: Routine bone-sawing procedures generate vast amounts of respirable aerosols (particles < 5 µm), which pose a significant risk of transmitting zoonotic infectious agents (e.g., Mycobacterium tuberculosis) throughout autopsy facilities.
Aerosol Magnitude: The stationary bone band saw produced the highest aerosol concentrations, reaching up to 19.6 x 10⁶ particles/cfm (particles < 5 µm) at the operator position.
Diamond Superiority: The diamond-coated cut grinder demonstrated significantly safer operation, reducing the generation of highly respirable particles (0.3-0.5 µm) by approximately 80% compared to the standard band saw.
Operational Controls: Aerosol generation is dependent on the mechanical state of the tool; dull blades produced significantly more particles (P < .0000008), and continuous moistening reduced aerosols for all sizes 0.3 µm to 5 µm (P < .0004).
Engineering Solutions: Effective risk mitigation requires dedicated engineering controls, including separate, high-efficiency ventilation systems (e.g., sawing cabins operating at 30 air exchanges/hour) and high-performance Personal Protective Equipment (PAPRs).
Material Requirement: The adoption of safer procedures necessitates highly durable, customized diamond materials (PCD/SCD) for abrasive tools that maintain sharpness and structural integrity under prolonged, rigorous use.

Technical Specifications

The following hard data points were extracted from the research concerning aerosol generation and control methods:

Parameter	Value	Unit	Context
Highest Particle Concentration (< 5 µm)	19.57 x 10⁶	particles/cfm	Operator position using Bone Band Saw in sawing cabin
Lowest Particle Concentration (< 5 µm)	6.54 x 10³	particles/cfm	Operator position using Butcher Handsaw in autopsy hall
Critical Respirable Particle Size	0.3 - 5	µm	Aerosolized particles capable of reaching pulmonary alveoli
Diamond Grinder Efficacy (0.3-0.5 µm)	~80%	Reduction percentage	Relative reduction compared to Bone Band Saw
Aerosol Reduction by Moistening	Significant (P < .0004)	Statistical Significance	Reduction observed for all particle sizes 0.3 µm to 5 µm
Cabin Air Exchange Rate	~30	times/hour	Dedicated ventilation setup in the segregated sawing cabin
Aerosol Clearance Time (Cabin)	20	minutes	Time required to return to base particle levels after Band Saw use
PAPR Performance Factor (PF)	1.8 x 10⁵	Ratio	Concentration outside / inside Powered Air-Purifying Respirator

Key Methodologies

The study rigorously quantified aerosol production across various bone-sawing instruments under standardized, controlled conditions.

Instrument Testing: Five different cutting instruments were analyzed:
- Stationary Butcher Bone Band Saw
- Diamond-Coated Pathology Cut Grinder (D151, 0.3 mm blade)
- Oscillating Autopsy Saw (12,000-21,000 oscillation/min)
- Reciprocating Butcher Bone Saw
- Butcher Handsaw
Standardized Procedure: Sawing duration was fixed at 2 minutes, using standardized biological material (bovine humeri/femurs, pig spines, pig skulls) stored at 4 °C.
Environmental Control: Aerosol measurements were performed first in the main autopsy hall (10 air exchanges/hour) and then inside a custom, segregated sawing cabin with HEPA-filtered exhaust and a high air exchange rate (~30 times/hour).
Particle Measurement: A laser diode particle counter (CI-7300) combined with a 1:100 diluter (DIL-554) was used to measure particle counts (particles/cfm) across six size bins, ranging from 0.3 µm to >10 µm.
Variables Tested: The impact of blade sharpness (categorized as sharp, medium, or dull) and continuous tap water moistening on aerosol generation was statistically evaluated.
PPE Testing: The efficiency of a commercial Powered Air-Purifying Respirator (PAPR) was assessed using the TSI Portacount Pro+ Respirator Fit Tester, calculating the overall performance factor (PF).

6CCVD Solutions & Capabilities

The research validates that diamond abrasive tools are superior in mitigating aerosol risk compared to traditional blade saws. 6CCVD’s advanced MPCVD diamond materials are perfectly suited to supply the next generation of high-durability, low-aerosol cutting and grinding systems for biosafety-critical applications.

Applicable Materials

The study confirms that the diamond-coated cut grinder significantly minimizes the dangerous output of respirable particles. Replicating or extending this success requires highly stable, precision diamond material:

Engineering Grade Polycrystalline Diamond (PCD) Wafers: Ideal for manufacturing large-area, high-durability abrasive disks required for efficient and safe bone cutting. PCD offers exceptional wear resistance, ensuring blades maintain sharpness longer and reduce the aerosol production associated with dull tools (as highlighted in Fig. 10).
- 6CCVD Capability: PCD wafers up to 125 mm diameter and thicknesses up to 500 µm.
High-Purity Single Crystal Diamond (SCD): Used for micro-precision cutting edges or specialized sensory components where maximum uniformity and extreme hardness are required.
Boron-Doped Diamond (BDD) Electrodes: While not explicitly tested, the strong recommendation for air filtration and monitoring suggests a need for robust, real-time particulate or bio-agent detection. BDD is chemically inert and highly stable, making it the ideal electrode material for sensitive electrochemical sensors designed for harsh, contaminated air environments.

Customization Potential

The paper notes that currently available diamond grinders are mainly limited to small- or medium-sized bones. 6CCVD provides the necessary materials and services to overcome these limitations for industrial-scale safety instruments:

Service	6CCVD Offering	Relevance to Biosafety Tool Design
Custom Dimensions	Plates/wafers up to 125 mm (PCD)	Enables the development of large-diameter abrasive disks suitable for cutting large animal/human anatomy (e.g., bovine ribcages).
Precision Shaping	Laser cutting services	Allows for complex, custom blade geometries optimized to reduce bone dust and integrate water moistening ports effectively.
Surface Finish	Polishing to Ra < 5 nm (Inch-size PCD)	Minimizes friction and heat generation during grinding, enhancing the efficacy of water moistening (shown to significantly reduce aerosols) and increasing tool longevity.
Metalization	Custom application of Au, Pt, Pd, Ti, W, Cu	Essential for integrating diamond components into complex electrical or mechanical assemblies, ensuring robust attachment and thermal management in high-speed grinders.

Engineering Support

6CCVD’s in-house PhD team provides specialized consultation to engineers and researchers focused on high-performance materials for biosafety applications.

Material Selection for Low-Aerosol Cutting: We assist instrument designers in selecting the optimal MPCVD diamond grade (PCD vs. SCD) and structure (grain size, thickness) to maximize abrasion resistance and minimize mechanical dust generation in similar bone-cutting projects.
Design for Durability: Guidance on optimizing mounting and structure for PCD abrasive components to ensure long operational life, thus preventing the use of dull blades which the research proved are major sources of aerosol contamination.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Bone-sawing procedures are routinely performed during veterinary and human autopsies and represent an important source for infectious aerosols. Here we investigate the generation of aerosols during bone-sawing procedures using 5 different saws regularly used in veterinary and human pathology. In particular, the electrical bone band saw produced vast amounts of aerosolized particles less than 5 µm in diameter, which spread rapidly throughout the entire autopsy hall, leading to an exposure of all personnel. Other sawing devices tested were a diamond-coated cut grinder, an oscillating saw, a reciprocating saw, and a hand bone saw. Although these saws, especially the handsaw, generated fewer aerosolized particles than the band saw, the level of exposure of the saw operator would still be of concern in cases where infectious material would require sawing. Contamination of the entire autopsy area was successfully prevented by the construction of a separately ventilated sawing cabin inside the existing autopsy room. Saw operators in this cabin, however, were exposed to even higher aerosol concentrations. Protection of saw operators was achieved by using a powered air-purifying respirator. In conclusion, our results demonstrate that all bone-sawing procedures applied in veterinary and human pathology can generate aerosols that are of concern for the health of autopsy personnel. To reduce the risk of aerosol infections from bone-sawing procedures, efficient and properly designed ventilation systems to limit the spread of aerosols and appropriate personal protective equipment against aerosols for exposed personnel should be implemented.