Colourimetric analysis of thermally altered human bone samples

Area of Science:

• Forensic Science
• Anthropology
• Materials Science

Background:

• Objective temperature estimation for skeletal remains after fires is currently unavailable.
• Heat exposure significantly alters bone color, offering a potential indicator of temperature.
• Accurate temperature data is crucial for legal and forensic investigations.

Purpose of the Study:

• To develop an objective, non-destructive method for estimating the temperature exposure of skeletal remains.
• To systematically study heat-induced color changes in human bone using image analysis.
• To create a reliable decision model for differentiating temperature clusters based on bone color.

Main Methods:

• Systematic study of heat-related color changes in 1138 human bone samples (diaphysis and epiphysis).
• Exposure of samples to temperatures ranging from room temperature to 900°C in various media and durations.
• Image analysis using calibrated flatbed scanners and DSLR cameras to collect Red, Green, Blue (RGB) values and Lightness, A-, and B-coordinates.
• Statistical analysis including cluster analysis to define discriminating thresholds.

Main Results:

• Established discriminating thresholds for Lightness and B-coordinate values.
• Developed a decision rule model capable of differentiating between seven distinct temperature clusters.
• Achieved relatively high precision and accuracy in temperature estimation using the developed model.
• Demonstrated the objective, robust, and non-destructive nature of the proposed method.

Conclusions:

• The developed color-based decision model provides an objective method for estimating the temperature exposure of heated bone.
• This approach offers a significant advancement for forensic investigations involving fire-related skeletal remains.
• The non-destructive nature of the method preserves valuable evidence for further analysis.