Effect of decontamination agents following biological contamination on fingermarks, footwear, documents and DNA

Abstract

Chemical, biological, radiological, nuclear and explosive (CBRNE) response teams are responsible for mitigating and investigating events such as the distribution of anthrax letters throughout the US Postal Service in 2001. One consideration will be the examination of contaminated physical evidence to identify those responsible. Decontamination agents are often used to inactivate or neutralize chemical and/or biological warfare agents so that once-contaminated objects can be handled safely. The objective of this project was to determine the impact of different decontamination agents on physical evidence including DNA, documents, fingermark and footwear evidence. In Phase 1, vaporous hydrogen peroxide (VHP), gamma irradiation, dry fogging, chlorine dioxide, MODEC MDF-500, Bioxy-S, ozone and formaldehyde were tested. Promising decontamination agents were selected for Phase 2 when physical evidence was exposed to Bacillus thuringiensis (Bt), an anthrax surrogate, prior to decontamination. VHP, gamma irradiation, dry fogging, formaldehyde and chlorine dioxide were tested in Phase 2. Results indicate that several forensic analyses were impacted. VHP and gamma irradiation were used across different laboratories with inconsistent results observed for some forensic protocols. Further investigation indicated that these results could be explained by variation in contamination protocols between laboratories.

Les équipes d'intervention chimique, biologique, radiologique, nucléaire et explosive (CBRNE) sont chargées d'atténuer et d'enquêter sur des événements tels que la distribution de lettres d'anthrax dans l'ensemble du service postal américain en 2001. Une considération sera l'examen des preuves physiques contaminées pour identifier les responsables. Les agents de décontamination sont souvent utilisés pour inactiver ou neutraliser les agents de guerre chimiques et/ou biologiques afin que des objets autrefois contaminés puissent être manipulés en toute sécurité. L'objectif de ce projet était de déterminer l'impact de différents agents de décontamination sur les preuves physiques, y compris l'ADN, les documents, les traces de doigt et les chaussures. En phase 1, le peroxyde d'hydrogène vaporeux (VHP), l'irradiation gamma, la brumisation sèche, le dioxyde de chlore, le MODEC MDF-500, le Bioxy-S, l'ozone et le formaldéhyde ont été testés. Des agents de décontamination prometteurs ont été sélectionnés pour la phase 2 lorsque des preuves physiques ont été exposées à Bacillus thuringiensis (Bt), un substitut de l'anthrax, avant la décontamination. Le VHP, l'irradiation gamma, la brumisation sèche, le formaldéhyde et le dioxyde de chlore ont été testés à la phase 2. Les résultats indiquent que plusieurs analyses médico-légales ont été touchées. VHP et l'irradiation gamma ont été utilisée dans différents laboratoires avec des résultats incohérents observés pour certains protocoles médico-légaux. Une enquête plus approfondie a indiqué que ces résultats pourraient s'expliquer par la variation des protocoles de contamination entre les laboratoires.

Keywords:

• Biological decontamination agents
• fingerprints
• DNA
• footwear
• documents

MOTS CLÉS::

• agents de décontamination biologique
• empreintes digitales
• ADN
• chaussures
• documents

Acknowledgement

This work has been presented at the Microbial Forensics Symposium in March 2017 (Winnipeg, Manitoba); the Australian New Zealand Forensic Science Society Conference in September 2016 (Auckland, New Zealand) and the International Fingerprint Research Group Meeting in October 2015 (Patiala, India). Sgt. Maryse Laurin and Dr. Rolanda Lam of the Royal Canadian Mounted Police are kindly thanked for help in developing fingerprint samples and for proofreading the manuscript, respectively. The authors would also like to thank Dr. Rebecca Hoile for helpful discussions during the experimental design of this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Toronto Police Services (TPS); Royal Canadian Mounted Police (RCMP); Centre of Forensic Sciences (CFS).

2 * Australian samples for decontamination with gamma were split between CC (Footwear, documents and DNA) and ANSTO (Fingerprints).

⁺ Decontamination agents not recommended for Phase 2 testing.

3 Each of the five agencies decontaminating document ink samples received one additional document sample sheet as a control sample.

4 Each of the five agencies decontaminating DNA samples received one additional DNA sample sheet as a control sample. Each test and control sheet contained three negative controls of which only one was examined.

5 Of the five agents tested, VHP and gamma were applied in three and two different laboratories respectively bringing the number of tests to 8.

6 VMD was not available during this phase of the research.

7 Only one out of three test samples prepared were received for document examination.

8 Each of the four agencies decontaminating document ink samples received one additional document sample sheet as a control sample.

9 Each of the four agencies decontaminating DNA samples received one additional DNA sample sheet as a control sample. Each test and control sheet contained three negative controls of which only one was examined.

10 Gamma-discoloured paper yellow, but did not interfere with results.

11 Ozone-discoloured paper, but did not interfere with results.

Additional information

Funding

This research was supported by the CBRNE Research and Technology Initiative, Defence Research and Development Canada, Canada under Grant Number 07-0148TD; and by the Technical Support Working Group, Department of Homeland Security, US under Grant Number CB-3501.