Assessing the use of environmental DNA (eDNA) as a tool in the detection of human DNA in water

Abstract

Environmental DNA (eDNA) is a highly sensitive and cost‐effective tool that is increasingly being applied to studies of biodiversity and species detection. This non‐invasive method relies on the collection of environmental samples that contain genetic material being shed into surrounding environment by the target organism/s. While forensic science has a long history of using molecular tools for collecting DNA from the environment, the detection of human DNA from environmental water samples has been limited. This study investigated the detection and degradation rates of human eDNA in water samples under controlled laboratory conditions. Using a human‐specific qPCR assay targeting the ND1 region of human mitochondrial DNA, eDNA degradation over time in water spiked with human blood was assessed. Recovery of nuclear DNA was investigated by determining if routine DNA short tandem repeat (STR) profiles of the blood source could be generated. Results demonstrated that human eDNA remains detectable for up to 11 days under laboratory conditions in environmental water and up to 35 days in distilled water. Partial STR profiles could be recovered from environmental water only up to 24 h, while, in distilled water, partial profiles continued to be recovered up to 840 h. These findings demonstrate that sampling human eDNA from aquatic samples can provide reliable human DNA detection within relatively short time windows, assisting law enforcement agencies by providing information about the potential time an individual may have been present in an area or assisting in the detection and location of a body or remains in aquatic environments.

Emerging use of air eDNA and its application to forensic investigations – A review

“…Dass et al. [74] specifically targeted human eDNA in the water purportedly in order to develop methods for locating missing individuals or narrowing down the search resources in aquatic environment. Human blood (100 µL) degradation diluted in a plastic chamber containing either 20 L of distilled water or environmental water from a dam was tested in three replicates.…”

Environmental DNA: Enhancing Species Detection and Study Comparability with Synthetic DNA Tracers

“…Another emerging area of eDNA application is in forensic analysis, wherein environmental samples such as water or dust can be used to detect human DNA 61 or geographically localize humanenvironment encounters 62 .…”