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The effect of bleaching agents on the DNA analysis of bloodstains on different floor coverings

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Blood at crime scenes is one of the most significant traces of evidence in investigation proceedings. Cleaning up these traces with household cleaning products, often containing bleaching agents, inhibits or complicates the detection of DNA. In this study, human blood was applied onto different floor coverings (carpet, laminate, parquet, PVC, tile) and subsequently cleaned with water and bleaching agents (hydrogen peroxide, sodium hypochlorite, DanKlorix®, Vanish Oxi Action®) at different times. Samples have been collected afterwards from the floors. The samples underwent a quantitative and qualitative DNA analysis. Cleaning smooth surfaces with water is usually sufficed to prohibit retrieving a DNA profile in most of the cases. Cleaning carpets was more difficult due to their absorbent surface whereas the use of bleaching agents caused an additional reduction of verifiable DNA concentrations. Retrieving partial or complete profiles after the use of bleaching agents was only possible when cleaning with low concentrations of 3% hydrogen peroxide.
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ORIGINAL ARTICLE
The effect of bleaching agents on the DNA analysis of bloodstains
on different floor coverings
C. Edler
1
&O. Krebs &A. Gehl
1
&K. Palatzke
2
&N. Tiedemann
2
&A. S. Schröder &A. Klein
Received: 13 September 2019 /Accepted: 14 January 2020 / Published online: 20 January 2020
#Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract
Blood at crime scenes is one of the most significant traces of evidence in investigation proceedings. Cleaning up these traces with
household cleaning products, often containing bleaching agents, inhibits or complicates the detection of DNA. In this study,
human blood was applied onto different floor coverings (carpet, laminate, parquet, PVC, tile) and subsequently cleaned with
water and bleaching agents (hydrogen peroxide, sodium hypochlorite, DanKlorix®, Vanish Oxi Action®) at different times.
Samples have been collected afterwards from the floors. The samples underwent a quantitative and qualitative DNA analysis.
Cleaning smooth surfaces with water is usually sufficed to prohibit retrieving a DNA profile in most of the cases. Cleaning
carpets was more difficult due to their absorbent surface whereas the use of bleaching agents caused an additional reduction of
verifiable DNA concentrations. Retrieving partial or complete profiles after the use of bleaching agents was only possible when
cleaning with low concentrations of 3% hydrogen peroxide.
Keywords Forensic medicine .DNA analysis .Bloodstains .Cleaning products .Bleaching agents
Introduction
DNA analysis from bloodstains is quite often a vital part of the
investigation proceedings in crime scenes. Over the past de-
cades, offenders have shown a growing awareness of leaving
as few traces as possible by cleaning up the crime scene. After
committing a crime cleaning bloodstains with bleaching
agents, found in household cleaning products, has also repeat-
edly been reported as bleaching agents cause DNA degrada-
tion [1].
Several studies have investigated the effect of bleaching
agents on standard preliminary blood tests, such as luminol
and Bluestar® [15]. Castelló et al. concluded that these pre-
liminary test methods lead to negative results in detecting blood
following the use of bleaching agents. However, a DNA
analysis had still been possible in these cases, thus their recom-
mendation to carry out a DNA analysis on questionable visible
bloodstains notwithstanding a negative preliminary test [5]. It is
also common knowledge that chlorinated bleaching agents pro-
duce a false positive reaction when using luminol [6]. This
poses a problem particularly in detecting latent traces of blood.
Solely Thabet et al. [7]andHarrisetal.[8]reportedonthe
detection of DNA in bloodstains on fabrics and after washing
them with bleaching agents. Additionally, Harris et al. also
tested laminate, vinyl, and glass. However, to the best of our
knowledge, there are no systematic studies in German or
English literature dealing with the detection of DNA on differ-
ent floor coverings after having been cleaned with bleaching
agents.
The aim of this study is to test different bleaching agents on
typical floor coverings to provide information on the possibil-
ities and limits of a DNA analysis after cleaning.
Material and methods
Choice of bleaching agents
Bleaching agents are mostly used to remove unwanted discol-
orations from textiles or paper. Differentiated are mainly
O. Krebs, A.S. Schröder and A. Klein contributed equally to this work.
*C. Edler
c.edler@uke.de
1
Department of Legal Medicine, University Medical Center
Hamburg-Eppendorf, Hamburg, Germany
2
Technical College of Applied Sciences, Police Academy Hamburg,
Hamburg, Germany
International Journal of Legal Medicine (2020) 134:921927
https://doi.org/10.1007/s00414-020-02250-y
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Cleaning agents such as hydrogen peroxide and sodium hypochlorite are known to damage DNA [6,7,21]. Passi et al. amplified the CSF1PO locus of bloodstains on cotton treated with sodium hypochlorite (unknown treatment condition) and visualized degraded DNA smears on agarose gel. ...
... DNA quality was found to be high, but some DNA degradation was observed in a lowering of interlocus balance. Edler et al. reported similar negative effects when cleaning bloodstained carpets with Haiter and Vanish [21] but this was not observed in our study, possibly due to the difference in treatment conditions (visible vs invisible stains) and the amplification technique (direct vs conventional PCR). We therefore used slightly harsher pretreatment Fig. 3 RDI plot for the peak heights recovered from laundered bloodstains on cotton washed at different water temperatures (cold to 95 ℃) using Omo. ...
... Multiple washes meant more exposure to water, detergent, and scrubbing, which dislodged bloodstains and destroyed or degraded DNA in the process. It is worth noting that even after five washes (or scrubbing 1000 times with hands and knuckles), we obtained 21,17,16,15, and 0 alleles using direct STR typing, which could be useful or interpretable depending on local standard operating protocols. ...
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... The techniques proposed by Sild-Pausak and Varetto [9,10], for the removal of flaking epithelial cells, are probably also suitable for the treatment of dried blood, but require the availability of instrumentation that is difficult to find in forensic laboratories and medium-long times for sample treatment. Also sodium hypochlorite, present in the saturated solution proposed by Burnett [8], is particularly effective in the removal of dried blood; its cell-degrading properties are widely known [12,13]. Calcium hypochlorite, on the other hand, used by the author to reduce the solubility of GSR particles in water, has proved difficult to find in several university and police laboratories because it is not generally used in forensic science. ...
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