All this talk about pools, chorine taken from home, etc....got me thinking about the use of bleach as a disinfectant commonly used in healthcare. Specifically, about its effects on DNA testing (as LE statements imply they have taken DNA samples, are testing trace evidence, etc..).
It appears the VERY GOOD news is that chlorine bleach, while it may kill pathogens and in fact does have more deleterious effect than other cleaning agents on DNA......only negatively impacts results 15-20% of the time. (Don't freak about germs - google eukaryotic vs prokaryotic cells, viruses, etc). Of course, it increases over time.
And, to be factually accurate, this study was specific to blood stains and effects on a strain of the Hepatitis B virus (not all DNA).
"3. Results and discussion
Out of all the cleaning agents bleach had the most deleterious effect on the quality of the DNA
profile obtained. In about 80% of cases, where a negative KM test was obtained, subsequent DNA
extraction provided a profile from porous materials. Attempts to obtain profiles from non-porous
materials were unreliable when duplicates were compared. In bleach treated materials the resultant
profiles continued to decline in quality exhibiting increased scatter of Hbx over time, suggesting a
continued degradation of the DNA. This was not seen in substrates cleaned with soap or nonchlorine
disinfectant. Regardless of cleaning agent used, stutter peaks were observed with
proportions less than 15%. Split peak frequencies were low (less than 16%) for all cleaning agents.
Substrate type and time were found to be insignificant variables. DNA quality was found to be
appreciably high despite the use of chlorinated and non-chlorinated cleaning agents."
http://www.google.com/url?sa=t&rct=...kID4Cg&usg=AFQjCNFrwhJ0D7A5al6B8LOIldxxgwdL5w
KM = Kastle-Meyer test
Hbx = Hepatitis B virus X