Emily C. Lennert
blood, crime scene, cleaning, OxiClean, Lysol, Arm & Hammer, stain remover, multipurpose cleaner, detergent booster, Bluestar, chemiluminescence
Adams, J.L.; Rancourt, E.D.; Christensen, A.M. The effect of household oxidizing cleaners on chemiluminescence of blood using Bluestar®. Journal of Forensic Sciences. 2018.
Disclaimer: The opinions expressed in this review are an interpretation of the research presented in the article. These opinions are those of the summation author and do not necessarily represent the position of the University of Central Florida or of the authors of the original article.
Following the commission of a crime, perpetrators may attempt to clean or remove blood from the crime scene, clothing, and other surfaces. Traces of blood found on a suspect’s clothing, items belonging to a suspect, or found in the crime scene may play a significant role in the development of a case. Presumptive tests for blood are a common means of identifying latent, or hidden, bloodstains and may include tests such as luminol or Bluestar Forensic®. Bluestar® has been shown in previous research to be a powerful tool for the identification of latent bloodstains, allowing for more sensitive detection of diluted blood when compared to luminol. Additional studies have been conducted using Bluestar® and have highlighted the need for studies in which the effects of various cleaning products on Bluestar® are studied.
In this study, blood was applied to ceramic floor tiles and cleaned with one of three cleaners: Lysol® with Hydrogen Peroxide Multi-Purpose Cleaner, OxiClean® Versatile Stain Remover, and Arm & Hammer® Super Washing Soda Detergent Booster. Prior to analysis, a series of control experiments were conducted. First, an uncleaned tile was treated with Bluestar® to ensure that no chemiluminescence occurred from the tile. Then, each cleaner was tested with Bluestar® to ensure that no chemiluminescence occurring from the cleaners was observed. Finally, a tile with a bloodstain, uncleaned, was tested with Bluestar® to ensure that chemiluminescence would occur.
Each sample was prepared by dropping one droplet of blood from a platic pipette 5 feet above the tile. The resulting bloodstain was approximately circular, and was allowed to dry for 1 hour before sample preparation continued. After drying, a 79 mm diameter circle was drawn around the droplet. Eight tiles were prepared for each cleaning product, for a total of 24 tiles. OxiClean® and Arm & Hammer® cleaning products were prepared according to manufacturer’s instructions. The Lysol® product was already in a liquid state, and thus required no preparation. After preparation of the cleaning products, each tile was cleaned with its designated cleaning product. Tiles were cleaned with a toothbrush for 1 minute in circular motions, and then wiped with a paper towel to mimic a “hasty” cleaning. Following cleaning, no blood was visible on any of the tiles. Tiles were then treated with three sprays of Bluestar® in a darkened area. The darkened area used was a household garage, with the garage doors doors closed, lights shut off, and partly cloudy daytime conditions outdoors. Upon spraying the Bluestar®, a photograph was taken of each sample. Photographs were taken using a Nikon D5600 DSLR camera at a 10 s exposure time at a distance of 2’ 2”.
Images were uploaded into ImageJ to allow for the subsequent quantification of chemiluminescence. RGB values were determined for each sample’s regions of interest. Four regions of interest were defined per sample, with one falling within the circle that had encompassed the bloodstain and three falling outside of the bloodstain area. RGB values were converted to a brightness value. Simple statistical significance tests, i.e. paired t-tests, were performed to compare the mean RGB values of the untreated areas, i.e. blood free and uncleaned, and treated areas, i.e. blood applied and cleaned. The treated areas of the three products were also compared.
For each individual sample, it was reported that the regions of interest in the untreated areas had little variations and were therefore averaged for subsequent analyses. Overall, cleaning with Lysol® produced lower levels of chemiluminescence compared to cleaning with OxiClean® and Arm & Hammer®. The chemiluminescence observed in samples cleaned with OxiClean® and Arm & Hammer® were noted to be “significantly visible” compared to the Lysol® samples. All cleaners produced significantly higher chemiluminescence in treated areas compared to untreated areas, indicating that all cleaners failed to remove the bloodstains from the tiles.
To compare the cleaners, the percent change in chemiluminescence between untreated and treated area was used, due to variation in the chemiluminescent signal from the untreated areas between each cleaner sample. This variation may have been due to photographic conditions or background chemiluminescence, and thus the variation was removed by using the percent change RGB value. Lysol® produced the smallest change in chemiluminescence, i.e. produced the least chemiluminescence, with a change of 6.7%, whereas Arm & Hammer® and OxiClean® produced higher, comparable changes in chemiluminescence. Arm & Hammer® was found to increase 20.7%, while OxiClean® increased 19.2%. This indicated that the Lysol® reduced the chemiluminescent signal to a greater degree than the OxiClean® and Arm and Hammer®.
- All three cleaning products tested failed to completely remove blood from tiles, with all producing chemiluminescence with Bluestar®.
- Lysol® produced the greatest reduction of chemiluminescence with Bluestar®.
- Results obtained by OxiClean® and Arm & Hammer® were comparable, with both producing visible chemiluminescence after the application of Bluestar®.
Following a crime, a perpetrator may attempt to clean up the scene, clothing or other relevant items. It is therefore important for investigators to understand how different cleaning products may affect the usefulness of presumptive tests such as Bluestar Forensic®.
Cleaning products may decrease the chemiluminescent signal observed from blood when using Bluestar Forensic®.