Trends in the forensic analysis of cosmetic evidence

ORAİBİ H. Health Risk Assessment of Some Heavy Metals in Lipsticks Sold in Local Markets in Iraq

Heavy metals found in cosmetics are a safety threat to the health of consumers. Therefore, in this study, we evaluated the levels of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), zinc (Zn), and arsenic (As) in lipstick makeup. The level of heavy metals in lipstick was discovered by using an analytical technique with high selectivity and sensitivity, namely atomic absorption spectrometry. Twenty lipsticks were selected from the same brands, yet differing in price. Ten original (expensive) and ten knockoff (cheap) lipsticks were chosen from shops in Diyala, Iraq. The detection-limit (LOD) was in between 0.01 and 0.1, the quantification-limit (LOQ) was within 0.03 and 0.33, the recovery values (Rec.%) ranged from 100.17% to 101.1%, the RE values were 0.81%, and the RSD values were 1.33%. The results also revealed that the levels of metals are in the order of Pb > Cd > Zn > Cu > As > Cr. However, the levels of heavy metals that were estimated in this study were less than the permissible limit set by the executive authorities, so there seems to be no concern associated with these heavy metals. However, the daily and frequent use of lipstick by women exposes them to low levels of toxic metals as these metals accumulate over time and pose adverse effects on the health of the users. The results of the hazard quotient (HQ) and health risk index (HI) indicate there was no harmful effect on human health related to heavy metals present in lipstick. Whereas the results of the biological activity of the samples indicated that there was no bacterial growth in expensive samples, cheap samples were contaminated with some types of organisms; this indicates poor quality.

On the discrimination between facial creams of different brands using Raman Spectroscopy and partial least squares discriminant analysis for forensic application

Determining the origin of cosmetic traces is an important aspect of forensic investigations, that helps linking a suspect to a crime. Such type of evidence can help further narrow down the undergoing investigations. This paper reports the first use of Raman Spectroscopy (RS) coupled with the exploratory principal component analysis (PCA) and supervised partial least squares-discriminant analysis (PLS-DA) in facial creams. 40 facial cream samples of 8 different brands were studied in this work. Preliminary assessments through visual inspection of their Raman spectra revealed the presence of oxides, titanium dioxide, castor seed oil, and beeswax. Also, the peaks of alkyne groups were indicative of the presence of talc or mica compounds. The exploratory PCA correctly segregated the samples into 8 clusters and the supervised PLS-DA model correctly classified them into 8 classes. Further evaluation of the performance of the trained PLS-DA model resulted in perfect classification shown by the receiver operating characteristic (ROC) curves. The PLS-DA model also resulted in 100% accuracy of correctly assigning the brand on the face wipes on each of the five substrates viz. cotton, dry and wet tissue paper, nylon substrate, and polyester. This validation was done treating these samples as unknowns. The study has a potential for use under actual forensic casework conditions.

Rapid and non-destructive analysis of eye-cosmetics using ATR-FTIR spectroscopy and chemometrics

Cosmetic evidence recovered during crime investigations, particularly in cases of physical and sexual assault against women can be utilised as associative evidence in the court of law. This evidence can provide a link between the suspect, the victim, and the crime scene and assist in solving criminal cases. A mismatched profile of exhibit's source of origin can also be utilised to definitely exclude the suspect exhibits. In the present study, ATR-FTIR (attenuated total reflectance-fourier transform infrared) spectroscopy has been employed for the analysis of eye-cosmetics (eyeliner and eyeshadow) samples. Chemometric tool- PCA (principal component analysis) has been used for the recognition of patterns in the data. PCA-LDA (linear discriminant analysis) utilized for classification purpose showed calibration accuracy of 100% and 98% for eyeliner and eyeshadow respectively while validation result showed 97% and 97% respectively. Preliminary substrate study has been performed in the current study. Result suggests that substrates such as cotton cloth and tissue paper hinder the analysis of eyeliner while the stain of eyeshadow on substrates such as cotton cloth, tissue paper, glass, and plastic could be correctly matched with its parent source.

Chemometrics in forensic science: approaches and applications

Forensic investigations are often reliant on physical evidence to reconstruct events surrounding a crime. However, there remains a need for more objective approaches to evidential interpretation, along with rigorously validated procedures for handling, storage and analysis. Chemometrics has been recognised as a powerful tool within forensic science for interpretation and optimisation of analytical procedures. However, careful consideration must be given to factors such as sampling, validation and underpinning study design. This tutorial review aims to provide an accessible overview of chemometric methods within the context of forensic science. The review begins with an overview of selected chemometric techniques, followed by a broad review of studies demonstrating the utility of chemometrics across various forensic disciplines. The tutorial review ends with the discussion of the challenges and emerging trends in this rapidly growing field.

Discrimination of vermilion (sindoor) using attenuated total reflectance fourier transform infrared spectroscopy in combination with PCA and PCA-LDA

Vermilion (sindoor) is considered sacred in the Hindu religion, and it is used routinely throughout the world by married Hindu women along the line of hair parting during marriage ceremonies, religious rituals, and festivals. Owing to its esthetic appeal, it is sometimes illegally used as a food additive; leading to potential health risks. Therefore, due to the aforementioned reasons, vermilion can likely be encountered as trace evidentiary material during crime investigations, particularly in cases of sexual and physical offenses against women. Analysis of such evidence can provide a link between the criminal, the victim, and the crime scene and thereby be utilized as associative evidence in the court of law. In the present study, ATR-FTIR spectroscopy has been used for the examination of 37 different manufacturers of vermilion. Chemometric methods such as principal component analysis (PCA) and PCA-LDA were performed on the obtained spectra for objective interpretation of results. PCA delivered 99.06% discrimination of samples while PCA-LDA employed for classification purpose delivered 95.25% calibration accuracy and 88% validation accuracy. Afterward, the validity of the chemometric methods employed was tested by blind testing of samples. A preliminary study on the effect of selected substrates (cotton cloth, tissue paper, glass, and plastic) on sample analysis indicates that while sample stain on substrates could be linked to its parent source even after a month, linking an aged samples (after 8 months) could be hindered due to evaporation of components present in vermilion. Overall, the current methodology utilized has a potential prospect in future forensic-casework.