A Systematic Review of Mercury Exposures from Skin-Lightening Products.

BACKGROUND: The Minamata Convention on Mercury (Article 4) prohibits the manufacture, import, or export of skin-lightening products containing mercury concentrations above 1 ppm. However, there is a lack of knowledge surrounding the global prevalence of mercury-added skin-lightening products. OBJECTIVE: The objective of this study was to increase our understanding of worldwide human mercury exposure from skin-lightening products. METHODS: A systematic search of peer-reviewed scientific literature was performed for relevant articles in four databases (PubMed, Web of Science Core Collection, Scopus, and TOXLINE). The search strategy, eligibility criteria, and data-extraction methods were established a priori. The search identified 2,303 unique scientific articles, of which 41 were ultimately deemed eligible for inclusion after iterative screens at the title, abstract, and whole-text levels. To facilitate data extraction and synthesis, all papers were organized according to four data groups a) "Mercury in products," b) "Usage of products," c) "Human biomarkers of exposure," and d) "Health impacts." RESULTS: This review was based on data contained in 41 peer-reviewed scientific papers from 22 countries worldwide published between 2000 and 2022. In total, we captured mercury concentration values from 787 skin-lightening product samples [overall pooled central median mercury level was 0.49µg/g; interquartile range (IQR): 0.02-5.9] and 1,042 human biomarker measurements from 863 individuals. We also synthesized usage information from 3,898 individuals and self-reported health impacts associated with using mercury-added products from 832 individuals. DISCUSSION: This review suggests that mercury widely exists as an active ingredient in many skin-lightening products worldwide and that users are at risk of variable and often high exposures. These synthesized findings identify data gaps and help increase our understanding of the health risks associated with the use of these products. https://doi.org/10.1289/EHP10808.

Comparison and Agreement of Toxic and Essential Elements Between Venous and Capillary Whole Blood.

For practical and ethical reasons, there is an interest in the use of capillary blood as an alternative to classical human biomonitoring methods that use venipuncture. However, with the exception of Pb, few elements have been studied in detail to understand potential differences in measures between capillary and venous blood. To increase our understanding of the agreement in concentrations of select toxic metal(loid)s and essential minerals in venous and capillary whole blood. Concentrations of As, Pb, Cd, Mn, Cu, Fe, and Se were measured with Inductively Coupled Plasma-Mass Spectrometry in venous and capillary whole blood samples obtained from 49 healthy adult members of the McGill University community in 2016. Measured concentrations of all elements were similar to values reported in background populations. There were strong correlations (i.e., p < 0.001) in measures taken for all these elements between capillary and venous blood. Using Bland-Altman, a deeper investigation of the agreement between the measures found relatively good agreement for blood As, Pb, Cu, and Fe. For blood Cd, Mn, and Se, the agreement between the measures taken in capillary and venous blood was less consistent, though more research is needed to determine if the method can be improved and/or if there are real differences. For the seven elements under investigation, there was relatively good correlation and agreement in measures taken between capillary and venous blood from the same individual. Further research is needed to confirm these findings (particularly from more diverse population groups), expand the number of elements analyzed, and explore the utility of capillary sampling in biomonitoring programs that take samples using traditional venipuncture methods.

Lead (Pb) exposure assessment in dried blood spots using Total Reflection X-Ray Fluorescence (TXRF).

Lead (Pb) exposure is often determined through the analysis of whole blood though venipuncture poses ethical, economic, and logistical barriers. Dried Blood Spots (DBS) may help overcome such barriers though past studies measuring Pb in DBS have been challenged with quality control, small sample volumes, and other issues. Total Reflection X-Ray Fluorescence (TXRF) may help address some of these challenges but has yet to be used to measure Pb in DBS. As such, the aim of the current study was to develop, validate, and apply a method to analyze Pb in DBS samples using TXRF for use in human biomonitoring studies. First, we developed a novel method (tested a range of parameters), and then used blood reference materials to validate the method against performance criteria listed in ICH Q2A and Q2B and the European Bioanalysis Forum. Finally, we applied the method to two populations who exemplify divergent conditions (41 university members with relatively low Pb exposures sampled in a clinical environment; 40 electronic waste workers with relatively high Pb exposures sampled in a contaminated field setting). The limits of detection and quantification of the method were 0.28 and 0.69 µg/dL, respectively. The overall precision and accuracy of the method were 15% and 111%, respectively. The mean (±SD) DBS Pb levels by TXRF in the university members and e-waste workers were 0.78 (±0.46) and 3.78 (±3.01) µg/dL, respectively, and these were not different from Pb measures in venous whole blood using ICP-MS. Bland-Altman plot analyses indicated good agreement between DBS Pb measures by TXRF versus whole blood Pb measures by ICP-MS in both groups. By combining data from the two population groups, there was no significant constant bias (intercept of 0.02 µg/dL) or proportional bias (slope was -0.02) between the two measures, and the lower and upper LoA were -0.86 and 0.91 µg/dL, respectively, with a LoA range of 1.77 µg/dL. These results demonstrate that TXRF-based analysis of Pb content in DBS is a good alternative to the gold standard (i.e., ICP-MS analysis of whole blood), and helps overcome some of the challenges associated with current methods.

Bioaccumulation of metal(loid)s in Cardisoma crassum and pollution assessment in a mangrove protected area in Mexico.

The bioaccumulation of several elements in "mouthless crabs" (Cardisoma crassum) and their concentrations in environmental samples were assessed in a mangrove forest within a natural protected area located in the middle of Puerto Vallarta, Mexico. The concentrations of Al, As, Ba, Cd, Cr, Cu, Fe, Ni, Pb, Sr, Si, V, and Zn in sediments, mangrove litterfall, and pore water and their bioaccumulations in the muscle and shell tissue of C. crassum were determined during rainy and dry seasons. Two different sampling sites were compared, selected according to the influence of the tide. The samples were analyzed by ICP-OES. In pore water, half of the elements of interest were below the limits of detection. Pb and Cd concentrations were only detected in the sedimentary phase. Al and Fe presented the highest concentrations at both sampling sites in the sediments and mangrove litterfall. There were no significant differences between sampling seasons in water samples (P > 0.05). Only Cu presented significant differences between sampling seasons in the mangrove litterfall samples and V in the sediment samples (P < 0.05). The sediment quality guidelines indicated that only Cd was above the threshold effect limit. As, Cd, Cr, Ni, and Pb remained below the limits of detection in muscle tissue and shell samples. The biota-sediment accumulation factors (BSAFs) determined for Cu and Zn were above 1.0, indicating the accumulation of these elements in the muscle tissue of C. crassum, while the BSAF values in the shell were above the threshold for Ba, Si, and Sr.