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oai:repisalud.isciii.es:20.500.12105/142052025-04-29T12:56:47Zcom_20.500.12105_2052com_20.500.12105_2051com_20.500.12105_15322col_20.500.12105_19608col_20.500.12105_19613col_20.500.12105_16959

00925njm 22002777a 4500 dc Salcedo-Bellido, Inmaculada author Gutierrez-Gonzalez, Enrique author García-Esquinas, Esther author Fernandez de Larrea-Baz, Nerea author Navas-Acien, Ana author Tellez-Plaza, Maria author Pastor-Barriuso, Roberto author Lope Carvajal, Virginia author Gómez-Ariza, José Luis author García-Barrera, Tamara author Pollan-Santamaria, Marina author Jimenez-Moleon, Jose J. author Perez-Gomez, Beatriz author 2021 Toenails have been used as biomarkers of exposure to toxic metals, but their validity for this purpose is not yet clear and might differ depending on the specific agent. To evaluate this issue, we reviewed the literature on: a) the time-window of exposure reflected by toenails; b) the reproducibility of toenail toxic-metal levels in repeated measures over time; c) their relationship with other biomarkers of exposure, and; d) their association with potential determinants (i.e. sociodemographic, anthropometric, or lifestyle characteristics) or with sources of exposure like diet or environmental pollution. Thus, we performed a systematic review, searching for articles that provided original data for levels of any of the following toxic metals in toenails: aluminum, beryllium, cadmium, chromium, mercury, nickel, lead, thallium and uranium. We identified 88 articles, reporting data from 67 different research projects, which were quite heterogeneous with regard to population profile, sample size and analytical technique. The most commonly studied metal was mercury. Concerning the time-window of exposure explored by toenails, some reports indicate that toenail cadmium, nickel and lead may reflect exposures that occurred 7-12 months before sampling. For repeated samples obtained 1-6 years apart, the range of intraindividual correlation coefficients of aluminum, chromium and mercury was 0.33-0.56. The correlation of toxic metal concentrations between toenails and other matrices was higher for hair and fingernails than for urine or blood. Mercury levels were consistently associated with fish intake, while other toxic metals were occasionally associated with specific sources (e.g. drinking water, place of residence, environmental pollution, and occupation). The most frequently evaluated health endpoints were cardiovascular diseases, cancer, and central nervous system diseases. Available data suggest that toenail mercury levels reflected long-term exposures and showed positive associations with fish intake. The lack of standardization in sample collection, quality control, analytical techniques and procedures - along with the heterogeneity and conflicting results among studies - mean it is still difficult to conclude that toenails are a good biomarker of exposure to toxic metals. Further studies are needed to draw solid conclusions about the suitability of toenails as biomarkers of exposure to toxic metals. Environ Res. 2021;197:111028. 10.1016/j.envres.2021.111028 1096-0953 Environmental Research 33753073 http://hdl.handle.net/20.500.12105/14205 Biomarker Biomonitoring Exposure Toenail Toxic metals Toxic metals in toenails as biomarkers of exposure: A review