2026-08-05T09:54:38Zhttps://repisalud.isciii.es/rest/oai/requestoai: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
Repisalud
author
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
funder
Unión Europea. Fondo Europeo de Desarrollo Regional (FEDER/ERDF)
funder
Instituto de Salud Carlos III
funder
Plan Nacional de I+D+i (España)
funder
NIH - National Institute of Environmental Health Sciences (NIEHS) (Estados Unidos)
2022-04-27T11:58:36Z
2022-04-27T11:58:36Z
2021
Environ Res. 2021;197:111028.
10.1016/j.envres.2021.111028
1096-0953
Environmental Research
33753073
http://hdl.handle.net/20.500.12105/14205
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.
eng
Biomarker
Biomonitoring
Exposure
Toenail
Toxic metals
Toxic metals in toenails as biomarkers of exposure: A review
research article
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