Non-Essential Trace Elements Dietary Exposure in French Polynesia: Intake Assessment, Nail Bio Monitoring and Thyroid Cancer Risk

Document Type: Research Articles

Authors

1 Radiation Epidemiology Group, Centre for Research in Epidemiology and Population Health (CESP), UMR 1018 Inserm, Villejuif, France.

2 Gustave Roussy, Villejuif, France.

3 Faculty of Medicine, University Paris Sud 11, Le Kremlin-Bicêtre, France.

4 Université de Paris-Est, Anses, Laboratory for food safety, F94700 Maisons-Alfort, France.

5 Area of population health and optimal health practices, CHU de Québec Research Center, Québec, Canada.

6 Laboratoire d’Étude et de Surveillance de l’Environnement, Institut de Radioprotection et de Sécurité Nucléaire, Papeete, Tahiti, French Polynesia.

7 Institute of Research for Development (IRD), Papeete, Tahiti, French Polynesia.

8 Institute of Research for Development (IRD), Laboratoires d’études rurales, Montpellier, France.

9 Non-Communicable Diseases Unit, Oceanian Islands Ecosystems-UMR 241, Louis Malardé Institute, Papeete, Tahiti, French Polynesia.

10 Endocinology Unit, Territorial Hospital Taaone, Papeete, Tahiti, French Polynesia.

11 IPRAME, Papeete, Tahiti, French Polynesia.

12 Paofai Clinic, Papeete, Tahiti, French Polynesia.

13 Endocrinologist, Papeete, Tahiti, French Polynesia.

14 Laboratory of Anatomy and Cytopathology, Territorial Hospital Taaone, Papeete, Tahiti, French Polynesia.

15 Institut de Recherche pour le Développement (IRD), Hydrosciences (HSM), Montpellier, France.

Abstract

Background: In French Polynesia, thyroid cancer mortality and incidence is reported to be the highest in the
world. Excessive levels of non-essential trace elements (nETE) in the body are associated with several types of cancer.
Objective: The present study aims to provide quantitative information on food contamination by mercury (Hg), lead
(Pb), arsenic (As) and cadmium (Cd) in French Polynesia and its potential correlation with measurements performed
in fingernails of Polynesians, and then to investigate the potential association between these nETE and different
thyroid cancer risks. Methods: The study population included 229 interviewed cases and 373 interviewed controls We
performed a descriptive analysis of Polynesian food and examined the association between thyroid cancer risk and daily
intake levels of nETE and with fingernail nETE levels. Results: Hg contamination was mainly present in sea products,
Pb contamination was present in almost all samples, Cd was detectable in starchy food and As was detectable in all
sea products. No patient exceeded dietary contamination WHO limits for Pb, 2 participants exceeded it for Hg and 3
individuals (0.5%) for cadmium. In fingernail clippings, the most detectable pollutant was Pb (553 participants), then
Hg (543 participants) then Cd (only in 130 participants). Thyroid cancer risk was increased more than 4 times by Pb
daily intake in patients with a history of cancer in first-degree relatives than in ones without (p for interaction =0.01),
and 2 times more in women with more than 3 pregnancies than in those with none or less (p for interaction =0.005); it
was also increased following As intake by more than 30% in patients with a history of cancer in first-degree relatives
than in ones without (p for interaction =0.05). Conclusion: Locally produced foods are not a source of nETE exposure
in French Polynesia. Dieatry nETE exposure and fingernail nETE concentration are not associated to differentiated
thyroid cancer risk. No correlation found between nETE dietary exposure and fingernail nETE concentration.

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