Status and interrelationship of toenail elements in Pacific children

Objective: Elemental deficiencies or in excess effects growth and development. Pacific population are at a disadvantage due to food insecurity as compared to New Zealand European households. This study aims to evaluate the status and interrelationship of elements (essential, non-essential and toxic) in nine-year-old Pacific children who were part of the Pacific Island Families Study living in New Zealand.

Materials and methods: This observational study included 278 eligible nine-year-old children. Essential elements (including calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, selenium, zinc, molybdenum), non-essential and toxic elements (arsenic, aluminum, antimony, boron, cadmium, lead, mercury, nickel,) were determined in toenails and after acid digestion, analysed using inductively coupled plasma mass spectrometry. Principal component analysis and multivariate analysis of covariance was used to identify differences in the groups of elements and the inter-correlations between elements.

Results: The mean calcium (868μg/g Ca), selenium (0.35μg/g Se) and zinc (129μg/g Zn) concentrations were lower while the mean cadmium (0.21μg/g Cd) lead (0.86μg/g Pb) and mercury (0.72μg/g Hg) concentrations were higher than the optimal health requirements. Ethnic differences in relation to toenail elemental concentrations were observed for aluminium and iron. Gender differences were observed for aluminium, antimony, arsenic and lead. Selenium and molybdenum were inversely associated with mercury. Manganese, zinc and calcium were positively associated.

Conclusions: This research contributes to the understanding of the elemental concentrations for Pacific children by using tissue samples from toenails, which improves the completeness of sampling than other tissues and provides a longer exposure time frame. The study also reports several inter-correlations between essential, non-essential and toxic elements in Pacific Island population.