Spatial analysis of urine zinc (Zn) concentration for women of reproductive age and school age children in Malawi

• Type of Material: Article
• Authors: Felix P. Phiri, University of Nottingham; E. Louise Ander, British Geol Survey; R. Murray Lark, University of Nottingham; Edward J. M. Joy, London School of Hygiene & Tropical Medicine; Alexander A. Kalimbira, Lilongwe University of Agriculture & Natural Resources; Parminder Suchdev, Emory University; Jellita Gondwe, Ministry of Health; Elliott M. Hamilton, British Geol Survey; Michael J. Watts, British Geol Survey; Martin R. Broadley, University of Nottingham
• Language: English
• Date: 2020-08-30
• Publisher: SPRINGER
• Publication Version: Final Published Version
• Copyright Statement: © The Author(s) 2020
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1007/s10653-020-00700-5
• Title of Journal or Parent Work: ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
• Volume: 43
• Issue: 1
• Start Page: 259
• End Page: 271
• Grant/Funding Information: Funding for this study was provided by the University of Nottingham (UoN), the British Geological Survey (BGS), and the Royal Society-UK Department for International Development (DFID) under project AQ140000, “Strengthening African capacity in soil geochemistry for agriculture and health”.
• Keywords: NUTRITION; Environmental Sciences; TRACE-ELEMENTS; Technology; Science & Technology; Biomarker; Urine zinc; Water Resources; Engineering, Environmental; Sub-Saharan Africa; Public, Environmental & Occupational Health; Micronutrient survey; Life Sciences & Biomedicine; Environmental Sciences & Ecology; Casual urine; Physical Sciences; Engineering
• Research Categories: Health Sciences, Nutrition; Engineering, Biomedical; Environmental Sciences; Health Sciences, Public Health

Abstract

Zinc (Zn) is an essential micronutrient, and Zn deficiency remains a major global public health challenge. Recognised biomarkers of population Zn status include blood plasma or serum Zn concentration and proxy data such as dietary Zn intake and prevalence of stunting. Urine Zn concentration is rarely used to assess population Zn status. This study assessed the value of urine Zn concentration as a biomarker of population Zn status using a nationally representative sample of non-pregnant women of reproductive age (WRA) and school-aged children (SAC) in Malawi. Spot (casual) urine samples were collected from 741 WRA and 665 SAC. Urine Zn concentration was measured by inductively coupled plasma mass spectrometry with specific gravity adjustment for hydration status. Data were analysed using a linear mixed model with a spatially correlated random effect for between-cluster variation. The effect of time of sample collection (morning or afternoon), and gender (for SAC), on urine Zn concentration were examined. There was spatial dependence in urine Zn concentration between clusters among SAC but not WRA, which indicates that food system or environmental factors can influence urine Zn concentration. Mapping urine Zn concentration could potentially identify areas where the prevalence of Zn deficiency is greater and thus where further sampling or interventions might be targeted. There was no evidence for differences in urine Zn concentration between gender (P = 0.69) or time of sample collection (P = 0.85) in SAC. Urine Zn concentration was greater in afternoon samples for WRA (P = 0.003). Relationships between urine Zn concentration, serum Zn concentration, dietary Zn intake, and potential food systems covariates warrant further study.