Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Environmental Health Sciences

Content Description

1 online resource (ii, xiii, 214 pages) : illustrations (some color)

Dissertation/Thesis Chair

Beth J Feingold

Committee Members

Erin M Bell, Patrick Parsons, David Strogatz, Jennifer Bobb


Blood pressure, Global health, Nails, Nutrition transition, Trace elements, Food habits, Diet, Food preferences, Trace elements in the body, Trace elements in nutrition, Nutrition

Subject Categories

Environmental Health | Epidemiology


The paving of the Interoceanic Highway (IOH) brought rapid development to the Madre de Dios (MDD) region in the Peruvian Amazon. Development brings concerns of toxic trace element exposures, and road development has been a major driver of the transition from traditional to calorie-dense processed ‘Western’ diets in lower and middle-income countries. Investigacion de Migracion, Ambiente, y Salud (IMAS) (Investigation of Migration, the Environment, and Health) is the first analysis of health, diet, and integrated toxic trace elements in nails in the region. In 2014 we collected household surveys from 310 households in 46 communities along the IOH and nails from 418 adults. We examined whether nail selenium is an appropriate biomarker to measure the nutrition transition; differences in toxic trace element concentrations in nails by selected individual and household characteristics, and local land uses; and the complex relationships between joint exposures to arsenic, cadmium, lead, mercury, and selenium and blood pressure. We calculated household Western diet weighted sum factor scores based on principal component analysis of consumption frequency of 26 food items and assessed the effect of this score on individual nail selenium using generalized estimating equations (GEE). Associations of selected characteristics with each trace element were tested by bivariate and multivariate analyses. Joint exposures in nails and systolic and diastolic blood pressure of 394 adults were modeled using GEE linear regression and Bayesian kernel machine regression (BKMR). Western diet score was significantly inversely associated with nail selenium only in urban areas, and effect modification by urban/rural status was observed. Mining activities were associated with higher concentrations of arsenic, cadmium, and mercury. Fishing was associated with higher arsenic, mercury, and lead concentrations, while more frequent household fish consumption was associated with higher concentrations of mercury and lower concentrations of cadmium. While a suggested positive association between mercury and diastolic blood pressure was observed, none of the associations between trace elements and blood pressure reached significance in either the GEE or BKMR. We conclude that total nail selenium is not an appropriate biomarker for stage of dietary transition in the primarily rural settlements in MDD. Although no international standards for toxic trace elements in nails exist to infer health implications, exposure patterns were identified that warrant further investigation. Future investigations should consider using other biomarkers, particularly for lead and cadmium.