Cornell University, 2020

Abstract: The resources that shape our environment, including soils, play an immense role in determining our health. Yet, not much attention has been given to the study of the soil–human health nexus. In this dissertation, we address this research deficiency by conducting a cross sectional observational multi-study on the soil and human mineral interlinkages of rural subsistence female tribal farmers in Jharkhand, India. We conducted a survey and collected soil, rice (staple crop) and human hair samples (as bio-indicator of human mineral status) from 43 rice fields spanning seven districts in Jharkhand, and analyzed them for mineral content in addition to soil physical and biological health indicators (in the case of soil samples) and the antinutrient phytate content (in the case of rice). Chapter 1 provides a comprehensive literature review of 24 mineral elements and presents their critical levels and reference ranges in soil, rice and human hair. It highlights the varying degrees of essentiality and toxicity to plants and humans, which are oftentimes contested within the scientific community, as well as varying beneficial and detrimental impacts on critical processes that impact plant and animal/human health. Chapter 2 conducts an analysis on the effects of geo-environmental, socio-demographic and lifestyle effects of rural Jharkhand, Indian women-farmers on their mineral nutrition. The results of this chapter showed that differences in mineral composition in hair is the result of a combination of inherent and anthropogenic effects, and that a myriad of these factors influence the nutritive health of humans. Chapter 3 characterizes the soil health as well as mineral status of the soil, rice and human hair in Jharkhand, India and assesses their interlinkages. This chapter showed that some soil health indicators are significantly correlated with rice and human mineral status, and that relations among minerals are mostly cross-correlations with few connecting the same minerals along the soil-rice-hair nexus. In general, this dissertation underscores the extent to which humans are nutritionally tied to their land, but that the nature of these interlinkages are highly complex and involve a network of indirect and direct associations.

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