ARSENIC EXPOSURE IN RURAL POPULATIONS LIVING IN THE RIFT VALLEY OF ETHIOPIA AS MONITORED BY KERATIN IN TOENAILS

Arsenic contamination of drinking water is an important issue in the Rift Valley of Africa where the contaminant is naturally occurring above the WHOs maximum contaminant level (MCL) of 10ppb. Its health effect in the area however is not well studied, particularly among vulnerable and rural communities, who consume well water as their primary drinking water source. The objective of this study was to use human keratin in the form of toenails, water geochemistry, survey tools and nutritional data to understand arsenic exposure and bioaccumulation. Groundwater drinking well samples (n=34) were collected along with corresponding toenail samples (n=58) in rural populations in the MER. Water samples were analyzed for arsenic and other trace metals using inductively coupled plasma mass spectrometry (ICP-MS). Fifty three percent of the wells tested had arsenic level above the MCL of 10ppb. Arsenic in toenails was significantly correlated to corresponding drinking water (r=0.72; R²=0.52; p<0.001). This correlation improved for drinking water with arsenic concentrations above 2ppb (r=0.74; R²=0.54; p<0.001) implying that there may be some concentration at which nails begin to accumulate arsenic which is in agreement with previous studies conducted by other authors. Male minors (<18 years old) were found to be more sensitive to arsenic accumulation in nails than adult males. Arsenic dose from drinking water sources alone was also associated with nail concentrations. While not statistically significant, participants who consumed meat at least once per week had lower arsenic-nail concentrations than participants who consume meat less frequently (p=0.2). Access to drinking water is not only about quantity but quality. Arsenic measurement in nails is a reliable method for detecting exposure in residents living in rural areas of the MER demonstrating that arsenic contamination of water sources is an issue in the region that needs to be addressed