Table 1.

Summary of the approaches and primary objectives of each of the three human studies referred to in this manuscript.

Study title	Approaches and primary objectives
Methods validation and kinetic study 2010 to 2011	Develop urinary exposure biomarker and blood spot mechanism-based biomarker method and conduct urinary excretion kinetic study in the USA (n=10) and biomarker validation study in Guatemala (n=177) [6, 14]
One year human biomarker study 2011 to 2012	Collect maize, urine, and blood spots from Chimaltenango, Escuintla, and Jutiapa every 3 months for 1 year to determine if the levels of the urinary exposure biomarker [15] and mechanism-based blood spot biomarker are correlated (n=1240). The results of the blood spot analysis are reported herein.
Biomarker response validation study 2012 to 2013	Conduct a survey in 2012 of maize across Guatemala [17] in order to select new sampling sites for validation of the biomarker results from the 2011 to 2012 one year human biomarker study [15]. Collect maize, urine, and blood spots from Sacatepéquez, Santa Rosa, and Chiquimula from February to March 2013 to determine if the relationship between the urinary exposure biomarker and mechanism-based blood spot biomarker observed in the 2011 to 2012 one year human biomarker study could be replicated (n=299). The results of the urinary exposure biomarker and mechanism-base blood spot biomarker analysis are reported herein.