PILOT SCOPE - Southeast Center for Agricultural Health and Injury Prevention - PILOT PROJECTS Smartphone app to quantify nitrate concentration using testing strips

Agricultural workers are negatively affected by groundwater contamination, particularly nitrate leaching from commercial fertilizer or manure. Chronic exposure through private well water has been linked to adverse health outcomes, including methemoglobinemia and elevated risks for certain cancers. Yet, monitoring tools available to agricultural communities remain either prohibitively expensive, fabrication-intensive, or too imprecise for reliable use. Commercially available test kits are low-cost but are highly variable in accuracy across water matrices and heavily reliant on subjective visual interpretation (D’Andrea & Kumpel, 2025). While technically promising, prior attempts at using smartphones to enhance detection accuracy either require fabrication of custom colorimetric sensor strips (Sicard et al., 2015), or a complete system incorporating smartphone (Fang et al., 2021). These limitations make these methods unsuitable for end users such as agricultural workers. The proposed research addresses these limitations by developing an Android application integrated with off-the-shelf colorimetric test strips and a standardized color reference card, augmented by on-device machine learning (ML) to generate accurate concentration estimates. This approach will make nitrate monitoring accessible for agricultural workers, while establishing a scalable platform extendable to other contaminants (e.g., phosphate, arsenic, fluoride, etc.). While the primary focus is on well water due to human health impacts to agricultural workers, the app could be used in other contexts such as edge-of-field monitoring or surface waters to more effectively reduce the risk of nitrate leaching.