As outlined by measure 7061A from the Environmental Protection Agency, atomic absorption/gaseous hydride is the current method for arsenic detection in wastes, soils, and groundwater. The method begins with a nitric or sulfuric acid digest. Using tin chloride, the arsenic is reduced into its trivalent state and converted into a volatile hydride. The hydride is then swept into an argon-hydrogen flame.The subsequent radiation is read by a spectrophotometer; the result is proportional to the arsenic concentration in the environmental sample. This process requires highly trained technicians and a significant delay for laboratory proceedings to be completed, costing up to $150 per sample.
Evidently, the acid digest method for arsenic detection is simply not reasonable for the impoverished people of Bangladesh, who face a severe crisis in arsenic contamination. It is estimated that nearly 57 million citizens of the Bengal basin are currently consuming water that exceeds the World Health Organization’s standard of arsenic concentration at ten parts per billion (Henke, 2009). WHO investigators estimate that more than 20% of deaths in Bangladesh could be attributed to dangerous concentrations of arsenic in tube wells. Additionally, the United States military remains concerned about exposure of troops to unsafe environmental conditions,
including arsenic-contaminated drinking water. These issues show an urgent need for a field-effective,
inexpensive sensor for arsenic.
Arsenic is a toxic chemical that plagues populations around the world. Due to the direct relationship between arsenic contamination and a country’s disease burden, arsenic infiltration into soil and groundwater poses a serious threat to international productivity. Unfortunately, arsenic contamination in both developing and developed countries continues to beleaguer populations with health concerns due to the expensive and time-consuming nature of arsenic testing.
These problems are especially relevant to soldiers, who are often deployed in resource-scarce field environments. The Cadets2Vets team has harnessed the principles of synthetic biology to develop an inexpensive, portable means of arsenic detection. The biological portion of our arsenic sensor is made up of E. coli plasmid DNA. Encoded in this genetic material is an arsenic regulatory protein (ArsR) that triggers expression of a green fluorescent protein (GFP) in the presence of arsenic ions.
Our construct is designed to function on a paper-based ticket built by the Edgewood Chemical and Biological Center (ECBC). Additionally, the Cadets2Vets team and ECBC have created a low-cost camera prototype for quantitative assessment of arsenic in our tickets. The ultimate goal of this project is to distribute our arsenic sensor to populations that are struggling with environmental contamination and its medical repercussions, as well as provide a tool to the United States military for detection of harmful substances.
"Cadets2Vets is a team that unites military and civilian resources to investigate new ways of detecting toxic arsenic contamination in the environment. Our team is a community lab made up of students from the U.S. Military Academy at West Point, high school, and undergraduate students from schools in the Puget Sound area. We are using synthetic biology to develop a gene circuit that detects arsenic ions and then produces a reporter protein in response. The arsenic sensor can be used in military or civilian applications to help inform people of the possible dangers they may encounter while out in the field or at home."