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Project Description


The goal of our project is to create a low-cost biosensor by using the metal ion homeostasis system of Bacillus subtilis to quantify environmental levels of cadmium in drinking water.

Health Effects:

Cadmium (Cd) is a toxic heavy metal which has no known biological function. Ingestion of Cd-contaminated water can induce diarrhea, severe vomiting, bone fracture, Itai-Itai disease, infertility, damage to the central nervous and immune systems, cancer development and ultimately death. For instance, in late 20th century Japan, cadmium contamination of water in the Jingzu River led to significant kidney problems and Itai-Itai bone disease in a fairly large population.

Level of danger:

Of late, cadmium levels have been better controlled by industrial regulation, but it still poses formidable problems. The Environmental Protection Agency (EPA) has set cadmium level regulations at a maximum of 5µg/L in drinking water. Of the 1,669 hazardous waste sites on the EPA's National Priorities List (NPL), 1,014 contain cadmium. The Australian National Pollutant Inventory (NPI) has ranked cadmium number 6 out of 400 of the most toxic substances based on health and environmental hazards and human and environmental exposure to the substance. According to the NPI, Cd has a total hazard rating of 4.3 as compared to 2.8 for carbon monoxide and 4.0 for arsenic.

Current cadmium measurement techniques:

Atomic absorption spectroscopy is an accurate way of determining heavy metal concentration in a solution, however, it is bulky and more expensive than a bacterial bio-sensor.