The DNA Difference in Drinking Water

• By Marty Dugan
• Feb 12, 2010

Heavy metal contamination in drinking water is a serious concern for those who manage community water supplies. Naturally occurring heavy metals such as arsenic, lead, cadmium, mercury, silver, copper, and uranium are not harmful to humans in small amounts but can impair mental and central nervous function, lower energy levels, and damage blood and vital organs in large amounts and over a long-term exposure. Water managers monitor the concentrations of heavy metals to minimize these risks.

A 2007 University of Cincinnati study of common contaminants, titled United States Drinking Water Quality Study Report, summarized data from the U.S. Environmental Protection Agency, the U.S. Bureau of Census, and publicly available consumer reports. The data, which covered 77 highly populated metropolitan areas accounting for more than 60 percent of the U.S. population, mapped information on low, medium, and high concentrations of lead levels . Most of the areas studied were within EPA guidelines, but the report also showed that 24 areas had high concentrations of lead, confirming the need for testing.

Traditional methods of testing for heavy metals in drinking water include X-ray fluorescence (XRF), inductively coupled plasma (ICP), and chemistry based tests. These tests, which can cost between $50 and $200, require a laboratory setting and a trained chemist to ensure their reliability and accuracy.

The pollution control industry now has a new, less complex way to detect heavy metal contaminants in drinking water samples. ANDalyze, Inc., has developed a DNA sensor technology and combined it with a hand-held fluorimeter platform to give state and federal regulators, municipal drinking operations, and industrial water managers results within two minutes of testing. This method allows managers to complete testing and reporting in a fraction of the time and cost of traditional methods, using no particular skills or chemistry knowledge. Traditional testing also requires a technician to take the water sample, package and ship it to a laboratory, order the testing, manage the invoice, and track documentation. The new solution costs a fraction of the overall cost per test and provides almost immediate results in the field, which gives the testing technician the option to take further samples at a site or to re-test immediately.

DNA as a Testing Mechanism

While studying RNA splicing in the 1980s, Thomas R. Cech discovered that RNA molecules can catalyze enzymatic reactions. These were named ribozymes.

Demonstrations in the 1990s revealed that DNA also can act as enzymes, termed deoxyribozymes or DNAzymes. The fact that DNA/RNA not only store and transfer genetic information but also act as catalysts for various biological reactions (and thus called catalytic DNA/RNA, (deoxy) ribozymes, or DNA/RNAzymes), opened up the possibility of other potential uses for DNA.

Metal ions play essential roles in DNAzymes, so the study and application of these new metalloenzymes became a new frontier in bioinorganic chemistry. At the University of Illinois, Yi Lu, Ph.D., developed the core research of this technology. From this science and with U.S. Environmental Protection Agency grants in 2006, engineers at ANDalyze designed and developed a hand-held fluorimeter (AND1000 Fluorimeter) and lead sensor (Lead100 Sensor) combination that uses a synthetic form of DNA for detecting and quantifying heavy metals in water based on DNA's catalytic properties.

The product contains sensor units specific to a contaminant, such as lead or uranium, for example. A reaction occurs when a water sample containing lead ions is introduced, producing a rate of fluorescence in direct correlation to the amount of metal ion present. The amount of light is measured and logged by the AND1000 hand-held fluorimeter.

This technology is currently being validated by the US EPA as a method for testing lead in paint and is currently undergoing field testing and quality control studies for testing drinking water by ANDalyze as it comes to market early in 2010. Sensors for lead and uranium are available, and several more are planned for release in the next 12 months. This technology, although initially targeting heavy metal contamination, can be developed for organic chemical and bacteriological contaminants as well.