Drinking water contamination is not just a problem for the developing world – developed countries increasingly face water contamination problems. To tackle all water contamination issues time is of the essence, here Bret Barnhizer discusses moving live-threat water quality testing times from days to hours
Conventional thinking is that quality drinking water is only an issue in developing countries, where women and children commonly walk miles each day to bring back water for the family. However, in 2008 the European Environmental Agency estimated 10 of 12 waterborne disease outbreaks reported in Europe were linked to the contamination of private wells. Pesticide pollution of drinking water has been identified as a problem in Belgium, Denmark, France, Germany, the Netherlands and the UK (Eureau, 2001) where it is estimated that between 5 and 10% of resources are regularly contaminated. Meanwhile in the EU15 countries, nitrate contamination is a problem commonly identified, with 29% of small wells in Belgium possessing nitrate levels in excess of 50 mg/l nitrate (OECD EPR Belgium, 1997). Additionally, in Poland 75% of the country’s river water is too polluted even for industrial use and the Baltic Sea is among the most polluted in the world today. These are just a few examples of how developed countries are increasingly facing their own water problems, as water contamination from current and past industrial development and an ever-expanding population continue to strain water sources and quality.
Poor water quality from chemicals, sewage or pathogenic bacteria can cause severe illnesses, such as stomach flu, skin rashes, pinkeye, respiratory infections, meningitis, and hepatitis. Of course, water treatment makes water fit for human consumption, but unfortunately treatment does nothing to protect people when they are exposed to polluted waterways and streams. As such, regular monitoring of all potential pollution sources and strategies for reducing water contamination are crucial in maintaining safe water standards for human consumption and for protecting water in the general environment.
In the United States, the Environmental Protection Agency (EPA) is working to establish frequent testing standards to control the levels of pollutants in drinking water, ground water and waterways. The urgency of the water pollution problem was recently discussed by the Natural Resources Defence Council (NRDC), in its latest Testing the Waters annual report. The NRDC found that the number of beach closings and advisories in 2010 soared to its second-highest level in the last 20 years, and had increased 29% over 2009. NRDC also found that the number of beaches being monitored declined in 2010, resulting in an increase in undetected water pollution that puts swimmers and local economies at risk. To prevent or reduce these water-spread diseases, experts recommend a variety of preventative measures, the most important of which is frequent water-quality testing.
The primary limitations of traditional water testing methods include long wait times for definitive test results, and the necessity to take samples to a lab for analysis. However, considerable efforts are underway around the world to develop and implement new materials and technologies for improving the speed of getting water test results.
Traditionally, water quality from source water and waterways is analysed using Petri culture methods. This tried and true approach is often the default process to test for bacterial contamination, because the culture provides a definitive result on whether the microorganisms found in a sample are living and therefore a health threat. Although highly accurate, the Petri culture method is slow in producing definitive culture results. This creates a lag time of a day or more between obtaining samples and alerting the public of a health hazard, leaving the population vulnerable to water-borne illnesses in the meantime.
Over the past decade, however, attempts at speeding up this detection time from 24 hours or more to just a few hours or even a few minutes have been introduced with varying success. The quantitative polymerase chain reaction (qPCR) method has grown in popularity due to its ability to detect pathogens in water by identifying DNA sequences. The qPCR analysis offers promising progress in water treatment, by decreasing waiting times for both bacterial and viral test results to approximately 18 hours, when overnight enrichment times are factored in. However, 18 hours is still too long to wait before alerting the public of potential water contamination. Additionally, the NRDC report notes that “unlike traditional culture methods, qPCR cannot distinguish between genetic material from dead bacteria and genetic material from live bacteria.” Experts believe that the concentration of live-threat bacteria is a better indicator related to human health impacts than just detecting DNA in a water sample. DNA can be detected from dead non-threatening pathogens resulting in false-positives diagnoses. As such, under a court order resulting from a suit brought by the NRDC, the EPA is working to develop a rapid testing method for monitoring source water quality by the end of 2012 that detects live-threat bacteria.
The EPA is currently working with NanoLogix, involving rapid detection and identification of live-threat bacteria and protozoa. NanoLogix’ BioNanoFilter (BNF) technology is a quick on-site test to identify live-threat contamination in drinking and source water. The goal is for BNF technology to allow the target pathogen to be isolated in as little as one cell per litre of water. BNF has the potential to reduce detection time from more than 24 hours to just a few hours, depending on the pathogen being tested. Currently NanoLogix and the EPA have a Cooperative Research and Development Agreement (CRADA) to increase recovery rates of Cryptosporidium, E. coli, and nontuberculous mycobacterium (NTM), as well as to explore the process as a detection system for viruses.
Unlike traditional culture methods, qPCR cannot distinguish between genetic material from dead bacteria and genetic material from live bacteria
More novel methods are also seeking to improve on the long wait times of qPCR and Petri culturing for water testing. Western New England College and the Massachusetts’ company Physical Sciences is conducting a study funded by the U.S. Army to determine if sound waves can be used to detect water contamination. In this method, water flows through a cavity where it is exposed to an acoustic standing wave. Bacterial spores in the water are then subjected to three forces: buoyancy/gravity, the drag of the fluid as it flows along and the acoustic pressure from the standing wave. By balancing these forces to specific levels, any water borne spores of Bacillus cereus bacteria can be trapped, indicating its presence in the water sample. The technique being developed is suited for large volume testing of water sources.
Meanwhile, the company Sensicore has developed a lab-on-chip micro-sensor array technology that incorporates chemical selective sensors and physical measuring devices on a single silicon chip. This panel of tests is in a handheld device called the WaterPOINT 870, and can be used to chemically profile drinking water (and/or other liquids) in approximately five minutes. Presently the device tests for substances like chlorine, calcium, ammonium and carbon dioxide, but the use of lab-on-chip technology holds promise for detecting illness-causing cells and spores.
As water resources become further strained in the coming years, both developing and developed countries are requiring new means to more rapidly gain test results from water sources. New technologies and methods hold much promise to more rapidly and accurately provide results that can help prevent millions of cases of water-borne illnesses simply by providing actionable data faster.
Bret is CEO of NanoLogix , an Ohio biotech company