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Application of Quantitative Polymerase Chain Reaction Technology to the Beach Monitoring Program
 Study participant is interviewed by EPA scientist. |
Science Question
How can we develop rapid techniques to detect potential microbial contaminants at recreational beaches?
The Research
Monitoring of recreational waters for indicators of fecal contamination has been required for decades in the implementation of EPA Ambient Water Quality Criteria (AWQC) to protect swimmers against acute gastrointestinal illness (AGI). The AWQC criteria were established after epidemiology studies were conducted in the late 70s and early 80s which demonstrated a correlation of AGI illness rates to E coli and enterococci levels in the water. While these are good indicators water quality, they require a 24 hour analysis period after sampling to find out if the water quality is acceptable for swimming. Recent intensive EPA monitoring studies have demonstrated that typical water quality may change rapidly so the water quality often can not be ascertained on the day a person is swimming.
Quantitative Polymerase Chain Reaction (QPCR) technology can circumvent the problems of having to wait for 24 hours or longer to determine if safe levels of indicator organisms occur on any given beach day. QPCR provides the capability to determine water quality within 2 hrs of the start of sample analysis. QPCR methodology is being studied by the EPA for its use in measuring enterococci in recreational waters as well as the correlation with levels of AGI from swimming exposure. Companion studies of this technology are being conducted to determine if Bacteroides fragilis may also qualify as a recreational water quality indicator. This fecal bacterium is present in high numbers in the human body and doesn't grow outside of it.
Contribution to Environmental Outcomes
The benefits of the QPCR technology applied to recreational criteria monitoring is that sampling can be done early in the day before swimmers go to the beach (or during rainfall runoff events which can wash contaminants into the waters), and within 2 hrs the beach operators can know if the their waters are safe or if they must close or post a swimming area to protect the health of would-be swimmers. The application of this technology will greatly reduce the disease risks and associated costs of illness (doctors, medicines, days off work, etc). This technology in the future can also be applied to protection of other human uses of our nation's waters.