2004 National Atrazine Occurrence Monitoring Program using the Abraxis ELISA method

The goal of this project was to gain a better understanding of atrazine occurrence in the United States by surveying drinking water utilities' sources and finished water for atrazine on a weekly basis for seven months. Atrazine is a contaminant of interest because the United States Environmental Protection Agency (USEPA) has found short-term atrazine exposure above the drinking water maximum contaminant level (MCL) to potentially cause heart, lung, and kidney congestion, low blood pressure, muscle spasms, weight loss, and damage to the adrenal glands. Long-term exposure to atrazine concentrations above the drinking water MCL has been linked to weight loss, cardiovascular damage, retinal and muscle degeneration, and cancer. This survey effort improved upon previously conducted atrazine surveys through intensive, high frequency sampling (participating plants sampled their raw and finished water on a weekly basis for approximately seven months). Such an intensive effort allowed the authors to gain a better understanding of short-term atrazine occurrence and its variability in drinking water sources. This information can benefit the drinking water industry by facilitating (1) better atrazine occurrence management (i.e., awareness when plants may be more susceptible to atrazine), (2) more efficient atrazine control (e.g., effective treatment alternatives and more effective response to atrazine occurrence), and (3) treatment cost reduction (e.g., efficient atrazine control can result in substantial cost savings). Forty-seven drinking watertreatment plants located primarily in the Midwestern United States participated in the survey and sampled their raw and finished water on a weekly basis from March through October. Samples were analyzed using the Abraxis enzyme-linked immunosorbent assay (ELISA) test kit. Confirmation samples for quality assurance/quality control (QA/QC) purposes were analyzed using solid-phase extraction (SPE) followed by gas chromatography mass spectrophotometry (GC/MS). Several important conclusions can be drawn from this study including (1) surface waters were confirmed to be more vulnerable to atrazine contamination than groundwater sources, (2) peak atrazine concentrations corresponded well to precipitation/runoff events, and (3) atrazine occurrence tended to be uniform geographically when compared by river drainage basins. In addition, this project confirmed that the Abraxis atrazine ELISA test kit tended to have a positive bias (i.e., the measured ELISA concentration was higher than the actual concentration) in most measured samples. Finished samples tended to have more of a positive bias than raw water samples. Therefore, this bias may limit the effectiveness for ELISA for regulatory monitoring. There are many other applications for ELISA, however, including frequent monitoring for early detections of atrazine concentration changes that might trigger conventional analysis by GC/MS or be used for activated carbon dosing or other treatment operating controls.