Immunoassay tests "screen" a water sample for specific pesticides. They provide an indication that certain pesticides might be present, but they cannot confirm their precise concentration. They can sometimes detect other pesticides or pesticide breakdown products, although typically to a significantly lesser degree. Immunoassay screens are a low-cost alternative to more expensive tests and analyses. Detection limits for the screens are suitably low enough for water testing, but the screens are not an absolute indicator of the exact quantity of a pesticide or of drinking water safety.
Available immunoassay screens and most commercially available quantitative tests and analyses cannot detect many pesticides or breakdown products that may be contaminating a private well. Nevertheless, results of qualitative immunoassays or quantitative tests and analyses may help determine if routine screens, tests or analyses are warranted to verify any health concerns.
Pesticide & Fertilizer Management Division