Consumers could soon be able to test their own foods for the presence of pesticides with a simple litmus-like paper "dipstick" that you merely dip into the food and watch for a distinctive color change in less than 5 minutes.

Detecting pesticides in foods today is a complicated process involving sophisticated test equipment that can take hours to detect and measure the amount of contamination. Now a new paper test strip method has been developed that permits consumers to test their own foods for contamination by common pesticides, according to professor John Brennan, who developed the new test method with colleagues in the Department of Chemistry and Chemical Biology at McMaster University (Hamilton, Ontario).

Consumers today must depend upon testing labs to detect and measure how much contamination with pesticides is contained in foods. Unfortunately, these tests can take hours to perform, and even then there is no standardized method of presenting the results to consumers. Some conscientious food store franchises take it upon themselves to perform such tests and post "no detectable pesticides" on produce, but today consumers are usually forced to choose more expensive "organic" varieties of foods to avoid ingesting pesticides.

Particularly in developing countries where the availability of organic foods is rare, and their expense prohibitive, an inexpensive procedure is needed to enable consumers to test their own foods for contamination by common pesticides. A recently demonstration of the effectiveness of the new paper dipstick method showed how they can be directly exposed to suspect foods, then read for level of contamination by how much color change is observed.

In a recent test on intentionally contaminated milk and apple juice samples, white paper dipsticks were fabricated and impregnated with the chemicals that change color when exposed to pesticides containing organophosphates. In the tests, the paper dipsticks were able to detect the presence and display the amount of contamination in the beverages. The tests took less that 5 minutes to perform, but nevertheless displayed results that were consistent with laboratory testing procedures that required hours to perform on expensive test equipment.

The scientists claim that their new reagent-less bioactive paper-based solid-phase biosensor testing method will be particularly appreciated in developing countries where the quick, simple testing procedure by non-skilled personnel can substitute for a lack of availability of expensive testing equipment and in some cases even the electricity to run a lab. The dipstick testing method also displays its results in an easy-to-read color-change format that can be interpreted by anyone, regardless of their language skills. In addition, the low cost of the paper dipsticks, which are prepared by inkjet printing of biocompatible sol-gel derived silica layers onto paper, should make the method easy to widely distribute, as well as eco-friendly and non-toxic.