Researchers at UC Davis are seeking a patent on a simple, inexpensive method for detecting mercury pollution that uses the same principle as at-home pregnancy tests. Rather than antibodies, however, the new test uses sulfur-containing compounds that preferentially bind to mercury, which occurs naturally and as an industrial byproduct. "Mercury pollution is a global problem with serious implications for human health," says Ferenc Szurdoki, a postgraduate researcher who developed the new test with doctoral candidate Horacio Kido. (The work was done in the laboratory of UC Davis entomologist Bruce Hammock, who has pioneered the use of immunoassays to detect pesticides in the environment.) To test for mercury, the researchers coat proteins with a sulfur-containing compound that is chemically attracted to mercury. A water sample is then introduced along with certain "reporter" enzymes that attach to the sulfur compound and mercury. After the addition of another chemical, the enzyme triggers a chemical reaction that causes a color change indirectly proportional to the concentration of mercury in the sample.