Mercury Contamination of Commercial Fish Abstract: Mercury in its methylated form is teratogenic and neurotoxic and is of particular concern to pregnant women, women of child-bearing age, and young children due to the damage a developing child could suffer. The primary source of methylmercury for humans is fish consumption. Although many people consume fish for its health benefits, there is limited information on mercury levels in local commercial fish. I collected 3-5 samples of 34 different types of fish, shellfish, and shrimp from a local Fort Worth market spanning a period of two months. I examined the total mercury in each fish using a DMA mercury analyzer. Swordfish had the highest mercury content (1827.9 mean ppb) and catfish had the lowest mercury content (8.1 mean ppb). In many of the species, there was either an absence of data or deviations from published FDA information on mercury contamination, confirming the need for local monitoring of commercial fish to provide more accurate information to the public concerning mercury contamination in fish. Micaela Mercer and Dr. Ray Drenner, Biology Department, Texas Christian University, Ft. Worth, TX 76129 Introduction: Fish is an excellent source of low fat protein and omega 3- fatty acids in the diet, but many fish also contain high and unhealthy levels of methylmercury. Mercury contamination primarily affects the central nervous system but is also capable of affecting the kidneys and the gastrointestinal tract as well as causing muscle weakness, skin rashes, and hair loss 1 . The developing fetus is especially susceptible to mercury, which can damage the central nervous system, lower IQ, delay the onset of fine motor skills, and lead to poor verbal memory 2 . Many states have consumption advisories available for self- caught fish, but few state agencies have examined the concentration of mercury in commercial fish 3 . Methods: Over a period of two months, 34 different species of fresh fish, shellfish, and shrimp were purchased from a local market. Three to five samples of each species were collected. Each specimen was placed in a freezer bag, labeled, and frozen immediately. A 0.1-0.4g (wet weight) sample was taken from the muscle of each frozen specimen (Fig. 1). Total mercury was measured in parts per billion by the DMA mercury analyzer (Fig.2). Following EPA protocol, I used Mess-2 and PACS as references, multiple blanks, and two duplicates. Fig. 1 Fig. 2