Women of childbearing years should limit consumption of fatty fish--- bluefish, salmon, striped bass, swordfish and fish from fresh waters, especially the Great Lakes.

      Air pollutants entering the water account for 58 percent of toxic PCB's, 86 percent of a cancer-causing substance contained in coal and wood smoke, and nearly all of the lead that enters Lake Michigan.

      In a November, 1988 progress report issued by the National Oceanic and Atmospheric Administration (which monitors both sediment off the U.S. coast and the levels of contaminants in various aquatic creatures) reported that the highest concentrations for any particular contaminant have been at the 20 sites near Boston, New York, San Diego, Los Angeles or Seattle. Among the contaminants found were polychloronated biphenyls (PCB's), polyaromatic hydrocarbons (PAHs) and 12 trace elements.

      In a study of 313 infants born to mothers who ate Lake Michigan fish contaminated with PCB's two to three times a month during their pregnancy, it was discovered that the infants weighed 7 to 9 ounces less at birth, showed developmental delays compared to mothers who didn't eat contaminated fish, and at 7 months scored more poorly on memory recognition tests.
      The larger the fish, the more contaminants are present.

      PCB's are also stored in breast tissue and can pass through breast milk to the baby.
      Shellfish are the most dangerous due to their ability to metabolize the compounds---sometimes 10 times higher than the levels found in fish. They do this in the liver, which also concentrates high amounts of the toxins.
      Therefore, the hepatopancreas, i.e., the tomalley in lobster or the "mustard" in blue crab should never be eaten.
      The same applies to fish livers and fish liver products such as cod liver oil.
[ It should be noted that eating shellfish and popping huge doses of vitamin C can prove fatal. Researchers in the animal sciences dept. at the University of Illinois report that several foods, especially shrimp and prawns, contain high concentrations of pentavalent arsenic compounds. These are normally harmless, but high doses of vitamin C convert the pentavalent compounds into trivalent arsenic, a highly toxic poison. ]

      The effects of eating contaminated fish can last a long time. W.R. Swain, a Dutch researcher, determined that starting with a 20-year-old woman who eats fish contaminated with PCB's and gives birth to a daughter, it will take five generations for the woman's initial PCB's levels to pass out of the family---provided that no more contaminated fish is eaten by her descendants.

      Cooking methods matter a great deal.
      A 9/88 Michigan State U. study found that dioxin levels decreased 46 percent in medium-rare carp fillets that were char-broiled and 37 percent in those roasted under covers, but only 24 percent in those roasted in uncovered pans. In fillets that were cooked to well-done, levels dropped between 50 and 60 percent, depending on the cooking method. It is suspected that the dioxin was lost in the drippings.

      Farm-raised fish are a safe bet, though not without drawbacks.
      Though the antibiotics routinely fed to the fish (namely oxytetracycline) are purged from their system by the time the fish are sent to market, the concern is that 90 percent of the antibiotics are excreted in the feces.
      Oxytetracycline persists in the sediment below fish farms for months.
      Resistance to antibiotics could be transferred from bacteria that cause fish disease to bacteria that cause illnesses in people.