WATCHING the amount of mercury in your diet does not have to mean avoiding seafood

You can eat a plate of salmon almost every day of the week. The same with fish fillet sandwiches, which are usually made from pollock. Both of those fish are on the New York City Health Department’s list of seafood that women of childbearing age and young children can eat five times a week without risk from mercury. The list and other information on mercury in seafood is available on a topics page at nytimes.com/dining

Also among the sea creatures with the lowest known levels of mercury are shrimp, oysters, clams, sardines, anchovies and herring, as well as the somewhat less exciting hake, tilapia, crayfish and whiting

And several of those fish also have good amounts of omega-3 fatty acids, which may help prevent heart disease: pollock, salmon, sardines, anchovies, and herring

Atlantic mackerel, crabs, and scallops also provide omega-3’s, but they have slightly higher levels of mercury. They are on the list of fish that the department says those women and children can eat up to twice a week, along with catfish, black cod, flounder, mussels, shad, sole, squid, trout, and whitefish. The department’s advice is based on a six-ounce serving

The federal Food and Drug Administration and the Environmental Protection Agency advice women and children to avoid king mackerel, shark, swordfish and tilefish, and limit their consumption of some tuna. But while concerns about mercury in those species are well known, many people would be surprised to learn that the city health department also advises women and children to avoid some other fish completely because of their high levels of mercury, including Chilean sea bass, grouper, Spanish mackerel, marlin and orange roughy

Many popular varieties of seafood, including black bass, striped bass, bluefish, halibut, lobster, monkfish, black cod, skate and snapper, are so high in mercury that the department suggests no more than one serving a week of any of them for those women and children

Not all scientists are convinced that mercury at the levels regularly found in fish causes health problems. And many researchers as well as seafood-industry advocates believe that the benefits of eating fish far outweigh the risk from mercury. But a panel convened by the National Academy of Sciences reported in 2000 that 60,000 children were born each year exposed to levels of methylmercury, the main variety found in fish  that could cause neurological and learning problems. This helped lead to warnings by the Food and Drug Administration and the Environmental Protection Agency, including a recommendation that women of childbearing age and young children eat no more than six ounces of albacore tuna a week and no more than 12 ounces a week of light tuna and other seafood with lower levels of mercuryThese warnings concern only the risks to developing children. But some studies have raised concerns about possible health effects of low levels of methylmercury for adults, including an increased risk for cardiovascular disease

A study last year by the New York City Health Department found that about one-quarter of New Yorkers tested had blood mercury at levels so high that by law they should be reported to state health officials for possible follow-up action. One reason, the department suggested, was that affluent New Yorkers were likely to eat expensive fish high in mercury, like swordfish and tunaThe study also found that foreign-born Chinese residents had a blood mercury level more than two and a half times that of the general population in the city. The fish highest in mercury are not frequently seen in Chinese kitchens but Chinese-Americans ate fish three times more often than others in the city, the study found

Even if someone is eating fish that has modest amounts of mercury, but they eat it twice a week, or three times a week or more, their mercury level is going to be higher,” said Daniel Kass, the assistant commissioner for environmental surveillance and policy at the Health Department. “That’s what we think is happening.” Both the health department and the federal Environmental Protection Agency will be testing mercury levels in various species of fish bought in New York. The city will be looking at fish for which there is little or no current data from the Food and Drug Administration, which oversees seafood safety