Two studies are adding to the debate about the health risks of eating fish containing highlevels of the metal mercury (水银,汞)。 One study __25__ that people who eat fish high inmercury may increase their risk __26__ a heart attack. Yet another study found no __27__ between mercury and heart disease.
Mercury is a natural __28__ . Some bodies of water have become __29__ with mercury.High levels of the metal have been found in large fish, __30__ shark and swordfish. Scientistssay mercury can be __31__ to people. For example, it can harm the developing brain of afetus(胎儿) or child. So some experts say that pregnant women __32__ fish containing highlevels of mercury.__33__ , the American Heart Association and other experts have __34__ Americans to eat fish at least two times a week. Fish __35__ important substances, and theyare believed to __36__ the risk of heart disease.
Scientists in Maryland organized one of the new studies. They examined __37__ recordsof more than one thousand and four hundred men from Israel and eight European countries.They __38__ men who had suffered a heart attack with healthy men. The study found that__39__ levels in the men who had a heart attack were fifteen percent __40__ than those withno history of heart disease. However, a study by the Harvard School of Public Health inCambridge, Massachusetts __41__ the findings. The Harvard scientists compared twogroups of about five hundred American men. All the men in one group __42_ a heart attackand the other men showed no __43__ of heart disease. The Harvard scientists found no linkbetween mercury and the risk of heart disease.
Many doctors say people should not stop eating fish because of __44__ about mercury.