21.   Although most researchers say HIV, the virus that causes AIDS, is not easily transmitted through oral sex, they caution that such transmission is possible.

22.   Although the Baltimore study was conducted among inner city youths, the researchers said the disease is common among all population groups.

23.   Although the current study found no hint of an increase in breast cancer, the researchers said three years was not long enough to assess such a risk.

24.   Although the findings had been shadowed by revelations last year of scientific misconduct, researchers said that fudged data did not change the conclusions.

25.   Although the researchers said that chemical pollution might have contributed to the mutations, they thought the more likely cause to be radiation.

26.   Although they cannot point to specific damage resulting from the loss of birds, some researchers say they fear damage to trees may be under way.

27.   Although these vaccines are safe for human use, it is not yet clear how effective they are, researchers say.

28.   Among adolescent psychiatric patients, for example, the researchers said it was five times harder for those without insurance to be admitted than for those with insurance.

29.   An older woman with a positive test for the virus should then have further tests to look for cancer or precancerous conditions, the researchers said.

30.   An antidepressant drug can help people quit smoking, even those who are not depressed and would not normally take such a medication, researchers say.