I am working on research toward a Ph.D. in chemical engineering. My husband and I are hoping to get pregnant, but I am concerned about my work environment and the effect it may have on the fetus. I regularly work with such chemicals as sulphuric acid, mercuric sulphate and diethyl ether. What is the risk associated with these? If I were to wear a mask over my nose and mouth, would that prevent any toxicity?

--C.N.

Mercury is the only compound you mention that is known to cause harm to a developing baby. Gloves and a mask should be worn to avoid breathing in the vapors or having the chemicals come in contact with your skin. Levels of mercury (and lead, too, if you are exposed to that) in your blood should be tested before you conceive, and, if they are elevated, should be allowed to normalize before conception.

You can get more information on potentially harmful substances by calling one of the regional teratogen information centers. In the Eastern United States, the number is 617-466-8474, and in the Western United States, it is 801-328-2229. REPRORISK is another teratogen information center, with a toll-free number: 800-525-9083. Online, you can check out the Organization of Teratogen Information Services (OTIS). You should realize that studies have not been conducted on all chemicals, so you need to get information as much as possible on the substances you are working with and take necessary precautions.