What is it that dentists are doing that exposes people? Mercury in dental amalgam fillings primarily, but there are other materials that may be addressed soon. Due to the multiple metals in saliva scenario, an electrical current is generated in fillings in the mouth. Amalgam (the common silver-mercury filling) emits mercury when electrical charges are generated within them. This mercury can either be inhaled into the lungs where it has access to the blood stream, or it can be mixed with foods and saliva, and enter the stomach, where it is eventually absorbed into the blood stream. From the blood stream, mercury has access to all tissues in the body, for there are no barriers to the entrance to mercury. It readily crosses the blood brain barrier as well as the placental barrier.

There are only two well-documented sources of birth defects in our society. One is X-radiation, or X-rays, which we all know we should avoid during pregnancy. The other is mercury exposure. It should be publicized that we actually encourage mercury exposure during the first trimester of pregnancy. Obstetricians frequently recommend that pregnant women visit the dentist right away and get any cavities filled (with mercury fillings usually) so that they will be less likely to have an abscessed tooth during the final weeks of discomfort just prior to delivery.

How can dental mercury produce birth defects? What are the mechanisms? During normal cell division, our cells undergo a process called mitosis in which all the internal substance of a cell duplicates itself, then the contents divide evenly, and migrate to opposite ends of the cell until the cell looks something like an exercise dumbbell. Finally it squeezes itself in the middle until it separates into two identical cells. Mercury can stop this duplication process at any of its multiphasic steps resulting in an abnormal cell. If this new cell is capable of reproduction, then the abnormality may show up as a birth defect. If it is deep within a tissue, it may alter the function of a tissue or organ without being readily observed.

Another common mechanism for creation of birth defects is to alter one's chromosomes. Chromosomes are your genetic code. Mercury is good at cleaving off segments of chromosomes so that they do not contain the appropriate number of genes. If a break occurs at the planning and initial growth stage of pregnancy, then several things can happen. If chromosomal damage is in critical areas like the heart or brain, this usually produces a spontaneous abortion, or the mother's body will reabsorb the fetus. Non-critical defects, like alteration in the number of fingers, toes, etc, may be allowed to survive, but problems in the heart liver, kidney or brain will probably be aborted.

Another problem that is frequently overlooked is that a baby can not only be exposed to mercury from its mother during pregnancy, but if breast fed, the baby can still receive a source of mercury that can alter its growth and development patterns.

Mercury can be a pregnancy problem even prior to conception. Mercury has been found in the ovaries and testes of people who have been exposed to mercury. One researcher suggests that mercury in the ovaries could be responsible for the lack of implantation of fertilized eggs. He also states that mercury in the testes could be an adequate source of genetic disturbance to produce birth defects.

One researcher, Kuntz, identified that the number of dental fillings in the mother correlated with the amount of mercury in her blood. Since Chang has pointed out that the fetus is eight times more sensitive to mercury than its mother prior to pregnancy, people would be well-advised to know that a reduction in the number of fillings in both parents prior to conception could result in less exposure to their new baby.