Study Finds Chemicals in Pregnant Women; What Can Be Done About It?

You have probably already seen the headlines, ranging from the emotional "Pregnant Women Awash in Chemicals. Is That Bad for Baby?" to the simply factual "Toxic Chemicals Found in Pregnant U.S. Women." Yes, it heralds yet another study that confirms what toxicologists increasingly know: the plethora of chemicals in our environment and consumer products do stay in the body, from whence the once reassuring blood-brain barrier or placental barrier effects have proven less reliable than hoped. The study, Environmental Chemicals in Pregnant Women in the US: NHANES 2003-2004 was released online in Environmental Health Perspectives

Tracey Woodruff, director of the Program on Reproductive Health and the Environment at the University of California, San Francisco (UCSF) headed up the study, which analyzed data on chemicals detected in blood and urine samples taken as part of the National Health and Nutritional Examination Survey (NHANES). In addition to being fodder from Woodruff's study, NHANES is a powerful force for good health: the NHANES studies are behind advances like iron fortification of grains and cereals and the ban on leaded gasoline.

Take-away Message for Women

So what can we learn from a study that proves that over 99% of women have at least 43 of the chemicals examined in their bodies at the time of their pregnancy? Is this a cause to worry, if you are expecting, or even expecting to be expecting?

First, for the expecting women, let me answer with a resounding "No." Hakuna matata, don't worry. Just because we can detect a chemical does not mean it is present in sufficient quantities to cause harm. And it is not something you can control very well, so there are better things for you to prioritize. If you have some extra energy for preoccupation with what is best for your baby, then take your folic acid, get a balanced and nutritional diet, and good pre-natal care. If you have any of the clearly bad habits -- like smoking, alcohol, or drugs -- you may have to make an extra effort to do what is right for your baby.

Bottom Line for Science

But for the scientists and researchers, this study should be a trigger for more work on the topic. Clearly, the old model of toxicology is dead. Under the old assumptions, a person might be exposed to a chemical with toxic properties, but their bodies would soon eliminate or isolate the chemicals so that no further harm could be expected. It is not a terrible assumption: your magnificently efficient organs will reduce most exposures to what experts believe are harmless levels quite quickly. If this was not the case, you could take one birth-control pill and that would do it for the rest of your life (which would sort of defeat the utility). But clearly the clean-up process can only go so far. We are stuck with some left-overs for good. This is substantiated by the finding of chemicals in our bodies which have long since been banned, like PCBs.

Another old assumption holds that the amounts of chemicals found in women's bodies, barely detectable levels really, cannot be dangerous. As humans, we have a terribly hard time grasping extremely large or very tiny numbers, and consequently can barely communicate about such concepts. In the case of this study, the highest concentration of a chemical found in blood was 226 micrograms per liter of mono-ethyl phthalate (a chemical which is made when the body metabolizes diethyl phthalate, a common ingredient of cosmetics and personal care products).

To provide a context for understanding this number: the normal level of estradiol (the primary estrogen in the female body) ranges from 0.025 to 0.300 micrograms per liter. Any woman who has experienced the effects of menopause can tell you that chemicals at this level in the blood do have an effect on the body. While there is no reason to believe that any of the chemicals in this study have activities anywhere near the powerhouse estradiol, some of these chemicals are believed to mimic hormones. So it is conceivable that they may be active in the body at concentrations of hundreds or thousands of times that of biologically active molecules.