What's gotten into you?

Modern science is now better able to address that question. Government scientists have put a number of our fellow citizens under the microscope to see just what has gotten into them. More precisely, the Centers for Disease Control and Prevention (CDC) has taken urine and blood samples from 2,500 people and analyzed them for 116 different chemicals contained in the things we eat, drink, inhale, or even touch.

It has long been known that our bodies carry around hundreds of substances that we have absorbed one way or another from the air, water, or food. So why is the government only now looking for those substances? The first part of the answer is, because it can. The technology is now available to detect extremely minute quantities of a number of substances - for some, less than a millionth of a gram, which is 30 billionths of an ounce. The second part of the answer has to do with CDC's goals to establish a baseline of what average citizens carry around in their bodies, broken down by age, gender, and other factors, to assess the effectiveness of efforts to reduce exposures, and to set priorities for research on whether the presence of any of these substances has any effect on health.

CDC found most of the chemicals it was looking for in its volunteers. CDC carefully pointed out that the mere presence of a chemical does not signify risk to health. Assessing risk is a far more complex task than just knowing if a substance is present in a body - it depends on many things, such as what the substance is, how much of it we carry around in our blood and tissues, and how long it lingers in the body. [see related Did You Know on Risk]. But the new data are helpful to assessing risk from environmental chemicals.

There are lots of things the biomonitoring data do not tell us. Unfortunately, the data don't tell us where the exposures came from, or whether individual values represent high or low exposures (were your plant estrogen levels high because you ate extra tofu for dinner last night?). Biomonitoring data alone can't be indicative of adverse health effects. Biomonitoring data alone doesn't constitute a complete exposure assessment (studies of absorption, distribution, metabolism, and excretion are needed to convert biomonitoring data into estimates of dose). These exposure and dose estimates in turn must be evaluated with toxicological data before they can be used to predict potential health risks.

All those interested in the protection of public health, from industry to environmentalists to health officials, agree on one point: the CDC work is an excellent beginning. But it is just the beginning. The process needs to be pursued over time to develop exposure trend lines and valid statistical findings. Only then will it begin to illuminate and improve the human condition.

Click here for information on biomonitoring data for phthalate metabolites.

Last Updated: August 12, 2003