Body Burden (the “Rain Barrel”)
By Robin Bernhoft, MD, FACS
Classical toxicology deals with acute exposure to high doses of pollution. Environmental medicine, or clinical ecology, in contrast, deals with the cumulative effects of chronic exposure to low doses of pollution. Over the past fifty years or so, a great deal of work has been done in this hemisphere, Europe, Russia, China, Japan and Australia determining the impacts of chronic low doses of environmental chemicals (xenobiotics) on the health of humans and animals.
We now know that there are several dozen liver enzymes involved in processing and excreting chemicals which come into our bodies. These enzymes can be classed into two stages: Phase I, in which the structure of the toxic chemical is changed slightly, to prepare it for Phase II, in which another chemical is tacked on to the toxic one, making the combination water soluble, and therefore able to be excreted in the urine or bile.
The products of Phase I detoxification are often more toxic than the parent chemical, and if they are not quickly shunted into Phase II (and out of the body) they can do more damage than the parent chemical. Hence, it is vitally important that Phase I and Phase II be in balance, so damage is minimized.
This can often be accomplished through nutrition: one can supply vitamin and mineral cofactors for specific enzymes which will improve their ability to function and bring the system into balance.
That process is complicated in people who have genetic abnormalities (Single Nucleotide Polymorphisms, or SNPs) which alter the effectiveness of one or more detox enzymes. Often, though, these abnormalities can be over-ridden by supplying larger than usual doses of the relevant cofactors.
People in whom Phase I and II are functioning well can tolerate high doses of xenobiotic chemicals. This is why some people can smoke for 90 years and never get serious disease, while others can’t. Or why some farm workers with low levels of an enzyme called PON1 get very sick from pesticide exposures, while others with high levels do not.
If your body can clear whatever you take in, you never build up a significant body burden. (In the modern world, this is very rare – even Inuit women in the far north have high levels of xenobiotics from our part of the world in their breastmilk.) But if you take in more than you can excrete, the difference builds up over time. Most xenobiotics are fat-soluble and tend to deposit in fatty tissues, especially, for some reason, in the subQ fat of the back. They are released slowly, over time, like time-release capsules, into the bloodstream, and affect any number of bodily functions.
from Rea, W. Chemical Sensitivity. Lewis, Boca Raton 1992., vol 1 p. 182.
Dr Bill Rea, medical director of the Environmental Health Center – Dallas, explains body burden by comparing it to a rain barrel. Xenobiotic chemicals accumulate in the body like rain in a barrel. The last chemical in causes the barrel to overflow (producing symptoms), so patients usually consider themselves to be sensitive to that chemical. But if the barrel hadn’t already been filled with other chemicals, it wouldn’t have overflowed (they wouldn’t have developed symptoms). So the problem isn’t just the last chemical in, it’s the entire barrel full of accumulated toxins. Symptom relief usually requires lowering the level of toxins in the barrel (diminishing body burden through detoxification).
Total body burden of chemicals matters.
from: Casarrett and Doull’s Toxicology: The Basic Science of Poisons, Curtis D Klaassen, PhD, Editor, McGraw-Hill, New York, 2001, p. 136.
Selected References:
- Second National Report on Human Exposure to Environmental Chemicals, Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia, March, 2003.
- Kolaczinski JH et al. Chronic illness as a result of low-level exposure to synthetic pyrethroid insecticides: a review of the debate. Food Chem Toxicol. 2004: 42(5):697-706
- Weis BK, et al. Personalized exposure assessment: promising approaches for human environmental health research. Environmental Health Perspectives 2005; 113(7):840-8.
- Paustenback D, et al. Biomonitoring: is body burden relevant to public health? Regul Toxicol Pharmacol 2006; 44(3):249-61.
- Munoz-de-Toro M, et al. Estrogenic microenvironment generated by organochlorine residues in adipose mammary tissue modulates biomarker expression in ERalpha-positive breast carcinomas. Breast Cancer Res. 2006; 8(4): R47.