This is not an article about possible toxic effects from megadoses of vitamins or minerals. Rather, it is information that all of you should know about chemical toxicity. Nowadays, almost everyone is exposed to a vast number of pesticides including insecticides, herbicides, and fungicides, petroleum solvents and cleaning agents; volatiles from paints and coatings; and other chemicals. Toxicologists, clinical ecologists, and those in the environmental sciences call these chemicals "xenobiotics."

Almost all of these xenobiotics are poisons because they interfere with normal metabolic processes, or with functioning of the nervous or immune systems, or they damage cell structure, which in turn alters or impairs our normal biochemistry. Some chemicals block enzymatic activity, some interfere with neurotransmitter process, while others disrupt membrane or cellular transport processes. Although pesticides are designed to kill insects, fungi, larvae of insects, and so on, the precise mechanism of poisoning in higher animals may be unknown. For example, the pesticide DDT was studied for many years before chemists and naturalists learned that it blocked an enzyme (carbonic anhydrase). Birds need this enzyme for proper calcium carbonate metabolism and eggshell formation. Despite the 1972 ban on DDT use in the United States, I have seen clinical laboratory work for many people contaminated even today with a breakdown product of DDT called DDE. In fact, in 1980 there was calculated to be one billion pounds of DDE in the world’s ecosystem. We don’t know precisely why DDT and DDE make humans sick, but they do.

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Almost all of these xenobiotics are poisons because they interfere with normal metabolic processes, or with functioning of the nervous or immune systems, or they damage cell structure, which in turn alters or impairs our normal biochemistry.

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The potential hazard of pesticides, including insecticides, herbicides, and fungicides, is categorized by the toxicity rating. This rating depends on the oral or dermal "dose" that is lethal to 50 percent of the animals on which it is tested. This is the "LD₅₀" dose; usually it is short-term, acute exposure under controlled experimental conditions. The animals used are usually white rats, though sometimes rabbits or mice are used. The LD₅₀ dose, or the toxicity categorization, may not reflect the relative hazard to humans, because conditions of exposure are different and because human metabolism is significantly different. Humans don’t make vitamin C, for example, while rats and rabbits do. The rating categories in the accompanying table are according to G.W. Ware, Complete Guide to Pest Control, 2^nd edition, Thompson Publications, Fresno, California (1988). A similar categorization with ratings for individual xenobiotics is available in M. Sittig, Pesticide Manufacturing and Toxic Materials Control Encyclopedia, Noyes Data Corporation, Park Ridge, New Jersey (1980).

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*mg = milligram = one thousandth of a gram = 0.000035 ounce
kg = 1000 grams = 2.2 pounds
mg/kg = milligrams/kilogram of animal body weight

Most pesticides (including insecticides, herbicides, and fungicides) and other petrochemicals are not water-soluble. They are oil- or lipid-soluble and, as a result, can wind up in the fatty tissue of our bodies. The liver does not have an enzymatic detoxification** process for altering these chemicals into forms that are water-soluble (going to kidneys and urine) or bile-soluble (going to intestines and fecal matter). To do this, the xenobiotic must be carried by the bloodstream to the liver, and the liver must have readily available the nutrients needed for detoxification.

Ten important factors and nutrients for detoxification are:

If you get into pesticide spray or a sprayed area, these additional measures could be helpful:

For those concerned with the possibility of chemical contamination or exposure to pesticides or other xenobiotics, there is a new laboratory test that your doctor can do: D-glucaric test of the urine. D-glucaric acid is a generic biomarker for many (not all) xenobiotics. An elevation on D-glucaric acid in urine can mean that a foreign chemical is present in the liver. (Alcohol and caffeine also can raise your D-glucaric acid level.) Your doctor can order this test from Doctor’s Data Laboratory in West Chicago (773-231-3649).