Richard R. MacMahon, Ph.D.
We have learned some bitter lessons concerning pesticides over the last fifty years. Our scientists have found that chlorinated hydrocarbons, PCB’s and dioxins all have persisted in the environment long after their manufacture and use was banned (Carson, 1962; Colborn
et al
, 1996; Tschirley, 1986). Yet we continue to use an enormous array of over 10,000 poisonous chemical formulations as pesticides to this day. And more of these toxic compounds are being approved for use each year. (Wargo, 1996) We have learned that these compounds are toxic in large doses, and that many of them are carcinogenic at much lower, sub-toxic levels. Recently we have begun to realize that many of these persistent chemicals also may act as hormone disruptors at low levels, causing abnormal development especially of the nervous, reproductive and immune systems (Colborn
et al
, 1996).
The fact is that we
all
have pesticide residues in our bodies, particularly in fatty tissue. There is virtually nothing that we eat that is not contaminated with these residues. The rational for permitting these toxins in our foods is that they are present at levels that are tolerated by our bodies. Thus there are tolerance levels assigned to almost all residues in foods. These are levels that have been calculated as “safe” by the FDA and EPA. Unfortunately they do not seem to have taken into account accumulation of these toxins in fatty tissues or the hormonal disruptions that may occur at very low levels (Wargo,1996; Colborn
et al
, 1996).
If we examine Figure One again, we can obtain a better sense of the methods by which many of these contaminants reach our food. Metals may be present in the soil naturally, or they may have been introduced from contaminated water, in pesticides or as air-borne particulates. Water may be contaminated from run-off, from inadequate sewage treatment and from absorbing particulates from the atmosphere. Some atmospheric contaminants are present naturally, such as turpenes and ozone, while others are the products of man, such as acid rain. Many organic compounds in the soil are deliberately introduced as pesticides, while others come from the atmosphere and are deposited by rain.
Environmental text books often show accumulation of contaminants in the food chain (Miller, 1990), but they seldom seem to show what happens in cultivated ground. And this is extremely important because it is from cultivated fields that we obtain almost all of our foods. These same contaminants are present both in vegetables and fruits, and also in meats. All of our commonly eaten meat animals, including cattle, swine, sheep and poultry, derive all of their food materials from plants.
There are a great number of pesticides used on crops, and they are often used frequently. Some crops are sprayed up to twenty times a growing season. Why? For two reasons. First of all, they are sprayed to minimize loss to insects and other pests. Secondly, they are sprayed for cosmetic reasons. Each plant crop has cosmetic criteria, including color, surface appearance and blemishes. Many fungicides are sprayed to minimize surface blemishes. But these blemishes have nothing to do with the wholesomeness of the fruit or vegetable, only with the surface appearance. So why use them? Because all produce is graded, and the producer is paid based on the grade of his produce. Have you ever peeled a nice orange orange, only to find that the color comes off on your fingers? A cosmetic dye was used on that orange, and it probably was a carcinogenic aniline dye. How much got into the part that you ate?
One other serious problem that we have not discussed is what happens to these toxic residues once they are in garden produce. These residues are taken up by the plant along with water and minerals from the soil (Fig. 1). As such they are incorporated into the cells and tissues of the plant. They cannot be washed off, as can some air-borne residues. Thus we ingest these residues directly when we eat plants and secondarily when we eat animals (Wargo, 1996). And our bodies must deal with these residues as best they can. We have already seen that these residues may be both carcinogenic and act as hormone disruptors (Wargo,1996; Colborn
et al
, 1996). Unfortunately, even with the knowledge that we have, it is very difficult to get the government to act to eliminate the use of the pesticides in question.
In 1962 Rachel Carson alerted the country and the world to the dangers of chlorinated hydrocarbons, especially DDT. Wargo and Colborn have raised the same cry in 1996 with regard to pesticide residues of all types, especially their accumulation in children. But to this date the government has not responded in any decisive manner. Part of the problem is the fact that responsibilities for monitoring and regulating pesticides fall under the jurisdiction of three separate federal agencies Ð the USDA, the EPA and the FDA. These agencies use different sampling procedures, different analytical procedures and different statistical methods. The end result is that it is very difficult to obtain action from any of these agencies.
Another problem is one of human nature. It is very difficult for any of these federal agencies to admit that they made a mistake. Instead of admitting that their knowledge was imperfect ten years ago, they mostly hold to their original position regarding any pesticide. If they approved it, it must be OK to use it. (Wargo, 1996). A classic example is the mercury poisoning at Minimata, Japan. These victims are still, to this day, trying to get the Japanese government to admit that they were negligent (Smith and Smith, 1975). And it is virtually impossible to get a corporation to admit to culpability in these types of cases (Harr, 1995).
While the United States prohibits the sale and use of a number of pesticides, we are often the world’s largest producer of a prohibited pesticide (DDT is a good example). We export tons of these pesticides, mostly to third-world countries. And we get these pesticides back in imported produce, in what is called the “Boomerang Effect”. Each year we import more and more fresh produce from abroad. The cantaloupe you buy in the supermarket in February were not produced in this country, but probably came from Ecuador, Costa Rica or Mexico. And in these countries, they use pesticides that are prohibited in the United States, and some that have never even been registered in this country. So this is another way in which the residue level in our bodies is increased.
Is there any way by which the pesticide levels in our bodies can be lowered or at least held at present levels? Yes, there is. People can raise more of their own food, and do it pesticide-free. And this has been the entire point of this paper. I have attempted to show how growing your own crops in an organic garden can minimize the amount of pesticide residue that is entering your body. You may not be able to do much about those residues found in produce in the supermarkets, but you can cut down on residue intake if you use foods raised in your own garden. You may also buy produce raised pesticide-free, so-called “organic produce”. Some states now have requirements for organic certification by producers, and “certified organically-grown” seals on the resulting produce. (Armstrong, 1983; Bergin and Grandon, 1984).
Finally, let me say that most of the students I have taught in our program have become very enthusiastic about gardening the organic way. And most importantly they have gained self-respect and pride in being able to complete a garden of their own. For these reasons and for the health of our children, I urge you to try this unit. It is very rewarding both for students and teachers.
1. Environmental influences on soil and plant. (Note that some contaminants may enter the soil by more than one method).
(figure available in print form)
Figure 2. Simple Layout of garden plot
(figure available in print form)