Environmental Medicine, Part 4: Pesticides — Biologically Persistent and Ubiquitous Toxins

Alternative Medicine Review, Oct, 2000 by Walter J. Crinnion

Abstract

Although the use of pesticides has doubled every ten years since 1945, pest damage to crops is more prevalent now than it was then. Many pests are now pesticide resistant due to the ubiquitous presence of pesticides in our environment. Chlorinated pesticide residues are present in the air, soil, and water, with a concomitant presence in humans. Organophosphate and carbamate pesticides--the compounds comprising the bulk of current pesticide use--are carried around the globe on air currents. Municipalities, schools, churches, business offices, apartment buildings, grocery stores, and homeowners use pesticides on a regular basis. Pesticides are neurotoxins that can cause acute symptoms as well as chronic effects from repeated low-dose exposure. These compounds can also adversely affect the immune system, causing cell-mediated immune deficiency, allergy, and autoimmune states. Certain cancers are also associated with pesticide exposure. Multiple endocrine effects, which can alter reproduction and stress-handling capacity, can also be found. Limited testing is available to assess the toxic overload of these compounds, including serum pesticide levels and immune system parameters. Treatment for acute or chronic effects of these toxins includes avoidance, supplementation, and possibly cleansing.

(Altern Med Rev 2000;5(5)432-447)

Introduction

The objective of pesticide use to prevent crop loss from insects remains unachieved. K. Ausubel in his book, Seeds of Change, The Living Treasure, notes that since 1945 overall pesticide use has risen 3,300 percent, while overall crop loss due to insects has risen 20 percent in the same time period.[1] Ausubel reminds us about Martin Borlaug and the "Green Revolution," which introduced F1 hybrid seeds that provided exceptional crop yield when augmented by utilizing high nitrogen fertilizer. To protect plant growth, herbicides were needed to prevent weeds from competing for nutrients and space, as well as pesticides to prevent pest-induced crop damage.

The killing of primary pests with pesticides has paved the way for secondary pests to come to the fore. Where previously there were 10 primary pest insects -- defined as causing greater than one million dollars of crop damage per year -- there are now 300. Of the 25 most serious pests, 24 were previously secondary pests and 72 percent of these are now pesticide resistant.[1]

Non-Occupational Pesticide Exposure

Of the 2.5 million tons of pesticides used worldwide each year, less than 0.1 percent reaches the target pest.[2,3] Thus, 99 percent of currently applied pesticides are being released indiscriminately into the environment, many of which will persist for years and travel far from the point of application.

Chlorinated pesticides found in the soil can persist for decades. Dichlorodiphenyltrichloroethane (DDT-see Figure 1) has been shown to accumulate in soils where it was used agriculturally.[4] Soil-based DDT is incorporated into grasses growing in the soil, into cattle consuming the grass, and eventually into the milk and fat tissue of the cows.[5] While the half-life of DDT had been thought to range between 4-30 years, evidence from the Yakima River drainage in Washington State, and in other areas, points to a much more extended half-life.[6] The studies in this area show increased levels of p,p'-DDT in the soil and the persistence of ratios of p,p'-DDT: o,p'-DDT found in the parent compound applied 25 or more years earlier. This indicates that in certain soils DDT degradation is not occurring as rapidly as previously thought.

[Figure 1 ILLUSTRATION OMITTED]

Such persistence has been found in other areas of the United States, such as soil in Texas and New Mexico.[7] When soil previously used agriculturally is excavated to accommodate housing sites, DDT finds its way into nearby streams and rivers via erosive run-off. The study of the Yakima River drainage found DDT in 100 percent of the fish sampled from that river. Other rivers, such as the South Platte, show a multitude of organochlorine pesticides in both sediment and fish.[8]

When houses are built on previously contaminated land, pesticides can easily be brought from the soil (from residents merely being "outside," from working in the garden, etc.) into the house, where they contaminate the home as house dust, as previously shown to do.[9] Pesticide exposure via house dust has been shown to cause higher serum levels of pesticides than what is incurred by eating contaminated foods.[10] There is also the possibility of pesticide contamination of vegetables grown in the home garden.

Those compounds not trapped in soil, tree bark, sediment, animals, humans, or other stable material begin a wind-driven leapfrogging around the globe.[11] Volatile chemicals move more frequently whenever the ambient temperature is sufficient to volatilize them. Less volatile compounds, like DDT, stay in place longer before being volatilized again.

Residues of DDT and other halogenated compounds have been found in medicinal herbs picked in the forests of Poland and Germany, where no spraying of DDT in these areas has been reported.[12,13] In a Polish study, herbs from all regions of the country were found to contain pesticide residues. The authors concluded, "Pesticide contents in most of the herbal raw materials should be attributed to the global contamination of the environment."