Silent Spring II

from the Summer 1997 Food First newsletter

Recent Discoveries Reveal New Threats of Pesticides to Our Health


We have known since Rachel Carson wrote Silent Spring' in 1962 that pesticides accumulate in the food chain and cause cancer, and that we need to keep residue levels in our food low. But new findings brought to public attention suggest that pesticides have much more dramatic effects at much lower doses than previously suspected. In fact, these findings may be so grave as to question the entire notion of using pesticides to produce food.

As it becomes clear that many developmental and reproductive disorders are caused by the complex interactions of multiple pesticides with our hormone systems, a whole new area of pesticide research and policy discussion is emerging. New studies are showing that pesticides have many dangerous health impacts other than causing cancer. Additionally alarming is the significant synergistic effect when several pesticides interact.

Silent Spring warned us of health and environmental impacts, and brought pesticide use under public scrutiny for the first time in the early 1960s. Since then most research on the health consequences of pesticides has focused on cancer, trying to estimate the risk of specific cancers caused by individual pesticides as the basis for setting tolerance levels that government agencies feel are safe for human consumption.

This narrow focus on cancer silenced the voices of other scientists who were quietly studying many other pervasive and detrimental effects of pesticides on humans, animals, and the environment. These scientists are now amassing evidence revealing how complex the interactions between our body chemistry and pesticides really are, and how the multiple pesticide residues in our diet can magnify each other's effects.



Unfortunately pesticide policy is still focused on establishing tolerance levels for single pesticides and does not address combinations of pesticides, or even the cumulative impact of pesticides that function in similar ways. The Environmental Protection Agency sets a limit for how much of each pesticide is okay to have in our air, water, and food. But considering that over 700 pesticides are licensed for use in California alone, we are in fact all continually exposed to a diverse mixture of hazardous pesticides.



Concerns raised over the last 35 years have focused on acute toxicity and cancer. For years we have known that pesticides can kill or permanently harm people who work in direct contact with them. The acute reaction to many pesticides are well documented; affecting the liver, kidneys, lungs, skin, eyes, and brain. Long-term chronic effects on humans include a whole series of cancers, liver and kidney disfunction, sterility, neurological disorders and birth defects."



Since Silent Spring we have also known that pesticides that take a long time to break down in the environment accumulate in organisms as they move up the food chain. For example, the concentration of persistent organochlorine chemicals in lake water may be extremely low and well below the standards established by the U.S. Environmental Protection Agency (EPA). But in algae that concentration is increased up to 250 times. As the filter-feeding zooplankton eat the algae this concentration doubles; tiny shrimp eat so much zooplankton that the concentration jumps as high as 45,000 times that of the surrounding water. Fish eat the shrimp, and birds and other top predators eat the fish. These top predators have concentrations 25 million times that found in the surrounding water. Humans are top predators and thus can accumulate relatively high concentrations of pesticides through the food supply.'



New evidence indicates that proper functioning of the human body's endocrine / hormone system, can be severely altered by low-level cumulative pesticide exposure. This system is directly linked to our neurological and immunological systems, further increasing the risks and potential impacts of pesticide exposure. This evidence indicates that while low level exposure may not cause acute toxicity in adults, it can cause chronic reproductive, immunological, and neurological disorders. More alarming, low-level exposure to unborn children can affect a wide range of developmental processes from reproductive system formation to brain function.

The endocrine system is the central, internal regulator of body chemistry, coordinating the 50 trillion cells in our body into a controlled and integrated organism. Without it our body cannot function. This system functions by releasing specific hormones, each from one of over a dozen glands, into the bloodstream. Key glands include the pituitary, thyroid, pancreas, adrenal, and testis in men, and ovaries in women. Hormones produced in these glands are released into the blood stream where many of them bind with specific proteins which help them arrive at their final destination. Once they reach specific receptor cells of their target organs they cause very specific reactions. In turn, these reactions either increase or decrease the amount of hormone released, creating a self-regulating feedback loop. In this manner, the endocrine system controls an incredible number of biochemical functions ranging from the reabsorption of water in the kidneys to the regulation of blood sugar levels, from heart rate to responses of the immune system, and the timing of the menstrual cycle. Additionally, many important develop mental processes are controlled by hormones making this system of extreme importance for unborn babies and developing children.

It is now clear that a wide variety of pesticides and other industrial toxins (e.g. PCBs and dioxins) can distort the effects of hormones, sending the wrong messages to organs and disrupting the delicate balance of our internal biochemistry. There are many stages in this process which are vulnerable to this disruption, and different periods in our life when we are more vulnerable to specific types of disruption. Additionally, each stage of the process may be disrupted by different mechanisms.

The most commonly discussed type of hormone disruption is called hormone mimicking. A synthetic chemical binds to a receptor site and produces the normal response to a specific (absent) hormone. This can create unsolicited responses from receptor cells and may accelerate or prolong responses which were begun by hormonal glands. Another mechanism is hormone blocking. Here a synthetic compound binds to the receptor site and does not produce the effect of the hormone, but occupies the receptor site making active hormones ineffective. Other mechanisms include disturbing the production process of the hormones, interfering with the helper or transport proteins, suppressing hormones, and altering the breakdown of hormones once they have served their function.



In the last fifty years, human sperm count and quality has decreased, prostate cancer has skyrocketed, testicular cancer has nearly doubled, and the incidence of breast cancer has

increased by one percent per year for the last twenty years. Today it is estimated that one in every eight or nine women in the U.S. will develop breast cancer in their lifetime. While there is substantial evidence that endocrine disrupting chemicals including pesticides can cause these disorders, we still haveinsufficient evidence to directly connect these over-all trends.

The known impacts of endocrine disruptors for women include the disruption of normal sexual differentiation of the fetus, reduced ovarian function, reduced rates of fertilization, implantation, and pregnancy.

Exposure to organochloride insecticides is suspected to play an important role in breast cancer. One known mechanism involving organochlorines provokes a change in the natural breakdown of estradiol, the most predominant form of estrogen in women. Normally, estradiol is changed into one of two products: one is benign, the other is not. The deleterious compound binds to certain breast cells and causes continuous cell divisions. Uncontrolled growth of these cells leads to breast cancer. Excessive exposure to organochlorines can significantly increase the ratio deleterious to benign estradiol by-product. This ratio has become a biological marker of risk for breast cancer. It is estimated that forty percent of all cancers in women are hormonally mediated.

Endometriosis, an extremely painful reproductive and immunological disease, is on the rise and currently affects 5 million women in the U.S.. It too is on the probable suspect list of diseases caused by endocrine disruption. Additionally, women in Ventura County, California reported a synchronization of their menstrual cycles with the spraying of malathion in attempts to eradicate the Mediterranean Fruit Fly. While the mechanisms of this are not fully understood it is quite likely related to estrogen mimicking. Another study found that young women are reaching puberty at much earlier ages, raising additional troubling questions about the impacts of environmental estrogens.

For men, the suspected impacts of endocrine disrupting chemicals are reduced sperm production, reproductive system abnormalities and testicular cancer. Additionally, a recent study found a correlation between number of nearby acres sprayed with herbicide and prostate cancer deaths.

In males, one gene on the Y chromosome triggers the development of the testis. All of the other distinguishing features of male physiology are developed by the testosterone and androgen which are produced there. Some of the developmental disorders associated with hormone disruption in male newborns are undescended testicles (cryptorchidism) and abnormal urethral openings (hypospadias), which have also doubled in the last half century.

Documented effects of endocrine disrupting chemicals on wild animals include the low male hatching rates and survival in western gulls apparently resulting in same sex nesting among females. Alligators in Lake Apopka, Florida contaminated in 1980 with dicofol spilled by the Tower Chemical Company, have continued to exhibit reproductive problems, including underdeveloped penises long after water sampling has shown the lake to have recovered. We have seen the feminization of rainbow trout, masculinization of marine snails, mosquito fish, grizzly and black bears; and decreased hatching of bald eagle, Foster's tern, cardinal, mocking bird, and snapping turtle eggs; and reduced thyroid function of salmon and herring gulls.



A recent study published in Science showed that pesticides may be thousands of times more potent than previously thought. It demonstrated that, when tested alone, each of two particular organochlorine pesticides had to be at concentrations on the order of 100,000 times greater than natural estrogen to cause responses in yeast cells reactive to estrogen. Yet the same two organochlorines mixed together only required concentrations between 10 and 100 times more than natural estrogen to induce the same response. Thus, exposure to multiple pesticides may be thousands of times more potent in mimicking estrogen than was previously thought. A recent study found thirty percent of apples contain at least three different pesticide residues. Considering the diversity of pesticides found in our environment the increased potency of combined pesticides raises many questions. Does this mean that current tolerance levels set for individual pesticide residues allowed in our food are actually far above dangerous limits when combined? What are the implications for the unborn, children, and adolescents? In light of these findings, how should pesticide use be assessed? How should new chemicals be evaluated? And, what are the implications for future pesticide policy formulation?



The significance of the synergistic nature of pesticides is evident in light of the extensive use and accumulation of pesticides in both the environment and living organisms. Since WW II, world pesticide use has increased dramatically. In 1993, approximately 4.5 billion pounds of "conventional pesticide active ingredients" used for agricultural purposes were applied throughout the world; 24% of those pesticides or over 1 billion pounds used in the US alone-equivalent to 4.1 pounds per person. In 1995, California applied over 210 million pounds of active ingredient, (almost five percent of global use.) or an alarming 6.6 pounds per person. Actual pesticide exposure is nearly impossible to estimate on an individual basis because there are so many distinct exposure pathways. Pesticides are in our food, water, and air. They are now a nearly universal feature of our environment found in every ecosystem in the world. They're used not only in food production and commercial forestry, but also in our homes, schools, public parks, and work places. Pesticides are a pervasive part of our environment virtually impossible to avoid.



Even as we are now discovering that pesticides pose a much greater threat to society than ever suspected, the U.S. government is undermining already limited regulations. August 3, 1996 marked a new era for pesticide regulation roll back, as President Bill Clinton signed into law the Food Quality Protection Act, dramatically weakening the way we regulate the dangers of pesticides in our food. This new law, which President Clinton preferred to call the "Peace of Mind Act," cleverly eliminated the Delaney clause of the Federal Food, Drug, and Cosmetic Act which prohibited the existence of carcinogenic residues in all processed foods. As industry cheers "Ding-dong Delaney's dead," known carcinogens and other toxic chemicals are being allowed into our food supply, but only in quantities which are determined "safe" by the EPA. Policy makers, moved by major pesticide industry lobby groups such as the American Crop Protection Association (ACPA), have lowered our food safety standard from one of banning known carcinogens, to just "managing" the risk of having them in our food.

In light of endocrine disruption, this new reliance on tolerance levels and risk management poses many problems for consumers. First and fore most, a high proportion of pesticides registered for use have never had full toxicological studies and risk assessments performed on them. This is due to a lack of funding and political will on the part of state and federal agencies. Secondly, the only pesticides tested for endocrine disruption are those that are related to very specific events linking them to a rare health or environmental impact, thus bringing them under suspicion.

There is no routine screening protocol or series of tests for endocrine disruption that all pesticides must pass to get registered. Third, there are specific windows of vulnerability to specific endocrine disrupters such that we have different susceptibility at different ages. Thus each test must be done on the different stages of human development starting in the first trimester of pregnancy and continuing through adolescence and adulthood creating different tolerances for different stages of development. Fourth, pesticides react with the endocrine system in unpredictable ways', some are estrogen mimickers at low doses and estrogen blockers at high doses. Finally, tolerance levels based on single chemicals do not take into account the synergistic or additive effects of two or more endocrine disrupters or the cumulative effects of pesticides which have the same bio-chemical impacts on our bodies.

The Environmental Protection Agency has created the Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC) to try to address some of these issues. The work groups which have been established include members of the chemical industry, governmental agencies, university researchers, and public interest groups. The quantity of research that would be required to begin to set new tolerance levels combined with the poor regulatory and enforcement track records of our federal and state agencies bring this whole approach into question.

One of the most prominent examples of the lack of control by the Food and Drug Administration (FDA) occurred when illegal residues of chlorpyrifos, an organochlorine insecticide, were detected in Cheerios breakfast cereal. By the time it was discovered, over one year's worth of Cheerios had already been sold and consumed, and the FDA could not recall boxes already in commerce without declaring a public health emergency. Furthermore, General Mills sold the remaining 18 million bushels of contaminated oats as animal feed which, if used for either meat or dairy production, could still reach consumers through accumulation in the food chain. This contamination of our food supply is a direct reflection of the broader failure of the FDA's regulatory power.



If so many illegal residues already slip through the system, perhaps the FDA and EPA are not the answer. We must ask the more fundamental question: Is lowering tolerance levels and increasing pesticide monitoring an appropriate strategy to guarantee a safe and secure food supply?

The fact that we have residues of hundreds of industrial and agricultural chemicals in our bodies is a direct invasion of our most private property. Chemicals that present serious health risks, should simply be banned from use. Under such a policy, research would only focus on detecting those chemicals which cause such problems. This would eliminate the whole research task of developing tolerance levels and eliminate the risk rather than attempting but failing to manage it. Effective alternatives currently exist for most pesticides. The social costs of continuing their use outweigh the short-term economic gains they provide to the chemical and food companies.

Although organic food is more expensive than that grown with pesticides, the external costs of pesticides are not included in the price of commercially grown food. It has been very roughly estimated that a direct investment of $4 billion in pesticides saves about $16 billion in crop losses, but causes an estimated $8 billion in environmental and health costs to society. Five billion of that is paid for by society and not by chemical companies or direct users. Buying organic food from local farms not only enhances our own health and that of future generations, but also benefits us as it decreases pollution, supports local, small-scale farmers and makes farming itself more sustainable in the long run.

Environment watch