Book Review 29
Review
Title: The Myths of Safe Pesticides
Author(s): André Leu
Editor(s):
Publisher: Acres, U.S.A., Austin, Texas, U.S.A.
ISBN 13: 9781601730848
Published: 2014
Pages: 142
Format: Paperback
Cost: $16.95
Rating (1-5): 5
Submitted By: Francis, Charles A.
Additional Reviewer: Joshua Miller
Date posted: April 03, 2015
Well-documented review of current pesticides and testing.
By Joshua Miller and Charles Francis, Univ. Nebraska – Lincoln, U.S.A.
Rarely does a book come out that explores the key issues of a controversial technology with the level of documentation as Myths of Safe Pesticides. Author Andre Leu, an organic farmer in Australia and currently the president of IFOAM [International Federation of Organic Agriculture Movements], presents a tightly referenced critique based on scientific publications about chemicals and their effects. The book presents a strong statement by this committed organic farmer who believes fervently in the dangers of undesirable impacts of chemical pesticides. To encourage people to read the book and to reach their own conclusions, we have taken a ‘point-counterpoint’ approach to reviewing this extensive review of relevant literature. One of us [J. Miller] has worked as a crop consultant with farmers in Maryland and Pennsylvania, recommending best management practices for use of all available technologies. The other [C. Francis] teaches science-based organic farming in a university class that objectively evaluates available organic production technologies and systems from the technical and practical points of view. We provide arguments on both sides of the pesticide controversy, and intend this as a guide for readers to evaluate key issues and reach their personal conclusions about this impactful technology. We examine the ‘myths’ one by one, giving support for each and then technical challenges.
Myth 1: “Rigorously Tested” [all agricultural pesticides are scientifically tested to ensure safe use]
Support: The book carefully examines current pesticide testing procedures and finds them sorely lacking, citing a presidential panel that points out the paucity of data on the majority of over 80,000 chemicals in use today. The author raises the issue of ‘cocktails’ of individual components that tested alone are below allowed limits, but that show enhanced biological activity when found in mixtures, a danger reported by Rachel Carson five decades ago. Likewise the dangers of untested ‘inert ingredients’ are not assessed in conventional testing, and formulations carry risks not detected by analysis of active ingredients alone. It is clearly impossible to test all possible combinations of the plethora of chemical components and added compounds, but there should be an attempt to do so. Lacking from the arguments is recognition of potential biological hazards of combining chemical and biological control agents, another hazard of untested cocktails that have yet to be tested.
Challenges: Although this book provides multiple citations to support the author’s claims, his choice of wording and examples may sabotage the effectiveness of key points for an audience not sharing his same convictions. The first sentence of Chapter 1 [“Rigorously Tested”] introduces a polarizing style of writing used throughout the book. The term “agricultural poisons” is used to describe synthetic pesticides used by the majority of farmers today [p. 1]. This introduces a consistent bias that conveys the author’s passion about actual safety of pesticides. His arguments are undermined by examples that are misleading, designed to generate outrage rather than inform the public. He challenges the lack of safety testing today and the claim that “only a few hundred of the more than 80,000 chemicals in use in the United States have been tested for safety”, and the reader will assume this refers to pesticides [p. 1]. In fact, the presidential panel that Leu is citing refers to all chemicals used in the United States, including industrial, medical, natural, and of course agricultural. The number this same panel cites for agricultural chemicals is 900 active ingredients, and none of these are categorized as ‘not tested for safety’. To be more effective, Dr. Leu should focus on 900 active ingredients he is warning against and use them to illustrate potential problems. He makes valid arguments that testing of pesticide products should be more thorough to include inert ingredients because these can have detrimental health effects. These points are diluted by over-exaggerated claims like his description of organophosphate insecticides, discovered by chemists developing nerve gases for World War II [p. 15]. Although this is true, it is not the issue at hand. Sarin gas used as a chemical weapon is not a pesticide used by farmers. Rather, safe chemicals that share similar constitutive properties like hydrophobicity and ester bonds represent the organophosphates used today in agriculture.
Myth 2: “Very Small Amounts” [residues are too low to cause any problems]
Support: Our lack of appreciation of non-linear dosage responses of test animals to chemicals raises the serious question of dangers from low doses that can cause endocrine disruption and other hormone-like reactions. Results of rigorous testing of chemicals reported in reviewed technical journals confirm the potentials for serious impacts on animal reproductive behavior, even with acceptable levels of these pesticides in our water. Although the graphs of diabetes incidence, thyroid cancer rates, and deaths due to obesity must be challenged as associational with increase in pesticide use, and there is limited epidemiological evidence for cause and effect, one must appreciate concerns about the ubiquitous presence of chemicals in our environment from pesticides and multiple other sources. Some natural pesticides have been selected for in plants through selection, yet many chemical formulations are not part of our environment, and thus we have no genetic history of human selection for resistance to new dangers, a point not included in this chapter. Is this a compelling reason to follow the preventive principle in future pesticide use?
Challenges: In the section describing pesticides applied at very small amounts, Dr. Leu introduces an interesting concept unknown to many readers: that non-linear dose responses may be non-monotonic[BS1] . This occurs when lower doses cause no response until a critical threshold is reached, and then the response increases again. These results plus the argument that fetuses and young children are more susceptible to adverse chemical effects are important concepts that merit further review. The quest to increase safety of products used in all segments of industry will never be complete. However, introducing these concepts as valuable warnings is overshadowed by the author’s desire to raise concerns over current products. Dr. Leu cites an example of a study from Pennsylvania to illustrate the effects of extremely low levels of pesticides, in this case atrazine [p. 43]. He claims that low levels of atrazine caused deformities in frog populations, while it is not mentioned that the study was primarily looking at the interaction between tadpoles and a parasitic flatworm, and that levels of pesticide were a separate variable. The actual findings indicate that tadpoles exposed to the flatworm developed abnormalities. The presence of three different pesticides did influence the rate of deformities, but that was not the cause as eluded to in the book. It is important to make sure that the whole story is told in order to have an honest conversation, particularly with polarizing issues addressed by this book.
Myth 3: “Breakdown of Pesticides” [modern pesticides rapidly biodegrade]
Support: We are lulled by current advertisements claiming that modern pesticides “are mostly biodegradable, and therefore do not concentrate in the food chain” [p. 49]. Although valid on the surface, the argument fails to examine the breakdown products and their potential dangers. A widely-publicized example is the impact of dioxin, a contaminant found with what was considered relatively harmless 2,4-D and 2,4,5-T components in Agent Orange, and that has caused untold human suffering in Vietnam[BS2] ; such emergent properties of pesticides are not anticipated nor tested for in current evaluations. The need for breakdown metabolite studies introduces further costly and near-impossible testing challenges due to the multiplicity of combinations of concern. Is this just a price we pay for ‘progress’ and for use of ‘convenient technologies?”
Challenges: To say that pesticide breakdown into secondary metabolites is generally not understood is an error. When pesticides, in particular organophosphate insecticides, are taken up by an organism, whether insect or mammal, they are metabolized either through a detoxification or activation process. The goal of this evolutionary metabolism is to rid the organism of the xenobiotic, or foreign compound, making it more hydrophilic and consequently more easily excreted. In making the pesticide more hydrophilic, some chemical processes such as oxidation actually activate the chemical making it more toxic. This is the case for many organophosphate insecticides such as malathion. The book states that this pesticide becomes more toxic when it is “broken down” [p. 50], but this is not unexpected. Dr. Leu describes the activation process to shed negative light on an apparent unknown consequence of pesticide metabolism. However, the oxidation of malathion from a relatively benign parent molecule to the more toxic metabolite malaoxon was better understood after introduction of the insecticide. This process is known to occur rapidly in insects (the target) and slowly in humans (non-target). An alternative metabolic process occurs in humans and other mammals, called hydrolysis, whereby malathion is converted to an inactive form. This process occurs rapidly in mammals, so the net effect of exposure to malathion is rapid activation in insects to toxic malaoxon, and rapid detoxification in mammals. Simply stating that pesticides can become more toxic when they “break down” is misleading the reader into believing that these processes happen randomly. The fact is that scientists, using knowledge about the physiochemical properties of pesticides and the unique metabolic processes employed by different organisms, design and test pesticides to be effective against target organisms while maintaining safety to non-target organisms that may come into contact. [BS3]
Myth 4: “Reliable Regulatory Authority” [trust us, we have it all under control]
Support: Voices from public regulatory agencies echo the claims of industry that pesticides are well regulated and pose minimal or no potential for human harm. In fact, as reported above, most ingredients and especially mixtures have not been tested, nor are there protocols for assessing the millions of combinations of pesticides, fertilizer components, and other compounds found together in the production environment. Of even greater concern is the apparent reliance of regulators on unpublished industry-generated testing data that has not been through peer review and replication by unbiased scientists without economic incentive attached to the results. Few scenarios could be more questionable for setting toxicity standards for chemicals that enter our food chain and bodies with regularity. The several graphs of increase in human diseases along with increased pesticide use are less convincing, since again they should not be taken to illustrate ‘cause and effect’, yet their coincidence does raise disturbing questions. The author’s call for greater reliance on “transparent, published, peer-reviewed science” [p. 79-80] is absolutely clear, and should be heeded in the future regulatory arena.
Challenges: The author addresses an important concept in the fourth myth when describing testing of pesticides and activities of regulatory authorities. Are standards in regulations adequate to account for the safety of all agricultural pesticides and their interactions? This question needs to be examined further to determine if further testing and additional criteria are needed to ensure the public is safe from unintended consequences of pesticide exposure. One daunting but key test is to determine interactions of pesticides within the environment and effects on the human population. Although almost impossible to achieve, with large numbers of pesticides in use, comprehensive testing is worth discussing. However, the author suggests that regulatory agencies around the world are consciously neglecting key data in regards to pesticide safety, when this is simply not the case. To encourage objective conversation about pesticide testing, Dr. Leu should have described the Food Quality Protection Act of 1996 (FQPA), a law that changed the way the U.S. Environmental Protection Agency (EPA) sets limits for pesticide residues in food and reviews pesticides for safety. Instead, he simply states that EPA is ignoring data [p. 59] while in reality the EPA now uses a method called the ‘risk cup’ that substantially increased the requirements for pesticides to be deemed safe. At present, the residue tolerance of any one pesticide in a group is based on total exposure to all of pesticides in that group. With this act, total potential aggregate exposure to the pesticide is considered, including from food, drinking water and other nonoccupational sources, instead of just dietary exposure. Today, ‘no observable effects levels’ (NOELs) established through laboratory animal testing must be reduced ten-fold to account for physiological differences between humans and test animals, another ten-fold to account for potential differences in susceptibility in the population, and potentially another ten-fold to ensure added protection for children who may be more susceptible. This means that when a NOEL is established, that number is reduced 1000-fold to account for the chance of increased susceptibility in the population. It is difficult to say that regulations are lacking when you actually examine laws that have been passed by the regulatory authorities.
Myth 5: “Pesticides are Essential to Farming” [we will starve to death without pesticides]
Support: One of the most compelling arguments found in advertising of chemicals and in the popular press is the absolute necessity of pesticides to produce enough food for a growing global population. This section presents documented cases of successful farming systems that operate without chemical pesticides. As the author points out, there is a paucity of research on non-chemical ‘organic’ methods of pest management compared to the mega-funds poured into chemical research. This is understandable, since our system rewards innovation and economic benefits from products that are protected by patents, and cultural practices or system designs without chemicals and without such legal protection have no benefits to the private sector. As clearly documented with peer-reviewed results, many agroecological non-chemical systems are highly productive using current information and technologies, and one could only speculate on their potentials if there were concerted research efforts toward improvement. Scientific reports from universities, research institutes, and FAO agree that there are untold potentials in organic and other non-chemical farming systems, and to ignore this would be to foreclose on one of the greatest opportunities we have to produce food with methods that are safe to us and to the environment.
Challenges: The last myth is one of the most important, and often a common ground for proponents of organic and of conventional agriculture. Those supporting ‘best management’ agriculture believe there is value in utilizing all available technologies and knowledge to create the best cropping systems conceivable to feed a rapidly growing population. The author does illustrate several examples where organic farmers are achieving high yields and profitable returns. These successes should be applauded and appropriate practices shared with all cropping systems researchers. Organic and conventional farming practices should not be considered mutually exclusive. Benefits of reduced tillage, crop rotations and cover crops have all been realized by organic farmers striving to increase yields, and are also being employed by conventional farmers to improve overall health and diversity of soil biota. Although most discussions make a clear division between organic and conventional farming, everyone is working towards the same goal of providing food in a sustainable and profitable manner to feed a hungry human population. Instead of demonizing either side, authors discussing agricultural technologies should find common ground where both sides can benefit from shared knowledge and cooperation.
Conclusions
From these evaluations of five key “myths”, with both support and challenges for each, we hope that serious readers will be encouraged to access this comprehensive review Myths of Safe Pesticides and promote objective discussions of the challenges we all confront with the wide use of chemical pesticides. Their proven benefits for maintaining food production must be examined along with potential negative impacts on people and the environment. We need to examine available alternatives for enhancing our safe food supply, and both local and global ecosystems must be rigorously evaluated as we chart a future course toward sustainable food systems. There is no debate about the importance of increasing food production in the most environmentally safe and economically efficient manner. World population is slated to reach over nine billion people, and rising demand for animal protein and adequate diets for those currently in poverty with limited access to adequate food is one of the compelling issues of our time. The questions before us are whether large-scale and appropriate use of pesticides is the only possible agricultural strategy to meet this demand, where to find objective evaluations of proven and future costs of this singular strategy, and if there are viable alternatives as suggested by the author? The future of pesticide use will be determined by further research results, exploration of alternatives, food safety testing, and public opinion that accompanies the interpretation of these advances. We urge students, teachers, farmers, and informed consumers to read this book and draw their own conclusions about the safest and most desirable strategy for a sustainable future.
Submitted by: Joshua Miller and Charles Francis, UNL