Chemical pesticides are commonly used in agriculture to prevent crops from being eaten and damaged by insects, birds, weeds and other natural pests that have the potential to reduce a farmer’s yields. So yes, pesticides are helpful to farmers, but if they’re able to kill and deter living organisms, what impact can pesticide exposure have on human health, wildlife, and the environment? It’s a complex question, with multiple contributing and conflicting evidence and opinions. At the end of the day, pesticides are poisons. Unfortunately, they can harm more than just the pests at which they are targeted.
What’s in this article?
Wildlife poisoning: the silent killers in our food chain
Wildlife poisoning is one of the most serious impacts that our ecology is facing. This includes the use of herbicides and pesticides. When plants or animals are poisoned, this removes an essential organism from the ecosystem; one that can never be replaced.
To prevent poisoning of wildlife, farmers need to stick to instructions on pesticide labels, follow the warnings and precautions, and lock pesticides away when not in use. Farm workers should be trained on the safe handling of these inputs and warned against the potential threat of criminal syndicates that may want to get their hands on these products. Ideally, they should also be educated as to the value in the ecosystem of vultures and why it is critically important to maintain their populations.
Although safe handling of pesticides may help reduce instances of wildlife poisoning, the best solution is for farmers to move away from pesticide and herbicide use entirely. To some, this may sound like a lofty ambition, but, with a commitment to long-term, sustainable solutions, it is certainly possible.
An example of the effects of pesticide poisoning on wildlife
Vultures are nature’s clean-up crew; important scavengers that are able to dispose of carcasses more quickly and efficiently than any other vertebrate on Earth. Sadly, hundreds of these birds have been found dead as a result of poisoning. The decline in apex scavengers like vultures can drastically alter food webs, as well as impact disease management. Chemicals can also indiscriminately poison non-target carnivores, insects and other scavengers. The issue is made even more concerning by the fact that 69% of all vulture species are already listed as threatened or near-threatened; most of these classified as endangered or critically endangered.
Why are vultures being poisoned?
- Deliberate targeting for their body parts to be sold in muthi markets
- Sentinel poisoning to conceal a poached kill (to prevent having vultures circling around a kill and exposing the activities of the poachers)
- Livestock owners lacing meat, fruit and carcasses with toxic pesticides to kill predators
- Pesticides used by farmers in the area leaching into the natural environment.
The issue of vulture poisoning highlights the detrimental effects of pesticides on the delicate ecology of birdlife and other creatures that are integral to the natural circle of life. These poisons not only affect vultures and birds, but can have potentially significant effects on the health of humans, wildlife and the ecosystem.
People and pesticides: what’s the cost to human health?
In an opinion piece published in the March 2019 issue of Acres U.S.A. magazine, André Leu – an Australian organic farmer, author and director of Regeneration International – discusses how current methods of testing miss most diseases caused by pesticides. Leu is the author of The Myths of Safe Pesticides and Poisoning Our Children books in which he delves into a wealth of respected scientific journals to present peer-reviewed evidence that disproves the claims of chemical companies and pesticide regulators.
What is the most common cause of pesticide poisoning?
Most of us get our exposure to pesticides from the food we eat. We are also exposed to chemicals in body care and household products. Yet neither the pesticide and medical industries nor the government regulators have any evidence to state that known nerve toxins are not contributing to the current non-communicable chronic diseases (NCD) epidemic.
Some people are more vulnerable than others to the harmful effects of pesticides:
- Infants and young children – whose organs, nervous systems and immune systems are still developing
- Farmworkers can be exposed to pesticides in agriculture through the treatment of crops and livestock
- Pesticide applicators
- Those who live close to where pesticides are used can be exposed to pesticide drift
- Pesticide residues found on (and in) our food also puts us at risk.
What kind of poisoning can be caused by pesticides?
According to Pesticide Reform, pesticides can cause adverse acute (short-term) health effects as well as long-term, chronic effects that can occur years after exposure.
Signs of pesticide poisoning in humans include:
- Stinging eyes
Examples of known chronic effects include:
- Congenital disabilities
- Reproductive harm
- Neurological and developmental toxicity
- Disruption of the endocrine system
Chronic health effects may not appear for weeks, months or even years after exposure. This makes it difficult to link these health impacts to pesticides.
Why should we be concerned about pesticide poisoning?
The World Health Organization (WHO) suggests that there is a global epidemic of NCDs, which are the leading (and growing) cause of mortality in the world. Examples of NCDs are stroke, heart disease, cancer, diabetes and chronic respiratory diseases. These are not diseases you can catch from other people; their causes are a result of environment and lifestyle.
The problem with OECD chemical testing guidelines
“The fact is that studies using Organisation for Economic Co-operation and Development (OECD) or similar guidelines that do not find cancer, autism or any other diseases, cannot say that a chemical does not cause these diseases. The absence of a disease in these tests does not mean that it does not cause the disease and is safe. The opposite is true. It means there is no evidence that the chemical is safe.”
Leu believes that pesticides and chemicals are strongly implicated in this global epidemic of NCDs. However, he says that the full extent of their role is being ignored by researchers and health professionals: “This is because the current best practice testing guidelines for pesticides, food additives and chemicals are designed to miss the majority of diseases.”
The OECD Guidelines for the Testing of Chemicals are regarded as best practice for testing animals for diseases caused by chemicals. Essentially, Leu argues that the guidelines sizes for animal testing groups are too small to achieve accurate results. The guidelines require a test group of at least 100 animals and a control group of at least 100 animals. Each group must contain at least 50 animals of each sex. So, if you are testing for cancers caused by a chemical, for example, the numbers of cancers in the test group are compared with the number of cancers in the control group. If the numbers are the same, then the researchers will conclude that the cancers were not caused by the chemical, allowing people to say that a chemical or pesticide does not cause cancer.
Let’s say that just one animal from the test group gets cancer. The results will then say that the chemical caused one animal in 100 to contract cancer – 1%, or 1,000 people per 100,000. But what if the actual rates of cancer from environmental exposure are below 1% (as they often are)?
In humans, rates of diseases are reported as the number of people with the disease per 100,000 people. The U.S. Centers for Disease Control and Prevention (CDC) reports incidences of these common types of cancers as follows:
- Lung cancer: 57.5 people per 100,000 (0.0575%)
- Colon and rectum cancer: 38 per 100,000 (0.038%)
- Non-Hodgkin lymphoma: 18.4 per 100,000 (0.0184%)
- Leukemias: 13.2 per 100,000 (0.0132%)
- Pancreatic cancer: 12.8 per 100,000 (0.0128%)
- Liver and intrahepatic bile duct cancers: 8.3 per 100,000 (0.0083%)
All of the above cancers occur in far less than 1% of the population, meaning that a group of 100 animals simply cannot present sufficient evidence.
The problematic testing methodology is further exacerbated in that some cancers are more common among (or only apply to) a certain sex, whittling the test group down to only 50 animals because there are just 50 animals of each sex in a group. For these reasons, Leu says: “There is no statistically valid way to determine that a dosed group of 100 animals that shows no sign of cancer can determine that the chemical in question cannot cause cancer at rates below 1,000 people per 100,000. All of the current cancers found in our communities will be missed.”
Studies that use OECD or similar guidelines that do not find cancer, autism or other diseases, cannot conclusively say that a chemical does not cause these diseases, because the absence of a disease does not mean that the chemical does not cause the disease and is safe. Leu says that the opposite is true – it means there is no evidence that the chemical is safe. “In my opinion, it is a gross misrepresentation to say that any of the current published toxicology studies can be used to say that any of the thousands of pesticide products used in the world do not cause cancer or other diseases,” Leu says.
The link between glyphosate and the autism spectrum of diseases
Glyphosate is a herbicide that is applied to the leaves of plants to kill both broadleaf plants and grasses. It’s one of the major ingredients in the weedkiller Roundup. Along with negative impacts on the environment and manganese uptake in plants, glyphosate came into the spotlight when groundskeeper Dewayne Johnson won a massive civil case against Bayer’s Monsanto, claiming that Roundup caused his cancer. A paper by the International Agency for Research on Cancer (IARC) showed how glyphosate caused cancer in test animals, although the manufacturer states that it does not cause non-Hodgkin lymphoma or any other cancer. Nevertheless, the decision by the IARC and the verdict in the Dewayne Johnson court case agreed that glyphosate is linked to non-Hodgkin lymphoma.
Leu says that the published studies on glyphosate (and other pesticides) use numbers of animals that are too small to detect any of the current cancers, and therefore there is no basis to say that it doesn’t cause cancer. Looking at non-Hodgkin lymphoma as an example: this cancer affects 18.4 people per 100,000 in America. This means that to positively determine that glyphosate does not cause non-Hodgkin lymphoma, an experiment would need a control group of 100,000 rats along with three dose groups of 100,000 rats each – 400,000 rats in total. But guidelines suggest that only 100 animals are required per group, which doesn’t give the disease sufficient chance of presenting in this small sample size. There is no published evidence that a study of the adequate size has ever been done on a pesticide.
The developed world is currently experiencing an autism epidemic. “A dramatic increase in a disease like this should be attributed to environmental and lifestyle factors rather than genetics,” Leu says. The brain is the largest collection of nerve cells, and pesticides such as glyphosate are significant contributors to the ADHD, autism, schizophrenia and bipolar spectrums of diseases because of the way they damage developing nerve cells.
However, there are a number of reasons that chemicals are not being found responsible for an epidemic like autism, such as:
- The failure of current best practice testing guidelines, which need to be changed to reflect the real rate of diseases in our communities
- There has never been any testing of diseases in children
- Test groups are statistically too small
- Since autism can be evident at birth, there needs to be testing on the mother and foetus
Leu cites the peer-reviewed scientific papers by Samsel and Seneff, which have extensively reviewed the published medical and scientific literature on glyphosate. Their findings? That glyphosate is responsible for disrupting multiple metabolic and other biochemical pathways in animals. Samsel and Seneff presented a significant amount of peer-reviewed scientific evidence about the harm that glyphosate causes, which government regulators, the pesticide industry and some research scientists have rebutted, stating that glyphosate is not toxic enough to cause multiple diseases. However, these deniers have no evidence of its safety.
What are the harmful effects of using chemical pesticides in agriculture?
“In a chemical arms race, it’s the insect pests who are winning the war. For every 1 pest species, there may be as many as 1,700 non-pest insects who have become the unintended casualties of this war.”
- Nicole Masters, agroecologist and educator based in New Zealand.
Nicole Masters’ book, For the Love of Soil: Strategies to Regenerate Our Food Production Systems highlights some of the concerns around chemical insecticide use in agriculture. The book equips producers with knowledge, skills and insights to regenerate ecosystem health and grow farm profits.
In the early 1980s, three main broad-spectrum pesticides were in use:
Agriculture relied heavily on these insecticides, but they were becoming increasingly ineffective as pests began to develop resistance to them. In response to growers’ concerns that their crops would be unprotected against chemically-resistant insects (along with increasing environmental awareness), new systemic chemicals were developed. Since these new insecticides move systemically inside the plant (instead of being applied through aerial spraying), manufacturers argued they would only target chewing insects, and were thus more targeted and far less dangerous.
Examples of systemic pesticides include groups of chemicals such as neonicotinoids and phenylpyrazole (fipronil).
- Fipronal is used in households around the world to control termites, fleas and cockroaches. In 2018, Fipronal used by wine farmers was purportedly responsible for the death of about one million bees in the Cape.
- Neonics are chemically similar to nicotine. They disrupt the nervous system of insects, resulting in “mad bee disease” and death. As these chemicals travel throughout the plant, non-target insects are exposed to them through pollen, dew and nectar. In a global analysis of 198 honey samples, 75% of all samples were found to contain at least one neonic.
According to Masters, pesticides are the most inefficient of all agrochemicals.
- At best, 1% reach their target sites
- Nearly all is lost to run-off, spray drift or degraded in sunlight
- Only 10% of neonic treatment is taken up by the plant, leaving the remaining 90% to effect non-target species in soil, dust and waterways
What impact do these chemicals have on the environment?
As neonic use exploded in the mid-2000s, so was there a sudden collapse of bee, butterfly and bird populations. The impacts of this are far-reaching, and potentially catastrophic.
Insects provide a multitude of benefits in an ecosystem, including:
- Nutrient cycling
- Feeding the food web
Ironically, the use of chemicals can actually cause an increase in certain types of pests. For example, mite populations boom when their natural predators (lacewings, ladybirds and parasitic wasps) are wiped out. Because mites lack the receptors that neonics target, they are unaffected by the systemic pesticides. And that’s not the only reason they proliferate.
In a breakthrough study, researchers uncovered that the activity of over 600 genes in the trees themselves was altered with the application of a single neonicotinoid. Many of these genes are responsible for detoxification, cell wall structure, and the switching on of phytohormones and enzymes involved in defence. Neonics were also found to increase the digestibility of nutrients, making more nutrition available for the mites and allowing them to multiply faster. In summary, the insecticide created optimal conditions to weaken the plant and invite other pests to the table.
It’s clear that broad-brush chemical controls have set agricultural systems up for the proliferation of pests and diseases?
Is it possible to go pesticide-free?
The use of pesticides in food production is currently a hotly-contested topic of debate. Can humans increase food production and feed a growing population without relying on conventional farming techniques such as pesticides? Developing pest resistance starts by having a healthy soil, which produces healthy crops. Effective soil-management practices boost the natural defence mechanisms of plants, making them more resistant and/or less attractive to pests.
Your regenerative farming solution
At Zylem, we believe in reducing (and possibly phasing out) pesticides as part of a sustainable farming solution. Using pesticides isn’t a regenerative solution to pest problems as weeds, insects, and other pests are able to develop resistance to the chemicals that are designed to destroy them. This means that chemical companies must constantly develop new pesticides.
By implementing sustainable farming methods and focusing on soil health, farmers can produce healthy plants and crops from the inside-out, instead of relying on potentially harmful chemical inputs. A healthy soil produces healthy plants that are pest- and disease-resistant, which means less reliance on pesticides and herbicides; and fewer herbicides and pesticides leads to less wildlife and habitat destruction and more diversity, allowing farmers to feed the world’s growing population in a sustainable manner.
Integrated pest management is safer and more sustainable. It uses a variety of methods to solve pest problems while simultaneously minimising risks to people and the environment.
These practices can include:
- Crop rotation
- Sanitation measures to remove disease vectors, weed seeds, and habitat for pest organisms
- Cultural practices that enhance crop health
- Introduction of predators of the pest species
- Nonsynthetic controls such as traps, lures, and repellents
- Mulching with fully biodegradable materials to suppress weeds
- Livestock grazing
Are you interested in investing in a future without harmful pesticides that also improves your profitability? Get in touch with the Zylem team to find out more about how to improve soil health, reduce chemical inputs and farm more ethically and sustainably.