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Explainer – An Overview of Pesticide Pollution

Photo by Henry & Co. on Unsplash

18th May 2021

“We have to do something before it’s too late,

To help save bees from a horrible fate.” – Hedgey-A and the Honey Bees

In December 2020, I self-published my debut children’s picture book, Hedgey-A and the Honey Bees. Hedgey-A looks at how pesticides are harming bee populations and sets out to save the bees with a visit to the Queen. This fun book is aimed at introducing a younger audience to a difficult topic. Print copies are available here in the UK, or from global Amazon stores.

We rely on bees and insects to pollinate three-quarters of crops, meaning that they are of vital importance to our food supply. Yet bee populations are in stark decline, and it’s believed that pesticides have played a significant role in this.

In this post I therefore wanted to explore some of the impacts of pesticides. Some startling pesticide facts include:

  • Some pesticides are absorbed by plants, meaning they are inside fruit and vegetables. So simply washing the outer surface may not rid your food of pesticides in all cases.
  • Pesticides such as neonics can persist for up to 19 years in the soil. They can contaminate water courses and entire ecosystems as they enter groundwater, rivers and lakes.
  • Pesticide companies have aggressively lobbied against legislation changes, going as far as ‘buying’ scientists and attacking those who publish negative findings about pesticides, according to a report by the United Nations.
  • The United Nations’ damning report about pesticide companies, explored the ‘catastrophic’ effects pesticides have on people and the environment and is a must-read for anyone wishing to understand the industry further.
  • Organic agriculture has access to 28 pesticides under EU legislation (compared to 490 pesticides for conventional farming). Of these 28, the Pesticide Action Network only has concerns about two of them and notes that pesticide residues are rarely found on organic products.
  • We can grow enough food without the use of pesticides.
  • Neonics are some of the most widely used pesticides today. Neonics are 10,000 times more powerful than DDT, which Rachel Carson wrote about in Silent Spring.

The implications of pesticide use are therefore far-extending. Things we eat or drink could potentially be contaminated by pesticides. Swimming in rivers, lakes and seas may expose us to these toxins. Living close to farmland (or on former agricultural land recently turned into housing developments) could bring a plethora of health risks if the previous owner used pesticides on their crops.

These are just a few of the reasons why a ban on pesticides is necessary. But before we get into that, let’s explore some of the most common pesticide questions.

What are pesticides?

“This industry is a child of the Second World War. In the course of developing agents of chemical warfare, some of the chemicals created in the laboratory were found to be lethal to insects. The discovery did not come by chance: insects were widely used to test chemicals as agents of death for man.” – Rachel Carson, Silent Spring

The World Health Organisation (WHO) defines pesticides as, “Chemical compounds that are used to kill pests, including insects, rodents, fungi and unwanted plants (weeds).” The European Commission splits pesticides into two groups: Plant Protection Products (PPPs) and biocides. It’s estimated there are more than a thousand types of pesticides in use today.

What’s the difference between pesticides, insecticides and herbicides?

Pesticides are an umbrella term for chemical products that are used to kill ‘pests’. In this sense, the word ‘pests’ is quite vague and encompasses, amongst other things, insects, fungi, weeds, rodents and bacteria.

Other types of chemical products fall under pesticides, but were designed with specific purposes in mind. For example, insecticides kill insects, herbicides kill weeds, fungicides target fungi and parasiticides destroy parasites.

What are neonicotinoids?

Neonicotinoids (neonics) are a type of systemic pesticide, which means they are absorbed by plants through their leaves, roots and flowers. George Monbiot has described neonics as “the new DDT”, noting that when similar volumes are compared, neonics turn out to be 10,000 times more powerful than DDT.

Launched in 1991 by Bayer, they are now applied to over 140 types of crop, targeting insects such as aphids and grubs. As of 2014, they accounted for around a quarter of pesticide sales, and have now become the most commonly used insecticide around the globe. According to the Pesticide Action Network UK (PAN UK), the use of neonics in the UK increased by 232% between 2000 and 2016. In the US, neonics are applied to 150 million acres of crops annually, in the form of seed coatings for wheat, corn, cotton and a range of other crops. Garden Organic estimates that almost 100% of corn grown in China, Canada and Australia is treated with neonics.

Neonics have three primary active ingredients, comprised of thiamethoxam, clothianidin and imidicloprid. These active ingredients increase the toxicity of the landscapes where they’re applied, which has resulted in a cascade of environmental issues.

How do pesticides work?

Pesticides can work in different ways, depending on the type used. Organophosphates, carbamates and thiocarbamates work by interrupting nerve impulse transmissions. The Canadian Centre for Occupational Health and Safety (CCOHS) goes on to explain that an enzyme called cholinesterase is disrupted, and this in turn is responsible for regulating a neurotransmitter called acetylcholine. Without acetylcholine, muscles are not able to contract properly and functioning is impaired. Meanwhile organochlorines and pyrethroids work by interfering with nerve-impulse transmission.

According to the NRDC, neonics are typically applied to a plant’s roots or coated on their seed. When an insect ingests the pesticide, it attacks their central nerve system. It destroys their nerve cells, after binding onto them and overstimulating them. The result can be twitching, uncontrollable shaking or paralysis, followed by death.

Are pesticides banned in the UK?

Pesticide policies used to be set at the European Union level. However, there is some uncertainty what route the UK will go down post-Brexit. PAN UK, sets out the UK’s possible policy routes in a handy guide here.

When it comes to neonics, there are two which are currently allowed for use in the UK. According to the Pesticide Action Network, these are thiacloprid and acetamiprid. But thiacloprid is believed to harm human health and therefore is being removed from use.

The Conservative government came under fire in 2013, as one of the former Ministers for the Environment, Owen Paterson, promised Syngenta – one of the chemical companies – that he would intensify his efforts at preventing a ban on insecticide use.

What are the disadvantages of pesticides?

There are many negative health and environmental impacts associated with pesticide use. These will be discussed in more detail below.

Which pesticides are the most persistent?

Some pesticides persist for long periods of time, and pose significant risks as they ‘biomagnify’ their way up food chains, according to the WHO. The CDC notes that most persistent pesticides are organochlorine pesticides. Some examples of persistent organic pollutants (POPs) or persistent toxic substances (PTS) provided by the WHO include: chlordane, aldrin, mirex, DDT and toxaphene. These are all examples of organochlorine pesticides.

Neonics can also last for up to 19 years in soil, and accumulate over time, meaning that the toxicity of the soil increases with each additional application. Seeds coated with neonics have a toxic concentration for 2-3 weeks, while neonics applied to trees can remain at a toxic concentration for more than 3 years.

Which pesticides are the least persistent?

Pesticides that are less persistent are known as non-persistent pesticides. The CDC lists several examples of non-persistent pesticides, which include: herbicides, fungicides, chlorinated phenols and cholinesterase-inhibiting pesticides.

According to PAN UK, “Older organophosphate and carbamate insecticides tend to degrade quite rapidly in the environment.” These are part of the cholinesterase-inhibiting pesticides.

Are pesticides bad for the environment?

Yes. Their persistence and toxicity make them a threat to a wide range of flora and fauna. Entire ecosystems can be impacted as pesticides bioaccumulate their way up food chains.

Pesticides can also accumulate in the soil, increasing the toxicity of the soil with each new application. Neonics can remain the soil for up to 19 years, while some may enter the groundwater or get washed into rivers which thereby contaminates more ecosystems and habitats. When rivers enter the sea, they also risk contaminating marine ecosystems.

A case study in point can be found in George Monbiot’s Guardian blog. He writes about a pesticide called chlorpyrifos, which was washed down a sink. The amount washed down “was equivalent – in pure form – to two teaspoonsful.” This amount was enough to pass through the sewage treatment works in Marlborough, where the pesticide evidently wasn’t ‘treated’. It continued into the River Kennet, where it destroyed the majority of invertebrates along a fifteen mile stretch of river.

What are the effects of pesticides on the environment and biodiversity?

Persistent pesticides like neonics, can remain active for up to 19 years. If the pesticide enters the soil, it can contaminate the soil and groundwater. The contamination of soils affect all the organisams that live within them. Researchers have discovered that pesticides negatively impact a range of organisms that include beetles, earthworms and springtails.

Where surface runoff occurs from rainfall, these pesticides can then enter watercourses. The NRDC notes that neonics have killed aquatic invertebrates, which also harms populations of fish and birds which rely upon them. In addition, butterfly and bird population decreases have been linked with neonics.

When one organism ingests pesticides, they can be passed on to the next organism that eats them, and so forth. POPs can therefore accumulate in concentrations in mammals, as they make their way up the food chain.

Are pesticides harmful to animals?

Yes. As mentioned above, pesticides can bioaccumulate as they pass up food chains. Friends of the Earth lists impacts on wildlife including:

  • Earthworms – pesticides can increase their risk of mortality, reduce growth and affect the activities of their enzymes.
  • Birds – According to an opinion article in the journal PNAS, neonics ingestion by birds is widespread and a study found that 100% of sparrows had neonics in their feathers. This is because birds consume arthropods (e.g. insects).
  • Butterflies – A study between 1985-2012, showed that areas with the most application of pesticides had a decline in 15 different types of butterfly.
  • Frogs, amphibians and reptiles – Tests conducted in the field and laboratories have linked pesticides with death in toads and frogs.
  • Mammals – a decrease in insects which has resulted from pesticide use is affecting populations of mammals such as hedgehogs, which rely on insects for food.

Are pesticides harmful to bees?

Yes, there are many adverse impacts on bees. According to PAN UK, pesticides can disrupt, “foraging behaviour, homing ability, communication and larval development.” Studies have shown that even low exposure to insecticides has affected bees’ immune systems, which has resulted in bees being more prone to infections caused by disease or parasites.

US-based research, which looked at 380 pesticides used in the country between 1992 – 2016, found that despite a reduction in pesticide usage, the toxicity impact has doubled in the space of a decade. To evidence just how toxic pesticides can be, George Monbiot writes that honeybee exposure to neonics, of 5 nanogrammes, will result in half of the honeybees dying.

How much is a nanogramme? A nanogramme is one billionth of a single gram. In 2016, 87,704 kilogrammes of neonics were sprayed in the UK alone. So to put that in context, the equivalent of 87,704,000,000,000,020 nanogrammes of pesticide were sprayed in the UK in 2016 – and we know that exposure to just 5 nanogrammes is enough to kill half of honeybees. It therefore goes some way towards explaining bee population decline.

A report from the Wildlife Trusts has therefore called on pesticide use to be halved by 2030, to help protect bees and other wildlife.

How do pesticides kill insects?

Neonics work by targeting the central nervous system. According to the Pesticide Action Network UK, “They bind to receptors of the enzyme nicotinic acetylcholine, causing excitation of the nerves, leading to eventual paralysis and death” of insects. This is more of an issue for bees, due to the fact that they have more receptors for the neonics to bind too. To compound matters further, bees also have less ability to ‘detoxify’ chemicals in their bodies, as they have fewer genes enabling this process to happen.

How do pesticides enter the food chain?

There are a number of ways in which pesticides can enter the food chain. Looking at the example of neonics, they are sprayed onto our plants and/or coat plant seeds prior to planting. When we either ingest these plants (for example apples, cherries, strawberries etc.) we may be exposed to residue from neonics. Neonics are also absorbed by plants, and the NRDC says this means that they’re inside some of our vegetables and fruits. There it’s not possible to simply wash them off.

Another source is through water. Neonics can stay in the soil for up to 19 years. When neonics are used for covering seeds, the NRDC notes that around, “5% of the pesticide is absorbed by the plant at best—the other ~95% stays in the soil.”  This means that with crop irrigation or rainfall, neonics can infiltrate and percolate through the soil entering our groundwater. Surface runoff can also wash neonics and pesticides directly into rivers, lakes or other water bodies which may be used for human consumption.

Pesticides also accumulate as they work their way up food chain, species by species. So it’s also possible that we eat animals which have ingested pesticides directly or indirectly.

Can pesticides remain as toxins on food?

Yes. A 2019 Guardian article quotes a report from the Environmental Working Group, which showed that around 70% of the USA’s fresh produce contained residues from pesticides. Kale was highlighted as a particular example of extreme exposure, with 92% of kale containing residues. Kale grown using current farming techniques could have as many as 18 pesticides present.

Not only are pesticides on the outside of fresh produce, but PAN UK notes that many new systemic pesticides are designed to be absorbed by plants and contained inside fruit and vegetables. As such, washing the surface of fruit and vegetables may not be sufficient to stop the ingestion of these pesticides.

Are pesticides harmful to human health?

Yes, there are many health impacts and side effects associated with pesticides. Silent Spring by Rachel Carson, is a great book for beginning to explore these impacts.

PAN UK defines some acute effects of pesticides as:

  • Headaches
  • Sore throat with/or a cough
  • Irritation of the skin and eyes
  • Diarrhoea
  • Vomiting
  • Nausea
  • Weakness and/or seizures
  • Death

The longer term chronic effects of pesticides listed by PAN UK can include:

  • Asthma
  • Depression/anxiety
  • ADHD
  • Parkinson’s disease
  • Leukaemia
  • Non-Hodgkin’s lymphoma

The most widely used pesticides today are neonics. These work by attacking the nervous system, and research has suggested that exposure in early life or inside the womb could be related to heart deformations, muscle tremors, memory loss and other developmental issues.

Can pesticides cause cancer?

There appears to be some uncertainty in the scientific literature about this. But the International Agency for Research on Cancer (IARC) is a leading research organisation funded by the WHO, and in 2015, they said that glyphosate was “probably carcinogenic”. Glysophate is used in a wide range of weedkillers, which could therefore constitute a possible link between pesticides and cancer.

Can pesticides cause Parkinson’s disease?

A study conducted by the National Institutes of Health and the Parkinson’s Institute and Clinical Center, showed that people who used paraquat and rotenone pesticides had a 2.5 times higher risk of developing Parkinson’s disease. This indicates that there is a link between the use of certain pesticides and Parkinson’s disease.

Are there pesticides in organic food?

The EU has approved 490 types of substance for use as pesticides. However, out of these 490, only 28 are allowed for organic farming, according to PAN UK. The majority of these pesticides have a low toxicity in regards to human health, aside from copper and pyrethrins, which PAN UK would like to see removed from organic farming.

However, PAN UK note that even though these 28 pesticides are allowed, “There is almost never a detectable pesticide residue present on organic produce.” This means that eating organic food can reduce our exposure to pesticides.

What pesticides are allowed in organic farming?

EU regulations have approved 28 pesticides for use in organic farming. Some of the active substances allowed for use in EU agriculture can be viewed in this list from PAN UK.

Why should pesticides be banned?

A report by the United Nations states that, “Few people are untouched by pesticide exposure. They may be exposed through food, water, air, or direct contact with pesticides or residues.” The report quotes figures from the Pesticide Action Network estimating that between 1m – 41m people are affected by pesticide exposure each year. It then goes on to list some of the risks related to pesticide exposure, which include: hormone disorder, sterility, Alzheimer’s, cancer and Parkinson’s disease. There are also an estimated 200,000 annual deaths from acute pesticide poisoning.

There are numerous environmental impacts, which have been discussed throughout this post. The report by the United Nations goes so far as calling them, “catastrophic impacts on the environment”.

The United Nations has also said that it’s a ‘myth’ that we need pesticides to feed a growing global population, and was highly critical of the tactics employed by the pesticide industry to maintain that pretence in this Guardian article.

There is therefore a clear case to move away from pesticide usage, to more traditional and less ‘catastrophic’ farming methods, which have notable success.

Why hasn’t a global ban come into place on pesticides?

A damning report from the United Nations (UN) shows that the wealth and power of pesticide companies has hindered any kind of meaningful reform or ban on pesticide use. The UN report states that, “The pesticide industry’s efforts to influence policymakers and regulators have obstructed reforms and paralysed global pesticide restrictions globally.”

The UN report goes on to accuse pesticide companies of more deceitful tactics, including:

  • “Companies often contest scientific evidence of the hazards related to their products, with some even standing accused of deliberately manufacturing evidence to infuse scientific uncertainty and delay restrictions. There are also serious claims of scientists being “bought” to restate industry talking points.”
  • “Other egregious practices include infiltrating federal regulatory agencies via the “revolving door”, with employees shifting between regulatory agencies and the pesticide industry.”
  • “Scientists who uncover health and environmental risks to the detriment of corporate interests may face grave threats to their reputations, and even to themselves. One of the most prominent examples are the actions of Novartis (later Syngenta), producer of atrazine, which engaged in a campaign to discredit scientists whose studies suggested adverse health and environmental impacts of this pesticide.”

To understand how these companies can be so powerful, one only need look at their revenues from pesticide sales. An investigation in February 2020 by Unearthed and Public Eye, showed the extent of pesticide company revenues. The report looked at the five largest pesticide companies in the world: Syngenta, Corteva Agriscience, BASF, FMC and Bayer Crop Science. These companies make up five of the six that are part of the CropLife International lobby group and trade association.

According to the report, chemicals which have been linked to birth defects, cancer or endocrine disruption, made up $3bn of the CropLife sales analysed. Glyphosate, which is one of the most popular weedkillers in the world, made up $1.1bn of these sales. Around $1.3bn of sales came from chemicals that are classed as highly toxic to bees, including neonics produced by Bayer and Syngenta. Highly hazardous pesticides (HHPs) made up $4.8bn of revenue. Low and middle income countries, such as India and Brazil, were the target for sales of HHPs.

Until governments shut the ‘revolving door’ and stand up to these pesticide companies by enacting new legislation, nothing will change. But governments have a questionable record when it comes to standing up to lobbyists (many of whom are involved in funding political campaigns).

How can we grow vegetables without pesticides? How can we get rid of bugs on vegetable plants naturally?

Organic farming uses far fewer pesticides, and of those used, few remain as residues on fruit or vegetables according to PAN UK. One type of sustainable farming is agroecology, which works in sync with nature. According to a report by the United Nations, “Agroecology is capable of delivering sufficient yields to feed the entire world population and ensure that they are adequately nourished.” A 2017 study concurred that nearly all farms could produce just as much food as at present, by using far fewer pesticides.

Friends of the Earth puts forward the case for moving away from industrial monocultures to more diverse farming practices, which can help restore soil nutrients and encourage more wild species such as those who would naturally feed on insects and pests, thereby reducing the need for pesticide use.

A world without pesticide use is therefore possible and is one we should strive to achieve as soon as possible. Policymakers need to be guided away from lobbyists, towards protecting our wellbeing and it’s up to us to make that a reality. Visit The Guardian, PAN UK or Georgina Downs’ website for further information.

My debut children’s picture book, Hedgey-A and the Honey Bees, is about the need to protect bees from pesticide pollution. If you live in the UK, you can purchase a copy online here.

Published inPesticide Pollution