Skip to main content

From peregrines to european starlings

A federal court has ordered the US Environmental Protection Agency to ban the pesticide chlorpyrifos because it is harmful to human health.   This is good news for the environment as much as it is for human safety.

From peregrine falcons to European starlings

Just as peregrine falcons help alert us to the harmful effects of organochlorine pesticides,  European starlings alert us to the harmful effects of organophosphates.   The studies of these birds demonstrate the harmful effects on wildlife.



In 1973 I was a student of Zoology at Manchester University.   For my very first assignment, my tutor gave me the name of a species,  the peregrine falcon, Falco perigranus, and a set of dates, and asked me to do some research in the library and write a short report.

During the 1940s and 1950s, Derrick Ratcliff of the British Nature Conservancy noted a sharp decline in peregrine falcons across Europe. Soon after this observation correlations between eggshell thickness and reproductive failure in these falcons, other raptors, and fish-eating birds were discovered. The sharp fall in the population of falcons was due to the effects of a pesticide, DDT on egg-shell thickness.  The egg-shells were breaking, causing the dramatic fall in reproductive success and thus the numbers of birds.

Organochlorine pesticides

The discovery that organochlorine pesticides could reduce eggshell thickness in raptorial species is perhaps the most well-known and extensively documented event in wildlife toxicology.  These findings and evidence of human exposure to DDT led to a ban on their use in the United States in 1973, the year I started my studies in zoology, and in Europe in the 1980s.  Sadly, DDT is still used in pesticides in many parts of the developing world.

As a student, this story excited me because it showed the practical importance of pure nature research and conservation.  It continues to inspire me to this day.  We, humans, owe a great deal to the peregrine falcon! 

In this case, action was taken to ban these harmful organochlorine pesticides.  Now, studies reveal the harmful effects of other pesticides,  including organophosphates. 

Our understanding of organophosphates and the way they work as neurotoxins should at least have raised alarm bells for their effects on wildlife and on humans.  Any substance designed to be neurotoxic is likely to be just that.   It begs a question, why these alarm bells have been ignored. 

Assurances were given that these pesticides are used in very low doses in crop pesticides and the residues do not have a prolonged life.  Yet, evidence has accumulated for its harmful effects on wildlife beyond the 'pest' species.  

These pesticides are not specifically targeted at 'pests'.  They make little or no distinction between 'pest' bugs and non-pest bugs, or between bugs and other animal species. 

They work by disrupting brain function, and as such are particularly harmful to the developing brains of young animals, including human children.  They disrupt behaviour and cognition.   This is now recognised in the court judgement in the United States. 

In the northern bobwhite (Colinus virginianus), for example, low doses of organophosphate are found to affect the ability to avoid predation.

European Starlings

In the 1980s, studies with European starlings (Sturnus vulgaris) demonstrated reduced reproduction in birds nesting where organophosphate pesticides are used.   During the breeding-season starlings feed primarily on terrestrial invertebrates that live in direct contact with pesticides present in the soil. This was evidence of these pesticides affecting the food chain.

Onus should be on the agrochemical industry to show they are not harmful

Why then does it take so long for these effects demonstrated in the 1980s to impact policies?  Why have these pesticides not been banned sooner?   We have known they are neurotoxic.  They were designed to be so.  Their effects on wildlife were in large part predictable and predicated on their impact on the brains of animals. 

The problem lies in the balance between the ever growing demand for food, the agrochemical business, and the effects on wildlife.  In that balance the cost to wildlife has been ignored.  The agrochemical business is a powerful lobby.

The process of approval of pesticides needs to change.  The agrochemical industry must demonstrate that they are safe before approval is given, and not the other way around.  They should demonstrate the effects on wildlife and on the environment with systematic studies.  Else it takes many decades of poorly funded research to accumulate data showing such harms.  We should not rely on this suck it and see approach.

About the author: Ray Noble is a certified biologist and Fellow of the Royal Society of Biology

Comments

Popular posts from this blog

The lion and the wildebeest

Birds flock, fish school, bees swarm, but social being is more than simply sticking together.  Social groups enable specialisation and a sharing of abilities, and enhances ability, learning and creating new tricks. The more a group works together, the more effective they become as a team.  Chimpanzees learn from each other how to use stones to crack nuts, or sticks to get termites.  All around us we see cooperation and learning in nature.  Nature is inherently creative.  Pulling together becomes a rallying cry during a crisis.  We have heard it throughout the coronavirus pandemic.  "We are all in this together", a mantra that encourages people to adopt a common strategy. In an era of 'self-interest' and 'survival of the fittest,'  and 'selfish gene', we lose sight of the obvious conclusion from the evidence all around us.   Sticking together is more often the better approach.  This is valid for the lion as it is also for the wildebeest.   We don't

No evidence for vaccine link with autism

Public health bodies are worried that an alarming drop in childhood vaccinations is leading to a resurgence of diseases in childhood that we had all but eradicated.  Misinformation and scare stories about the harmful effects of vaccines abound on the internet and in social media.  Where they are based on 'science', it is highly selective, and often reliance is placed on falsehoods.  Conspiracy theories also abound - cover-ups, deception, lies. As a result, too many parents are shunning vaccinations for their children.  So, what does the published, peer-reviewed literature tell us about vaccincations? Are they safe and effective, or are there long term harmful effects?  A new report now provides some of the answers. New evidence published in the Cochrane Library today finds MMR, MMRV, and MMR+V vaccines are effective and that they are not associated with increased risk of autism. Measles, mumps, rubella, and varicella (also known as chickenpox) are infectious diseases cau

Therapeutic animal stress

Interacting with animals is known to be therapeutic,  particularly in reducing stress.  But do we consider sufficiently the effects this may have on the animals involved?   We might assume that because it is calming for us, then it must be so for the therapeutic animals, but is this so?  New research suggests that it isn't always without stress for the animals involved.  Positive human-animal interaction relates to changes in physiological variables both in humans and other animals, including a reduction of subjective psychological stress (fear, anxiety) and an increase of oxytocin levels in the brain.  It also reduces the 'stress' hormone, cortisol. Indeed, these biological responses have measurable clinical benefits.  Oxytocin has long been implicated in maternal bonding, sexual behaviour and social affiliation behaviours and in promoting a sense of well-being .  So far, so good.  We humans often turn to animals for stress relief, companionship, and even therapy.  We kno