I've handed the reins of my blog over to Mark Avery for most of June. Mark's sharing the successes and challenges of saving nature around the world in the run up to the Rio+20 Earth Summit.
This year marks the 50th anniversary of the publication of Rachel Carson’s Silent Spring which raised awareness over the use of pesticides and was one of the factors that led to the banning of products such as DDT many years later.
In the Northamptonshire arable fields near my home I still see farmers spraying the crops of wheat and oil seed rape. Should I be at all worried about this sight?
Each crop will receive many different sprays from growth regulators (to make the crop put most of its effort into seed rather than stalk), fertilisers and a variety of ‘-cides’. There are herbicides, fungicides, molluscicides, nematicides and insecticides where in each case the ‘-cide’ comes from the same Latin word as suicide, genocide and homicide – these are all about killing.
Dichlorodiphenyltrichloroethane, or DDT to its friends (and enemies), was a potent insecticide which helped, and because it is still used in some countries, helps, control diseases by killing their insect vectors. And it went through the testing regimes of the day and was regarded as safe to use.
Only after years of widespread use did we learn that DDT causes birds of prey to lay eggs with thin shells which break in the nest and this leads to population declines. Declines of the USA’s national bird, the bald eagle, helped draw attention to the harmful environmental impacts of this persistent agricultural chemical.
A general message from the DDT story is that testing chemicals for environmental safety is difficult. With the best will in the world, it would be difficult to predict eggshell-thinning and test for it before commercial release of a product.
I’m struck by two examples of chemicals that have, for me, surprising impacts. Neither is an agricultural pesticide; each is a medicine that you may be taking today. Aspirin is a great boon to our lives – but it can be lethal for cats. And if you take diclophenac instead of aspirin to easy your aches and pains then think of its lethal impacts on Asia’s vultures. Veterinary use of diclophenac for cattle has led to carcase-eating vultures being brought from populations of tens of millions to the brink of extinction because diclophenac kills vultures.
I bring DDT, cats and vultures to mind whenever I hear that a chemical has been rigorously tested and is completely safe. Complete safety is difficult to promise. Currently, concern is focussed on a set of insecticides in widespread use – the neonicotinoids (or neonics) (see recent media coverage: here, here, here).
The thinking behind neonics is good – instead of spraying them into the farmed environment the idea is to get them incorporated into the crop so that only pests eating the crop are harmed but it now seems that pollinators such as bees pick up the chemicals through pollen, and the doses they receive may kill them but may also intoxicate them.
If you tested alcohol on people in the laboratory you would find that it rarely killed people – even at high single doses, but you might notice some pretty strong behavioural changes – loss of inhibition, vows of eternal love, a propensity to anger and perhaps vomiting. We put very strong restrictions on the use of alcohol in our lives even though its impacts as a lethal poison are few.
The widespread use of agricultural chemicals is part of our lives and that of our farmers these days. Their use has helped increase food production but we must remain vigilant over unintended environmental harm.
Reducing the pesticides you use in the garden is just one small step you can take for the environment. Find out what else you can do in your garden here.
Dr Mark Avery is a former Conservation Director of the RSPB and now is a writer on environmental matters. We’ve asked Mark to write these 20 essays on the run up to the Rio+20 conference. His views are not necessarily those of the RSPB. Mark writes a daily blog about UK nature conservation issues.
hi, I was quite surprised on my recent holiday to France, camping from Calais to Cahors, to commonly hear Cuckoo. Really I noticed the difference on six camp sites farmland/woodland edge, sand dune/reedbed, river/Loire near Vichy, mountains at the source of the Dordogne and on oak/limestones causses a Quercy. I am now semi plus convinced that this Cuckoo decline is due to the decline of its food source in our English countryside. It is simply too intensive for most wildlife to survive; it as you say drenched in chemicals.
Peter Plover
It is not an easy problem to solve. The wider use of chemicals and the increasing strains on our environment in other directions are really symptomatic of a bigger issue and that is of the ever increasing human population. The world urgently needs to put in place some form of birth control programme, then, over the coming centuries these types of environmental dangers and risks can be slowly reduced, otherwise if this is not done they will only get worse.
Having said this, we also need to address the immediate issues. Clearly, experience shows that no pesticide is entirely safe to both humans and to all other non target species and to the environment as a whole. So that despite the testing of a substances prior to their use all regulations granting use of chemicals must also say that a chemical must, and will be, with drawn from use immediately there is any indication of significant damage to non target species and the environment.
redkite