Reports of mass bird mortality from pesticide use made environmentalist Rachel Carson speak of a 'silent spring' in her groundbreaking 1962 book.
Forty seven years after the publication of the book, uncounted millions of birds around the world continue to die from the effects of pesticides. The industry still resists regulation and governments are slow to deal with the problem.
Dr Pierre Mineau, a leading expert on pesticide ecotoxicology, conducts research for Canada's federal department of the environment at the National Wildlife Research Centre in Ottawa.
Laura Sevier: Would you say that birds are still the canary in the coalmine?
Pierre Mineau: Yes, I think that's a great analogy on several levels. They can be very quick to move in after the fields have been sprayed so they put themselves at risk by being in the wrong place in the wrong time. We judge it's not safe for people to go back until 14 days even though people are a whole lot bigger and they're not eating - and then we're surprised when there are problems when birds fly into these areas. It's common sense.
LS: What impact did reading Silent Spring have on you?
PM: I've read it twice. Having re-read it 8 months ago I was amazed at how many things she got right. Because she was so vilified at the time everyone thought she was making it up... But you know what? She was pretty close to the mark.
LS: Is the threat of a silent spring behind us now?
PM: Well it's really a different threat. We've replaced a lot of the old persistent organochlorine pesticides products with other pesticides. In terms of bringing some species close to the brink - such as the sparrowhawk in Britain from aldrin and dieldrin seed treatments and the pelican and the bald eagle from DDT - the situation isn't as bad. However when you consider the total loss of bird biomass it's probably worse today. What's shifted is that the impact is now on birds lower down the food chain. Although these smaller birds (sparrows and so on) can more easily recover from population losses than a sparrowhawk or eagle.
LS: Is this the case throughout the world?
PM: I would really say it's throughout the world. You really live in a bit of a bubble in the UK. Because you are a nation of bird lovers, very early on there was a political decision in your country to ban pesticides that cause bird mortality. That had a positive impact on the birds. That was unheard of; the only country where that happened.
The whole Wildlife Incident Investigation Scheme (WIIS) here - that's unique also in how thorough it is. Compounds known to cause problems were removed from broad use.
A lot of other countries are still struggling with those compounds - whether N. America or parts of southern Europe. Europe is probably cleaning up its compounds faster as a result of the EU. Most of developing countries are still making massive use of these bird-toxic products. The pesticides are off-patent and there are now a number of manufacturers including offshore, cheap Chinese knock-offs. In fact, the use of such compounds appears to be increasing in developing countries of Latin America, Africa, Asia.
LS: What's the most shocking thing you've ever seen or heard of in relation to pesticides?
PM: What I find really shocking is when a company does studies that show significant impacts and then continue to market the pesticide around the world. Take granular carbofuran. The first time they did the tests for the EPA they found 799 dead birds of a single species (a lark) in a few fields. Other species were affected also but not in such numbers.
Nevertheless, it took about 15 years for that product to be removed from North America - it continues to be used worldwide. When your profit from selling a pesticide is high enough, it pays to oppose and delay any regulatory change. Every year you delay you're making millions. My calculation is that every year this product was killing between 17-91 million birds in US maize fields alone.
LS: How do pesticides affect birds - is it through eating contaminated things or through the spray?
PM: In the case of granule formulations or seed treatments, it is clearly ingestion. When it comes to sprays, exposure takes place through several routes, chief of which appears to be dermal contact from the feet and body. This is not yet acknowledged by regulators who still assume all exposure is dietary. ...
There are studies where you manipulate conditions. An American study carried out almost two decades ago paved the way. It was very inventive. Birds were exposed to pesticide sprays in a controlled environment under varying conditions, e.g. some of them wearing little raincoats etc... and various routes isolated. We've done some work along those lines and arrive at the same conclusions.
LS: What do you propose should be done? Is it a question of more regulation?
PM: Yes, I think the ball is clearly in the court of the governments. The evidence is there, the replacement chemicals exist. I think it's a matter of saying: those chemicals - chiefly the organophosphorous and carbamate insecticides - were brought in at the same time as DDT. These 1940s, 50s, 60s, 70s products don't belong in this millennium. They really don't.
The problem with that message is that it seems like you have to start all over again in every country because with migratory birds every government has got to follow suit. Then of course the industry will demand that studies be repeated and evidence be amassed in every country. It's going to take a long time.
There are a few bright lights out there. In the US there was an act (the Food Quality Protection Act) which put the emphasis on children's exposure. It said for the first time that the compounds which have a similar toxic mode of action should be considered as a group. This led to the removal of many pesticides and pesticide uses and, as a result, the situation has been getting better for birds in the last 10 years or so - but this was in order to reduce the risk to children.
LS: What about GM crops? How do they affect birds?
PM: For birds, large amounts of insecticide sprays were replaced by BT cotton and BT corn. In the Americas cotton receives 12-15 sprays of extremely toxic insecticides. In terms of acute direct impact on birds the impact of GM crops with built-in insecticide has been positive.
LS: Do you think the ultimate answer is organic?
PM: This is not necessarily always the case. For example, a lot of tillage is not good for birds either. Chemical tillage has been shown to be actually less disruptive to upland-nesting waterfowl.
LS: Can there be such a thing as a bird friendly, chemical-based pesticide though?
Just because they're chemical-based that does not mean they're necessarily bad for birds. You have to consider the product's toxicity and direct and indirect impact on birds on a case by case basis.
LS: So there are alternatives that have lower levels of toxicity?
PM: Yes. It's quite rare now that we have an agronomic need to use the more toxic products.
LS: What are the obstacles preventing these less toxic pesticides being used more widely?
PM: It's economics. First of all, pesticides broadly effective against a wide array of pests are economically desirable - even if ecologically more damaging. Also, the price that they sell pesticides at has very little to do with manufacturing costs - it is what the market will bear.
For example new pesticides tend to be more complex and expensive to make. The older style pesticides (like organophosphorus), are more simple and cheaper to make. The research costs have all been paid off so the profit margin is much higher. Hence industry's desire to keep these products around for as long as possible.
The one thing that changes this is when governments start applying pressure saying: 'We don't like this - you have to do more studies to demonstrate safety'. When the studies start to mount then the economics are turned around.
But let's just start with the obvious. Let's get rid of those compounds that are killing birds. The indirect impacts are harder to decipher.
LS: Is your work often attacked or dismissed by the chemical industry. in the same way that Rachel Carson's was?
PM: Oh yes. Years ago they handed out pamphlets to every wheat and canola farmer in Canada to tell them what an irresponsible scientist I was. That my research was wrong...
LS: But it hasn't stopped you?
PM: Not yet.
Laura Sevier is the Ecologist's Green Living editor
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