Feed on

Matt Ridley corrects the quote I used from his book on this long and interesting post on DDT and Rachel Carson:

By the way, in my book I say that Rachel Carson `expected DDT “to cause practically 100 per cent of the human population to be wiped out from a cancer epidemic in one generation”’. This is inaccurate: I slipped up. I relied on an article in a magazine called Front Page in July 2003 for this quotation, and unusually I did not check it with Carson’s original text. Alerted by a reader, Ed Darrell (thanks!) I have now checked Carson’s Silent Spring, and while Carson strongly implies that she does indeed expect a major mortality from cancer caused by DDT, what she actually wrote is the following:

In the springof 1961 an epidemic of liver cancer appeared among rainbow trout in many federal, state, and private hatcheries. Trout in both eastern and western parts of the United States were affected; in some areas practically 100 per cent of the trout over three years of age developed cancer. …The story of the trout is important for many reasons, but chiefly as an example of what can happen when a potent carcinogen is introduced into the environment of any species. Dr. Hueper has described this epidemic as a serious warning that greatly increased attention must be given to controlling the number and variety of environmental carcinogens. ‘If such preventive measures are not taken,’ says Dr. Hueper, ‘the stage will be set at a progressive rate for the future occurrence of a similar disaster to the human population.’

My book criticises Carson and her followers for their exaggerated pessimism which led to the phasing out of DDT as an anti-mosquito weapon and hence led directly to the resurgence of malaria. This is a story that has been well told in many places and deserves to be better known. But I find many of DDT’s defenders then go on to make a claim that I do not believe is correct, namely that DDT had no impact on birds, and that the story that it led to the thinning of eggshells in birds at the end of long food chains, such as falcons and pelicans (and also damaged the reproduction of predatory mammals such as otters), is false. I simply do not accept that. The evidence of bioaccumulation in fat, of eggshell thinning and of DDT’s role in the decline of raptors and other predatory birds in the 1960s seems to me fairly strong, though not overhwelming. The ending of indiscriminate and widespread spraying of DDT is probably a good thing.

It is, fortunately, very easy to use DDT against malarial mosquitoes without poisoning birds. The solution is to use it sparingly on the inside walls of houses, where anopheline mosquitoes rest during the day. This targets the pest while not allowing the pesticide to contaminate the food chain in nearby ecosystems. The best of both worlds.

Of course, this changes nothing about the point I was making, which was that the risks to humans from pesticides has regularly been extremely exaggerated, and has not led to any epidemic in cancers caused by chemical pollution – and I relayed what Ridley relayed above in his post. I was saying nothing about the impact of DDT on wildlife. And just to get this from out of the comments and onto the site, Carson dedicates her book this way:

Man has lost the capacity to foresee and forestall. He will end by destroying the Earth.

You can check that here.

One Response to “Carson, Silent Spring and Doom”

  1. Michael says:

    It’s nice to read an open discussion of DDT. In my opinion, the enviros tend to do their movement more harm than good with the “science is settled” mantra. There were (and are) a lot of questions concerning DDT, CFCs, and now CO2. At least with CO2, there is a recognition of some sort of balance needed, although most still don’t see the tradeoffs.

Leave a Reply