DDT: angel or devil?
What can we learn from previous cases where a technology has faced widespread public criticism?
DDT was at first thought to be a saviour but was recast as a villain, and some say it now needs to be rehabilitated. Just like many other scientific advances, DDT has had wavering support. There are clear links between the case of DDT and nanotechnology.
Insect pests eat crops and spread disease, and chemicals to kill them are potential lifesavers, as well as an aid to farmers. DDT (dichlorodiphenyltrichloroethane) was first made in 1874 by the German chemist Othmar Zeidler. Later, in the 1930s, Paul Müller and colleagues discovered its powerful insect-killing properties – for which they won a Nobel Prize.
DDT came into wide use in World War II to help prevent troops catching malaria, typhus and yellow fever. After the war, it was used widely in agriculture and to prevent insect-borne diseases. DDT may have saved more lives than any other single chemical.
Then the picture changed. DDT’s long life meant it accumulated in the environment, and creatures high up a food chain could end up heavily loaded with DDT. It increased the chances of cancer in people. It also affected wildlife, as documented memorably in environmentalist Rachel Carson’s classic Silent Spring in 1962. By the early 1970s, there were bans on the use of DDT and similar compounds in many countries.
However, although there are alternatives for farmers in the USA and Europe who want to protect their crops, DDT is still one of the best and cheapest ways to kill mosquitoes. As yet there is no vaccine against malaria, which is spread by mosquito bites and kills more than a million people every year, mainly in Africa.
Some people argue that a blanket ban on DDT is unjustified when it has the potential to do so much immediate good. The longer-term hazards may be worth the local gains.Lead image:
Tim Lang/Flickr CC BY NC