The most potent of these is DDT. The US National Academy of Sciences estimated DDT had saved 500 million lives from malaria by 1970. In India, effective spraying had virtually eliminated the disease by the 1960s, so much so that the mosquito nets which were ubiquitous in my childhood had disappeared from urban houses by the time I was at university in the late 1950s. The indoor residual spraying of DDT decreased the cases of malaria from 100 million a year in 1953 to 150,000 by 1966; deaths due to malaria, which were nearly a million a year in the 1940s, decreased to about 1,500 a year in 1966.

Then in the 1970s, largely as a result of an environmental scare promoted by Rachel Carson’s book Silent Spring, US President Richard Nixon’s Environmental Protection Agency under William Ruckelshaus banned DDT — against all the expert advice he had been given. Foreign aid agencies and various UN organisations began to take a jaundiced view of DDT, and the use of DDT declined. Not surprisingly, the mosquitoes hit back and endemic malaria returned to India. By 1997, UNDP’s Human Development Report 2000 estimated there were about 2.6 million malaria cases.

So why did DDT fall out of favour despite its demonstrated merits? Rachel Carson in 1962 started the DDT hysteria with her claim that its use had devastating effects on bird life, particularly those higher up the food chain. It was also claimed that DDT causes hepatitis and cancer in humans. Numerous scientific studies showed these fears to be baseless. It was shown to be safe to humans — causing death only if eaten in the size of pancakes! In 1971, in defense of its use, the distinguished biologist Philip Handler, then president of the National Academy of Sciences said: “DDT is the greatest chemical that has ever been discovered”. Commission after commission, expert after Nobel Prize‐​winning expert has given DDT a clean bill of health. (See E M Whelan, Toxic Terror, 1993, and for India, K N Mehrotra, ‘Use of DDT and its Environmental Effects in India’, Proceedings of the Indian National Science Academy, 1985, and for a recent survey: “Use of DDT in fighting malaria”, www​.appope​dia​.org.).

But this evidence had no effect on environmentalists, whose misanthropic views were summarized by Alexander King, co‐​founder of the Club of Rome, who in 1990 said, “My chief quarrel with DDT in hindsight is that it has greatly added to the population problem”. Paul Ehrlich said this about India: “I came to understand the population explosion emotionally one stinking hot night in Delhi… The streets seemed alive with people. People eating, people washing, people sleeping, people visiting, arguing and screaming. People thrusting their hands through the taxi window, begging. People defecating and urinating. People clinging to buses. People herding animals. People, people, people.” Whilst another has argued: “It may be unkind to keep people dying from malaria so that they could die more slowly of starvation”. Whilst yet another has said: “Some day anti‐​malarial vaccines will probably be developed, which may even wipe out the various forms of the disease entirely, but then another difficulty will arise: important wild areas that have been protected by the dangers of malaria will be exposed to unwise development.” (Cited in R Tren and R Bate, When Politics Kills: The political economy of malaria control, 2001).