6. Leaded petrol: In 1965, a geochemist of US Clair Patterson made a discovery which was a shock for the world.
Patterson tried to draw public attention to the problem of increased lead levels in the environment and the food chain due to lead from industrial sources. Many scientists opposed his findings.
It took until 1970 for Patterson to get the Clean Air Act passed, and a further 17 years to get lead banned from gasoline (petrol).
Some 30 years after his research conclusively proved all this lead was toxic to us, the government finally removed it from food containers and paint—a delay that means the average American now has 625 times more lead in their blood than people in the 19th century.
The elimination of leaded gasoline has led to prevention of premature deaths of more than 1.2 million people annually.
Imagine, how many million people may have died because of leaded gasoline in the last 100 years.