Context: DDT, sprayed on the walls of houses, is an organochlorine that has been used to fight malaria since the 1950s. Recent policy statements by the World Health Organization have given stronger support to this approach. However, DDT and other organochlorine pesticides have been banned in most countries worldwide because of their persistence in the environment and human toxicity. DDT use is not always effective, as resistance to DDT was identified in Africa as early as 1955, and by 1972 nineteen species of mosquito worldwide were resistant to DDT.

Question: What kind of pesticide is DDT?
Answer: an organochlorine

Question: Why have DDTs been banned in some areas?
Answer: persistence in the environment and human toxicity

Question: Is DDT 100% guaranteed to work?
Answer: DDT use is not always effective

Question: How may species have been found to be resistant to DDT?
Answer: nineteen

Question: When were 19 new species of mosquito discovered in Africa?
Answer: Unanswerable

Question: How long has DDT been banned worldwide?
Answer: Unanswerable

Question: How supportive is Africa about DDT being banned?
Answer: Unanswerable

Question: In what year was DDT first invented?
Answer: Unanswerable

Question: When were mosquitoes first discovered to carry Malaria?
Answer: Unanswerable