WASHINGTON, D.C. ? Expanded indoor use of the pesticide DDT won’t harm people or the environment and is critical in the fight against malaria, the World Health Organization said Friday.

Officials said they hoped their endorsement of the controversial insecticide would influence countries in southern and eastern Africa to allow its application in moderation. They also anticipated that environmental groups would be alarmed by the announcement.

DDT is history’s most notorious insecticide. It was banned in the U.S. in 1972 after decades of widespread agricultural spraying led to environmental damage around the globe.

But health officials said Friday that there is a distinct difference when it comes to using DDT for agricultural purposes and using it to coat once or twice a year the inside walls of mud huts or other dwellings.

A small number of malaria-plagued countries already use DDT, backed by a 2001 United Nations treaty that set out strict rules to prevent environmental contamination.