Shedding light on DDT and the threat it poses to raptor populations

Kailen Padayachee, a doctoral candidate at the FitzPatrick Institute of African Ornithology at the University of Cape Town and a research fellow at the University of the Witwatersrand, Arjun Amar, an associate professor at the institute, and Chevonne Reynolds, a senior lecturer at the University of the Witwatersrand, write about the threat that the pesticide DDT poses to birds of prey around the world.

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It was once regarded as a miracle chemical to protect against disease and improve global food production. The man who discovered its properties even won a Nobel Prize in Physiology or Medicine. But today, dichlorodiphenyltrichloroethane (DDT) is best known for its devastating effects on the environment, as well as animal and human health.

It was first used in the Second World War to protect Allied soldiers against malaria and typhus, which are spread by mosquitoes and body lice respectively. After the war, DDT became a widely available pesticide to kill insect crop pests and insects that caused disease in humans.

However, it became clear that DDT was toxic to more than its intended targets. Continued exposure to the chemical can cause neurological damage, endocrine disorders and reproductive failure in both humans and animals.

Awareness of this damage was in no small part due to Rachel Carson’s book Silent Spring, published in 1962. The book brought global attention to DDT’s environmental impacts and sparked a public outcry that forced much of the developed world (the ‘Global North’) to ban the use of the pesticide in the 1970s and 1980s.

In 2004, the Stockholm Convention on Persistent Organic Pollutants, those that stay in the environment for a long time after use, was adopted by over 150 nations. DDT was among the most dangerous pesticides, industrial chemicals and by-products placed on the convention’s ‘Dirty Dozen’ list, and was banned in most parts of the world.