Aflatoxin is a type of toxin caused by a fungus (certain kinds of Aspergillus) that occurs naturally in hot and humid climates. It’s a silent killer as it doesn’t change the taste of food, according to Ayalew, a plant pathologist and the program manager for the Partnership for Aflatoxin Control in Africa (PACA). This tenacious carcinogen also resists cooking, making it hard to eradicate once it enters the food system.

Well over half the world’s population is chronically exposed to aflatoxin, which is one of the most powerful naturally occurring carcinogens known to science. Aflatoxin contributes to up to 28% of all cases of liver cancer. It also leads to childhood stunting and immunosuppression. There’s a direct economic toll as well, with African countries annually losing $670 million worth of exports to the EU because of food that’s higher in aflatoxin levels than allowed.