BOGOTÁ, Colombia — As class begins at Sanitas University, a cohort of young men gathers the supplies they'll need for the lesson: a plastic doll, rash ointment and diapers. Felipe Contreras, 30, their ...

After his daughter was born, Alon Cohen couldn’t stop thinking about the number of diapers the family was sending to landfill. In the past, he and his wife had taken out the trash once a week; now it ...