In contrast to popular images of the tropics as verdant Edens, forest dwellers face various pollutants with little-understood environmental health impacts. Drawing upon long-term ethnographic research in northern Guatemala through the lens of Mary Douglas' work on purity, danger, and culture, this paper describes how the inventive re-use of modern waste exposes rural people to new and unknown toxic substances from “matter out of place.” While environmental justice literature has emphasized industrial, extractive, and military disasters, this note draws attention to the less dramatic yet lethal pollutants encountered in the everyday lives of the rural poor through “chemical trespass.”